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The most unsolvable secret of the universe

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Nothing more than these

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One is the smallest in the world

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How did matter appear?

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How is it composed?

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The other is the largest in the world

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How do black holes evolve?

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What the past and future of the universe will look like

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In Quantum Bear Season 1 and 2

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we spent a lot of time

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introduced the smallest

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That is, what exactly is quantum mechanics?

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How to rewrite our understanding of the world

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and how we apply

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Such as quantum computers and quantum communications

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interesting thing

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When we turn our heads and look at the most mysterious black hole in the universe,

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to understand it

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Quantum mechanics is also needed to answer the question

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Now let us start from the tiniest quantum world

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Fly to the vastest universe

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Relativity and Quantum Mechanics

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Collision in a black hole

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Will reveal the end of the universe

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To understand the entire universe

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Let me ask a simple question first

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Hydrogen combines with oxygen to become water

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reactants before and after chemical formula

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Which one is more important than the product?

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you might think

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There is teaching in this country

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Do chemical reactions obey the conservation of mass?

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Of course it weighs the same

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No No No No No

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strictly speaking

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In the reaction equation for hydrogen and oxygen to produce water

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The products will be lighter than the reactants

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why

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Because this is Einstein’s theory

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The special theory of relativity is guaranteed

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I thought quantum technology

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Is it far from us?

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Quantum mechanics has developed

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Semiconductors affecting daily life

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Internet technology and communication tools

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GPS, nuclear energy, solar energy, maglev train

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Laser surgery, medical imaging...etc.

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And the much-anticipated quantum computer

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The world is preparing for the future of quantum information science

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How do you plan to join?

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Hurry up and join the QuBear micro-learning platform

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Let’s come to Quantum PAY together

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Imagine you are sitting on an airplane

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Nothing to do

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Sleep quietly or read a book

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For you and other passengers on the plane

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You stayed where you were.

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But on the ground

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For those who watch planes flying across the sky

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You actually moved with the plane.

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in motion

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In other words

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Displacement, rest and motion are relative concepts

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It depends on who you compare yourself with

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Not only that

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If the plane is traveling very smoothly

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Without the roar of the engine

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Small vibrations in the body

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Or the change of scenery outside the window

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You may not be able to tell when the plane is stationary

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Still in motion

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As early as the seventeenth century, the great scientist Galileo Galilei

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The above concept was proposed

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Let’s talk a little deeper

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Usually when we talk about the speed of an airplane

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In fact, a stationary reference frame has been preset

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that's the ground

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Although the plane is facing people on the ground

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Maybe 900 kilometers per hour.

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But when we switch the reference frame

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From the perspective of a passenger on the plane

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Relatively speaking, the plane is almost stationary

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When we measure the moving speed of any object

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With different reference systems

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measured value

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Naturally, there may be differences

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so far

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Things are intuitive and easy to understand

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right

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However, by the end of the nineteenth century

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A certain experiment brought new developments to things

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That was 1887

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By physicist Albert Michelson

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Experiments on the speed of light with Edward Morley

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Just like water waves need to be transmitted by water

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Sound waves travel through the air

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People at the time thought

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Light, that is, electromagnetic waves

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It is transmitted through a substance called "ether"

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Aether has no mass

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fill the entire universe

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When the sun moves the earth with it in the universe

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You will feel the wind formed by the flow of ether

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This is just like when we run

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You will feel like the wind generated by the air flowing around you

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So if we measure the speed of light traveling in the ether

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With changes in measurement direction

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Along the ether wind or against the wind, etc.

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will affect the value of the speed of light

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It's like we're on the bank of a river

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Watch fish swim upstream or downstream

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You will find that the swimming speed of the fish is different

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However, no matter how Maxson and Mo Li changed directions, they

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No light can be found flowing with the ether

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The resulting speed change

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This matter is so unresolved

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Until "that scientist" appears

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Yes, that's the one

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In 1905 Einstein published four

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Super super super heavyweight paper

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One of the articles later won him the Nobel Prize in Physics

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Photoelectric Effect Paper

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Interested viewers can watch our previous videos

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The second paper is Brownian motion

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Explaining pollen in water using molecular collisions

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Why do the burst particles move irregularly?

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Indirectly confirmed the existence of "molecules"

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The other two articles are the topics we are discussing now

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special relativity

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Einstein based on previous research by other scientists

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Plus your own unique insights

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Put forward two basic assumptions in the paper

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"Constant speed of light" and "Principle of relativity"

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Just start from these two assumptions

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can deduce the special theory of relativity

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Many incredible conclusions

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Make people call you "Li Xi Li Gong"

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First of all, the constant speed of light refers to

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to all observers

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No matter what frame of reference they are in

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The speed of light is the same

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So no matter how you measure

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It is absolutely impossible to detect light flowing with the ether

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The resulting speed change

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The principle of relativity says

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in all inertial reference frames

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That is, no matter you move at a constant speed at any speed,

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including stillness

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The laws of physics will remain the same

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This means you are in a high-speed train carriage traveling at a constant speed

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Throw a ball up

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Will throw a ball while you are at rest on the ground

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got the same result

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That is, the ball is thrown upward and then falls down again.

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back to you

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If Einstein was in special relativity

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The assumptions made are correct

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Then it was originally imagined

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Ether as the propagation medium of light

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There is no need to exist

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Confusion caused by the Michelson-Morley experiment

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That's solved

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Modern scientists no longer believe that ether exists

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So if you see it on the market

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Products claiming to have etheric energy

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Basically, they are in conflict with the current views of the scientific community.

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You may feel strange hearing this

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This is wrong

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Suppose we are on a moving train

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Shoot a bullet forward

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Then people on the ground measure the speed of this bullet

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You should find it

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measured value

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It will be the original speed of the bullet

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Plus the speed of the train

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So when we're on a moving train

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Shoots a beam of light forward

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Then people on the ground will measure this light

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Wouldn’t you find that the speed of light is faster than the speed of a train?

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How is it possible that as Einstein said

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Is the speed of light constant?

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This is because

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speed

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or speed

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is caused by an object within a certain period of time

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Determined by how much space distance has been moved

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So if time and space

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Can be coordinated in a unique way

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to ensure that the speed of light remains constant

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In other words time and space

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May vary depending on reference system

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and change

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Einstein’s views on space and time mentioned above

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For the academic circles at that time

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It's a big breakthrough

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In the past, people followed Newton's views

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believe that time and space are absolute

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does not change depending on the reference frame

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No matter what frame of reference we are in

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The flow of time

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distance from space

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It's the same for everyone

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But in special relativity

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It's not like this anymore

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Next comes the highlight

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Under the special theory of relativity

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as you move faster

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Others will notice that time passes more slowly for you

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called time dilation

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Moving objects on the other hand

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The length along the direction of movement will shorten

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called length contraction

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Let's open our minds to the limit

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Let’s do a thought experiment

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our galactic neighbor

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Andromeda Galaxy

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Located two and a half million light years away

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If only we could do it with 99.99999999%

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traveling at the speed of light

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It will only take a few decades to arrive

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But for people on earth

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But it will be 2.5 million years later

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This is because

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When we travel through space at extremely close to the speed of light

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Compared to the people who stayed on Earth

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Our time passes much more slowly

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So even though the earth has been 2.5 million years

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But we in the spaceship are only a few dozen years older

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But

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Wouldn't this make us exceed the speed of light?

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After all, it took decades

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It’s a distance of 2.5 million light years.

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The answer is

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and no

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Because for us

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It will feel like the entire universe is moving at a high speed compared to us

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And because of the length shrinkage effect

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So the distance from Earth to the Andromeda Galaxy

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shortened to only a few dozen light years

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And observers on Earth

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We will also see that it took us 2.5 million years

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Just arrived at the Andromeda Galaxy

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In this way

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Whether it is people on earth

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Or are we in the spaceship?

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Although both sides have different experiences

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But in the end the same result will be observed

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That is, we successfully reach our goal

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no contradiction

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In addition to the time dilation mentioned earlier

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and length shrinkage

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Special theory of relativity also gives other magical conclusions

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Like "simultaneity relativity"

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In simple terms

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Whether two events at different locations in space occur simultaneously

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in different reference systems

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There may be different answers

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in some reference frame

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Two things may happen at the same time

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But in other reference systems

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Two things may not happen at the same time

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For example, turn on a light on both sides of the carriage at the same time

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People in the middle of the carriage will find that the light reaches them at the same time

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But for standing outside the carriage

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For an observer with a certain relative speed to the car

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You will find that the two lights are not turned on at the same time

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This is the relativity of simultaneity

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In addition, Einstein’s famous

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mass-energy equivalence formula

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E = mc²

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Also from special relativity

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This formula tells us

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the mass of the object itself

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It's an energy

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On the other hand, energy can also be regarded as a kind of quality

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And this formula

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It also directly led to the subsequent atomic bomb

278
00:09:23,271 --> 00:09:25,189
and the invention of technologies such as nuclear power generation

279
00:09:25,189 --> 00:09:25,982
Not only that

280
00:09:25,982 --> 00:09:27,316
According to the special theory of relativity

281
00:09:27,316 --> 00:09:30,111
To accelerate an object with mass to the speed of light

282
00:09:30,111 --> 00:09:32,113
will require infinite energy

283
00:09:32,113 --> 00:09:33,823
Even if it's just an electron

284
00:09:33,823 --> 00:09:36,492
Conversely, particles that can travel at the speed of light

285
00:09:36,492 --> 00:09:37,451
such as photon

286
00:09:37,451 --> 00:09:39,704
Their rest mass must be zero

287
00:09:39,787 --> 00:09:40,580
In other words

288
00:09:40,580 --> 00:09:44,458
The speed of light is the upper limit of the speed at which any information or matter can travel.

289
00:09:44,458 --> 00:09:47,044
So if we see any tachyon energy water in the future,

290
00:09:47,044 --> 00:09:48,963
or tachyon-related products

291
00:09:48,963 --> 00:09:50,172
Never place an order

292
00:09:50,172 --> 00:09:52,425
Einstein does not provide customer complaints or returns.

293
00:09:52,633 --> 00:09:54,844
Finally, back to our initial question

294
00:09:54,844 --> 00:09:58,681
Why do hydrogen and oxygen react chemically to form water?

295
00:09:58,681 --> 00:10:00,016
Will the weight become lighter?

296
00:10:00,016 --> 00:10:02,768
Because this chemical formula is an exothermic reaction

297
00:10:02,768 --> 00:10:05,479
Some energy will be released during the process

298
00:10:05,479 --> 00:10:07,481
According to the mass-energy equivalence formula

299
00:10:07,481 --> 00:10:10,109
Since part of the energy escapes after the reaction,

300
00:10:10,109 --> 00:10:12,320
Then the remaining product is water

301
00:10:12,320 --> 00:10:13,654
The quality will be less

302
00:10:13,654 --> 00:10:15,489
Naturally, it will be lighter

303
00:10:15,489 --> 00:10:18,326
It’s just that the weight difference will be very small

304
00:10:18,326 --> 00:10:19,827
It's basically impossible to measure

305
00:10:19,827 --> 00:10:21,829
But the gap does exist

306
00:10:21,829 --> 00:10:22,622
in this episode

307
00:10:22,622 --> 00:10:24,749
We introduced Einstein's special theory of relativity

308
00:10:24,749 --> 00:10:26,542
and the important conclusions it brings

309
00:10:26,542 --> 00:10:27,793
But because of time

310
00:10:27,793 --> 00:10:30,713
Failed to explain in detail how those conclusions were reached.

311
00:10:30,713 --> 00:10:31,922
If interested to know

312
00:10:31,922 --> 00:10:33,299
Welcome to leave a message to tell us

313
00:10:33,299 --> 00:10:35,384
We will make another video later to explain

314
00:10:35,384 --> 00:10:37,094
But apart from special relativity

315
00:10:37,094 --> 00:10:40,097
Einstein also proposed the famous general theory of relativity

316
00:10:40,097 --> 00:10:41,182
And these two theories

317
00:10:41,182 --> 00:10:42,892
For modern physics research

318
00:10:42,892 --> 00:10:44,477
Like an invitation to a party

319
00:10:44,477 --> 00:10:46,979
Gives us a glimpse into how the universe evolves

320
00:10:46,979 --> 00:10:48,856
Or why black holes exist

321
00:10:48,856 --> 00:10:49,440
what

322
00:10:49,440 --> 00:10:50,608
I really don’t know if I don’t tell you.

323
00:10:50,608 --> 00:10:52,026
It turns out that as early as 1971

324
00:10:52,026 --> 00:10:53,194
Someone invented one

325
00:10:53,194 --> 00:10:55,780
A device that claims to be able to artificially generate a gravity field

326
00:10:55,780 --> 00:10:57,615
"Dynamic Mass Field Generator"
(kinemassic field generator)

327
00:10:57,615 --> 00:10:59,408
Also successfully applied for a U.S. patent

328
00:10:59,408 --> 00:11:01,702
No. 3626605

329
00:11:01,702 --> 00:11:03,454
In this case, why do we need rockets?

330
00:11:03,454 --> 00:11:06,415
Why not just let the starships lift off using artificial gravity fields?

331
00:11:06,415 --> 00:11:07,083
Well...

332
00:11:07,083 --> 00:11:09,168
We all know that according to the current technological power of mankind,

333
00:11:09,168 --> 00:11:11,379
Obviously it is not possible to create artificial gravity yet

334
00:11:11,379 --> 00:11:12,004
Just

335
00:11:12,004 --> 00:11:13,756
There is such a thing as artificial gravity

336
00:11:13,756 --> 00:11:15,424
Is it really impossible to come true?

337
00:11:15,424 --> 00:11:16,759
to discuss this topic

338
00:11:16,759 --> 00:11:18,302
We must first understand

339
00:11:18,302 --> 00:11:19,970
What is gravity?

340
00:11:23,724 --> 00:11:25,101
what is gravity

341
00:11:25,101 --> 00:11:25,935
in science fiction

342
00:11:25,935 --> 00:11:27,144
Or in animation or video games

343
00:11:27,144 --> 00:11:30,106
Manipulating or defying gravity is a common theme

344
00:11:30,106 --> 00:11:31,524
in fairy tales

345
00:11:31,524 --> 00:11:33,859
Humanity has already dreamed of soaring into the clouds and riding the mist

346
00:11:33,859 --> 00:11:36,320
Or be able to build wings and fly into the sky

347
00:11:36,320 --> 00:11:38,114
Modern airplanes and rockets

348
00:11:38,114 --> 00:11:39,949
It certainly satisfies mankind’s dream of flying.

349
00:11:39,949 --> 00:11:41,450
But planes and rockets

350
00:11:41,450 --> 00:11:43,160
All by generating new thrust

351
00:11:43,160 --> 00:11:44,620
to offset the constraints of gravity

352
00:11:44,620 --> 00:11:47,248
Therefore, it fundamentally blocks gravity

353
00:11:47,248 --> 00:11:49,875
Even attempts to create anti-gravity

354
00:11:49,875 --> 00:11:52,461
Historically, it can only be said to be in the ascendant

355
00:11:52,461 --> 00:11:54,714
Science fiction writer Herbert George Wells

356
00:11:54,714 --> 00:11:56,257
Published in 1901

357
00:11:56,257 --> 00:11:58,092
The First Men in the Moon

358
00:11:58,092 --> 00:12:00,177
It describes antigravity matter

359
00:12:00,177 --> 00:12:03,305
This substance surrounds the sphere that the protagonist rides on

360
00:12:03,305 --> 00:12:06,392
It will enable the protagonist to break away from the constraints of gravity and reach the moon.

361
00:12:06,392 --> 00:12:09,478
Regardless of whether these dreams may come true

362
00:12:09,478 --> 00:12:11,355
What exactly is gravity?

363
00:12:11,355 --> 00:12:12,982
How did it come about?

364
00:12:12,982 --> 00:12:13,858
in middle school

365
00:12:13,858 --> 00:12:16,569
We all learned Newton's law of universal gravitation

366
00:12:16,569 --> 00:12:19,363
There is an attraction between two objects

367
00:12:19,363 --> 00:12:22,825
The magnitude of the attraction is proportional to the product of their masses

368
00:12:22,825 --> 00:12:25,995
Inversely proportional to the square of the distance between the two centers of mass

369
00:12:25,995 --> 00:12:27,997
G is the constant of proportionality

370
00:12:27,997 --> 00:12:30,166
Commonly known as the universal gravitational constant

371
00:12:30,166 --> 00:12:32,334
But we've all heard it

372
00:12:32,334 --> 00:12:33,711
Gravity produced by black holes

373
00:12:33,711 --> 00:12:35,504
Even light can be captured

374
00:12:35,504 --> 00:12:38,466
It’s just that light has no rest mass at all

375
00:12:38,466 --> 00:12:39,925
According to Newton's formula

376
00:12:39,925 --> 00:12:42,845
How can light be attracted by gravity?

377
00:12:42,845 --> 00:12:43,721
At this time

378
00:12:43,721 --> 00:12:46,098
That man appears again

379
00:12:46,098 --> 00:12:47,767
Yes, that's Einstein

380
00:12:47,767 --> 00:12:50,352
After the birth of general relativity in 1915

381
00:12:50,352 --> 00:12:53,856
A completely new perspective on gravity

382
00:12:53,856 --> 00:12:54,982
Einstein thought

383
00:12:54,982 --> 00:12:57,151
Objects with mass and energy

384
00:12:57,151 --> 00:12:58,736
will have an impact on time and space

385
00:12:58,736 --> 00:13:00,446
causing space-time distortion

386
00:13:00,446 --> 00:13:02,239
Like a shot put on a trampoline

387
00:13:02,239 --> 00:13:03,991
Make the bed surface sink

388
00:13:03,991 --> 00:13:05,451
And another object nearby

389
00:13:05,451 --> 00:13:07,828
It will be because I feel the depression of time and space

390
00:13:07,828 --> 00:13:08,996
and be attracted to it

391
00:13:08,996 --> 00:13:11,916
Under the interpretation of gravity by general relativity

392
00:13:11,916 --> 00:13:13,626
light travels in space and time

393
00:13:13,626 --> 00:13:15,586
like a car walking on the ground

394
00:13:15,586 --> 00:13:18,714
It will inevitably be affected by potholes or slopes in the road

395
00:13:18,714 --> 00:13:20,549
resulting in path changes

396
00:13:20,549 --> 00:13:23,719
The degree of change depends on the strength of the gravitational field

397
00:13:23,719 --> 00:13:27,348
So when light passes near a massive star

398
00:13:27,348 --> 00:13:29,308
It will be like looking through a lens

399
00:13:29,308 --> 00:13:31,435
Significant path bending occurs

400
00:13:31,435 --> 00:13:33,187
gravitational lensing effect

401
00:13:33,187 --> 00:13:36,232
And when the gravitational field of the star is strong to a certain extent,

402
00:13:36,232 --> 00:13:39,401
When the surrounding space-time structure is distorted to an extreme

403
00:13:39,401 --> 00:13:41,320
Light can no longer be separated

404
00:13:41,320 --> 00:13:42,571
This is a black hole

405
00:13:42,571 --> 00:13:44,281
In fact, general relativity

406
00:13:44,281 --> 00:13:46,325
Be recognized by the academic circle from the beginning

407
00:13:46,325 --> 00:13:47,159
one of the reasons

408
00:13:47,159 --> 00:13:49,662
It was by the British scientist Sir Eddington

409
00:13:49,662 --> 00:13:50,913
The team he leads

410
00:13:50,913 --> 00:13:53,249
Evidence observed during a total solar eclipse

411
00:13:53,249 --> 00:13:55,918
He discovered the deflection of starlight near the sun

412
00:13:55,918 --> 00:13:57,920
Consistent with the predictions of general relativity

413
00:13:57,920 --> 00:13:59,922
This has caused newspapers around the world to rush to report on

414
00:13:59,922 --> 00:14:02,049
It also made Einstein famous

415
00:14:02,049 --> 00:14:03,467
Although it was later discovered that Eddington

416
00:14:03,467 --> 00:14:05,177
There were some problems with the data at that time

417
00:14:05,177 --> 00:14:07,930
I’ll have a chance to talk about this in detail later.

418
00:14:07,930 --> 00:14:10,266
On the other hand, the precession of Mercury's orbit

419
00:14:10,266 --> 00:14:12,935
That is Mercury’s perihelion point around the Sun.

420
00:14:12,935 --> 00:14:15,271
phenomena that change slowly over time

421
00:14:15,271 --> 00:14:17,273
General relativity can give

422
00:14:17,273 --> 00:14:20,234
A more precise description than Newton's law of gravity

423
00:14:20,234 --> 00:14:22,361
These successes allowed the general theory of relativity to

424
00:14:22,361 --> 00:14:25,197
It became an important basic theory for our understanding of gravity.

425
00:14:25,197 --> 00:14:27,199
Next we will explain further

426
00:14:27,199 --> 00:14:29,952
What important conclusions does general relativity bring?

427
00:14:33,956 --> 00:14:36,500
Let us recall our own experience

428
00:14:36,500 --> 00:14:37,585
when taking the elevator

429
00:14:37,585 --> 00:14:39,753
And when the elevator starts to rise,

430
00:14:39,753 --> 00:14:43,007
There seems to be a force pulling you down.

431
00:14:43,007 --> 00:14:44,758
The body seems to have become heavier

432
00:14:44,758 --> 00:14:47,136
In other words, the acceleration of the elevator rising

433
00:14:47,136 --> 00:14:50,431
It will make us feel like there is an extra downward gravity

434
00:14:50,431 --> 00:14:53,350
Acceleration can produce effects similar to gravity

435
00:14:53,350 --> 00:14:54,184
this matter

436
00:14:54,184 --> 00:14:56,061
In fact, it is exactly what is in the general theory of relativity

437
00:14:56,061 --> 00:14:57,229
equivalence principle

438
00:14:57,229 --> 00:14:58,480
means

439
00:14:58,480 --> 00:14:59,732
in a small range

440
00:14:59,732 --> 00:15:01,609
Observer located in the gravitational field

441
00:15:01,609 --> 00:15:03,444
physical effects felt

442
00:15:03,444 --> 00:15:06,614
When in a gravity-free environment with uniform acceleration of motion

443
00:15:06,614 --> 00:15:08,324
physical effects seen

444
00:15:08,324 --> 00:15:09,450
No difference

445
00:15:09,450 --> 00:15:12,161
Now let us imagine two scenarios

446
00:15:12,161 --> 00:15:14,204
One is on the surface of the earth

447
00:15:14,204 --> 00:15:16,165
The other is in the universe

448
00:15:16,165 --> 00:15:17,917
Acceleration due to gravity on the earth's surface

449
00:15:17,917 --> 00:15:21,003
In a spacecraft accelerating vertically

450
00:15:21,003 --> 00:15:22,838
The equivalence principle tells us

451
00:15:22,838 --> 00:15:24,757
The experimental results of the above two scenarios

452
00:15:24,757 --> 00:15:26,008
They should all be the same

453
00:15:26,008 --> 00:15:27,217
Next step

454
00:15:27,217 --> 00:15:28,761
Observer in two situations

455
00:15:28,761 --> 00:15:31,347
Each emits a light from the horizontal direction

456
00:15:31,347 --> 00:15:32,806
Observe the path of light

457
00:15:32,806 --> 00:15:34,350
Since one of the observers

458
00:15:34,350 --> 00:15:37,436
In a spacecraft accelerating vertically

459
00:15:37,436 --> 00:15:38,562
we can expect

460
00:15:38,562 --> 00:15:40,606
Because the light will take a short time

461
00:15:40,606 --> 00:15:42,191
to reach the other end of the room

462
00:15:42,191 --> 00:15:43,525
And during this time

463
00:15:43,525 --> 00:15:46,403
The spacecraft has accelerated a little further

464
00:15:46,403 --> 00:15:49,281
So he will see the light deflected slightly downward

465
00:15:49,281 --> 00:15:51,200
But the equivalence principle tells us

466
00:15:51,200 --> 00:15:53,535
Do the same experiment on the surface of the earth

467
00:15:53,535 --> 00:15:55,579
should talk to this observer inside the spacecraft

468
00:15:55,579 --> 00:15:57,122
Saw the same phenomenon

469
00:15:57,122 --> 00:15:59,833
So as long as the equivalence principle is correct

470
00:15:59,833 --> 00:16:01,460
Then the light is sure

471
00:16:01,460 --> 00:16:03,879
Will be deflected due to the influence of gravity field

472
00:16:03,879 --> 00:16:05,130
next experiment

473
00:16:05,130 --> 00:16:06,340
same situation

474
00:16:06,340 --> 00:16:09,551
But every situation has two observers

475
00:16:09,551 --> 00:16:11,512
one above the room

476
00:16:11,512 --> 00:16:13,222
Another one below

477
00:16:13,222 --> 00:16:14,390
observer below

478
00:16:14,390 --> 00:16:16,475
Flash the light every second

479
00:16:16,475 --> 00:16:18,060
observer above

480
00:16:18,060 --> 00:16:20,270
Then record the interval time between flashes

481
00:16:20,270 --> 00:16:23,399
Since the spaceship in the universe is accelerating

482
00:16:23,399 --> 00:16:26,235
That means the spacecraft is getting faster and faster

483
00:16:26,235 --> 00:16:28,320
This results in observer A below

484
00:16:28,320 --> 00:16:29,655
flash of light

485
00:16:29,655 --> 00:16:31,824
Each one shines brighter than the previous one

486
00:16:31,824 --> 00:16:35,160
Take a little more time to reach Observer B above

487
00:16:35,160 --> 00:16:37,413
So for A below

488
00:16:37,413 --> 00:16:40,624
Although the interval between each flash is exactly one second

489
00:16:40,624 --> 00:16:43,043
But the flash interval seen by B above

490
00:16:43,043 --> 00:16:46,088
It will be longer than one second shown on the watch on your hand

491
00:16:46,088 --> 00:16:48,132
In other words the same thing

492
00:16:48,132 --> 00:16:49,842
A It feels like a second has passed

493
00:16:49,842 --> 00:16:52,136
B will feel that it has passed longer than one second

494
00:16:52,136 --> 00:16:53,303
through this experiment

495
00:16:53,303 --> 00:16:56,265
We will find that A and B feel the speed of time

496
00:16:56,265 --> 00:16:57,558
is different

497
00:16:57,558 --> 00:16:59,935
B will feel that A’s time passes slower

498
00:16:59,935 --> 00:17:00,978
On the other hand

499
00:17:00,978 --> 00:17:03,605
A will feel that B’s time passes faster

500
00:17:03,605 --> 00:17:05,149
Then according to the principle of equivalence

501
00:17:05,149 --> 00:17:06,984
two observers on earth

502
00:17:06,984 --> 00:17:09,028
I should have seen the same phenomenon.

503
00:17:09,028 --> 00:17:11,030
Observers closer to the Earth's surface

504
00:17:11,030 --> 00:17:13,115
Time will pass slower

505
00:17:13,115 --> 00:17:14,908
observer from above

506
00:17:14,908 --> 00:17:16,827
Time will pass faster

507
00:17:16,827 --> 00:17:18,245
In general relativity

508
00:17:18,245 --> 00:17:19,747
How fast time passes

509
00:17:19,747 --> 00:17:21,790
due to the gravity environment of the location

510
00:17:21,790 --> 00:17:23,500
and produce different changes

511
00:17:23,500 --> 00:17:24,418
that's why

512
00:17:24,418 --> 00:17:26,211
Notable science fiction movies of 2014

513
00:17:26,211 --> 00:17:27,379
In "Interstellar"

514
00:17:27,379 --> 00:17:29,048
Landing on a planet close to a black hole

515
00:17:29,048 --> 00:17:30,799
But the protagonists of more than 3 hours

516
00:17:30,799 --> 00:17:32,593
When returning to the distant space station

517
00:17:32,593 --> 00:17:35,179
You will find that your colleague has aged 23 years

518
00:17:35,179 --> 00:17:36,847
Finally if you still remember

519
00:17:36,847 --> 00:17:39,933
There was big news that shocked the world in 2016

520
00:17:39,933 --> 00:17:42,311
That is the Laser Interferometer Gravitational-Wave Observatory (LIGO)

521
00:17:42,311 --> 00:17:43,312
Officially announced

522
00:17:43,312 --> 00:17:45,439
They orbit each other from twin black holes

523
00:17:45,439 --> 00:17:48,233
The system then collides and merges into a new black hole.

524
00:17:48,233 --> 00:17:49,943
The existence of gravity waves has been observed

525
00:17:49,943 --> 00:17:50,944
In simple terms

526
00:17:50,944 --> 00:17:52,821
When an object has mass and energy

527
00:17:52,821 --> 00:17:54,907
When accelerating in space and time

528
00:17:54,907 --> 00:17:58,327
It will be like ripples caused by a ship sailing on the water

529
00:17:58,327 --> 00:18:00,871
Gravity changes in space and time will occur at the speed of light

530
00:18:00,871 --> 00:18:03,165
propagates outward in a wave-like form

531
00:18:03,165 --> 00:18:04,708
This is gravity wave

532
00:18:04,708 --> 00:18:07,544
However, because the effect of gravity waves is very weak

533
00:18:07,544 --> 00:18:10,714
So it wasn’t until a hundred years after the birth of general relativity

534
00:18:10,714 --> 00:18:12,674
Humans finally observed it

535
00:18:12,674 --> 00:18:14,093
This is also general relativity

536
00:18:14,093 --> 00:18:16,929
The last important prediction that was directly confirmed

537
00:18:20,682 --> 00:18:22,267
push back time

538
00:18:22,267 --> 00:18:24,186
After the general theory of relativity was proposed

539
00:18:24,186 --> 00:18:26,438
Einstein himself was full of confidence

540
00:18:26,438 --> 00:18:29,691
Before Eddington's observations of a total solar eclipse came out

541
00:18:29,691 --> 00:18:31,860
Some students asked Einstein

542
00:18:31,860 --> 00:18:34,863
What if it turns out that general relativity is wrong?

543
00:18:34,863 --> 00:18:35,823
What should I do?

544
00:18:35,823 --> 00:18:37,950
Einstein smiled and replied

545
00:18:37,950 --> 00:18:40,119
Then I would feel sorry for you dear God.

546
00:18:40,119 --> 00:18:41,870
Because my theory is correct

547
00:18:41,870 --> 00:18:42,830
after that

548
00:18:42,830 --> 00:18:44,998
Many surprising things about general relativity

549
00:18:44,998 --> 00:18:46,834
Anti-predictions from daily life experience

550
00:18:46,834 --> 00:18:48,836
All proved to be true one by one

551
00:18:48,836 --> 00:18:52,464
It also gives us a new perspective on gravity

552
00:18:52,464 --> 00:18:55,300
General relativity is now a common theory for all scientists

553
00:18:55,300 --> 00:18:57,386
The cornerstone of understanding gravity and studying the universe

554
00:18:57,386 --> 00:18:59,221
From the origin and evolution of the universe

555
00:18:59,221 --> 00:19:00,556
to the appearance of a black hole, etc.

556
00:19:00,556 --> 00:19:02,266
All rely on general relativity

557
00:19:02,266 --> 00:19:05,185
In reality, the GPS commonly used in our daily life

558
00:19:05,185 --> 00:19:06,895
General relativity is also included

559
00:19:06,895 --> 00:19:08,438
and modifications to the special theory of relativity

560
00:19:08,438 --> 00:19:09,731
to accurately locate

561
00:19:09,731 --> 00:19:11,400
But on the other hand

562
00:19:11,400 --> 00:19:13,152
It still has some shortcomings

563
00:19:13,152 --> 00:19:14,820
The biggest problem with general relativity

564
00:19:14,820 --> 00:19:17,990
I just didn't take quantum effects into account.

565
00:19:17,990 --> 00:19:18,824
until now

566
00:19:18,824 --> 00:19:20,409
Scientists are still working hard to construct

567
00:19:20,409 --> 00:19:23,787
A theory capable of unifying quantum mechanics and general relativity

568
00:19:23,787 --> 00:19:26,248
That's the quantum theory of gravity

569
00:19:26,248 --> 00:19:28,750
But it seems there is still some distance to go before success.

570
00:19:28,750 --> 00:19:30,002
also because of this

571
00:19:30,002 --> 00:19:31,461
when we want to study

572
00:19:31,461 --> 00:19:34,089
Some situations where quantum effects are very important

573
00:19:34,089 --> 00:19:36,008
Like the very early days of the birth of the universe

574
00:19:36,008 --> 00:19:37,259
Or the center of a black hole

575
00:19:37,259 --> 00:19:39,678
Singularity point with infinite space-time curvature

576
00:19:39,678 --> 00:19:40,888
will run into trouble

577
00:19:40,888 --> 00:19:43,307
There is no suitable theory to describe them

578
00:19:43,307 --> 00:19:44,433
And this thing

579
00:19:44,433 --> 00:19:45,726
It also happens to be "Interstellar"

580
00:19:45,726 --> 00:19:48,437
The most important core question at the end of this movie

581
00:19:48,437 --> 00:19:49,479
if not solved

582
00:19:49,479 --> 00:19:51,064
Humanity has no future

583
00:19:51,064 --> 00:19:53,025
Let’s go back to the question at the beginning

584
00:19:53,025 --> 00:19:56,486
Is it really possible for humans to find so-called antigravity matter?

585
00:19:56,486 --> 00:19:58,363
Not only will it not be attracted by gravity,

586
00:19:58,363 --> 00:20:00,157
will also be repelled by the earth's gravity

587
00:20:00,157 --> 00:20:01,825
And "fall" toward the sky?

588
00:20:01,825 --> 00:20:05,412
Or invent a device that claims to be able to generate a gravity field

589
00:20:05,412 --> 00:20:07,831
"Dynamic Mass Field Generator"?

590
00:20:07,831 --> 00:20:09,708
About whether there is antigravity matter

591
00:20:09,708 --> 00:20:11,126
As long as we use the principle of equivalence

592
00:20:11,126 --> 00:20:12,753
Let's reimagine

593
00:20:12,753 --> 00:20:13,795
Put the experimental environment

594
00:20:13,795 --> 00:20:16,632
Move into a spaceship accelerating vertically

595
00:20:16,632 --> 00:20:17,549
obviously

596
00:20:17,549 --> 00:20:19,718
All materials suspended in the cabin

597
00:20:19,718 --> 00:20:21,929
They will all be hit by the rising floor.

598
00:20:21,929 --> 00:20:24,139
Never getting farther and farther from the floor

599
00:20:24,139 --> 00:20:27,309
So antigravity matter, matter that is repelled by gravity

600
00:20:27,309 --> 00:20:28,602
I'm afraid it's difficult to exist

601
00:20:28,602 --> 00:20:30,145
So far we haven't found it

602
00:20:30,145 --> 00:20:32,397
Any evidence of antigravity matter

603
00:20:32,397 --> 00:20:34,942
As for the artificially generated gravity field

604
00:20:34,942 --> 00:20:36,443
According to current scientific knowledge

605
00:20:36,443 --> 00:20:38,070
Probably only through acceleration

606
00:20:38,070 --> 00:20:39,780
Or like the movie "Interstellar"

607
00:20:39,780 --> 00:20:42,908
Use a rotating space station to simulate the effect of gravity

608
00:20:42,908 --> 00:20:45,994
Otherwise, we need to control gravity in a fundamental way

609
00:20:45,994 --> 00:20:47,621
Still an impossible task

610
00:20:47,621 --> 00:20:48,789
Unless one day

611
00:20:48,789 --> 00:20:51,208
We gain a deeper understanding of gravity

612
00:20:51,208 --> 00:20:53,627
For example, the secret of quantum gravity was discovered

613
00:20:53,627 --> 00:20:56,338
Maybe there is room to bargain with gravity

614
00:20:56,338 --> 00:20:57,172
All in all

615
00:20:57,172 --> 00:20:58,423
General relativity changed

616
00:20:58,423 --> 00:21:01,343
Our fundamental understanding of gravity, space-time, and the universe

617
00:21:01,343 --> 00:21:03,011
Research in modern cosmology

618
00:21:03,011 --> 00:21:04,846
It is an indispensable tool

619
00:21:04,846 --> 00:21:06,014
but it's not perfect

620
00:21:06,014 --> 00:21:08,267
It also needs to be integrated with quantum mechanics

621
00:21:08,267 --> 00:21:09,351
we will see with our own eyes

622
00:21:09,351 --> 00:21:10,686
Does the sun turn into a black hole?

623
00:21:10,686 --> 00:21:11,979
why dazzling stars

624
00:21:11,979 --> 00:21:13,647
It will become like not even letting the light go.

625
00:21:13,647 --> 00:21:15,190
What about the black hole that swallows everything?

626
00:21:15,190 --> 00:21:17,401
What does a black hole look like?

627
00:21:17,401 --> 00:21:19,111
In order to answer these "cosmic puzzles"

628
00:21:19,111 --> 00:21:21,363
We spent two episodes introducing the theory of relativity

629
00:21:21,363 --> 00:21:25,117
How to rewrite our understanding of the universe, space-time and gravity

630
00:21:25,117 --> 00:21:26,076
Thank you, Einstein

631
00:21:26,076 --> 00:21:27,077
Finished the theory

632
00:21:27,077 --> 00:21:28,662
Next, we will actually go to the universe

633
00:21:28,662 --> 00:21:30,706
See how black holes appear

634
00:21:30,706 --> 00:21:33,208
What does the inside and outside of a black hole look like?

635
00:21:33,208 --> 00:21:33,834
But

636
00:21:33,834 --> 00:21:35,043
The star that determines the end

637
00:21:35,043 --> 00:21:36,712
Will it become a black hole?

638
00:21:36,712 --> 00:21:38,338
Not just general relativity

639
00:21:38,338 --> 00:21:39,673
And that important one

640
00:21:39,673 --> 00:21:40,841
"Quantum Mechanics"

641
00:21:43,802 --> 00:21:45,012
you know a star

642
00:21:45,012 --> 00:21:45,887
For example the sun

643
00:21:45,887 --> 00:21:47,097
How was it born?

644
00:21:47,097 --> 00:21:49,224
The universe is not empty

645
00:21:49,224 --> 00:21:51,435
Hydrogen molecules are almost everywhere

646
00:21:51,435 --> 00:21:52,728
Made of some hydrogen molecules

647
00:21:52,728 --> 00:21:53,353
"Molecular cloud"

648
00:21:53,353 --> 00:21:54,396
quite huge

649
00:21:54,396 --> 00:21:56,565
May be hundreds of light years in diameter

650
00:21:56,565 --> 00:21:58,942
Masses range from millions of times that of the sun

651
00:21:58,942 --> 00:22:00,527
Gravity in this molecular cloud

652
00:22:00,527 --> 00:22:02,654
will balance with the kinetic energy of the molecules

653
00:22:02,654 --> 00:22:04,114
So it won't collapse inwards

654
00:22:04,114 --> 00:22:07,909
But when these molecular clouds are disturbed by interstellar space

655
00:22:07,909 --> 00:22:10,162
For example, the shock wave of a supernova explosion

656
00:22:10,162 --> 00:22:12,622
will make gravity greater than the thermal kinetic energy of the molecules

657
00:22:12,622 --> 00:22:15,250
thus collapsing and separating many blocks

658
00:22:15,250 --> 00:22:16,835
These little nebulae

659
00:22:16,835 --> 00:22:19,838
will continue to collapse under the influence of its own gravity

660
00:22:19,838 --> 00:22:22,591
Gases are also heated during movement

661
00:22:22,591 --> 00:22:25,344
When internal radiation pressure balances with gravity

662
00:22:25,344 --> 00:22:27,512
Gas clouds condense into spheres

663
00:22:27,512 --> 00:22:29,181
That is, "protostar"

664
00:22:29,181 --> 00:22:31,516
The whole process takes about hundreds of thousands of years

665
00:22:31,516 --> 00:22:32,309
good

666
00:22:32,309 --> 00:22:34,394
If the mass of the molecular cloud is large enough

667
00:22:34,394 --> 00:22:36,563
Increased core pressure and temperature

668
00:22:36,563 --> 00:22:39,024
Finally ignited the nuclear fusion reaction

669
00:22:39,024 --> 00:22:40,776
This is the birth of a star

670
00:22:40,776 --> 00:22:41,485
However

671
00:22:41,485 --> 00:22:43,862
There are also some molecular clouds that are not of sufficient quality

672
00:22:43,862 --> 00:22:47,074
Insufficient to generate a core temperature that would cause nuclear fusion reactions

673
00:22:47,074 --> 00:22:48,909
Became a "brown dwarf"

674
00:22:48,909 --> 00:22:51,536
They cannot shine and heat like other stars

675
00:22:51,536 --> 00:22:54,873
It will gradually cool and fade away over hundreds of millions of years.

676
00:22:54,873 --> 00:22:55,665
these stars

677
00:22:55,665 --> 00:22:58,627
Converting hydrogen into helium atoms through nuclear fusion

678
00:22:58,627 --> 00:23:00,545
Release huge amounts of energy at the same time

679
00:23:00,545 --> 00:23:01,922
form what we are familiar with

680
00:23:01,922 --> 00:23:04,883
Various stars such as the sun and Sirius

681
00:23:04,883 --> 00:23:07,552
What about our earth and other planets?

682
00:23:07,552 --> 00:23:08,678
In fact, the concept is similar

683
00:23:08,678 --> 00:23:11,056
It's just made of dust and gas around the star

684
00:23:11,056 --> 00:23:12,265
It’s just condensed

685
00:23:12,265 --> 00:23:14,643
But stars are not the end

686
00:23:14,643 --> 00:23:15,894
mature star

687
00:23:15,894 --> 00:23:18,480
The inward squeezing gravity still exists

688
00:23:18,480 --> 00:23:19,815
Simultaneously hot core

689
00:23:19,815 --> 00:23:23,110
Will expand outward due to thermal pressure generated by high temperature

690
00:23:23,110 --> 00:23:24,236
between the two

691
00:23:24,236 --> 00:23:27,239
Achieving a state called "hydrostatic equilibrium"

692
00:23:27,239 --> 00:23:29,074
And remain without collapse

693
00:23:29,074 --> 00:23:29,866
That is to say

694
00:23:29,866 --> 00:23:31,451
Nuclear fusion inside stars

695
00:23:31,451 --> 00:23:33,745
It can be said to be the key to maintaining the growth of stars

696
00:23:33,745 --> 00:23:34,913
including the sun

697
00:23:34,913 --> 00:23:36,415
These can be achieved through nuclear fusion

698
00:23:36,415 --> 00:23:39,000
The star stage that continues to shine and heat

699
00:23:39,000 --> 00:23:40,627
Known as "main sequence" (main sequence)

700
00:23:40,627 --> 00:23:42,170
Why it’s called “main sequence star”

701
00:23:42,170 --> 00:23:45,173
That's because stars in this phase are in a process called

702
00:23:45,173 --> 00:23:46,716
On the chart of "H-R diagram"

703
00:23:46,716 --> 00:23:49,386
Mainly distributed in the "main sequence zone"

704
00:23:49,386 --> 00:23:50,137
Wait

705
00:23:50,137 --> 00:23:51,471
So what is the Hero-Russian diagram?

706
00:23:51,680 --> 00:23:52,431
Good question

707
00:23:52,431 --> 00:23:54,433
If you want to know the fate of a star

708
00:23:54,433 --> 00:23:55,976
You don't have to rub the crystal ball

709
00:23:55,976 --> 00:23:57,269
Open the "Hero-Russell Diagram"

710
00:23:57,269 --> 00:23:58,478
It is the birth chart of a star

711
00:23:58,478 --> 00:24:00,939
Want to know the past and future of stars

712
00:24:00,939 --> 00:24:01,898
You can rely on it

713
00:24:01,898 --> 00:24:03,316
The horizontal axis of this Hertz-Russell diagram

714
00:24:03,316 --> 00:24:04,985
is the surface temperature of the star

715
00:24:04,985 --> 00:24:06,778
The vertical axis is luminosity

716
00:24:06,778 --> 00:24:08,280
Surface temperature can tell us

717
00:24:08,280 --> 00:24:10,574
The color of a star in the visible spectrum

718
00:24:10,574 --> 00:24:12,075
Usually the higher the temperature

719
00:24:12,075 --> 00:24:13,952
Observationally it will be closer to blue

720
00:24:13,952 --> 00:24:16,621
The lower the temperature, the reddish color

721
00:24:16,621 --> 00:24:19,583
Luminosity is based on the luminosity of the sun as a unit

722
00:24:19,583 --> 00:24:23,003
Will be proportional to the temperature, radius, and even mass of the star

723
00:24:23,003 --> 00:24:23,753
Nothing wrong

724
00:24:23,753 --> 00:24:25,297
No need for complicated birthdays and horoscopes

725
00:24:25,297 --> 00:24:28,633
Only two pieces of information, surface temperature and luminosity, are needed

726
00:24:28,633 --> 00:24:31,887
can let us know the types and evolution of stars

727
00:24:31,887 --> 00:24:33,346
Because from the color of stars

728
00:24:33,346 --> 00:24:34,806
Or color tone

729
00:24:34,806 --> 00:24:37,100
We can know the surface temperature of the star

730
00:24:37,100 --> 00:24:38,435
The luminosity of the star

731
00:24:38,435 --> 00:24:40,896
It is also equivalent to the rate of energy consumption

732
00:24:40,896 --> 00:24:42,439
The more massive the star

733
00:24:42,439 --> 00:24:44,149
Often have higher luminosity

734
00:24:44,149 --> 00:24:46,151
The rate of energy consumption is also faster

735
00:24:46,151 --> 00:24:47,652
Therefore the lifespan is usually shorter

736
00:24:47,652 --> 00:24:49,404
Like a lit stick of dynamite

737
00:24:49,404 --> 00:24:50,197
On the contrary

738
00:24:50,197 --> 00:24:52,115
Like those with smaller mass and lower temperature

739
00:24:52,115 --> 00:24:53,033
"red dwarf"

740
00:24:53,033 --> 00:24:54,242
like a candle

741
00:24:54,242 --> 00:24:57,037
They correspond to the position of the horizontal axis "M" of the H-R diagram

742
00:24:57,037 --> 00:24:59,331
Its nuclear fusion rate is relatively slow

743
00:24:59,331 --> 00:25:01,458
There will be a longer main sequence phase

744
00:25:01,458 --> 00:25:03,460
Likely to last hundreds of billions of years

745
00:25:03,460 --> 00:25:04,836
Even several trillion years

746
00:25:04,836 --> 00:25:06,546
And what about our sun?

747
00:25:06,546 --> 00:25:07,464
in the HR diagram

748
00:25:07,464 --> 00:25:10,050
Corresponds to the position of "G-type" main sequence stars

749
00:25:10,050 --> 00:25:13,011
This stage usually lasts for tens of billions of years

750
00:25:13,011 --> 00:25:13,803
That is to say

751
00:25:13,803 --> 00:25:16,223
The sun is currently about 5 billion years old

752
00:25:16,223 --> 00:25:18,475
Equivalent to being in the prime of life of a star

753
00:25:18,475 --> 00:25:19,851
but in the end

754
00:25:19,851 --> 00:25:21,895
Whether it's a bomb or a candle

755
00:25:21,895 --> 00:25:23,939
The stars will eventually come to an end

756
00:25:23,939 --> 00:25:25,023
heroic ending

757
00:25:28,860 --> 00:25:31,655
Just like everything has its own life cycle

758
00:25:31,655 --> 00:25:35,075
The nuclear fuel inside the star will one day be exhausted.

759
00:25:35,075 --> 00:25:36,952
Once the hydrogen in the core is used up

760
00:25:36,952 --> 00:25:39,204
The nuclear fusion reaction will no longer be able to continue

761
00:25:39,204 --> 00:25:42,666
At this time, the fate of the star will be determined by "mass"

762
00:25:42,666 --> 00:25:43,875
stars of different masses

763
00:25:43,875 --> 00:25:45,460
Have different life journeys

764
00:25:45,460 --> 00:25:47,170
Like the "red dwarf" mentioned just now

765
00:25:47,170 --> 00:25:48,922
Such stars with very small masses

766
00:25:48,922 --> 00:25:50,632
Nuclear fusion reactions occur slowly

767
00:25:50,632 --> 00:25:53,385
Although the temperature and luminosity will gradually increase

768
00:25:53,385 --> 00:25:55,387
But it may take tens of billions of years

769
00:25:55,387 --> 00:25:56,555
Even trillions of years

770
00:25:56,555 --> 00:25:59,099
In addition, because the speed of using hydrogen is relatively slow

771
00:25:59,099 --> 00:26:01,476
Convection occurs throughout the interior of the star

772
00:26:01,476 --> 00:26:03,812
so that the density distribution is relatively uniform

773
00:26:03,812 --> 00:26:05,730
No significant expansion will occur

774
00:26:05,730 --> 00:26:08,191
So at most it can only be from a red dwarf star

775
00:26:08,191 --> 00:26:10,902
Become a "blue dwarf" with a higher temperature

776
00:26:10,902 --> 00:26:12,404
Just based on calculation

777
00:26:12,404 --> 00:26:14,656
Blue dwarfs take trillions of years to form

778
00:26:14,656 --> 00:26:17,325
Our universe is currently only 13.8 billion years old

779
00:26:17,325 --> 00:26:18,493
So we actually

780
00:26:18,493 --> 00:26:21,079
There is no way to actually observe the existence of such a blue dwarf.

781
00:26:21,079 --> 00:26:22,789
What about our sun?

782
00:26:22,789 --> 00:26:25,542
0.8 to 10 times as massive as the Sun

783
00:26:25,542 --> 00:26:27,586
This type of "intermediate mass" star

784
00:26:27,586 --> 00:26:28,920
The fates will be very similar

785
00:26:28,920 --> 00:26:31,172
After the hydrogen in the core is completely fused,

786
00:26:31,172 --> 00:26:32,340
This "helium core"

787
00:26:32,340 --> 00:26:34,968
Will no longer create outward supporting thermal pressure

788
00:26:34,968 --> 00:26:36,261
thus starting to shrink

789
00:26:36,261 --> 00:26:39,014
Originally, nuclear fusion reactions mainly occurred only in the core

790
00:26:39,014 --> 00:26:40,640
It has nothing to do with the surrounding gas

791
00:26:40,640 --> 00:26:42,851
But now because the internal temperature is high enough

792
00:26:42,851 --> 00:26:45,979
Enough to cause the hydrogen outside the nucleus to begin nuclear fusion

793
00:26:45,979 --> 00:26:49,149
At this time, the radiation pressure will push outward to the surface of the star.

794
00:26:49,149 --> 00:26:51,401
Gradually expand the size of the star

795
00:26:51,401 --> 00:26:54,279
Expansion also increases the surface area

796
00:26:54,279 --> 00:26:55,614
Energy density becomes smaller

797
00:26:55,614 --> 00:26:57,115
Therefore the surface of the star

798
00:26:57,115 --> 00:26:59,409
Instead, it will cool down and turn red

799
00:26:59,409 --> 00:27:00,994
It will be officially announced at this time

800
00:27:00,994 --> 00:27:03,288
The star enters the "red giant" stage

801
00:27:03,288 --> 00:27:05,290
Corresponds to the position in the upper right corner of the H-R diagram

802
00:27:05,290 --> 00:27:06,916
Our Sun’s “Midlife Crisis”

803
00:27:06,916 --> 00:27:09,377
expected to occur in five billion years

804
00:27:09,377 --> 00:27:10,503
The radius at that time

805
00:27:10,503 --> 00:27:13,048
It may become more than two hundred times the current size

806
00:27:13,048 --> 00:27:15,175
Inner planets including Earth

807
00:27:15,175 --> 00:27:16,468
They may all be swallowed up

808
00:27:16,468 --> 00:27:17,636
The story is not over yet

809
00:27:17,636 --> 00:27:19,763
Although the surface of the red giant cools

810
00:27:19,763 --> 00:27:22,182
But the high temperature inside the core still continues

811
00:27:22,182 --> 00:27:24,434
Probably at temperatures up to 100 million K

812
00:27:24,434 --> 00:27:27,562
will cause helium to begin to fuse into carbon and oxygen

813
00:27:27,562 --> 00:27:29,022
These heavier elements

814
00:27:29,022 --> 00:27:31,650
This stage lasts approximately millions of years

815
00:27:31,650 --> 00:27:32,984
But because the quality is not large enough

816
00:27:32,984 --> 00:27:35,362
Unable to proceed with reactions like carbon fusion

817
00:27:35,362 --> 00:27:37,364
The outward thermal pressure is not enough

818
00:27:37,364 --> 00:27:38,615
gas in the outer layers of a star

819
00:27:38,615 --> 00:27:40,408
There will no longer be support for radiation pressure

820
00:27:40,408 --> 00:27:42,494
At this time the core collapsed again

821
00:27:42,494 --> 00:27:44,496
In the end, when disaster strikes, we all fly away

822
00:27:44,496 --> 00:27:47,040
Dissipates outward at a rate of tens of kilometers per second

823
00:27:47,040 --> 00:27:49,084
Formed a "planetary nebula"

824
00:27:49,084 --> 00:27:52,170
At this time, only the core composed of carbon and oxygen remains

825
00:27:52,170 --> 00:27:54,756
Naked and exposed in the center of the nebula

826
00:27:54,756 --> 00:27:56,049
This remaining core

827
00:27:56,049 --> 00:27:58,051
It's the so-called "white dwarf"

828
00:27:58,051 --> 00:28:00,261
Corresponds to the block below the H-R diagram

829
00:28:00,261 --> 00:28:01,346
The important thing is coming

830
00:28:01,346 --> 00:28:03,932
White dwarfs have very high densities

831
00:28:03,932 --> 00:28:05,350
Very, very high density

832
00:28:05,350 --> 00:28:08,186
It’s equivalent to compressing and re-compressing a sun

833
00:28:08,186 --> 00:28:10,772
into a volume slightly smaller than the earth

834
00:28:10,772 --> 00:28:13,400
Density is approximately per cubic centimeter

835
00:28:13,400 --> 00:28:14,818
It weighs three tons

836
00:28:14,818 --> 00:28:16,861
The gravity created by this high density

837
00:28:16,861 --> 00:28:20,115
In theory, it will cause the white dwarf to continue to collapse further

838
00:28:20,115 --> 00:28:22,367
But under such extreme conditions

839
00:28:22,367 --> 00:28:23,535
it appeared

840
00:28:23,535 --> 00:28:24,327
quantum mechanics

841
00:28:24,327 --> 00:28:26,037
White dwarfs are made by something called

842
00:28:26,037 --> 00:28:27,789
The power of "electron degeneracy pressure"
(electron degeneracy pressure)

843
00:28:27,789 --> 00:28:28,998
Hold up without collapsing

844
00:28:28,998 --> 00:28:32,168
This pressure comes from a special rule of quantum mechanics

845
00:28:32,168 --> 00:28:33,878
"Baoli Exclusion Principle"

846
00:28:33,878 --> 00:28:35,380
It stipulates that any two electrons

847
00:28:35,380 --> 00:28:38,174
cannot occupy the exact same quantum state at the same time

848
00:28:38,174 --> 00:28:39,259
you can imagine

849
00:28:39,259 --> 00:28:40,885
It was a packed concert

850
00:28:40,885 --> 00:28:42,554
Every electron is like an audience

851
00:28:42,554 --> 00:28:43,930
Want to squeeze into the center of the field

852
00:28:43,930 --> 00:28:45,849
But quantum rules are like security

853
00:28:45,849 --> 00:28:48,393
Strictly stipulate that only one person can stand at each location

854
00:28:48,393 --> 00:28:51,062
You have to face different directions than the person next to you

855
00:28:51,062 --> 00:28:53,565
So the electrons had to hold each other apart

856
00:28:53,565 --> 00:28:56,276
This kind of strength that keeps each other from getting closer

857
00:28:56,276 --> 00:28:59,654
It is the source of the power of the white dwarf to support its own gravity.

858
00:28:59,654 --> 00:29:01,990
However, this kind of "holding on" also has its limits.

859
00:29:01,990 --> 00:29:05,618
Once the mass of the white dwarf exceeds 1.4 solar masses

860
00:29:05,618 --> 00:29:07,662
These audiences can't hold it anymore

861
00:29:07,662 --> 00:29:10,331
White dwarfs will further collapse or explode

862
00:29:10,331 --> 00:29:11,708
This upper limit is also called

863
00:29:11,708 --> 00:29:13,251
"Chandrasekhar Limit"
(Chandrasekhar limit)

864
00:29:13,251 --> 00:29:16,421
So a star much more massive than the sun

865
00:29:16,421 --> 00:29:17,922
What will be the fate

866
00:29:17,922 --> 00:29:18,590
actually

867
00:29:18,590 --> 00:29:21,009
The first half of their destiny is actually similar to that of the sun

868
00:29:21,009 --> 00:29:23,553
It’s just that after the hydrogen reaction in the core is over,

869
00:29:23,553 --> 00:29:27,265
High temperatures will cause helium to continue to fuse into carbon, neon, and oxygen

870
00:29:27,265 --> 00:29:30,435
Even to heavier elements such as silicon and iron

871
00:29:30,435 --> 00:29:32,937
At this time, layers will form inside the star

872
00:29:32,937 --> 00:29:35,023
structure made of different elements

873
00:29:35,023 --> 00:29:37,442
It’s like a chemical version of rainbow baumkuchen

874
00:29:37,442 --> 00:29:40,278
Main-sequence stars roughly 8 times more massive than the Sun

875
00:29:40,278 --> 00:29:41,780
Expansion scale can achieve

876
00:29:41,780 --> 00:29:43,323
"Supergiant" level

877
00:29:43,323 --> 00:29:45,617
And finally formed an iron core

878
00:29:45,617 --> 00:29:47,243
But why iron

879
00:29:47,243 --> 00:29:49,078
rather than other heavier elements

880
00:29:49,078 --> 00:29:51,289
This is written into the physical structure of atoms

881
00:29:51,289 --> 00:29:53,708
From hydrogen and helium, elements lighter than iron

882
00:29:53,708 --> 00:29:55,627
Energy is released during nuclear fusion

883
00:29:55,627 --> 00:29:57,337
Because the fused nuclei

884
00:29:57,337 --> 00:29:58,379
become more stable

885
00:29:58,379 --> 00:30:00,632
The particles inside are tied tighter to each other

886
00:30:00,632 --> 00:30:03,009
The extra energy can be released

887
00:30:03,009 --> 00:30:05,345
But iron happens to be the most stable nucleus

888
00:30:05,345 --> 00:30:07,680
Go up and incorporate heavier elements

889
00:30:07,680 --> 00:30:09,808
On the contrary, it will make the nucleus unstable

890
00:30:09,808 --> 00:30:12,352
Additional energy is needed to complete the reaction

891
00:30:12,352 --> 00:30:13,144
On the contrary

892
00:30:13,144 --> 00:30:14,521
elements heavier than iron

893
00:30:14,521 --> 00:30:16,147
Although fusion consumes energy

894
00:30:16,147 --> 00:30:17,857
But if you split it

895
00:30:17,857 --> 00:30:20,276
On the contrary, it will make the nucleus more stable

896
00:30:20,276 --> 00:30:22,111
This will release energy

897
00:30:22,111 --> 00:30:24,989
This is why nuclear power plants use nuclear fission raw materials

898
00:30:24,989 --> 00:30:26,908
It's uranium not hydrogen

899
00:30:26,908 --> 00:30:30,370
Therefore, iron is the end point of a series of nuclear fusion reactions

900
00:30:30,370 --> 00:30:32,956
At this time, because the nuclear fusion reaction stops

901
00:30:32,956 --> 00:30:35,458
The star no longer has any pressure to support it

902
00:30:35,458 --> 00:30:37,335
The core begins to collapse rapidly

903
00:30:37,335 --> 00:30:40,004
As the material in the outer layer is ejected,

904
00:30:40,004 --> 00:30:42,340
This is the most spectacular spectacle in the universe

905
00:30:42,340 --> 00:30:43,675
supernova

906
00:30:43,675 --> 00:30:44,300
Su Su Su

907
00:30:44,300 --> 00:30:44,884
Supernova

908
00:30:45,176 --> 00:30:46,761
The end of massive stars

909
00:30:46,761 --> 00:30:47,971
supernova explosion

910
00:30:47,971 --> 00:30:51,182
Arguably a more dramatic version of a planetary nebula

911
00:30:51,182 --> 00:30:53,685
There will also be a core remains left

912
00:30:53,685 --> 00:30:55,186
This core debris mass

913
00:30:55,186 --> 00:30:58,064
Typically greater than 1.4 times the mass of the Sun

914
00:30:58,064 --> 00:31:00,024
Thus forming a "neutron star" (neutron star)

915
00:31:00,024 --> 00:31:01,192
The simple understanding is

916
00:31:01,192 --> 00:31:03,653
When the density of the iron core reaches its limit

917
00:31:03,653 --> 00:31:04,195
Wow

918
00:31:04,195 --> 00:31:06,197
Not even the atomic structure can hold up

919
00:31:06,197 --> 00:31:08,199
Electrons are squeezed into protons

920
00:31:08,199 --> 00:31:09,492
Became a neutron

921
00:31:09,492 --> 00:31:11,536
The entire core thus becomes a pile of

922
00:31:11,536 --> 00:31:13,371
Tightly stacked neutron balls

923
00:31:13,371 --> 00:31:13,997
However

924
00:31:13,997 --> 00:31:17,375
Similar to the concept that white dwarfs are supported by "electron degeneracy pressure"

925
00:31:17,375 --> 00:31:19,836
There is a similar resistance between neutrons

926
00:31:19,836 --> 00:31:21,921
Called "neutron degeneracy pressure"

927
00:31:21,921 --> 00:31:24,132
Because of the existence of neutron degeneracy pressure

928
00:31:24,132 --> 00:31:26,634
Neutron stars will not collapse endlessly

929
00:31:26,634 --> 00:31:28,553
But the same problem comes

930
00:31:28,553 --> 00:31:32,891
Both electron degeneracy pressure and neutron degeneracy pressure have limits

931
00:31:32,891 --> 00:31:34,726
If the force of inward collapse

932
00:31:34,726 --> 00:31:36,269
exceed this pressure

933
00:31:36,269 --> 00:31:38,396
The most mysterious astronomical phenomenon

934
00:31:38,396 --> 00:31:39,814
It's finally coming

935
00:31:39,814 --> 00:31:40,565
black hole

936
00:31:45,862 --> 00:31:48,573
Neutron stars are much denser than white dwarfs

937
00:31:48,573 --> 00:31:49,949
The white dwarf I just mentioned

938
00:31:49,949 --> 00:31:53,077
Density is about three tons per cubic centimeter

939
00:31:53,077 --> 00:31:55,413
This is already a concept that is difficult for us to imagine

940
00:31:55,413 --> 00:31:56,706
What about neutron stars?

941
00:31:56,706 --> 00:31:59,125
The density is about 100 million times that of a white dwarf star

942
00:31:59,125 --> 00:31:59,959
More ridiculous

943
00:31:59,959 --> 00:32:03,504
Therefore the size of neutron stars can often be compressed to even smaller

944
00:32:03,504 --> 00:32:06,382
Probably only as big as a city

945
00:32:06,382 --> 00:32:08,051
But in such a small volume

946
00:32:08,051 --> 00:32:10,845
has 1.4 to 3 times the mass of the sun

947
00:32:10,845 --> 00:32:14,057
At the same time, neutron stars also have extremely strong gravity fields

948
00:32:14,057 --> 00:32:16,601
If you take a sewing needle to a neutron star

949
00:32:16,601 --> 00:32:18,269
The weight may be higher than that on Earth

950
00:32:18,269 --> 00:32:20,188
A thousand Paris towers are still heavy

951
00:32:20,188 --> 00:32:23,024
In addition, when a huge star collapses to a small size

952
00:32:23,024 --> 00:32:24,609
Requires conservation of angular momentum

953
00:32:24,609 --> 00:32:27,779
Just like when you put your hands in with a ballet dancer

954
00:32:27,779 --> 00:32:29,948
The same reason why the rotation speed will increase

955
00:32:29,948 --> 00:32:32,241
Neutron stars spin very fast

956
00:32:32,241 --> 00:32:33,868
Faster than your washing machine

957
00:32:33,868 --> 00:32:37,080
Eventually the neutron star's powerful magnetic field will move along the poles

958
00:32:37,080 --> 00:32:39,624
emit concentrated beams of electromagnetic radiation

959
00:32:39,624 --> 00:32:41,793
When this neutron star spins at high speed

960
00:32:41,793 --> 00:32:44,504
These beams of radiation are like lighthouse beams

961
00:32:44,504 --> 00:32:46,381
Continuously sweeping through the universe

962
00:32:46,381 --> 00:32:48,299
Whenever the beam happens to be pointed at the Earth

963
00:32:48,299 --> 00:32:50,259
we will receive a flash

964
00:32:50,259 --> 00:32:52,470
It's like the universe winked at us

965
00:32:52,470 --> 00:32:54,389
Therefore, it is also called "pulsar" (pulsar)

966
00:32:54,389 --> 00:32:56,557
Or directly transliterated as "wave"

967
00:32:56,557 --> 00:32:59,727
Of course, neutron stars also have an upper limit on mass.

968
00:32:59,727 --> 00:33:02,689
This value is about 3 times the mass of the sun

969
00:33:02,689 --> 00:33:04,565
That is "TOV limit"
(Tolman–Oppenheimer–Volkoff limit)

970
00:33:04,565 --> 00:33:06,442
Or "Oppenheimer's limit"

971
00:33:06,442 --> 00:33:06,985
That's right

972
00:33:06,985 --> 00:33:08,111
It's Oppenheimer

973
00:33:08,111 --> 00:33:10,113
proposed by colleagues in 1939

974
00:33:10,113 --> 00:33:11,239
Think about it

975
00:33:11,239 --> 00:33:14,492
If a star has mass in the main sequence stage

976
00:33:14,492 --> 00:33:17,203
Several times to dozens of times larger than the sun

977
00:33:17,203 --> 00:33:18,705
after the supernova explosion

978
00:33:18,705 --> 00:33:21,916
The remaining core can exceed about 3 times the mass of the sun

979
00:33:21,916 --> 00:33:23,835
At this time, the neutron degeneracy pressure

980
00:33:23,835 --> 00:33:26,170
Will be unable to withstand the powerful gravitational collapse

981
00:33:26,170 --> 00:33:29,382
In the end, the ending is brought to the "Achilles heel" of the laws of physics.

982
00:33:29,382 --> 00:33:30,133
black hole

983
00:33:30,133 --> 00:33:31,551
As early as the beginning of the 20th century

984
00:33:31,551 --> 00:33:33,302
Einstein in general relativity

985
00:33:33,302 --> 00:33:34,095
Indirectly predicted

986
00:33:34,095 --> 00:33:35,847
When a celestial body like a "black hole" exists

987
00:33:35,847 --> 00:33:37,015
physicists

988
00:33:37,015 --> 00:33:38,349
Got goosebumps one after another

989
00:33:38,349 --> 00:33:39,267
After all, this kind of celestial body

990
00:33:39,267 --> 00:33:41,602
Full of features that are counter-intuitive to human beings

991
00:33:41,602 --> 00:33:43,438
Such as the unimaginable gravity field

992
00:33:43,438 --> 00:33:44,564
can let light

993
00:33:44,564 --> 00:33:46,816
Even time is permanently trapped in it

994
00:33:46,816 --> 00:33:47,650
Or

995
00:33:47,650 --> 00:33:49,318
All substances that are inhaled

996
00:33:49,318 --> 00:33:50,945
They will all fall into a "point" and so on.

997
00:33:50,945 --> 00:33:52,280
Therefore astronomers

998
00:33:52,280 --> 00:33:54,824
Continuously calculate the upper limit of the mass of a star after its collapse

999
00:33:54,824 --> 00:33:57,326
To confirm whether black holes are really possible

1000
00:33:57,326 --> 00:33:58,661
people first discovered

1001
00:33:58,661 --> 00:34:00,705
The core exceeds the limit of Chandrasekhar

1002
00:34:00,705 --> 00:34:02,874
1.4 times the mass of the sun

1003
00:34:02,874 --> 00:34:05,460
White dwarfs will be unable to resist the compression of gravity

1004
00:34:05,460 --> 00:34:06,210
But fortunately

1005
00:34:06,210 --> 00:34:07,420
Physicists discovered

1006
00:34:07,420 --> 00:34:09,213
After this electron can't bear it

1007
00:34:09,213 --> 00:34:11,591
And the force between neutrons can support it

1008
00:34:11,591 --> 00:34:13,843
This also predicted the existence of neutron stars

1009
00:34:13,843 --> 00:34:16,512
However, after the Oppenheimer limit was proposed,

1010
00:34:16,512 --> 00:34:18,222
Physicists are starting to panic

1011
00:34:18,222 --> 00:34:18,639
wow

1012
00:34:18,639 --> 00:34:20,558
It turns out that neutron stars also have an upper limit

1013
00:34:20,558 --> 00:34:22,643
That's about 3 times the mass of the sun

1014
00:34:22,643 --> 00:34:24,145
Once this value is exceeded

1015
00:34:24,145 --> 00:34:25,897
Then all known forces

1016
00:34:25,897 --> 00:34:27,231
will be unable to resist gravity

1017
00:34:27,231 --> 00:34:29,192
completely compress matter

1018
00:34:29,192 --> 00:34:32,070
Stars will inevitably collapse into black holes

1019
00:34:32,070 --> 00:34:34,530
And after the 1960s and 1970s

1020
00:34:34,530 --> 00:34:35,865
People further discovered

1021
00:34:35,865 --> 00:34:39,035
Black holes don't just form from the collapse of massive stars

1022
00:34:39,035 --> 00:34:40,912
center of each galaxy

1023
00:34:40,912 --> 00:34:42,121
There seems to be one

1024
00:34:42,121 --> 00:34:43,372
"Supermassive Black Hole"
(supermassive black hole)

1025
00:34:43,372 --> 00:34:44,207
existence

1026
00:34:44,207 --> 00:34:46,959
Their mass weighs hundreds of thousands of the sun

1027
00:34:46,959 --> 00:34:48,669
Even billions of times

1028
00:34:48,669 --> 00:34:50,046
Compared to stellar black holes

1029
00:34:50,046 --> 00:34:51,756
It's a completely different dimension of existence

1030
00:34:51,756 --> 00:34:53,174
black hole at the center of a galaxy

1031
00:34:53,174 --> 00:34:54,801
Controlled the core structure

1032
00:34:54,801 --> 00:34:56,636
It even affects the evolution of galaxies

1033
00:34:56,636 --> 00:34:57,929
If we talk about "dark matter"

1034
00:34:57,929 --> 00:35:00,473
It's the "invisible skeleton" that maintains the galaxy. Okay

1035
00:35:00,473 --> 00:35:01,849
So a supermassive black hole

1036
00:35:01,849 --> 00:35:04,102
Probably more like the heart of the galaxy

1037
00:35:04,102 --> 00:35:05,645
You said: What is dark matter?

1038
00:35:05,645 --> 00:35:07,438
Come here to review review

1039
00:35:07,438 --> 00:35:09,607
In the decades after black holes were predicted

1040
00:35:09,607 --> 00:35:11,734
Since there has been no observational evidence

1041
00:35:11,734 --> 00:35:12,902
most physicists

1042
00:35:12,902 --> 00:35:15,613
Nor are they willing to confirm the existence of such a "monster" celestial body.

1043
00:35:15,613 --> 00:35:17,323
Similar status to the Loch Ness Monster

1044
00:35:17,323 --> 00:35:21,202
After all, black holes themselves are the product of celestial bodies under extreme conditions.

1045
00:35:21,202 --> 00:35:22,537
Or more like a

1046
00:35:22,537 --> 00:35:24,330
Hypotheses on mathematical equations

1047
00:35:24,330 --> 00:35:25,832
If it really exists

1048
00:35:25,832 --> 00:35:27,708
That has undoubtedly challenged people from ancient times to the present.

1049
00:35:27,708 --> 00:35:29,252
Many iron laws of physics

1050
00:35:29,252 --> 00:35:30,586
until 1964

1051
00:35:30,586 --> 00:35:33,131
Astronomers discover "Cygnus X-1"

1052
00:35:33,131 --> 00:35:36,634
emits powerful and unusual X-rays

1053
00:35:36,634 --> 00:35:37,635
But can't see it

1054
00:35:37,635 --> 00:35:39,846
Since the source of X-rays is very intense

1055
00:35:39,846 --> 00:35:40,888
Scientists think

1056
00:35:40,888 --> 00:35:43,766
This should be from the blue giant gas next to it

1057
00:35:43,766 --> 00:35:45,810
Falling into this "invisible" celestial body

1058
00:35:45,810 --> 00:35:47,478
The high temperature heating produced

1059
00:35:47,478 --> 00:35:48,938
That's a handful

1060
00:35:48,938 --> 00:35:49,856
Oops, that's incredible

1061
00:35:49,856 --> 00:35:51,816
The mass of this invisible companion

1062
00:35:51,816 --> 00:35:53,526
About 10 times more powerful than the Sun

1063
00:35:53,526 --> 00:35:55,611
Far beyond the Chandrasekhar limit

1064
00:35:55,611 --> 00:35:57,655
It also exceeds the Oppenheimer limit

1065
00:35:57,655 --> 00:35:59,365
So in 1975

1066
00:35:59,365 --> 00:36:02,493
A very famous bet in the world of physics has appeared

1067
00:36:02,493 --> 00:36:03,661
Stephen Hawking

1068
00:36:03,661 --> 00:36:05,496
With his colleague Kip Thorne

1069
00:36:05,496 --> 00:36:08,624
Bet on whether Cygnus X-1 is a black hole

1070
00:36:08,624 --> 00:36:10,042
Hawking bets not

1071
00:36:10,042 --> 00:36:11,836
But until 1990

1072
00:36:11,836 --> 00:36:12,962
Cygnus X-1

1073
00:36:12,962 --> 00:36:15,173
Already widely considered a candidate for a black hole

1074
00:36:15,173 --> 00:36:16,841
Hawking also admitted defeat.

1075
00:36:16,841 --> 00:36:19,343
Finally, Thorne was given a year's worth of Penthouse magazine.

1076
00:36:19,343 --> 00:36:19,886
Right

1077
00:36:19,886 --> 00:36:22,847
It is said that Hawking actually believed that Cygnus X-1 was a black hole.

1078
00:36:22,847 --> 00:36:23,848
So if you lose the bet

1079
00:36:23,848 --> 00:36:25,349
Then Hawking would be very happy as well

1080
00:36:25,349 --> 00:36:26,601
If the bet wins

1081
00:36:26,601 --> 00:36:27,852
If it's not a black hole

1082
00:36:27,852 --> 00:36:29,812
Hawking will also receive a year of Penthouse magazine

1083
00:36:29,812 --> 00:36:31,189
This positive gambler mentality

1084
00:36:31,189 --> 00:36:32,190
You can refer to it

1085
00:36:32,190 --> 00:36:33,691
Okay, that much has been said

1086
00:36:33,691 --> 00:36:35,610
What exactly is a "black hole"?

1087
00:36:35,610 --> 00:36:37,862
In fact, it is an upgraded version of the neutron star

1088
00:36:37,862 --> 00:36:39,030
pro max ultra

1089
00:36:39,030 --> 00:36:40,615
Has a super strong gravity field

1090
00:36:40,615 --> 00:36:41,449
How strong is it?

1091
00:36:41,449 --> 00:36:43,409
If you were standing on a neutron star

1092
00:36:43,409 --> 00:36:45,703
It will be as heavy as carrying a whole mountain on your back

1093
00:36:45,703 --> 00:36:47,330
So close to the black hole

1094
00:36:47,330 --> 00:36:48,581
It’s not just about gaining weight

1095
00:36:48,581 --> 00:36:50,082
You'll be like a sweet potato

1096
00:36:50,082 --> 00:36:52,376
Being stretched inch by inch from feet to head

1097
00:36:52,376 --> 00:36:53,920
Molecules and atoms in the body

1098
00:36:53,920 --> 00:36:55,213
Unable to hold on one after another

1099
00:36:55,213 --> 00:36:57,381
torn into invisible elementary particles

1100
00:36:57,381 --> 00:36:58,549
This is not about falling in

1101
00:36:58,549 --> 00:36:59,550
Is being "drawn"

1102
00:36:59,550 --> 00:37:01,469
At the same time, as you no doubt know

1103
00:37:01,469 --> 00:37:03,930
This gravitational field is so powerful that it can bend space-time

1104
00:37:03,930 --> 00:37:05,723
All surrounding light will be sucked in

1105
00:37:05,723 --> 00:37:06,724
and cannot escape

1106
00:37:06,724 --> 00:37:08,893
Therefore it is basically invisible to the naked eye

1107
00:37:08,893 --> 00:37:11,520
But in recent years, with the breakthroughs in astronomical detection technology,

1108
00:37:11,520 --> 00:37:13,064
We (humanity) are finally in 2019

1109
00:37:13,064 --> 00:37:15,816
Obtained the first black hole image in human history

1110
00:37:15,816 --> 00:37:17,902
is located at the center of the M87 galaxy

1111
00:37:17,902 --> 00:37:19,237
supermassive black hole

1112
00:37:19,237 --> 00:37:21,113
And the galaxy we live in

1113
00:37:21,113 --> 00:37:23,783
There is also a supermassive black hole in the center

1114
00:37:23,783 --> 00:37:25,076
"Sagittarius A*"

1115
00:37:25,076 --> 00:37:27,411
Photos of it were also revealed in 2022

1116
00:37:27,411 --> 00:37:29,830
How were these black hole photos taken?

1117
00:37:29,830 --> 00:37:31,999
What aspects of a black hole can be seen?

1118
00:37:31,999 --> 00:37:34,460
You can go back to our previous videos to review

1119
00:37:34,460 --> 00:37:36,254
I also urge everyone not to worry

1120
00:37:36,254 --> 00:37:37,755
We are far from the center of the Milky Way

1121
00:37:37,755 --> 00:37:39,757
About 27,000 light years away

1122
00:37:39,757 --> 00:37:42,426
Therefore, it will not be swallowed by supermassive black holes.

1123
00:37:42,426 --> 00:37:43,219
Well, I should

1124
00:37:43,219 --> 00:37:44,845
But what everyone is most curious about is definitely

1125
00:37:44,845 --> 00:37:46,639
What is it like inside a black hole?

1126
00:37:46,639 --> 00:37:48,599
If we really jump down

1127
00:37:48,599 --> 00:37:49,725
Jump into a black hole

1128
00:37:49,725 --> 00:37:51,060
what will happen

1129
00:37:51,060 --> 00:37:53,271
Is it really possible for us to travel through time?

1130
00:37:53,271 --> 00:37:55,273
Go to a completely different world?

1131
00:37:55,273 --> 00:37:56,607
Or its own existence

1132
00:37:56,607 --> 00:37:58,150
Will it be completely wiped out?

1133
00:37:58,150 --> 00:37:59,777
This has to do with quantum mechanics

1134
00:37:59,777 --> 00:38:00,945
What does it matter?

1135
00:38:00,945 --> 00:38:03,030
We don't reject anything

1136
00:38:03,030 --> 00:38:06,284
So don't take anything away from us

1137
00:38:06,284 --> 00:38:08,202
The meteor street of the universe is in the black hole

1138
00:38:08,202 --> 00:38:09,287
And the deepest part of the black hole

1139
00:38:09,287 --> 00:38:10,955
It's the singularity

1140
00:38:10,955 --> 00:38:13,124
Physicists want to study singularities

1141
00:38:13,124 --> 00:38:14,333
Although difficult

1142
00:38:14,333 --> 00:38:16,627
But that doesn't stop our curiosity

1143
00:38:16,627 --> 00:38:17,962
According to Einstein we can

1144
00:38:17,962 --> 00:38:19,505
general relativity left behind

1145
00:38:19,505 --> 00:38:21,382
Speculating on black holes and singularities within black holes

1146
00:38:21,382 --> 00:38:22,967
what does it look like

1147
00:38:22,967 --> 00:38:23,634
there

1148
00:38:23,634 --> 00:38:25,177
Is time and space out of control?

1149
00:38:25,177 --> 00:38:26,387
And after falling into a black hole

1150
00:38:26,387 --> 00:38:28,472
We will really disappear completely

1151
00:38:28,472 --> 00:38:31,142
Or can we discover the ultimate secret of the universe?

1152
00:38:31,142 --> 00:38:32,727
now this episode

1153
00:38:32,727 --> 00:38:34,437
Just dive into the black hole with us

1154
00:38:34,437 --> 00:38:37,064
See what the inside of a black hole looks like

1155
00:38:37,064 --> 00:38:38,232
But I have to say it first

1156
00:38:38,232 --> 00:38:39,233
Went in

1157
00:38:39,233 --> 00:38:40,276
I can't get out

1158
00:38:43,946 --> 00:38:47,033
In the last episode we talked about the fate of massive stars

1159
00:38:47,033 --> 00:38:48,617
May become a black hole

1160
00:38:48,617 --> 00:38:50,536
In addition, the center of every galaxy

1161
00:38:50,536 --> 00:38:52,747
There are also supermassive black holes

1162
00:38:52,747 --> 00:38:54,623
But a black hole that can swallow everything

1163
00:38:54,623 --> 00:38:56,542
Can it be described by the laws of physics?

1164
00:38:56,542 --> 00:38:57,877
We had a good chat before

1165
00:38:57,877 --> 00:39:00,087
Einstein's famous general theory of relativity

1166
00:39:00,087 --> 00:39:03,382
Explain the relationship between time, space and gravity

1167
00:39:03,382 --> 00:39:05,343
If you want to review, you can click here first

1168
00:39:05,343 --> 00:39:07,053
What was not mentioned at that time was

1169
00:39:07,053 --> 00:39:08,429
In general relativity

1170
00:39:08,429 --> 00:39:10,639
Contains one of the most important equations

1171
00:39:10,639 --> 00:39:12,600
Einstein's field equations

1172
00:39:12,600 --> 00:39:15,811
The left half of the equation describes the curvature of spacetime

1173
00:39:15,811 --> 00:39:17,938
On the right is the movement of matter

1174
00:39:17,938 --> 00:39:19,982
Like a cosmic poem

1175
00:39:19,982 --> 00:39:20,691
it says

1176
00:39:20,691 --> 00:39:22,943
Matter determines how space-time curves

1177
00:39:22,943 --> 00:39:25,738
And space and time tell matter how to move

1178
00:39:25,738 --> 00:39:28,366
Gravity from the perspective of general relativity

1179
00:39:28,366 --> 00:39:30,159
It is equivalent to the curvature of space-time

1180
00:39:30,159 --> 00:39:32,119
Not so much a force

1181
00:39:32,119 --> 00:39:34,038
Rather, it is a geometric effect

1182
00:39:34,038 --> 00:39:35,790
Why is it called a geometric effect?

1183
00:39:35,790 --> 00:39:36,624
You can think of it this way

1184
00:39:37,208 --> 00:39:38,167
There are two ants

1185
00:39:38,167 --> 00:39:39,377
At the equator of the globe

1186
00:39:39,377 --> 00:39:40,836
some distance apart

1187
00:39:40,836 --> 00:39:43,005
Both ants are heading straight north

1188
00:39:43,005 --> 00:39:44,757
Heading towards the North Pole

1189
00:39:44,757 --> 00:39:45,674
you will find

1190
00:39:45,674 --> 00:39:48,636
Obviously at the beginning, the two ants were moving in parallel.

1191
00:39:48,636 --> 00:39:50,513
Theoretically there will be no intersection

1192
00:39:50,513 --> 00:39:52,306
But as we get closer to the North Pole

1193
00:39:52,306 --> 00:39:53,140
Where are these two?

1194
00:39:53,140 --> 00:39:54,433
will be closer to each other

1195
00:39:54,433 --> 00:39:56,811
Finally meet at the North Pole

1196
00:39:56,811 --> 00:39:58,270
This closeness to each other

1197
00:39:58,270 --> 00:39:59,230
like gravity

1198
00:39:59,230 --> 00:40:01,273
Attract two qualities together

1199
00:40:01,440 --> 00:40:03,567
Seemingly pulled by an invisible force

1200
00:40:03,567 --> 00:40:04,360
But actually

1201
00:40:04,360 --> 00:40:06,695
It’s just because the sphere itself has curvature

1202
00:40:06,695 --> 00:40:08,447
The same gravity we are familiar with

1203
00:40:08,447 --> 00:40:09,615
In general relativity

1204
00:40:09,615 --> 00:40:11,951
is considered a geometric effect

1205
00:40:11,951 --> 00:40:14,036
It’s all because of the curvature of space and time

1206
00:40:14,036 --> 00:40:15,746
causing objects to approach each other

1207
00:40:15,746 --> 00:40:17,456
Or the path that light takes

1208
00:40:17,456 --> 00:40:18,374
produce bend

1209
00:40:18,374 --> 00:40:20,376
If you still don’t understand this formula

1210
00:40:20,376 --> 00:40:21,252
this is normal

1211
00:40:21,252 --> 00:40:24,797
Because this formula contains so many proper nouns

1212
00:40:24,797 --> 00:40:26,465
Do you think they are all a bunch of constants?

1213
00:40:26,465 --> 00:40:27,133
Wrong

1214
00:40:27,133 --> 00:40:29,135
For example, this symbol with two subscripts

1215
00:40:29,135 --> 00:40:31,887
It means that this element is a second-order tensor

1216
00:40:31,887 --> 00:40:33,472
In general relativity

1217
00:40:33,472 --> 00:40:35,766
is presented as a four by four matrix

1218
00:40:35,766 --> 00:40:36,392
That's right

1219
00:40:36,392 --> 00:40:37,893
This formula is extremely complex

1220
00:40:37,893 --> 00:40:39,186
Even Einstein himself

1221
00:40:39,186 --> 00:40:40,312
It took a lot of effort

1222
00:40:40,312 --> 00:40:42,064
Just find an approximate solution

1223
00:40:42,064 --> 00:40:44,442
Angle of deviation used to predict Mercury's orbit

1224
00:40:44,442 --> 00:40:45,818
But in Einstein

1225
00:40:45,818 --> 00:40:47,987
Two months after publishing the general theory of relativity

1226
00:40:47,987 --> 00:40:49,238
he received a letter

1227
00:40:49,238 --> 00:40:52,283
The sender was physicist Karl Schwarzschild

1228
00:40:52,283 --> 00:40:53,951
The celestial body is spherically symmetrical

1229
00:40:53,951 --> 00:40:55,786
Under the premise that it does not rotate and is not charged

1230
00:40:55,786 --> 00:40:57,955
Schwarzschild calculated an exact solution

1231
00:40:57,955 --> 00:41:01,625
The previous term represents how gravity affects time

1232
00:41:01,625 --> 00:41:05,004
This latter term represents how space is distorted

1233
00:41:05,004 --> 00:41:06,172
In order to commemorate him, future generations

1234
00:41:06,172 --> 00:41:08,299
It is called the "Schwarzschild metric"

1235
00:41:08,299 --> 00:41:10,926
Solving math problems is fun

1236
00:41:10,926 --> 00:41:13,554
But this solution is horrifying

1237
00:41:13,554 --> 00:41:14,805
Otherwise, look carefully

1238
00:41:14,805 --> 00:41:15,931
Look more carefully

1239
00:41:15,931 --> 00:41:17,349
Did you see a face?

1240
00:41:17,349 --> 00:41:18,559
Well, that's fine if you don't

1241
00:41:18,559 --> 00:41:20,394
Because the really scary thing about it is

1242
00:41:20,394 --> 00:41:21,604
According to Schwarzhi's solution

1243
00:41:21,604 --> 00:41:23,647
At a special "critical radius"

1244
00:41:23,647 --> 00:41:25,024
Strange things happen

1245
00:41:25,024 --> 00:41:26,484
When the r of a celestial body

1246
00:41:26,484 --> 00:41:27,526
That is the radius

1247
00:41:27,526 --> 00:41:29,904
When equal to 2GM / c²

1248
00:41:29,904 --> 00:41:32,406
The time term will be equal to 0

1249
00:41:32,406 --> 00:41:33,449
You heard it right

1250
00:41:33,449 --> 00:41:34,617
Time is zero

1251
00:41:34,617 --> 00:41:35,451
Zero yeah

1252
00:41:35,451 --> 00:41:37,578
In other words, time will almost stand still

1253
00:41:37,578 --> 00:41:40,623
Moreover, the space terms will diverge to infinity.

1254
00:41:40,623 --> 00:41:41,999
Represents space being distorted

1255
00:41:41,999 --> 00:41:43,792
Stretch to infinity

1256
00:41:43,959 --> 00:41:44,376
Yes

1257
00:41:44,376 --> 00:41:45,586
You still heard it right

1258
00:41:45,586 --> 00:41:46,462
Infinite

1259
00:41:46,795 --> 00:41:47,922
Infinite

1260
00:41:47,922 --> 00:41:50,466
If a celestial body is smaller than its critical radius

1261
00:41:50,466 --> 00:41:51,884
In terms of the sun

1262
00:41:51,884 --> 00:41:53,302
It’s a radius of three kilometers

1263
00:41:53,302 --> 00:41:56,347
This celestial body will form a singularity

1264
00:41:56,347 --> 00:41:58,682
All matter within the critical radius

1265
00:41:58,682 --> 00:42:01,143
Not even light can escape

1266
00:42:01,143 --> 00:42:02,269
This critical radius

1267
00:42:02,269 --> 00:42:04,230
It is called the "Schwarzschild radius"

1268
00:42:04,230 --> 00:42:07,024
And this singular point that even light cannot escape from

1269
00:42:07,024 --> 00:42:08,275
It's what we know

1270
00:42:08,275 --> 00:42:08,859
black hole

1271
00:42:08,859 --> 00:42:11,153
So what the hell are we encountering this black hole?

1272
00:42:11,153 --> 00:42:12,446
what will happen

1273
00:42:12,446 --> 00:42:14,573
Time and space are distorted to the limit

1274
00:42:14,573 --> 00:42:15,699
what does it mean

1275
00:42:15,699 --> 00:42:18,035
Why don't we get on a spaceship?

1276
00:42:18,035 --> 00:42:19,245
Travel to the black hole

1277
00:42:19,245 --> 00:42:20,663
from outside to inside

1278
00:42:20,663 --> 00:42:22,998
See what a black hole looks like

1279
00:42:22,998 --> 00:42:23,874
into a black hole

1280
00:42:23,874 --> 00:42:25,459
surrounding space and time

1281
00:42:25,459 --> 00:42:26,835
Will there really be changes?

1282
00:42:31,173 --> 00:42:32,675
when we go to a black hole

1283
00:42:32,675 --> 00:42:35,010
The first reason you will be surprised will be

1284
00:42:35,010 --> 00:42:36,303
Black holes are not actually black

1285
00:42:36,720 --> 00:42:37,388
about this

1286
00:42:37,388 --> 00:42:39,348
When we successfully took a picture of a black hole

1287
00:42:39,348 --> 00:42:40,516
Already know

1288
00:42:40,516 --> 00:42:42,101
But the gravitational field of the black hole

1289
00:42:42,101 --> 00:42:43,978
Can't even light be sucked in?

1290
00:42:43,978 --> 00:42:45,729
And why can it be photographed?

1291
00:42:45,729 --> 00:42:47,398
The ring structure in the photo

1292
00:42:47,398 --> 00:42:49,108
In fact, it is the "acretion disk" of the black hole

1293
00:42:49,108 --> 00:42:51,819
You can think of it like a substance before it's inhaled

1294
00:42:52,027 --> 00:42:53,279
Because of high-speed rotation

1295
00:42:53,279 --> 00:42:54,738
The "death vortex" formed

1296
00:42:54,738 --> 00:42:56,198
such as gas, dust

1297
00:42:56,198 --> 00:42:57,741
Stellar debris and other materials

1298
00:42:57,741 --> 00:42:59,326
Under constant frictional heating

1299
00:42:59,326 --> 00:43:01,370
It can even reach temperatures of hundreds of millions of degrees

1300
00:43:01,370 --> 00:43:03,080
Simultaneously releases high-energy rays

1301
00:43:03,080 --> 00:43:04,123
thereby being observed

1302
00:43:04,123 --> 00:43:04,832
now

1303
00:43:04,832 --> 00:43:07,001
Suppose our spacecraft is very strong

1304
00:43:07,001 --> 00:43:08,669
Can pass through the accretion disk smoothly

1305
00:43:08,669 --> 00:43:10,170
without being crushed by high temperature

1306
00:43:10,170 --> 00:43:12,298
We came to the front of the black hole

1307
00:43:12,298 --> 00:43:16,010
I just said that every black hole has a "Schwarzschild radius"

1308
00:43:16,010 --> 00:43:18,345
Simply put, this radius tells us

1309
00:43:18,345 --> 00:43:20,598
How small is the volume of an object compressed?

1310
00:43:20,598 --> 00:43:21,890
will become a black hole

1311
00:43:21,890 --> 00:43:22,766
Give an example

1312
00:43:22,766 --> 00:43:24,393
An object with the same mass as the sun

1313
00:43:24,393 --> 00:43:26,395
Its Schwarzschild radius is three kilometers

1314
00:43:26,395 --> 00:43:27,438
In other words

1315
00:43:27,438 --> 00:43:30,774
Just compress the sun's radius to only three kilometers

1316
00:43:30,774 --> 00:43:33,027
Approximately the area covered by Yangmingshan Mountain

1317
00:43:33,027 --> 00:43:34,445
will directly become a black hole

1318
00:43:34,737 --> 00:43:36,071
If it were the earth

1319
00:43:36,071 --> 00:43:38,407
It needs to be compressed into the size of a coin

1320
00:43:38,407 --> 00:43:39,783
to become a black hole

1321
00:43:39,783 --> 00:43:40,951
just said

1322
00:43:40,951 --> 00:43:42,369
Space will be distorted here

1323
00:43:42,369 --> 00:43:43,829
Stretch to infinity

1324
00:43:43,829 --> 00:43:45,205
what does this mean

1325
00:43:45,205 --> 00:43:48,125
Will we be so distorted that we can’t tell the difference between east, west, north and south?

1326
00:43:48,125 --> 00:43:50,836
This is related to the question of how light "walks"

1327
00:43:50,836 --> 00:43:52,963
We often hear that "light travels in a straight line"

1328
00:43:52,963 --> 00:43:55,299
But this actually only occurs when space and time are flat

1329
00:43:55,299 --> 00:43:58,302
This is only true if it is not severely distorted by gravity.

1330
00:43:58,302 --> 00:44:00,804
A more precise and general statement is

1331
00:44:00,804 --> 00:44:02,014
light always follows

1332
00:44:02,014 --> 00:44:04,933
The "shortest path" between two points in space and time

1333
00:44:04,933 --> 00:44:07,394
Physicists gave it a proper name

1334
00:44:07,394 --> 00:44:09,146
It's called "Geodesic"

1335
00:44:09,146 --> 00:44:11,774
In our familiar, nearly flat space-time

1336
00:44:11,774 --> 00:44:14,443
Geodesics are exactly the straight lines we know

1337
00:44:14,443 --> 00:44:15,944
But next to a black hole

1338
00:44:15,944 --> 00:44:19,239
The powerful gravity distorts space and time very much

1339
00:44:19,239 --> 00:44:20,574
The geodesic here

1340
00:44:20,574 --> 00:44:22,117
Of course it's no longer a straight line.

1341
00:44:22,117 --> 00:44:24,328
And on the critical boundary of the Schwarzschild radius

1342
00:44:24,328 --> 00:44:27,373
The distortion of time and space has reached the most extreme degree

1343
00:44:27,373 --> 00:44:29,708
Finally, starting from inside the event horizon

1344
00:44:29,708 --> 00:44:32,127
All "geodesics" pointing forward

1345
00:44:32,127 --> 00:44:34,004
all inevitably

1346
00:44:34,004 --> 00:44:36,507
Points unidirectionally toward the center of the black hole

1347
00:44:36,507 --> 00:44:39,677
It's like you're standing on the edge of a huge waterfall

1348
00:44:39,677 --> 00:44:40,803
Once you cross over

1349
00:44:40,803 --> 00:44:43,347
No matter which direction you paddle hard

1350
00:44:43,347 --> 00:44:44,807
final flow path

1351
00:44:44,807 --> 00:44:46,684
They will only fall downwards

1352
00:44:46,684 --> 00:44:47,476
here

1353
00:44:47,476 --> 00:44:49,853
There is no way to

1354
00:44:49,853 --> 00:44:51,522
"Outside" The geodesic of the world

1355
00:44:51,522 --> 00:44:52,481
That is to say

1356
00:44:52,481 --> 00:44:53,482
cross this line

1357
00:44:53,482 --> 00:44:54,900
the structure of space and time itself

1358
00:44:54,900 --> 00:44:57,319
It's decided that you can never look back

1359
00:44:57,319 --> 00:44:58,987
Not even the speed of light can save you

1360
00:44:58,987 --> 00:45:01,365
This range is called the "event horizon"

1361
00:45:01,365 --> 00:45:01,990
So

1362
00:45:01,990 --> 00:45:03,283
I also want to get off the boat and use the restroom.

1363
00:45:03,283 --> 00:45:03,951
please hurry up

1364
00:45:03,951 --> 00:45:04,660
Just to add

1365
00:45:04,660 --> 00:45:07,371
What I just assumed is a black hole that does not rotate.

1366
00:45:07,371 --> 00:45:09,540
For some "rotating black holes"

1367
00:45:09,540 --> 00:45:10,958
The periphery of the event horizon

1368
00:45:10,958 --> 00:45:12,418
There is also a layer of "ergosphere"

1369
00:45:12,418 --> 00:45:14,795
The space-time in this area is also being dragged along

1370
00:45:14,795 --> 00:45:16,088
But we have a chance through

1371
00:45:16,088 --> 00:45:17,339
"Penrose process"

1372
00:45:17,339 --> 00:45:19,383
to extract energy from black holes

1373
00:45:19,383 --> 00:45:21,510
And can successfully escape from the black hole

1374
00:45:21,510 --> 00:45:22,761
Want to know how to do it

1375
00:45:22,761 --> 00:45:23,846
Please leave a message to tell us

1376
00:45:23,846 --> 00:45:25,681
We will introduce it separately later

1377
00:45:25,681 --> 00:45:26,724
Here comes the key

1378
00:45:26,724 --> 00:45:28,016
After crossing the event horizon

1379
00:45:28,016 --> 00:45:29,643
Apart from being unable to return

1380
00:45:29,643 --> 00:45:31,520
our spacecraft and us

1381
00:45:31,520 --> 00:45:32,896
what will happen

1382
00:45:32,896 --> 00:45:35,023
Let’s see what kind of black hole this is.

1383
00:45:35,023 --> 00:45:37,484
What if this was a star that turned into a black hole?

1384
00:45:37,484 --> 00:45:38,944
Then it will come to an end soon

1385
00:45:38,944 --> 00:45:40,779
Because we don’t have to enter the event horizon yet

1386
00:45:40,779 --> 00:45:41,947
strong tidal force

1387
00:45:41,947 --> 00:45:44,742
I'll treat you like a dragon's beard and stretch it out like a candy

1388
00:45:44,742 --> 00:45:46,285
Then it will be crushed

1389
00:45:46,285 --> 00:45:48,162
The so-called tidal force is actually a kind of

1390
00:45:48,162 --> 00:45:49,079
imagination

1391
00:45:49,079 --> 00:45:49,788
it refers to

1392
00:45:49,788 --> 00:45:51,081
If you are on your head and on your feet

1393
00:45:51,081 --> 00:45:52,332
When approaching a black hole

1394
00:45:52,332 --> 00:45:54,668
The foot is subject to greater gravity

1395
00:45:54,668 --> 00:45:57,087
The weight on the head is relatively small

1396
00:45:57,087 --> 00:45:58,672
Uneven pressure on head and feet

1397
00:45:58,672 --> 00:46:00,716
The whole person will be sugared by the dragon’s beard

1398
00:46:00,716 --> 00:46:02,134
in astrophysics

1399
00:46:02,134 --> 00:46:03,469
This phenomenon is also called

1400
00:46:03,469 --> 00:46:05,179
The phenomenon of “spaghettification”

1401
00:46:05,179 --> 00:46:07,389
The tidal force is related to the size of the black hole

1402
00:46:07,389 --> 00:46:08,474
low mass black hole

1403
00:46:08,474 --> 00:46:10,058
some distance beyond the horizon

1404
00:46:10,058 --> 00:46:12,436
Strong tidal forces will crush objects

1405
00:46:12,436 --> 00:46:13,228
But

1406
00:46:13,228 --> 00:46:16,315
If you were facing a supermassive black hole at the center of a galaxy

1407
00:46:16,315 --> 00:46:17,691
The situation is different

1408
00:46:17,691 --> 00:46:20,068
The gravity value acting on various parts of your body

1409
00:46:20,068 --> 00:46:21,445
Won’t deviate too much

1410
00:46:21,445 --> 00:46:25,199
So you won't be torn apart outside the event horizon

1411
00:46:25,199 --> 00:46:25,783
On the contrary

1412
00:46:25,783 --> 00:46:28,202
You may even feel no discomfort at all

1413
00:46:28,202 --> 00:46:29,995
just crosses the event horizon

1414
00:46:29,995 --> 00:46:31,330
But in the end it will

1415
00:46:31,330 --> 00:46:31,997
Yeah

1416
00:46:31,997 --> 00:46:34,124
In order for our journey to continue

1417
00:46:34,124 --> 00:46:35,083
this journey

1418
00:46:35,083 --> 00:46:37,586
The supermassive black hole at the center of the Milky Way

1419
00:46:37,586 --> 00:46:38,921
It's probably not too late to tell now.

1420
00:46:38,921 --> 00:46:39,797
But this time

1421
00:46:39,797 --> 00:46:41,048
Although after entering the black hole

1422
00:46:41,048 --> 00:46:43,300
will fall in at a speed close to the speed of light

1423
00:46:43,300 --> 00:46:45,803
The experience of "time" is quite abnormal

1424
00:46:45,803 --> 00:46:47,554
The Schwarzschild metric tells us

1425
00:46:47,554 --> 00:46:50,265
Time will almost stand still at the event horizon

1426
00:46:50,265 --> 00:46:51,099
That is to say

1427
00:46:51,099 --> 00:46:52,476
After you fall into a black hole

1428
00:46:52,476 --> 00:46:54,561
Your partner is on a distant spaceship

1429
00:46:54,561 --> 00:46:55,771
will look at in surprise

1430
00:46:55,771 --> 00:46:58,148
Gravity slows down time

1431
00:46:58,148 --> 00:47:01,443
He will see your figure as if playing in slow motion

1432
00:47:01,443 --> 00:47:03,946
and freeze at the periphery of the event horizon

1433
00:47:03,946 --> 00:47:07,157
And because when light comes out from a place with strong gravity,

1434
00:47:07,157 --> 00:47:09,785
Just like climbing a hill, you lose energy.

1435
00:47:09,785 --> 00:47:11,286
If the light energy becomes low

1436
00:47:11,286 --> 00:47:12,830
The wavelength will become longer

1437
00:47:12,830 --> 00:47:14,456
The color will be reddish

1438
00:47:14,456 --> 00:47:15,749
Produce gravitational redshift

1439
00:47:15,749 --> 00:47:18,460
So the light emanating from you

1440
00:47:18,460 --> 00:47:21,630
Will move in the direction of infrared rays and radio waves

1441
00:47:21,630 --> 00:47:24,299
thus slowly disappearing within the visible range

1442
00:47:24,299 --> 00:47:25,634
from the outside world

1443
00:47:25,634 --> 00:47:27,302
It seems to be gradually "fading out"

1444
00:47:27,302 --> 00:47:29,638
Any signal we send at this time

1445
00:47:29,638 --> 00:47:31,932
No longer able to escape the event horizon

1446
00:47:31,932 --> 00:47:33,475
they will never know

1447
00:47:33,475 --> 00:47:36,019
What is happening to us inside the horizon?

1448
00:47:36,019 --> 00:47:37,646
But let’s not worry about our partners outside.

1449
00:47:37,646 --> 00:47:39,481
We are falling into a black hole right now

1450
00:47:39,481 --> 00:47:42,526
You may be experiencing a wonderful "time travel"

1451
00:47:42,526 --> 00:47:44,987
First of all, although gravity will slow down the flow of time,

1452
00:47:44,987 --> 00:47:46,446
But because of "our time"

1453
00:47:46,446 --> 00:47:48,490
He fell into the black hole with us.

1454
00:47:48,490 --> 00:47:50,784
So your watch still works fine

1455
00:47:50,784 --> 00:47:52,953
Your heart is still beating steadily

1456
00:47:52,953 --> 00:47:54,788
All physiological and physical processes

1457
00:47:54,788 --> 00:47:56,623
"In your eyes" everything is normal

1458
00:47:56,623 --> 00:47:59,626
However, if you have the opportunity to look back at the outside of the black hole

1459
00:47:59,626 --> 00:48:01,295
You will find that the starlight shifts blue

1460
00:48:01,295 --> 00:48:03,005
time passes quickly

1461
00:48:03,005 --> 00:48:04,923
Suppose the black hole you are in is big enough

1462
00:48:04,923 --> 00:48:06,550
It may take you hours

1463
00:48:06,550 --> 00:48:08,093
Just cross the event horizon

1464
00:48:08,093 --> 00:48:10,637
At this time you will be able to see the time outside

1465
00:48:10,637 --> 00:48:12,180
Thousands of years have passed

1466
00:48:12,180 --> 00:48:13,849
even millions of years

1467
00:48:13,849 --> 00:48:14,600
In other words

1468
00:48:14,600 --> 00:48:16,476
You will be able to see the future of the universe

1469
00:48:16,476 --> 00:48:18,145
After seeing all kinds of wonders

1470
00:48:18,145 --> 00:48:20,188
We finally reached the end of our journey​​​

1471
00:48:20,188 --> 00:48:21,982
That is the center of the black hole

1472
00:48:21,982 --> 00:48:22,983
"Singularity"

1473
00:48:27,029 --> 00:48:27,863
just said

1474
00:48:27,863 --> 00:48:30,657
The Schwarzschild metric predicts that at the Schwarzschild radius

1475
00:48:30,657 --> 00:48:32,743
The curvature of space-time will diverge to infinity

1476
00:48:32,743 --> 00:48:33,869
But actually

1477
00:48:33,869 --> 00:48:35,203
This is just a matter of coordinate system

1478
00:48:35,203 --> 00:48:36,580
Give me an example

1479
00:48:36,580 --> 00:48:37,539
on earth

1480
00:48:37,539 --> 00:48:40,500
We use longitude to distinguish time zones in different places

1481
00:48:40,500 --> 00:48:42,544
But we standing at the North Pole

1482
00:48:42,544 --> 00:48:45,213
All warp threads pass under the feet

1483
00:48:45,213 --> 00:48:47,758
So the concept of time zones doesn't work for us

1484
00:48:47,758 --> 00:48:49,426
But this does not represent the concept of "time"

1485
00:48:49,426 --> 00:48:50,844
It doesn't work for us

1486
00:48:50,844 --> 00:48:52,721
Our minute is still 60 seconds

1487
00:48:52,721 --> 00:48:54,973
A day is still 24 hours

1488
00:48:54,973 --> 00:48:55,891
The same reason

1489
00:48:55,891 --> 00:48:57,517
Problems with Schwarzschild radius

1490
00:48:57,517 --> 00:48:59,061
It is also the Schwarzschild coordinate system

1491
00:48:59,061 --> 00:49:02,189
Artifact caused by failure at this specific location

1492
00:49:02,189 --> 00:49:04,483
We call it "coordinate singularity"

1493
00:49:04,483 --> 00:49:07,569
This may not mean that the curvature of space-time is really infinite.

1494
00:49:07,569 --> 00:49:09,321
So how do we correctly judge

1495
00:49:09,321 --> 00:49:10,739
the curvature of space-time in a place

1496
00:49:10,739 --> 00:49:12,491
Is it really infinite?

1497
00:49:12,491 --> 00:49:13,575
Of course I need one

1498
00:49:13,575 --> 00:49:14,868
Does not change with the coordinate system

1499
00:49:14,868 --> 00:49:15,827
the amount of change

1500
00:49:15,827 --> 00:49:17,788
Physicist Erich Kreschmann

1501
00:49:17,788 --> 00:49:20,248
Proposed the "Kreschmann scalar"

1502
00:49:20,248 --> 00:49:21,458
The size of this scalar

1503
00:49:21,458 --> 00:49:23,794
Can reflect the true degree of curvature of space-time

1504
00:49:23,794 --> 00:49:25,754
No matter which coordinate system you use

1505
00:49:25,754 --> 00:49:27,422
The calculated values are all the same

1506
00:49:27,422 --> 00:49:30,342
When we calculate the Kreschmann scalar of the Schwarzschild spacetime

1507
00:49:30,342 --> 00:49:32,302
will be found within the Schwarzschild radius

1508
00:49:32,302 --> 00:49:35,097
The value of the Kreschmann scalar is still finite

1509
00:49:35,097 --> 00:49:38,433
It means that the event horizon is indeed just a "coordinate singularity"

1510
00:49:38,433 --> 00:49:39,851
rather than a physical singularity

1511
00:49:39,851 --> 00:49:41,979
But when we go inward

1512
00:49:41,979 --> 00:49:43,397
The calculated radius is equal to 0

1513
00:49:43,397 --> 00:49:46,984
That is, the Kreschmann scalar time at the center point of the black hole

1514
00:49:46,984 --> 00:49:49,027
it does diverge to infinity

1515
00:49:49,027 --> 00:49:51,905
This is the real physical singularity

1516
00:49:51,905 --> 00:49:52,990
in this place

1517
00:49:52,990 --> 00:49:54,491
It should be said on this point

1518
00:49:54,491 --> 00:49:57,327
The curvature of space-time has truly reached infinite

1519
00:49:57,327 --> 00:49:59,454
The density is also infinite

1520
00:49:59,454 --> 00:50:01,498
All the laws of physics we currently know

1521
00:50:01,498 --> 00:50:04,001
Including Einstein's general theory of relativity itself

1522
00:50:04,001 --> 00:50:05,961
They all completely fail at this point.

1523
00:50:05,961 --> 00:50:07,254
An infinite gravity

1524
00:50:07,254 --> 00:50:09,214
"Point" with infinite space-time curvature

1525
00:50:09,214 --> 00:50:10,799
Yeah, that's unreasonable

1526
00:50:10,799 --> 00:50:12,634
It’s so unreasonable that I want to say to myself

1527
00:50:12,634 --> 00:50:14,428
Do you want to listen to what you are talking about now?

1528
00:50:14,428 --> 00:50:15,804
We know that physically

1529
00:50:15,804 --> 00:50:17,180
"infinity" or "point"

1530
00:50:17,180 --> 00:50:18,557
These are all very old concepts

1531
00:50:18,557 --> 00:50:20,976
No matter how big it is, there must be an upper limit.

1532
00:50:20,976 --> 00:50:23,020
No matter how small it is, it must have a size

1533
00:50:23,020 --> 00:50:25,397
However, the "singularity" is a real one

1534
00:50:25,397 --> 00:50:27,607
The existence that scientists are least willing to accept

1535
00:50:27,607 --> 00:50:29,609
And, because the singularity is in the black hole

1536
00:50:29,609 --> 00:50:31,820
Therefore it must be surrounded by the event horizon

1537
00:50:31,820 --> 00:50:33,822
We can't see through the event horizon

1538
00:50:33,822 --> 00:50:36,033
This represents all currently known theories

1539
00:50:36,033 --> 00:50:37,451
Neither allows us to observe

1540
00:50:37,451 --> 00:50:39,536
Or learn the structure of singular points

1541
00:50:39,536 --> 00:50:40,829
Want to see but can't see

1542
00:50:40,829 --> 00:50:42,664
How itchy are physicists?

1543
00:50:42,664 --> 00:50:45,125
It's as if the universe is deliberately censoring

1544
00:50:45,125 --> 00:50:46,960
To prevent the singularity from being spied on

1545
00:50:47,294 --> 00:50:47,836
Wait

1546
00:50:47,836 --> 00:50:50,213
This is not because physicists can’t eat grapes and say they are sour.

1547
00:50:50,213 --> 00:50:51,590
This is really true

1548
00:50:51,590 --> 00:50:53,508
It’s called the “Cosmic Censorship Hypothesis.”

1549
00:50:53,508 --> 00:50:54,968
To avoid cosmic censorship

1550
00:50:54,968 --> 00:50:56,803
Many physicists are actively looking for

1551
00:50:56,803 --> 00:50:58,263
The possibility of "naked singularity"

1552
00:50:58,263 --> 00:51:00,974
That is, a singularity that is not surrounded by an event horizon.

1553
00:51:00,974 --> 00:51:02,601
But the current cosmic censorship hypothesis

1554
00:51:02,601 --> 00:51:04,853
The only naked singularity allowed to exist

1555
00:51:04,853 --> 00:51:05,937
It's the universe itself

1556
00:51:05,937 --> 00:51:08,148
According to the "Big Bang" model of the birth of the universe

1557
00:51:08,148 --> 00:51:09,024
our universe

1558
00:51:09,024 --> 00:51:10,442
Also from gravity and density

1559
00:51:10,442 --> 00:51:13,028
The "singularity point" with infinite space-time curvature was born

1560
00:51:13,028 --> 00:51:14,196
And it's very possible

1561
00:51:14,196 --> 00:51:15,697
It’s the naked singularity

1562
00:51:15,697 --> 00:51:19,034
However, physics is currently unable to effectively describe its nature.

1563
00:51:19,034 --> 00:51:21,870
Naturally, we cannot know how the universe was born.

1564
00:51:21,870 --> 00:51:24,331
Or is there a state before birth?

1565
00:51:24,331 --> 00:51:26,541
Finally, back to our black hole journey

1566
00:51:26,541 --> 00:51:28,418
After crossing the black hole's event horizon

1567
00:51:28,418 --> 00:51:31,588
Everything will inevitably fall into the singularity

1568
00:51:31,588 --> 00:51:32,672
Even if our equipment

1569
00:51:32,672 --> 00:51:34,883
Can help you isolate the radiation from the accretion disk

1570
00:51:34,883 --> 00:51:36,635
Resist strong tidal forces

1571
00:51:36,635 --> 00:51:39,721
But our final outcome is still to fall into the singularity point

1572
00:51:39,721 --> 00:51:40,847
Completely shattered and disappeared

1573
00:51:40,847 --> 00:51:42,307
Wait, is that really true?

1574
00:51:42,307 --> 00:51:43,391
We fell into a black hole

1575
00:51:43,391 --> 00:51:45,018
We can only face the ending of emptiness and silence

1576
00:51:45,018 --> 00:51:46,895
Is there no possibility of escape at all?

1577
00:51:47,104 --> 00:51:48,063
have you ever doubted

1578
00:51:48,063 --> 00:51:49,564
This world may not be real

1579
00:51:49,564 --> 00:51:51,900
We could be living in the world of The Matrix

1580
00:51:51,900 --> 00:51:52,901
And ourselves

1581
00:51:52,901 --> 00:51:54,569
It's just a set of virtual codes.

1582
00:51:54,736 --> 00:51:56,905
This is not just baseless science fiction imagination

1583
00:51:56,905 --> 00:51:58,156
Physicists have also proposed

1584
00:51:58,156 --> 00:51:59,491
"Holographic principle"

1585
00:51:59,491 --> 00:52:00,492
they want to

1586
00:52:00,492 --> 00:52:02,702
Could it be that our universe itself is similar?

1587
00:52:02,702 --> 00:52:04,287
What about information encoding structure?

1588
00:52:04,287 --> 00:52:06,498
Everything seems to happen in three-dimensional space

1589
00:52:06,498 --> 00:52:09,167
In fact, they can all be encoded on the two-dimensional boundary.

1590
00:52:09,167 --> 00:52:11,169
That is the outermost surface of the universe.

1591
00:52:11,169 --> 00:52:14,172
Hawking is also at the end of the book "The Universe in a Nut"

1592
00:52:14,172 --> 00:52:15,340
write question

1593
00:52:15,340 --> 00:52:17,509
Are we just a set of holograms?

1594
00:52:17,509 --> 00:52:19,511
The universe is a 2D "hologram"

1595
00:52:19,511 --> 00:52:21,346
The result of projecting into 3D

1596
00:52:21,346 --> 00:52:23,515
But why are these scientists so confused?

1597
00:52:23,515 --> 00:52:23,890
Uh

1598
00:52:23,890 --> 00:52:25,267
Or are you overthinking it?

1599
00:52:25,267 --> 00:52:27,227
It all comes from physicists

1600
00:52:27,227 --> 00:52:30,063
studied the most amazing thing in that universe

1601
00:52:30,063 --> 00:52:30,981
black hole

1602
00:52:30,981 --> 00:52:33,024
Not only matter will be shattered there

1603
00:52:33,024 --> 00:52:34,609
Relativity and Quantum Mechanics

1604
00:52:34,609 --> 00:52:36,153
Seems to have been affected too

1605
00:52:36,153 --> 00:52:38,697
Neither can fully explain black holes

1606
00:52:38,697 --> 00:52:40,699
Hawking and other scientists

1607
00:52:40,699 --> 00:52:43,410
then propose various new perspectives to study it

1608
00:52:43,410 --> 00:52:44,619
It can be said that studying black holes

1609
00:52:44,619 --> 00:52:47,455
can bring us one step closer to the reality of this world

1610
00:52:47,455 --> 00:52:50,458
In the last episode, we introduced falling into a black hole from outside a black hole

1611
00:52:50,458 --> 00:52:51,793
What feelings will you experience?

1612
00:52:51,793 --> 00:52:53,962
And now we have to take a closer look

1613
00:52:53,962 --> 00:52:55,297
Why do scientists think

1614
00:52:55,297 --> 00:52:57,841
Black holes hide the truth about the entire universe

1615
00:53:01,469 --> 00:53:03,013
Do you know how scary black holes are?

1616
00:53:03,013 --> 00:53:04,848
In the previous episode, we took you to experience

1617
00:53:04,848 --> 00:53:07,058
Once an object crosses the event horizon

1618
00:53:07,058 --> 00:53:08,351
powerful gravity field

1619
00:53:08,351 --> 00:53:11,229
will cause objects to inevitably fall into the abyss

1620
00:53:11,229 --> 00:53:13,732
Falling towards the "singularity point" of infinite density

1621
00:53:13,732 --> 00:53:16,359
There, the strong gravity will crush everything

1622
00:53:16,359 --> 00:53:18,987
Whether it’s a person, a laptop, or an entire library

1623
00:53:18,987 --> 00:53:21,156
Stars tens of thousands of times more massive than the sun

1624
00:53:21,156 --> 00:53:23,491
As small as the atoms and electrons in your body

1625
00:53:23,491 --> 00:53:25,202
After all this is swallowed up by a black hole

1626
00:53:25,202 --> 00:53:26,369
will be crushed

1627
00:53:26,536 --> 00:53:28,163
Looking from outside the event horizon

1628
00:53:28,163 --> 00:53:31,374
Black holes leave only three detectable physical quantities

1629
00:53:31,374 --> 00:53:32,876
The first one is "Quality"

1630
00:53:32,876 --> 00:53:35,170
It determines the curvature of space-time

1631
00:53:35,170 --> 00:53:36,713
The second is "angular momentum"

1632
00:53:36,713 --> 00:53:38,673
Equivalent to the degree of rotation of a black hole

1633
00:53:38,673 --> 00:53:40,425
like a rapidly rotating sphere

1634
00:53:40,425 --> 00:53:42,052
Will stir up surrounding water flow

1635
00:53:42,052 --> 00:53:44,596
The rotation of a black hole also drags nearby space-time with it

1636
00:53:44,596 --> 00:53:46,514
allows us to push back the angular momentum

1637
00:53:46,514 --> 00:53:48,350
The third one is the total charge

1638
00:53:48,350 --> 00:53:50,602
After all the charged particles fall into the black hole

1639
00:53:50,602 --> 00:53:53,688
Although the arrangement and movement of each other will be forgotten

1640
00:53:53,688 --> 00:53:56,942
But the overall charge will still be retained in the form of an electric field

1641
00:53:56,942 --> 00:53:58,360
As for other physical quantities

1642
00:53:58,360 --> 00:54:00,779
Neither can leave traces outside the black hole.

1643
00:54:00,779 --> 00:54:01,404
For example, magnetic field

1644
00:54:01,404 --> 00:54:03,156
Because it is a product of charged particles

1645
00:54:03,156 --> 00:54:04,324
rather than the charge itself

1646
00:54:04,324 --> 00:54:05,951
will eventually be erased

1647
00:54:06,159 --> 00:54:08,328
In short, once matter falls into a black hole,

1648
00:54:08,328 --> 00:54:11,039
All information will be swallowed up by the event horizon

1649
00:54:11,039 --> 00:54:13,208
Only mass, charge, and angular momentum remain

1650
00:54:13,208 --> 00:54:14,542
Three numbers can describe

1651
00:54:14,542 --> 00:54:15,543
say it again

1652
00:54:15,543 --> 00:54:16,962
All matter that falls into

1653
00:54:16,962 --> 00:54:18,213
Contains the black hole itself

1654
00:54:18,213 --> 00:54:20,006
No matter it was Pikachu in life

1655
00:54:20,006 --> 00:54:21,800
Godzilla or the whole earth

1656
00:54:21,800 --> 00:54:24,678
Eventually all "features" will cease to exist

1657
00:54:24,678 --> 00:54:26,513
It won't be a sphere, a cube

1658
00:54:26,513 --> 00:54:29,057
There won't be any lines or bulges

1659
00:54:29,057 --> 00:54:30,892
From the appearance, the entire black hole

1660
00:54:30,892 --> 00:54:32,727
It's extremely symmetrical and smooth

1661
00:54:32,727 --> 00:54:35,313
An abyss without any texture

1662
00:54:35,313 --> 00:54:36,606
not a hair

1663
00:54:36,606 --> 00:54:38,400
This is the "hairless theorem" of black holes

1664
00:54:38,400 --> 00:54:39,484
in daily life

1665
00:54:39,484 --> 00:54:40,735
Matter often does not "disappear"

1666
00:54:40,735 --> 00:54:42,153
But to change the "form"

1667
00:54:42,153 --> 00:54:45,282
For example, a piece of paper will not completely disappear after it is burned.

1668
00:54:45,282 --> 00:54:47,325
and will be converted into heat and ashes

1669
00:54:47,325 --> 00:54:50,078
When you press the "Permanently Delete" button on a mobile phone photo

1670
00:54:50,078 --> 00:54:51,663
The information still exists

1671
00:54:51,663 --> 00:54:52,998
Just turned into another kind

1672
00:54:52,998 --> 00:54:54,833
forms we may not recognize

1673
00:54:54,833 --> 00:54:57,419
In quantum mechanics, there is "positive property"

1674
00:54:57,419 --> 00:54:58,795
What does this mean?

1675
00:54:58,795 --> 00:54:59,587
do you remember

1676
00:54:59,587 --> 00:55:01,423
Mentioned in the first season of the Quantum Bear series

1677
00:55:01,423 --> 00:55:03,925
We usually cannot describe an electron accurately

1678
00:55:03,925 --> 00:55:06,303
at an exact location at an exact time

1679
00:55:06,303 --> 00:55:08,263
It must be expressed in terms of wave functions

1680
00:55:08,263 --> 00:55:11,266
You can imagine the probability of it appearing in different places

1681
00:55:11,266 --> 00:55:13,893
But no matter how the wave function evolves with time

1682
00:55:13,893 --> 00:55:15,478
That is, electrons are running around

1683
00:55:15,478 --> 00:55:17,105
When interacting with other things

1684
00:55:17,105 --> 00:55:19,941
The sum of the probabilities that it appears in the same space

1685
00:55:19,941 --> 00:55:22,110
It always has to be 100%

1686
00:55:22,110 --> 00:55:24,404
Just like a piece of clay no matter how you knead it

1687
00:55:24,404 --> 00:55:25,488
change its shape

1688
00:55:25,488 --> 00:55:27,574
Its total weight is still the same

1689
00:55:27,574 --> 00:55:30,785
And as long as you know how to knead the clay beforehand

1690
00:55:30,785 --> 00:55:32,120
we can always predict

1691
00:55:32,120 --> 00:55:34,289
What shape did this piece of clay take?

1692
00:55:34,289 --> 00:55:36,666
On the contrary, if we know what the finished product looks like

1693
00:55:36,666 --> 00:55:38,460
and how it was kneaded

1694
00:55:38,460 --> 00:55:41,296
We can go back to what the clay looked like in the beginning

1695
00:55:41,296 --> 00:55:43,548
This is the "reversibility" of quantum mechanics

1696
00:55:43,548 --> 00:55:44,466
It means

1697
00:55:44,466 --> 00:55:46,301
As long as we know the current state

1698
00:55:46,301 --> 00:55:48,720
You will definitely be able to know the previous status

1699
00:55:48,720 --> 00:55:51,056
Even if you burn a file to ashes

1700
00:55:51,056 --> 00:55:53,683
Or be turned into ashes by Thanos' snap of his fingers

1701
00:55:53,683 --> 00:55:56,519
If you had the ability to control every particle in smoke

1702
00:55:56,519 --> 00:55:58,605
Energy, position, etc.

1703
00:55:58,605 --> 00:56:01,733
"Theoretically" it can still be reconstructed back to its original appearance.

1704
00:56:01,733 --> 00:56:03,610
Of course, it’s almost impossible in terms of difficulty

1705
00:56:03,610 --> 00:56:06,738
So positivity and reversibility tell us

1706
00:56:06,738 --> 00:56:07,947
in quantum mechanics

1707
00:56:07,947 --> 00:56:09,532
Information is conserved

1708
00:56:09,532 --> 00:56:10,950
it's like a piece of clay

1709
00:56:10,950 --> 00:56:12,452
In the process of kneading

1710
00:56:12,452 --> 00:56:15,205
The total mass should be consistent from beginning to end

1711
00:56:15,205 --> 00:56:16,331
But here comes the point

1712
00:56:16,331 --> 00:56:18,166
If black holes are really that scary

1713
00:56:18,166 --> 00:56:19,918
That’s what the hairless theorem says.

1714
00:56:19,918 --> 00:56:22,379
Ability to "format" all information

1715
00:56:22,379 --> 00:56:24,923
Only mass, charge, and angular momentum are left

1716
00:56:24,923 --> 00:56:28,551
Is there any way we can go back to what this object originally looked like?

1717
00:56:28,551 --> 00:56:30,553
If the information really disappears

1718
00:56:30,553 --> 00:56:33,223
Does it mean that black holes violate quantum mechanics?

1719
00:56:33,223 --> 00:56:35,433
Let’s wait a moment. Let’s talk about the increase or decrease of information.

1720
00:56:35,433 --> 00:56:37,143
I have to mention that in the movie Tianneng

1721
00:56:37,143 --> 00:56:38,436
the most important word

1722
00:56:38,436 --> 00:56:39,020
entropy

1723
00:56:39,020 --> 00:56:40,814
Controlling entropy in Tianneng

1724
00:56:40,814 --> 00:56:42,440
can control the flow of time

1725
00:56:42,440 --> 00:56:43,441
Reverse time and space

1726
00:56:43,441 --> 00:56:44,442
so-called entropy

1727
00:56:44,442 --> 00:56:46,444
is used to describe the microscopic scale

1728
00:56:46,444 --> 00:56:48,321
The degree of particle chaos and disorder

1729
00:56:48,321 --> 00:56:49,948
In the second law of thermodynamics

1730
00:56:49,948 --> 00:56:52,158
"Entropy" in an isolated system does not decrease

1731
00:56:52,158 --> 00:56:53,743
From a macro perspective

1732
00:56:53,743 --> 00:56:55,829
Like coffee spilled on the floor

1733
00:56:55,829 --> 00:56:59,707
Its entropy will be much greater than the original state in the cup on the table.

1734
00:56:59,707 --> 00:57:02,627
And it must "automatically return" from a high-entropy state to a low-entropy state.

1735
00:57:02,627 --> 00:57:03,711
is impossible

1736
00:57:03,711 --> 00:57:06,714
Your room is safe without outside intervention from your mother.

1737
00:57:06,714 --> 00:57:07,715
It will only get messier

1738
00:57:07,715 --> 00:57:08,550
It won't happen suddenly

1739
00:57:08,550 --> 00:57:10,677
Clothes and books automatically return to the cabinet

1740
00:57:10,844 --> 00:57:12,512
Flowers will wither and people will age

1741
00:57:12,512 --> 00:57:13,555
Steel bars can also rust

1742
00:57:13,596 --> 00:57:15,515
If we look at these from a microscopic perspective

1743
00:57:15,515 --> 00:57:16,266
you will find

1744
00:57:16,266 --> 00:57:18,685
Time always moves in the direction of "disorder"

1745
00:57:18,685 --> 00:57:21,896
The second law of thermodynamics is also called the "entropy increase theorem"

1746
00:57:21,896 --> 00:57:24,649
But what does entropy have to do with black holes?

1747
00:57:24,649 --> 00:57:27,485
I just said that after burning a file to ashes

1748
00:57:27,485 --> 00:57:30,238
It would be impossible to restore it and rebuild it.

1749
00:57:30,238 --> 00:57:32,323
This is actually the result of "entropy increase"

1750
00:57:32,323 --> 00:57:34,075
Same thing when falling into a black hole

1751
00:57:34,075 --> 00:57:35,785
The more information is destroyed

1752
00:57:35,785 --> 00:57:37,078
The more entropy

1753
00:57:37,078 --> 00:57:38,746
So you can take the "entropy" of a black hole

1754
00:57:38,746 --> 00:57:41,249
Think of it as the amount of “information” falling into a black hole

1755
00:57:41,249 --> 00:57:43,877
Since black holes can swallow all kinds of things

1756
00:57:43,877 --> 00:57:45,587
The accumulated entropy must be very high.

1757
00:57:45,587 --> 00:57:47,547
However, the hairless theorem says

1758
00:57:47,547 --> 00:57:48,965
Black holes are so smooth

1759
00:57:48,965 --> 00:57:52,427
The information that went in only left mass, charge, and angular momentum.

1760
00:57:52,427 --> 00:57:53,803
The rest are destroyed

1761
00:57:53,803 --> 00:57:56,890
Can a black hole be so powerful that it can destroy "entropy"?

1762
00:57:56,890 --> 00:57:58,475
Does it violate the second law of thermodynamics?

1763
00:57:58,475 --> 00:57:59,267
Black hole, black hole

1764
00:57:59,267 --> 00:58:00,935
Physicists really don’t understand you

1765
00:58:00,935 --> 00:58:03,021
In order to solve this difficult problem

1766
00:58:03,021 --> 00:58:04,189
That man took action

1767
00:58:04,189 --> 00:58:04,981
It is love...

1768
00:58:04,981 --> 00:58:05,857
Wrong

1769
00:58:05,857 --> 00:58:07,108
This time it's another man

1770
00:58:07,108 --> 00:58:08,610
Hawking

1771
00:58:13,114 --> 00:58:14,115
To understand black holes

1772
00:58:14,115 --> 00:58:16,784
Physicists have invested in the study of "black hole thermodynamics"

1773
00:58:16,784 --> 00:58:19,954
If black holes can really swallow up entropy

1774
00:58:19,954 --> 00:58:22,165
Black holes violate the second law of thermodynamics

1775
00:58:22,165 --> 00:58:23,208
But if we think

1776
00:58:23,208 --> 00:58:25,251
Black holes do not violate this iron law

1777
00:58:25,251 --> 00:58:28,129
This means that there will be very high entropy inside the black hole.

1778
00:58:28,129 --> 00:58:29,297
However, according to thermodynamics

1779
00:58:29,297 --> 00:58:30,840
Objects with entropy

1780
00:58:30,840 --> 00:58:32,967
should release blackbody radiation

1781
00:58:32,967 --> 00:58:35,178
But not even light can escape from a black hole

1782
00:58:35,178 --> 00:58:37,263
We cannot observe blackbody radiation at all

1783
00:58:37,263 --> 00:58:38,556
Isn't this a contradiction?

1784
00:58:38,556 --> 00:58:41,935
Stephen Hawking calculated the solution in 1974

1785
00:58:41,935 --> 00:58:45,271
Hawking said: Black holes do emit radiation

1786
00:58:45,271 --> 00:58:46,940
You may have heard this saying

1787
00:58:46,940 --> 00:58:48,191
According to quantum field theory

1788
00:58:48,191 --> 00:58:49,317
at microscopic scale

1789
00:58:49,317 --> 00:58:51,653
There are always particles and antiparticles in the vacuum

1790
00:58:51,653 --> 00:58:54,322
Create and annihilate instantly in pairs

1791
00:58:54,322 --> 00:58:56,282
We can imagine these "virtual particle pairs"

1792
00:58:56,282 --> 00:58:58,618
Possibly electrons and positrons

1793
00:58:58,618 --> 00:58:59,827
or a pair of photons

1794
00:58:59,827 --> 00:59:00,995
They come out of nothing

1795
00:59:00,995 --> 00:59:02,455
But it will disappear instantly

1796
00:59:02,455 --> 00:59:04,749
This phenomenon occurs throughout space

1797
00:59:04,749 --> 00:59:06,417
Of course, it also includes the vicinity of black holes

1798
00:59:06,417 --> 00:59:08,169
If there is exactly a pair of virtual particles

1799
00:59:08,169 --> 00:59:10,046
Appears at the edge of the event horizon

1800
00:59:10,046 --> 00:59:12,173
One of the particles falls into the black hole

1801
00:59:12,173 --> 00:59:14,050
Another particle escapes

1802
00:59:14,050 --> 00:59:16,344
then this will appear to outside observers

1803
00:59:16,344 --> 00:59:17,804
form a radiation phenomenon

1804
00:59:17,804 --> 00:59:18,846
use this method

1805
00:59:18,846 --> 00:59:20,640
Black holes can continuously generate radiation

1806
00:59:20,640 --> 00:59:21,724
and send out

1807
00:59:21,724 --> 00:59:23,851
Keep black holes from violating the second law of thermodynamics

1808
00:59:23,851 --> 00:59:25,937
This radiation is "Hawking radiation"

1809
00:59:25,937 --> 00:59:27,230
But please pay special attention to

1810
00:59:27,230 --> 00:59:30,024
"The virtual particle pair is torn apart" This explanation

1811
00:59:30,024 --> 00:59:31,943
It was not Hawking’s original theory.

1812
00:59:31,943 --> 00:59:34,320
But in order to let the public understand this phenomenon, later generations

1813
00:59:34,320 --> 00:59:36,781
an intuitive metaphor proposed by

1814
00:59:36,781 --> 00:59:38,866
Although it’s easy to understand, it’s also a bit misleading.

1815
00:59:38,866 --> 00:59:41,452
In fact, Hawking started from quantum field theory

1816
00:59:41,452 --> 00:59:43,830
Calculating the behavior of quantum fields in black hole spacetime

1817
00:59:43,830 --> 00:59:45,540
He discovered that outside observers

1818
00:59:45,540 --> 00:59:47,959
You will see a stream of particles similar to blackbody radiation appearing.

1819
00:59:47,959 --> 00:59:49,252
In quantum field theory

1820
00:59:49,252 --> 00:59:51,629
"Vacuum" is not a blank space where there is nothing

1821
00:59:51,629 --> 00:59:53,548
but a superficial stillness

1822
00:59:53,548 --> 00:59:56,342
A field actually filled with tiny quantum fluctuations

1823
00:59:56,342 --> 00:59:59,762
These fluctuations consist of vibrational modes of the quantum field

1824
00:59:59,762 --> 01:00:02,223
Divided into positive frequency and negative frequency

1825
01:00:02,223 --> 01:00:05,059
Positive frequency modes can be regarded as "matter particles"

1826
01:00:05,059 --> 01:00:08,187
Negative frequency mode can be understood as "antimatter particles"

1827
01:00:08,187 --> 01:00:09,439
in flat space and time

1828
01:00:09,439 --> 01:00:12,483
These positive and negative modes balance and cancel each other out

1829
01:00:12,483 --> 01:00:14,569
So a vacuum looks "empty"

1830
01:00:14,569 --> 01:00:16,070
However, when a black hole forms

1831
01:00:16,070 --> 01:00:18,531
The surrounding space-time bends violently

1832
01:00:18,531 --> 01:00:19,741
This balance is destroyed

1833
01:00:19,741 --> 01:00:21,618
Especially near the event horizon

1834
01:00:21,618 --> 01:00:22,744
partial vibration modes

1835
01:00:22,744 --> 01:00:25,371
Will be "scattered" into the interior of the black hole by the geometry of space and time

1836
01:00:25,371 --> 01:00:27,248
while other modes are able to escape

1837
01:00:27,248 --> 01:00:28,916
This leads to the original vacuum

1838
01:00:28,916 --> 01:00:30,627
in the eyes of a distant observer

1839
01:00:30,627 --> 01:00:31,753
No longer "empty"

1840
01:00:31,753 --> 01:00:33,421
Instead, particle flow appears

1841
01:00:33,421 --> 01:00:35,089
That is what thermal radiation looks like

1842
01:00:35,089 --> 01:00:36,924
Therefore the nature of Hawking radiation

1843
01:00:36,924 --> 01:00:39,052
It's not a particle jumping out of the black hole's surface

1844
01:00:39,052 --> 01:00:40,303
But the curvature of space-time

1845
01:00:40,303 --> 01:00:43,389
Let the vibration patterns of the entire quantum vacuum recombine

1846
01:00:43,389 --> 01:00:44,766
observe from a distance

1847
01:00:44,766 --> 01:00:46,267
It's like a black hole is glowing

1848
01:00:46,267 --> 01:00:47,602
Hawking also derived

1849
01:00:47,602 --> 01:00:49,187
The wavelength of Hawking radiation

1850
01:00:49,187 --> 01:00:50,647
Related to black hole size

1851
01:00:50,647 --> 01:00:53,191
Small black holes emit high-energy short-wavelength radiation

1852
01:00:53,191 --> 01:00:55,318
Large black holes emit long wavelengths

1853
01:00:55,318 --> 01:00:56,611
low energy radiation

1854
01:00:56,611 --> 01:00:59,030
It looks cooler and radiates slower

1855
01:00:59,030 --> 01:01:02,116
But since this radiation releases energy from the black hole

1856
01:01:02,116 --> 01:01:04,452
Energy comes from mass

1857
01:01:04,744 --> 01:01:08,081
That means the mass of the black hole will slowly decrease over time.

1858
01:01:08,581 --> 01:01:10,792
You can't always get money from the bank

1859
01:01:10,792 --> 01:01:13,127
The amount in the account has not decreased at all, right?

1860
01:01:13,127 --> 01:01:13,961
This also means

1861
01:01:13,961 --> 01:01:17,465
When the mass of a black hole slowly decreases due to the emission of Hawking radiation

1862
01:01:17,465 --> 01:01:19,467
will eventually disappear

1863
01:01:19,467 --> 01:01:22,470
This process is like being evaporated bit by bit

1864
01:01:22,470 --> 01:01:24,305
Therefore it is called "black hole evaporation"

1865
01:01:24,305 --> 01:01:25,932
Of course, due to the evaporation process

1866
01:01:25,932 --> 01:01:28,267
Quantum fluctuations from the microscopic scale

1867
01:01:28,267 --> 01:01:30,395
It will take quite a long time

1868
01:01:30,395 --> 01:01:32,814
Approximately 1 followed by 66 zeros

1869
01:01:32,814 --> 01:01:35,108
to 90 and so many years

1870
01:01:35,108 --> 01:01:38,027
The more massive the black hole, the longer it will take

1871
01:01:38,027 --> 01:01:39,987
"Hawking Radiation" can be said to be Hawking himself

1872
01:01:39,987 --> 01:01:41,823
The most important research results of my life

1873
01:01:41,823 --> 01:01:43,950
This also made physicists begin to realize

1874
01:01:43,950 --> 01:01:46,285
Some unexplainable properties of black holes

1875
01:01:46,285 --> 01:01:48,079
May need to be combined with general relativity

1876
01:01:48,079 --> 01:01:50,081
Let’s answer it with quantum mechanics

1877
01:01:50,081 --> 01:01:51,541
Back to the original question

1878
01:01:51,541 --> 01:01:54,669
Hawking radiation solves black hole entropy problem

1879
01:01:54,669 --> 01:01:56,921
But what this can tell us about falling into a black hole

1880
01:01:56,921 --> 01:01:58,172
Where did you go?

1881
01:02:02,343 --> 01:02:03,261
you might say

1882
01:02:03,261 --> 01:02:05,138
Since black holes emit radiation

1883
01:02:05,138 --> 01:02:06,347
So the information that fell in

1884
01:02:06,347 --> 01:02:08,474
Otherwise, Hawking radiation will be released.

1885
01:02:08,474 --> 01:02:10,560
It's like burning the files to ashes

1886
01:02:10,560 --> 01:02:13,020
The information still exists, it just changed its form.

1887
01:02:13,020 --> 01:02:13,688
right

1888
01:02:13,688 --> 01:02:14,689
But don't forget

1889
01:02:14,689 --> 01:02:17,483
Hawking radiation releases particles from black holes

1890
01:02:17,483 --> 01:02:18,526
But these particles

1891
01:02:18,526 --> 01:02:21,821
It does not come directly from the matter that originally fell into the black hole.

1892
01:02:21,821 --> 01:02:24,490
But it comes from the space and time near the event horizon

1893
01:02:24,490 --> 01:02:26,117
Rearrangement of quantum fields

1894
01:02:26,117 --> 01:02:28,703
Let us see particles "appear out of thin air"

1895
01:02:28,703 --> 01:02:31,539
In other words, even if Hawking radiation really exists

1896
01:02:31,539 --> 01:02:34,959
What is radiated is not the information that was once devoured.

1897
01:02:34,959 --> 01:02:38,546
So where does the information that falls into the black hole go?

1898
01:02:38,546 --> 01:02:41,215
This is still the problem of the "Black Hole Information Paradox"

1899
01:02:41,215 --> 01:02:42,508
early 1970s

1900
01:02:42,508 --> 01:02:44,093
Hawking's theory of general relativity

1901
01:02:44,093 --> 01:02:46,596
Proved an important fact about black holes

1902
01:02:46,596 --> 01:02:48,181
When two black holes merge

1903
01:02:48,181 --> 01:02:50,975
The event horizon area of the new black hole after the merger

1904
01:02:50,975 --> 01:02:52,226
Must not be less than

1905
01:02:52,226 --> 01:02:55,605
It turns out that the sum of the individual areas of the event horizons of the two black holes

1906
01:02:55,605 --> 01:02:58,399
This may be a little different from what you usually encounter

1907
01:02:58,399 --> 01:03:01,194
For example, after two drops of rain fuse,

1908
01:03:01,194 --> 01:03:02,945
Total surface area may be reduced

1909
01:03:02,945 --> 01:03:04,197
is it important

1910
01:03:04,197 --> 01:03:06,574
This is very important for physicists

1911
01:03:06,574 --> 01:03:08,451
This means that the black hole has some kind of

1912
01:03:08,451 --> 01:03:09,994
properties that never decrease

1913
01:03:09,994 --> 01:03:12,079
This property is found in thermodynamics

1914
01:03:12,079 --> 01:03:13,623
We have long been familiar with each other

1915
01:03:13,623 --> 01:03:16,000
It is the "entropy" mentioned just now

1916
01:03:16,000 --> 01:03:17,835
The second law of thermodynamics tells us

1917
01:03:17,835 --> 01:03:20,963
The entropy of a closed system will only increase, not decrease.

1918
01:03:21,255 --> 01:03:21,964
At this time

1919
01:03:21,964 --> 01:03:24,258
Another physicist who lived at the same time as Hawking

1920
01:03:24,258 --> 01:03:25,802
Jacob Bekenstein

1921
01:03:25,802 --> 01:03:27,428
He boldly proposed an idea

1922
01:03:27,428 --> 01:03:29,847
Entropy that falls into a black hole does not disappear

1923
01:03:29,847 --> 01:03:30,890
it exists

1924
01:03:30,890 --> 01:03:33,893
and is proportional to the surface area of the event horizon

1925
01:03:33,893 --> 01:03:36,103
This idea corresponds to the second law of thermodynamics

1926
01:03:36,103 --> 01:03:38,606
Known as the "Second Law of Black Hole Thermodynamics"

1927
01:03:38,606 --> 01:03:39,565
Think about it

1928
01:03:39,565 --> 01:03:42,068
When you drop a cup of hot coffee into a black hole

1929
01:03:42,068 --> 01:03:43,027
After being swallowed by a black hole

1930
01:03:43,027 --> 01:03:46,113
The “visible” entropy of our universe has indeed decreased

1931
01:03:46,113 --> 01:03:48,241
But because the black hole swallowed the coffee

1932
01:03:48,241 --> 01:03:49,659
its mass increases

1933
01:03:49,951 --> 01:03:52,286
As the mass increases, the radius of the black hole increases

1934
01:03:52,286 --> 01:03:54,747
The surface area of the event horizon will also increase

1935
01:03:54,747 --> 01:03:56,541
If this increased surface area

1936
01:03:56,541 --> 01:03:58,626
is equivalent to the increased entropy of the black hole

1937
01:03:58,626 --> 01:04:00,670
Then as long as this increased "black hole entropy"

1938
01:04:00,670 --> 01:04:03,548
Greater than or equal to the entropy of coffee itself

1939
01:04:03,548 --> 01:04:06,676
Then the total entropy of the universe will never decrease.

1940
01:04:06,676 --> 01:04:08,427
Wow, we can safely say

1941
01:04:08,427 --> 01:04:09,637
second law of thermodynamics

1942
01:04:09,637 --> 01:04:11,430
can continue to apply to the entire universe

1943
01:04:11,430 --> 01:04:12,974
But this is actually weird

1944
01:04:12,974 --> 01:04:13,516
you see

1945
01:04:13,516 --> 01:04:15,226
The storage capacity of your wardrobe

1946
01:04:15,226 --> 01:04:17,144
It should be proportional to the volume, right?

1947
01:04:17,144 --> 01:04:18,479
rather than surface area

1948
01:04:18,479 --> 01:04:19,522
If the entropy of a black hole

1949
01:04:19,522 --> 01:04:21,858
Proportional to the "surface area" of the black hole's event horizon

1950
01:04:21,858 --> 01:04:22,942
this may mean

1951
01:04:22,942 --> 01:04:24,485
Information falling into a black hole

1952
01:04:24,485 --> 01:04:27,363
Probably stored on the surface of the event horizon

1953
01:04:27,363 --> 01:04:28,656
rather than in a black hole

1954
01:04:28,656 --> 01:04:30,825
If the universe really works like this

1955
01:04:30,825 --> 01:04:33,035
Then the black hole information paradox can be solved

1956
01:04:33,035 --> 01:04:34,829
Remember what we mentioned in the last episode

1957
01:04:34,829 --> 01:04:36,038
if you fall into a black hole

1958
01:04:36,038 --> 01:04:37,331
will anything happen

1959
01:04:37,331 --> 01:04:39,166
To an observer outside the black hole

1960
01:04:39,166 --> 01:04:40,501
Object falling into a black hole

1961
01:04:40,501 --> 01:04:42,128
will "stay" on the horizon surface

1962
01:04:42,128 --> 01:04:44,088
until redshifted and gradually erased

1963
01:04:44,088 --> 01:04:44,922
now

1964
01:04:44,922 --> 01:04:47,800
We reconsider the observer's perspective and the faller's perspective

1965
01:04:47,800 --> 01:04:49,468
Applying to the black hole information paradox

1966
01:04:49,468 --> 01:04:50,469
Then it will be

1967
01:04:50,469 --> 01:04:52,305
to outside observers

1968
01:04:52,305 --> 01:04:54,932
Information falling into a black hole appears to be frozen

1969
01:04:54,932 --> 01:04:57,018
Encoded on the event horizon surface

1970
01:04:57,018 --> 01:04:58,853
Then through Hawking radiation

1971
01:04:58,853 --> 01:05:01,480
Gradually release information back out of the black hole

1972
01:05:01,480 --> 01:05:03,190
So it does not violate the information paradox

1973
01:05:03,190 --> 01:05:04,734
Or the second law of thermodynamics

1974
01:05:04,734 --> 01:05:06,694
What about an observer falling into a black hole?

1975
01:05:06,694 --> 01:05:09,780
Information will also follow itself and objects across the horizon

1976
01:05:09,780 --> 01:05:11,032
Entering the inside of a black hole

1977
01:05:11,032 --> 01:05:12,700
won't violate anything

1978
01:05:12,700 --> 01:05:14,410
Two perspectives, internal and external, are "complementary"

1979
01:05:14,410 --> 01:05:16,162
That is, information comes in different forms

1980
01:05:16,162 --> 01:05:18,915
Exist simultaneously in the world of different observers

1981
01:05:18,915 --> 01:05:20,041
never disappear

1982
01:05:20,041 --> 01:05:21,375
This seems like a perfect explanation

1983
01:05:21,375 --> 01:05:23,711
The theory of what happens to information that falls into a black hole

1984
01:05:23,711 --> 01:05:26,005
Also known as the black hole complementarity principle

1985
01:05:26,005 --> 01:05:29,008
At this point, the problem of black hole information seems to be solved.

1986
01:05:29,008 --> 01:05:31,552
Physicists can lie down and sleep peacefully again

1987
01:05:31,552 --> 01:05:33,054
Appreciate this although it is mysterious

1988
01:05:33,054 --> 01:05:34,221
But cleverly designed

1989
01:05:34,221 --> 01:05:36,057
Amazingly beautiful universe

1990
01:05:36,057 --> 01:05:36,891
wait a moment

1991
01:05:36,891 --> 01:05:37,975
Physicists think of this

1992
01:05:37,975 --> 01:05:39,310
How could I possibly sleep?

1993
01:05:39,310 --> 01:05:40,561
This new perspective

1994
01:05:40,561 --> 01:05:42,730
It seems to rewrite our understanding of the universe

1995
01:05:42,730 --> 01:05:44,523
Even the meaning of our existence

1996
01:05:44,523 --> 01:05:46,233
We originally thought the "inside" of a black hole

1997
01:05:46,233 --> 01:05:47,693
All information is saved before

1998
01:05:47,693 --> 01:05:50,780
But after Bekenstein’s second law of black hole thermodynamics was proposed,

1999
01:05:50,780 --> 01:05:53,032
We know that black holes appear to be three-dimensional

2000
01:05:53,032 --> 01:05:56,077
But only stores all the information on the two-dimensional surface

2001
01:05:56,077 --> 01:05:57,578
All information that falls into a black hole

2002
01:05:57,578 --> 01:06:00,081
should be able to be saved within some sort of boundary

2003
01:06:00,081 --> 01:06:02,875
This concept was first proposed by Gerard Hooft

2004
01:06:02,875 --> 01:06:04,752
Proposed around 1993

2005
01:06:04,752 --> 01:06:06,587
Then Leonardo Suskan

2006
01:06:06,587 --> 01:06:08,756
Combining black hole thermodynamics and string theory

2007
01:06:08,756 --> 01:06:10,424
Formally proposed the "Holographic Principle"

2008
01:06:10,424 --> 01:06:12,468
Terre Hooft was a Nobel Prize winner

2009
01:06:12,468 --> 01:06:14,804
Suskan is one of the founders of string theory

2010
01:06:14,804 --> 01:06:16,931
Both are big names in theoretical physics.

2011
01:06:16,931 --> 01:06:18,933
His academic contribution is no less than that of Hawking

2012
01:06:18,933 --> 01:06:21,102
The holographic principle makes a bold guess

2013
01:06:21,102 --> 01:06:22,770
Will it be more than just black holes?

2014
01:06:22,770 --> 01:06:26,232
Our universe itself has a similar information encoding structure.

2015
01:06:26,232 --> 01:06:28,776
It's like a "hologram" covering the universe

2016
01:06:28,776 --> 01:06:31,779
Can project 2D information into 3D form

2017
01:06:31,779 --> 01:06:35,616
All 3D information is actually encoded in 2D photos

2018
01:06:35,616 --> 01:06:37,284
Don’t you know what’s so scary about this?

2019
01:06:37,284 --> 01:06:38,494
Vernacular means

2020
01:06:38,494 --> 01:06:39,620
real world

2021
01:06:39,620 --> 01:06:42,498
May only exist on the outer surface of the universe

2022
01:06:42,498 --> 01:06:43,624
is two-dimensional

2023
01:06:43,624 --> 01:06:46,544
The "three-dimensional" reality we usually experience

2024
01:06:46,544 --> 01:06:49,130
May just come from the outer boundary of the "two-dimensional" universe

2025
01:06:49,130 --> 01:06:50,631
The projection of this plane

2026
01:06:50,631 --> 01:06:52,883
This is why Hawking wrote the

2027
01:06:52,883 --> 01:06:56,178
"The Universe in a Nut" raises questions at the end of the book

2028
01:06:56,178 --> 01:06:58,389
Are we just a set of holograms?

2029
01:06:58,806 --> 01:07:00,307
Sounds crazy, right?

2030
01:07:00,307 --> 01:07:02,059
But this idea is not metaphysics

2031
01:07:02,059 --> 01:07:04,103
Have mathematical foundation and theoretical model

2032
01:07:04,103 --> 01:07:05,771
Do you think this is really the case?

2033
01:07:05,771 --> 01:07:07,023
As for other physicists

2034
01:07:07,023 --> 01:07:08,899
A crazier view of the universe

2035
01:07:08,899 --> 01:07:11,652
We will introduce it in detail in future programs

2036
01:07:11,652 --> 01:07:13,571
Leave a message first and tell us what you think.

2037
01:07:14,113 --> 01:07:15,698
From the foundation of general relativity

2038
01:07:15,698 --> 01:07:17,491
Black hole entropy and Hawking radiation

2039
01:07:17,491 --> 01:07:19,535
Let’s go to the holographic principle introduced today

2040
01:07:19,535 --> 01:07:21,871
This isn't just our attempt to understand black holes

2041
01:07:21,871 --> 01:07:24,165
It’s how physicists understand the universe

2042
01:07:24,165 --> 01:07:25,624
and the search for relativity

2043
01:07:25,624 --> 01:07:29,003
The process of whether quantum mechanics can be integrated into a "unified theory"

2044
01:07:29,003 --> 01:07:31,881
Where does information that falls into a black hole go?

2045
01:07:31,881 --> 01:07:33,549
This seemingly simple question

2046
01:07:33,549 --> 01:07:36,010
But it may explain why we can exist

2047
01:07:36,010 --> 01:07:37,344
This time the Quantum Bear series

2048
01:07:37,344 --> 01:07:38,888
Let's start from a different angle

2049
01:07:38,888 --> 01:07:40,514
Not from quantum mechanics itself

2050
01:07:40,514 --> 01:07:42,933
But all the way from the proposal of the theory of relativity

2051
01:07:42,933 --> 01:07:46,771
Finally coming face to face with quantum mechanics at the event horizon of a black hole

2052
01:07:46,771 --> 01:07:48,355
Look at the differences between different theories

2053
01:07:48,355 --> 01:07:50,357
Are there any contradictions?

2054
01:07:50,524 --> 01:07:53,527
And how much is missing from our understanding of the world?

2055
01:07:53,527 --> 01:07:55,196
But it's not over yet

2056
01:07:55,196 --> 01:07:57,364
It seems that we have just emerged from the entrance of a black hole

2057
01:07:57,364 --> 01:07:58,866
Glimpse into the mysteries of the universe

2058
01:07:58,866 --> 01:08:01,285
And it seems like the black hole itself

2059
01:08:01,285 --> 01:08:02,995
It also hides the endless reality of the universe

2060
01:08:02,995 --> 01:08:04,538
waiting for us to find out

2061
01:08:04,538 --> 01:08:06,415
Is there an exit from a black hole?

2062
01:08:06,415 --> 01:08:08,375
Is there really a white hole?

2063
01:08:08,375 --> 01:08:10,377
Are there wormholes in the universe?

2064
01:08:10,377 --> 01:08:13,214
Can create connections across time, space, and the universe

2065
01:08:13,214 --> 01:08:15,216
Can we go inside a massive black hole?

2066
01:08:15,216 --> 01:08:18,094
Build a civilized city or find alien life

2067
01:08:18,094 --> 01:08:19,220
And the most important thing

2068
01:08:19,220 --> 01:08:22,556
Is it possible to find a unified theory in black holes?

2069
01:08:22,556 --> 01:08:24,475
Let us fully understand this universe

2070
01:08:24,475 --> 01:08:27,103
Please continue to lock in the channels of Pan Science and Quantum Bear

2071
01:08:27,103 --> 01:08:28,729
Our journey to a black hole

2072
01:08:28,729 --> 01:08:30,189
not over yet

2073
01:08:30,189 --> 01:08:30,606
OK

2074
01:08:30,606 --> 01:08:33,067
The above is the content of the final episode of the third season of the Quantum Bear series

2075
01:08:33,067 --> 01:08:35,945
If you want to review the basics of quantum mechanics with your last breath

2076
01:08:35,945 --> 01:08:37,571
You can click here to review

2077
01:08:37,571 --> 01:08:40,574
If you want to see why quantum computers can beat traditional computers

2078
01:08:40,574 --> 01:08:41,700
You can click here

2079
01:08:41,700 --> 01:08:43,369
See you next time