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A superannuated giant
star finally explodes.
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This is a massive event that
entails a rapid shrinking
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of the dead star's core.
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In the end, it almost seems
that nothing is left
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but concentrated gravitational
force, a black hole.
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It's pole is so powerful,
it swallows up even light.
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But if neither emits nor reflects light,
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how can a black hole be found?
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In 2011, Japanese imaging equipment
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aboard the International Space Station
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detected the moment when a
black hole gulped down a star
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as large as our Sun.
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This is the image.
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On the left, a picture
taken on March 21, 2011.
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On the right, the same
area eight days later.
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A small blue dot has appeared,
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an intense burst of x-rays.
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At the moment when a star is
engulfed by a black hole,
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its temperature exceeds 10
million degrees Celsius,
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and it emits intense x-rays.
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The blue dot in the image we just saw
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represents that final burst of x-rays
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as the star was engulfed by the black hole.
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Such an event is one way
in which the presence
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of a black hole can be inferred.
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But for a long time, scientists debated
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the very existence of black holes.
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Were there really objects in space
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that could swallow up light itself?
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The opposition was, much
of it was motivated
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by the view that this object is so bizarre,
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so strange, that it's unphysical.
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And it's not likely that the true laws
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of physics will be predict such a thing.
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Now, at the leading edge of astrophysics,
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the cosmic front, scientists
are busy determining
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the exact shapes and
properties of black holes.
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How far have scientists succeeded
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in locating these invisible phenomena
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and revealing their amazing forms?
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This is a quest to find
and evaluate objects
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of endless fascination, black holes.
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A jet of water spouting
140 meters into the air.
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This is Switzerland's second
largest city, Geneva.
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In 2008, underneath this city,
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and extending into neighboring France,
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a gigantic experimental facility,
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27 kilometers in circumference was built.
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That's 50 times the
circumference of The Colosseum.
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It was operated by CERN,
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the European Organization
for Nuclear Research
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with the participation of some 20 countries
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including also, the
United States and Japan.
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This is where experiments took place
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to define a black hole by creating one.
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Pipes were laid 100 meters underground.
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Protons were accelerated
through it at high speed.
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When we get up to top energy,
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the protons are going 99.9999991
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times the speed of light.
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So very, very, very close
to the speed of light.
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And then we're, down the way,
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we're gonna collide them
inside the big experiments
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and see what we can see.
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When protons traveling
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at such blinding speed collide,
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they are smashed into infinitesimal bits.
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And at the moment of impact,
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it was thought microscopic
black holes would be produced.
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Producing black holes is
certainly a possibility.
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In many ways, a very exciting possibility.
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However, lawsuits were filed
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in Germany and the United States,
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demanding an injunction against
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such an allegedly dangerous experiment.
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The lawsuits argued that no
matter how small the black hole,
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once it started swallowing matter,
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it would become an unstoppable force.
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Eventually, so the claim went,
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our entire planet would be sucked in.
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The black hole.
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To trace its conceptual origins,
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we must go back 3 1/2 centuries
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to the time of Isaac Newton.
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Based on his Law of Universal Gravitation,
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scientists of his era came up
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with a fascinating hypothesis.
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The more massive a celestial body is,
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the stronger its gravity.
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The lighter it is, the weaker its gravity.
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So its mass determines the speed necessary
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to escape from its gravitational pull.
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For example, the speed necessary
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to escape Earth's gravity is
11 kilometers per second.
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A more massive object would require
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a faster escape velocity.
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Light travels at a speed of
300,000 kilometers per second.
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So, the more massive a star is,
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the harder it must be for
its own light to escape.
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Theoretically, there could
exist in the universe
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an object so massive, that not even light
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could escape its gravitational pull.
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If we could not see this star shine,
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it would be effectively a black star.
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That was our first conception
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of what we now call a black hole.
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Black holes were studied
more rigorously starting
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about a century ago.
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That was thanks to another
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of the great geniuses of
physics, Albert Einstein.
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It was Einstein who predicted
the curvature of space-time.
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This was his famous General
Theory of Relativity.
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Gravitational forces
distort the very fabric
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of the space-time continuum.
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The more gravitationally
powerful a star is,
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the more it distorts space-time.
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So that light, instead of following
a straight path, curves.
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A prediction confirmed
by direct observation.
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German physicist Karl Schwarzschild
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was the first to provide exact solutions
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to certain equations in Einstein's theory.
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Equations that describe the effects
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of gravity on space-time.
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Shrink a celestial object
in size but not mass.
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It's density and the curvature
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of nearby space-time relative to size,
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both increase.
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Continue shrinking it and
the space-time curvature
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increases to infinity.
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For example, if something
the size of the Sun
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were shrunk to a radius
of three kilometers,
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or the Earth to a radius
of nine millimeters,
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the curvature would be infinite.
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Light itself would be unable to escape,
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so the object would be invisible.
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That boundary is known
as the event horizon.
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It is the origin of a black hole.
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So the thinking was if subatomic particles
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were smashed into superdense bits,
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that could also create a black hole.
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But then, no matter how small,
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wouldn't such a black hole grow monterously
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engulfing everything around it?
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Eventually swallowing up the entire planet?
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That's why those lawsuits sought
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to stop the experiment in Geneva.
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Physicist John Ellis holds
that the device in Geneva,
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the Large Hadron Collider, or LHC,
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poses no danger at all.
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There's absolutely no worry
at all about black holes
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that might be produced by the LHC.
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If the LHC could make
any black holes at all,
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then cosmic rays, particles
from outer space
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that have been hitting the
Earth for billions of years,
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have been producing these black holes
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and we're still here.
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So, they can't be dangerous.
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Countless particles are constantly
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hurdling toward Earth
at the speed of light.
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And smashing to bits upon impact
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with our atmosphere,
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creating incredibly tiny black holes.
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But Ellis and other physicists argued
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that the life-span of
these tiny black holes
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is also incredibly brief.
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These arguments prevailed, and
the injunction was denied.
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What strange properties.
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The power to swallow up
anything and everything,
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but too short a life-span to do that in.
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Black holes have an even
more wondrous property.
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Professor Andrew Hamilton of
the University of Colorado
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uses computers to create and
evaluate remarkable phenomena
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involving black holes.
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The wonderful thing about
Einstein's General Relativity
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is that it is an extremely precise theory.
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It's embodied in a set of
equations which look well,
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they're just an equation
that relates curvature
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to the energy momentum
content of space-time.
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And what does it mean?
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It's a bunch of mathematics.
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But the miracle of that is
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that you can ask the mathematics questions.
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What is the structure of the space-time
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and how do things move in that space-time?
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And code that up as if you were writing
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a video game in software,
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and see what it looks like.
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This is one of Hamilton's
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computer-generated black holes.
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But the horizon of this so-called hole
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actually has the shape of a sphere.
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Map a grid of lines onto its surface,
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like those indicating Earth's
latitude and longitude
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and two points stand out.
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The black hole has a north
pole and a south pole.
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You can see the north pole and south pole
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of the grid simultaneously.
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Again, this is because the black hole
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is able to bend light around it
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so that you can see simultaneously
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the north and the south pole.
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Not something that you could see
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if you looked at the Earth, for example,
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from out in the solar system.
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Look what happens if you simply toss
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a cubicle box at a black hole.
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One would expect anything
at all to be sucked in,
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yet the box sails on by.
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Why is that so?
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This is a feature of black holes is
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that they do not suck.
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Let's go back down to the black hole here.
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They don't suck.
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If you want to throw
something into a black hole,
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you have to aim and aim carefully.
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So this time, a box
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is pitched directly at the center.
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The box twists under the stress
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of powerful gravitational forces.
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It falls towards the black hole.
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But strange phenomena continue to occur.
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One expects the box to disappear instantly
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into the black hole, but
instead it stays visible
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as it slowly falls.
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When it's finally reached the black hole,
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it seems to rest there
stuck on the surface.
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What's the explanation for that?
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As an object approaches a black hole,
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the gravitational attraction
increases rapidly.
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And according to the Theory of Relativity,
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the stronger the gravity, the
slower the passage of time.
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At the event horizon,
time actually freezes.
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As the box falls towards the black hole,
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it accelerates rapidly.
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But from the outside, time appears
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to slow down the closer the box gets.
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So eventually, the speed of the box seems
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to let up gradually.
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Finally, when it reaches the event horizon,
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the box seems to stop moving.
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As the probe approaches the horizon,
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it appears to slow down and freeze.
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Now in reality, the image would not only
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slow down and freeze, but
also become very dark.
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We would see very few photons emerging
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from this probe.
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So it would appear to fade to black.
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But, for the sake of seeing
what's happening here,
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I've kept it bright so that you can see
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the probe has become frozen on the horizon.
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A black hole is truly a
strange object in space.
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It may collapse as soon as it forms,
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yet it's powerful enough to stop time.
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00:17:04,574 --> 00:17:08,488
So how is the existence
of black holes verified?
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Doctor, what are you doing?
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I'm making a black hole.
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So a black hole of this
size would weigh roughly
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10 times what the Earth weighs.
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00:17:33,570 --> 00:17:36,403
So this would be a very,
very heavy black hole.
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00:17:39,476 --> 00:17:41,110
Kip Thorne is a physicist
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whose search for black holes
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is based on Einstein's General
Theory of Relativity.
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But he also pursues original topics
264
00:17:48,932 --> 00:17:53,073
such as time to find
wormholes and time machines.
265
00:17:58,161 --> 00:18:00,362
His interest in the
subject was first aroused
266
00:18:00,363 --> 00:18:02,197
by the intense scholarly debates
267
00:18:02,198 --> 00:18:05,523
over the very existence of black holes.
268
00:18:09,007 --> 00:18:13,100
The controversy raged for
more than half a century.
269
00:18:16,079 --> 00:18:18,647
Thorne was in direct touch
with the principle figures
270
00:18:18,648 --> 00:18:20,482
in those debates.
271
00:18:20,483 --> 00:18:23,575
He researched the entire
controversy in detail
272
00:18:23,576 --> 00:18:27,304
for the benefit of future
generations of scholars.
273
00:18:28,765 --> 00:18:32,628
There was great resistance
to the idea of black holes.
274
00:18:32,629 --> 00:18:36,291
The opposition was, much
of it was motivated
275
00:18:36,292 --> 00:18:39,435
by the view that this object
276
00:18:39,436 --> 00:18:44,340
is so bizarre, so strange
that it's unphysical.
277
00:18:44,341 --> 00:18:48,677
And it's not likely that
the true laws of physics
278
00:18:48,678 --> 00:18:51,512
will predict such a thing.
279
00:18:52,782 --> 00:18:56,683
This is Chennai on the east coast of India.
280
00:18:58,221 --> 00:19:01,557
At a college in this city in 1929,
281
00:19:01,558 --> 00:19:04,693
a young scientist first argued
for the actual existance
282
00:19:04,694 --> 00:19:07,950
of black holes in our universe,
283
00:19:11,555 --> 00:19:14,370
Subrahmanyan Chandrasekhar,
284
00:19:14,371 --> 00:19:16,372
his work at the age of 19
285
00:19:16,373 --> 00:19:18,841
on the internal structures of stars
286
00:19:18,842 --> 00:19:21,677
won him admission to the
University of Cambridge
287
00:19:21,678 --> 00:19:24,846
for post-graduate studies.
288
00:19:24,847 --> 00:19:26,816
Onboard the ship to England,
289
00:19:26,817 --> 00:19:28,917
Chandrasekhar gave some thought
290
00:19:28,918 --> 00:19:31,416
to white dwarf stars nearing the end
291
00:19:31,417 --> 00:19:34,326
of their life cycle.
292
00:19:34,327 --> 00:19:37,627
One could say that modern
black hole studies began
293
00:19:37,628 --> 00:19:41,831
with ancient white dwarfs.
294
00:19:41,832 --> 00:19:44,470
A star normally burns furiously,
295
00:19:44,471 --> 00:19:47,756
balancing gravitational
forces that could collapse it
296
00:19:47,757 --> 00:19:52,040
and explosive forces that could blow it up.
297
00:19:52,041 --> 00:19:55,545
But as its nuclear fuel is
used up, the star cools.
298
00:19:55,546 --> 00:19:58,147
And with those expansionary
pressures relenting,
299
00:19:58,148 --> 00:20:00,015
it begins to contract.
300
00:20:00,016 --> 00:20:02,184
Conventional theory held
that a star contracts
301
00:20:02,185 --> 00:20:05,754
to about twice the size of
the Earth, then it stops.
302
00:20:05,755 --> 00:20:09,550
That is what is called a white dwarf star.
303
00:20:13,430 --> 00:20:15,464
The reason why the contractions stops
304
00:20:15,465 --> 00:20:18,523
lies in the star's very atoms.
305
00:20:21,272 --> 00:20:24,740
As the star shrinks, its
atoms are compressed.
306
00:20:24,741 --> 00:20:26,809
Conventional theory held
that there are limits
307
00:20:26,810 --> 00:20:28,778
to that compression beyond which
308
00:20:28,788 --> 00:20:32,016
further shrinkage is impossible.
309
00:20:37,154 --> 00:20:39,732
This is a white dwarf star surrounded
310
00:20:39,733 --> 00:20:42,424
by an expanding nebula.
311
00:20:42,425 --> 00:20:44,914
The star, maximally compressed,
312
00:20:44,915 --> 00:20:49,282
is clearly recognizable within
a cloud of gas and dust.
313
00:20:51,401 --> 00:20:55,506
A white dwarf star is
compact and very heavy.
314
00:20:58,066 --> 00:21:00,876
In size, it may be comparable to Earth,
315
00:21:00,877 --> 00:21:03,546
but its mass is more like the Sun's.
316
00:21:03,547 --> 00:21:07,368
As if a lump of sugar weighed several tons.
317
00:21:08,619 --> 00:21:11,464
At the time of Chandrasekhar's
passage to England,
318
00:21:11,465 --> 00:21:13,375
it was thought that all stars ended
319
00:21:13,376 --> 00:21:16,274
their lives as white dwarfs.
320
00:21:21,398 --> 00:21:23,262
Chandrasekhar based his arguments
321
00:21:23,263 --> 00:21:25,701
on his calculations of
the changes undergone
322
00:21:25,702 --> 00:21:29,623
by white dwarfs as their density increased.
323
00:21:32,075 --> 00:21:34,210
His results were astounding.
324
00:21:34,211 --> 00:21:36,932
Beyond a certain mass, the white dwarfs
325
00:21:36,933 --> 00:21:39,174
shrink to infinity.
326
00:21:42,252 --> 00:21:44,319
Previous calculations held that the limit
327
00:21:44,320 --> 00:21:46,772
of a star's shrinkage would be a radius
328
00:21:46,773 --> 00:21:49,412
of 10,000 kilometers.
329
00:21:51,602 --> 00:21:54,029
But Chandrasekhar reckoned
that if a star were
330
00:21:54,030 --> 00:21:57,422
at least 1.4 times the mass of our Sun,
331
00:21:57,423 --> 00:21:58,867
it would be unable to resist
332
00:21:58,868 --> 00:22:01,270
its own gravitational pressures.
333
00:22:01,271 --> 00:22:03,161
It would completely collapse,
334
00:22:03,162 --> 00:22:06,294
and shrinkage would continue infinitely.
335
00:22:11,047 --> 00:22:14,749
This is precisely what we
now call a black hole.
336
00:22:14,750 --> 00:22:17,206
The black hole had emerged accidentally
337
00:22:17,207 --> 00:22:20,564
from a consideration of white dwarfs.
338
00:22:29,332 --> 00:22:31,233
Soon after arriving in Cambridge,
339
00:22:31,234 --> 00:22:34,771
Chandrasekhar presented a
paper on his findings.
340
00:22:40,277 --> 00:22:41,977
Cambridge was then the academic home
341
00:22:41,978 --> 00:22:45,781
of Sir Arthur Eddington, one of
the world's foremost experts
342
00:22:45,782 --> 00:22:48,721
on the internal structure of stars.
343
00:22:51,121 --> 00:22:53,526
Eddington was also famous as an explicator
344
00:22:53,527 --> 00:22:56,505
and defender of Albert
Einstein's just published
345
00:22:56,506 --> 00:22:59,526
General Theory of Relativity.
346
00:23:02,732 --> 00:23:06,501
All stars ended up as white
dwarfs, thought Eddington.
347
00:23:06,502 --> 00:23:10,039
Surprisingly, he nonetheless
praised Chandrasekhar's paper
348
00:23:10,040 --> 00:23:12,208
and promised to support it.
349
00:23:12,209 --> 00:23:14,168
But then...
350
00:23:16,076 --> 00:23:20,315
The time came when Chandra
was to present the results
351
00:23:20,316 --> 00:23:24,140
that he had to a meeting
of I think it was the,
352
00:23:25,760 --> 00:23:28,056
it may have been either
Royal Astronomical Society
353
00:23:28,057 --> 00:23:29,758
or the Royal Society of London.
354
00:23:29,759 --> 00:23:31,593
I don't recall which.
355
00:23:31,594 --> 00:23:36,298
And when he, right after
he presented the results,
356
00:23:36,299 --> 00:23:40,529
Eddington got up and
criticized them very severely.
357
00:23:42,105 --> 00:23:46,508
Eddington's rebuttal was caustic indeed.
358
00:23:46,509 --> 00:23:48,477
The eminent scientist asserted that a star
359
00:23:48,478 --> 00:23:51,113
might collapse to a few kilometers radius,
360
00:23:51,114 --> 00:23:52,881
but no smaller.
361
00:23:52,882 --> 00:23:55,618
"I think there should be a
law of nature," he said.
362
00:23:55,619 --> 00:23:57,313
"To prevent a star from behaving"
363
00:23:57,314 --> 00:23:59,785
"in this absurd way."
364
00:24:02,025 --> 00:24:04,459
Why exactly did Eddington criticize
365
00:24:04,460 --> 00:24:06,995
Chandrasekhar so harshly?
366
00:24:06,996 --> 00:24:09,608
Thorne believes that Eddington
was simply being fierce
367
00:24:09,609 --> 00:24:12,996
in his pursuit of scientific truth.
368
00:24:15,238 --> 00:24:18,669
It's my suspicion,
369
00:24:18,670 --> 00:24:21,799
I think that it is likely that in fact,
370
00:24:21,800 --> 00:24:24,686
Eddington was treating Chandra at that time
371
00:24:24,687 --> 00:24:25,981
as a colleague.
372
00:24:25,982 --> 00:24:30,119
And then, in England at the time there were
373
00:24:30,120 --> 00:24:34,189
serious intellectual battles
between colleagues.
374
00:24:34,190 --> 00:24:36,759
But Chandra had not yet
grown up to the point
375
00:24:36,760 --> 00:24:38,994
that he felt like he was a
colleague of Eddington's.
376
00:24:38,995 --> 00:24:42,110
He felt it was an unequal match.
377
00:24:42,111 --> 00:24:46,616
But Eddington, I think, I suspect
378
00:24:46,617 --> 00:24:50,295
that Eddington admired Chandra.
379
00:24:50,296 --> 00:24:52,963
He always said he did.
380
00:24:55,146 --> 00:24:57,012
After that, Chandrasekhar
381
00:24:57,013 --> 00:24:58,915
changed his workplace from England
382
00:24:58,916 --> 00:25:01,016
to the United States.
383
00:25:01,017 --> 00:25:04,309
Later, Thorne invited
him to come to Caltech,
384
00:25:04,310 --> 00:25:05,954
and they developed a close relationship
385
00:25:05,955 --> 00:25:10,458
lasting until Chandrasekhar's
death in 1995.
386
00:25:18,334 --> 00:25:23,019
In 1932, the black hole
controversy again ignited.
387
00:25:23,939 --> 00:25:27,864
The spark was provided by
a new theory in physics.
388
00:25:32,782 --> 00:25:34,683
It was known that an atomic nucleus
389
00:25:34,684 --> 00:25:38,239
was comprised of protons and neutrons.
390
00:25:40,890 --> 00:25:42,791
But under extreme compression,
391
00:25:42,792 --> 00:25:47,096
protons and electrons could
combine forming neutrons.
392
00:25:47,097 --> 00:25:50,467
And these could be compressed even further.
393
00:25:55,772 --> 00:25:58,573
That meant that the remaining
mass of an exploded star,
394
00:25:58,574 --> 00:26:01,944
1.4 times larger than our Sun or greater
395
00:26:01,945 --> 00:26:05,315
could turn into a neutron star.
396
00:26:12,422 --> 00:26:16,166
Neutron stars can now actually be observed.
397
00:26:17,827 --> 00:26:22,380
The Crab Nebula is the remnant
of a supernova explosion.
398
00:26:23,933 --> 00:26:27,681
A special camera can peer into its depths.
399
00:26:33,075 --> 00:26:34,843
The bright celestial body at the center
400
00:26:34,844 --> 00:26:38,422
of that gaseous disk is a neutron star.
401
00:26:42,018 --> 00:26:45,287
It is small, but incredible
heavy as if a lump
402
00:26:45,288 --> 00:26:49,108
of sugar weighed hundreds
of millions of tons.
403
00:26:54,764 --> 00:26:56,298
Scientists at the time thought
404
00:26:56,299 --> 00:26:59,845
that dense stars must be
either white dwarf stars
405
00:26:59,846 --> 00:27:02,116
or neutron stars.
406
00:27:03,866 --> 00:27:07,584
They denied the existence of black holes.
407
00:27:11,081 --> 00:27:14,734
At this point however, a
dissenting voice was raised,
408
00:27:14,735 --> 00:27:17,890
that of J. Robert Oppenheimer.
409
00:27:20,710 --> 00:27:23,058
A brilliant mathematician himself,
410
00:27:23,059 --> 00:27:25,461
Oppenheimer, like Chandrasekhar,
411
00:27:25,462 --> 00:27:29,200
calculated the mass of a neutron star.
412
00:27:30,800 --> 00:27:33,034
He found that a star at
least triple the mass
413
00:27:33,035 --> 00:27:37,071
of our Sun would not stop
at the neutron star stage,
414
00:27:37,072 --> 00:27:40,209
but would suffer complete
gravitational collapse,
415
00:27:40,210 --> 00:27:42,726
contracting infinitely.
416
00:27:49,036 --> 00:27:50,885
This constituted the reappearance
417
00:27:50,886 --> 00:27:53,989
of the theory that black
holes actually can exist
418
00:27:53,990 --> 00:27:56,346
in our universe.
419
00:27:59,362 --> 00:28:01,329
But a counter-argument was put forward
420
00:28:01,330 --> 00:28:04,099
by John Wheeler, one of
Oppenheimer's colleagues
421
00:28:04,100 --> 00:28:06,201
at Princeton University.
422
00:28:06,202 --> 00:28:08,538
When Kip Thorne was in graduate school,
423
00:28:08,539 --> 00:28:11,295
Wheeler was his mentor.
424
00:28:14,377 --> 00:28:18,113
As to why a massive star could
not become a black hole,
425
00:28:18,114 --> 00:28:21,846
Wheeler argued as follows,
426
00:28:21,847 --> 00:28:24,519
he said that a dying star
would discharge gases
427
00:28:24,520 --> 00:28:27,322
in a process that actually made it lighter.
428
00:28:27,323 --> 00:28:31,510
So every star would merely
become a neutron star.
429
00:28:33,663 --> 00:28:36,999
We can actually observe an aging giant star
430
00:28:37,000 --> 00:28:40,020
emitting huge volumes of gas.
431
00:28:42,668 --> 00:28:45,276
The controversy between
the two experts continued
432
00:28:45,277 --> 00:28:47,722
for over a decade.
433
00:28:49,256 --> 00:28:51,420
Wheeler was fierce in his refutations
434
00:28:51,421 --> 00:28:53,382
of Oppenheimer's thesis.
435
00:28:53,383 --> 00:28:55,717
But as he rechecked his calculations,
436
00:28:55,718 --> 00:28:59,567
he came to have doubts
about his own position.
437
00:29:02,191 --> 00:29:06,229
So John Wheeler, like Albert Einstein,
438
00:29:06,230 --> 00:29:10,766
had very deep physical
intuition and insights.
439
00:29:10,767 --> 00:29:14,589
And like Einstein, he was usually right,
440
00:29:14,590 --> 00:29:17,788
and sometimes wrong.
441
00:29:17,789 --> 00:29:20,441
Finally, even Wheeler
accepted the existence
442
00:29:20,442 --> 00:29:21,943
of black holes.
443
00:29:21,944 --> 00:29:23,699
He then pushed forward the study
444
00:29:23,700 --> 00:29:27,640
of black holes even
further than Oppenheimer.
445
00:29:29,986 --> 00:29:31,854
In fact, it was actually Wheeler
446
00:29:31,855 --> 00:29:35,390
who gave the strange infinitely
contracting celestial bodies
447
00:29:35,391 --> 00:29:38,668
the name of black holes.
448
00:29:41,798 --> 00:29:44,266
With Wheeler's conversion, a half century
449
00:29:44,267 --> 00:29:48,168
of controversy among
scientists was concluded.
450
00:29:51,768 --> 00:29:54,009
It was now accepted as indisputable
451
00:29:54,010 --> 00:29:56,511
that dying giant stars unable
452
00:29:56,512 --> 00:29:59,294
to withstand their own gravitational forces
453
00:29:59,295 --> 00:30:03,020
would contract infinitely,
forming black holes.
454
00:30:13,396 --> 00:30:17,199
It was Subrahmanyan Chandrasekhar
who set scientists
455
00:30:17,200 --> 00:30:19,234
on the path that led them to acknowledge
456
00:30:19,235 --> 00:30:23,276
the existence of black
holes in our universe.
457
00:30:27,777 --> 00:30:31,713
In 1983, Chandrasekhar's work
on the structure of stars
458
00:30:31,714 --> 00:30:33,948
and their evolution was recognized
459
00:30:33,949 --> 00:30:36,351
when he was named as co-recipient
460
00:30:36,352 --> 00:30:39,766
of the Nobel Prize for Physics.
461
00:30:42,925 --> 00:30:45,060
And I sent him a note of congratulations,
462
00:30:45,061 --> 00:30:47,075
and he acknowledged it.
463
00:30:47,076 --> 00:30:52,003
But I think we never
discussed the Nobel Prize.
464
00:30:52,004 --> 00:30:55,838
But he was among scientists I have known,
465
00:30:55,839 --> 00:30:59,875
he was one of the most self-critical,
466
00:30:59,876 --> 00:31:01,743
and the most intensely driven.
467
00:31:01,744 --> 00:31:03,782
But driven from within and not driven
468
00:31:03,783 --> 00:31:07,916
to receive acknowledgement
from other people
469
00:31:07,917 --> 00:31:10,301
for his discoveries.
470
00:31:13,791 --> 00:31:15,357
The result, not only were
471
00:31:15,358 --> 00:31:17,846
black holes acknowledged as existing,
472
00:31:17,847 --> 00:31:20,362
but light was shed even on the processes
473
00:31:20,363 --> 00:31:22,653
by which they were born.
474
00:31:24,867 --> 00:31:28,612
And yet, they existed only in theory.
475
00:31:37,347 --> 00:31:39,414
Actually discovering a black hole
476
00:31:39,415 --> 00:31:41,916
was a dream of many a scientist.
477
00:31:41,917 --> 00:31:45,849
Among them, a young Japanese enthusiastic.
478
00:31:49,525 --> 00:31:52,847
Boston, Massachusetts, USA.
479
00:31:52,848 --> 00:31:55,303
A certain Japanese man regularly stopped
480
00:31:55,304 --> 00:31:58,302
by this pet shop in 1963.
481
00:32:01,437 --> 00:32:03,205
He seemed to like watching mice
482
00:32:03,206 --> 00:32:06,199
and other small animals there.
483
00:32:09,345 --> 00:32:12,080
Little did anyone suspect,
that their activities
484
00:32:12,081 --> 00:32:16,251
concealed a key to the
development of black holes.
485
00:32:19,655 --> 00:32:23,359
Minoru Oda was at that time
a visiting faculty member
486
00:32:23,360 --> 00:32:26,682
at the Massachusetts
Institute of Technology.
487
00:32:30,733 --> 00:32:33,017
An MIT research group had launched
488
00:32:33,018 --> 00:32:35,471
cutting edge imaging equipment by rocket
489
00:32:35,472 --> 00:32:39,119
to obtain x-ray images from outer space.
490
00:32:42,578 --> 00:32:46,047
Bruno Rossi was in charge
of these observations.
491
00:32:46,048 --> 00:32:48,216
He was also the one who had invited Oda
492
00:32:48,217 --> 00:32:50,552
to the United States.
493
00:32:57,493 --> 00:33:01,013
It was known that the sun emitted x-rays.
494
00:33:03,500 --> 00:33:06,418
However, x-radiation from
other celestial bodies
495
00:33:06,419 --> 00:33:09,271
is absorbed by the Earth's atmosphere.
496
00:33:09,272 --> 00:33:10,972
Hardly any of it could be detected
497
00:33:10,973 --> 00:33:13,750
by Earth-based observation.
498
00:33:16,578 --> 00:33:18,846
Rossi's group, working on the hypothesis
499
00:33:18,847 --> 00:33:22,460
that there must be other x-ray
emitting celestial bodies,
500
00:33:22,461 --> 00:33:25,554
used a rocket to detect this radiation.
501
00:33:25,555 --> 00:33:27,522
They found even stronger x-rays
502
00:33:27,523 --> 00:33:30,048
than they had expected.
503
00:33:35,631 --> 00:33:37,331
The equipment they used however,
504
00:33:37,332 --> 00:33:38,367
could not tell them much
505
00:33:38,368 --> 00:33:42,005
about the direction the x-rays came from.
506
00:33:43,640 --> 00:33:48,054
Oda and Rossi talked it over
at the beach one summer.
507
00:33:51,714 --> 00:33:55,439
The area marked in red
they knew, emits x-rays.
508
00:33:56,653 --> 00:34:00,284
And they knew it was in
the constellation Cygnus.
509
00:34:00,285 --> 00:34:02,290
But they did not know whether the radiation
510
00:34:02,291 --> 00:34:05,660
emanated from particular
stars were more generally
511
00:34:05,661 --> 00:34:08,073
from that sector.
512
00:34:10,233 --> 00:34:13,969
So how could one pinpoint
the source of those x-rays?
513
00:34:13,970 --> 00:34:18,073
Oda got a clue from the pet
shop he'd been going to.
514
00:34:26,615 --> 00:34:28,239
Oda was fascinated by seeing
515
00:34:28,240 --> 00:34:31,353
something alternately hidden and revealed.
516
00:34:31,354 --> 00:34:34,289
When he got back to Japan,
he applied his insight
517
00:34:34,290 --> 00:34:37,706
to the development of an imaging device.
518
00:34:40,896 --> 00:34:44,365
Here are Oda's prototypes.
519
00:34:44,366 --> 00:34:46,827
Looking at the arrays of fine wires,
520
00:34:46,828 --> 00:34:50,896
he called his invention
a screen collimator.
521
00:34:55,776 --> 00:34:57,305
When two or more of these screens
522
00:34:57,306 --> 00:34:59,247
were placed in front of a detector,
523
00:34:59,248 --> 00:35:01,916
even slight differences
in the origin of x-rays
524
00:35:01,917 --> 00:35:03,951
would cause some to pass through,
525
00:35:03,952 --> 00:35:06,020
some to be blocked.
526
00:35:09,292 --> 00:35:10,956
The concept was that that could
527
00:35:10,957 --> 00:35:14,301
help refine estimates of directionality.
528
00:35:19,235 --> 00:35:21,946
At the time however, Japan had no rocket
529
00:35:21,947 --> 00:35:24,902
with which to launch such a device.
530
00:35:28,111 --> 00:35:29,978
So Oda, determined to pinpoint
531
00:35:29,979 --> 00:35:32,407
the source of that x-radiation,
532
00:35:32,408 --> 00:35:35,126
devised another way to provide his device
533
00:35:35,127 --> 00:35:37,352
with a space-based platform.
534
00:35:37,353 --> 00:35:40,598
There is archival video of his effort.
535
00:35:42,793 --> 00:35:47,573
The experiment took place in
Fukushima, Japan in 1966.
536
00:35:49,765 --> 00:35:54,219
Oda sent his screen collimator
aloft in a balloon.
537
00:36:26,882 --> 00:36:28,903
When its observations were done,
538
00:36:28,904 --> 00:36:31,172
it descended by parachute for recovery
539
00:36:31,173 --> 00:36:33,675
at sea or in the mountains.
540
00:36:33,676 --> 00:36:36,444
Observational missions
using Oda's collimator
541
00:36:36,445 --> 00:36:39,789
continued for four years.
542
00:36:45,488 --> 00:36:48,824
This helped narrow down
the source of the x-rays.
543
00:36:48,825 --> 00:36:51,326
The yellow oval marks the area identified
544
00:36:51,327 --> 00:36:54,596
by the collimator as containing the source.
545
00:36:54,597 --> 00:36:57,014
It was limited area.
546
00:37:01,370 --> 00:37:06,141
In 1970, the US launched Uhuru,
the world's first satellite
547
00:37:06,142 --> 00:37:10,042
for the detection of x-rays.
548
00:37:11,407 --> 00:37:13,181
It's very first observations were
549
00:37:13,182 --> 00:37:15,783
of those mysterious x-rays.
550
00:37:15,784 --> 00:37:19,388
Oda was a guest investigator
for this project.
551
00:37:28,561 --> 00:37:30,999
Uhuru refined further the calculations
552
00:37:31,000 --> 00:37:33,701
regarding the source of the x-rays.
553
00:37:33,702 --> 00:37:37,560
Even more detailed observations followed.
554
00:37:41,411 --> 00:37:45,146
April 1971, at last the origin
555
00:37:45,147 --> 00:37:47,683
of the x-rays was pinpointed.
556
00:37:47,684 --> 00:37:51,590
It had taken seven years
to solve the riddle.
557
00:37:56,291 --> 00:38:00,031
Near the source of the x-rays
was a blue supergiant star
558
00:38:00,032 --> 00:38:04,229
some 30 times the mass of our Sun.
559
00:38:04,230 --> 00:38:06,468
Analysis of the light from that star
560
00:38:06,469 --> 00:38:09,786
produced a startling discovery.
561
00:38:14,676 --> 00:38:18,346
The color of the star
was changing slightly.
562
00:38:18,347 --> 00:38:21,483
That indicated movement.
563
00:38:21,484 --> 00:38:23,218
Further analysis showed that the star
564
00:38:23,219 --> 00:38:25,559
was circling some other object
565
00:38:25,560 --> 00:38:28,827
in a brief cycle lasting 5.6 days
566
00:38:28,828 --> 00:38:31,188
for one revolution.
567
00:38:33,362 --> 00:38:35,463
It would take a massive object indeed
568
00:38:35,464 --> 00:38:39,368
to keep a supergiant star in its orbit.
569
00:38:41,661 --> 00:38:44,973
From the blue supergiant
star's movement and spectra,
570
00:38:44,974 --> 00:38:47,859
the mass of its unseen
partner was estimated
571
00:38:47,860 --> 00:38:51,764
as being equivalent to 10 of our Suns.
572
00:38:52,881 --> 00:38:55,183
But that celestial body could not be found
573
00:38:55,184 --> 00:38:59,720
at the expected location.
574
00:38:59,721 --> 00:39:02,761
A star 10 times the mass of the Sun,
575
00:39:02,762 --> 00:39:05,123
and yet invisible to us,
576
00:39:05,124 --> 00:39:08,896
emitting powerful x-rays as well.
577
00:39:08,897 --> 00:39:11,299
It had to be a black hole.
578
00:39:11,300 --> 00:39:13,704
The first actual black hole ever discovered
579
00:39:13,705 --> 00:39:16,320
though observation.
580
00:39:18,570 --> 00:39:22,395
It was named Cygnus X-1.
581
00:39:27,282 --> 00:39:29,674
Kip Thorne was one of
many scientists delighted
582
00:39:29,675 --> 00:39:32,286
by this discovery.
583
00:39:32,287 --> 00:39:36,024
Oh, it was very exciting when
Cygnus X-1 was observed.
584
00:39:36,025 --> 00:39:40,795
There had been predictions
585
00:39:40,796 --> 00:39:43,298
by several astrophysicists
586
00:39:43,299 --> 00:39:45,834
that if you had a black hole,
587
00:39:45,835 --> 00:39:49,771
and it captured matter from star,
588
00:39:49,772 --> 00:39:52,673
it would produce x-rays.
589
00:39:54,543 --> 00:39:56,845
When Cygnus X-1 was found to be the source
590
00:39:56,846 --> 00:39:59,347
of those intense x-ray emissions,
591
00:39:59,348 --> 00:40:01,182
Thorne made a bet with his friend,
592
00:40:01,183 --> 00:40:03,584
theoretical physicist Stephen Hawking
593
00:40:03,585 --> 00:40:07,346
as to whether it was a black hole or not.
594
00:40:10,525 --> 00:40:14,562
This is the wager as written.
595
00:40:14,563 --> 00:40:17,665
Thorne bet that Cygnus
X-1 was a black hole.
596
00:40:17,666 --> 00:40:21,215
Hawking bet against that proposition.
597
00:40:24,875 --> 00:40:28,361
At stake, were magazine subscriptions.
598
00:40:32,838 --> 00:40:35,683
After the initial discovery of Cygnus X-1,
599
00:40:35,684 --> 00:40:37,785
it was observed further.
600
00:40:37,786 --> 00:40:39,720
Examination of data on its mass
601
00:40:39,721 --> 00:40:42,297
and on variations in its x-ray emissions
602
00:40:42,298 --> 00:40:44,626
led to a broad scientific consensus
603
00:40:44,627 --> 00:40:47,970
that this was indeed a black hole.
604
00:40:54,203 --> 00:40:58,039
In 1990, 16 years after the wager was made,
605
00:40:58,040 --> 00:40:59,988
Hawking's concession was duly noted
606
00:40:59,989 --> 00:41:03,177
on the original betting contract.
607
00:41:03,178 --> 00:41:06,714
He bet that Cygnus X-1
was not a black hole,
608
00:41:06,715 --> 00:41:09,383
and he hoped that he was wrong.
609
00:41:09,384 --> 00:41:12,604
And I bet that it was a black hole.
610
00:41:14,690 --> 00:41:16,757
No one was more cautious than Hawking
611
00:41:16,758 --> 00:41:19,361
in interpreting observational data.
612
00:41:19,362 --> 00:41:22,197
And now, even he acknowledged Cygnus X-1
613
00:41:22,198 --> 00:41:24,751
to be a black hole.
614
00:41:31,049 --> 00:41:33,841
After the initial discovery of Cygnus X-1,
615
00:41:33,842 --> 00:41:35,844
Japan launched a series of satellites
616
00:41:35,845 --> 00:41:37,879
for x-ray observation,
617
00:41:37,880 --> 00:41:40,215
making significant
contributions to the study
618
00:41:40,216 --> 00:41:43,985
of black holes.
619
00:41:43,986 --> 00:41:48,222
Asuka, launched in 1993,
undertook further observations
620
00:41:48,223 --> 00:41:52,291
of Cygnus X-1 obtaining a
wealth of detailed data.
621
00:41:56,199 --> 00:41:58,703
The first black hole ever discovered,
622
00:41:58,704 --> 00:42:00,712
it's location around the middle
623
00:42:00,713 --> 00:42:04,772
of the neck of the
constellation Cygnus, the Swan
624
00:42:04,773 --> 00:42:08,693
7,500 light years from Earth.
625
00:42:15,818 --> 00:42:18,139
The black hole and its companion star
626
00:42:18,140 --> 00:42:21,522
are paired in what is
called a binary system.
627
00:42:21,523 --> 00:42:24,592
They are only 30 million kilometers apart.
628
00:42:24,593 --> 00:42:29,301
That's less than the distance
between the Sun and Mercury.
629
00:42:35,004 --> 00:42:37,338
Gases from the blue supergiant stream
630
00:42:37,339 --> 00:42:39,040
to the black hole.
631
00:42:39,041 --> 00:42:42,042
The gases, heated by
friction, reach temperatures
632
00:42:42,043 --> 00:42:45,012
as high as 10 million degrees Celsius,
633
00:42:45,013 --> 00:42:48,850
and generate powerful x-rays.
634
00:42:48,851 --> 00:42:50,518
The mass of the black hole is equal
635
00:42:50,519 --> 00:42:53,421
to more than 13 our Suns,
636
00:42:53,422 --> 00:42:57,259
yet it's radius is a mere 40 kilometers.
637
00:42:59,995 --> 00:43:03,849
Above and below the black
hole are two jets.
638
00:43:09,838 --> 00:43:12,534
The discovery and
elucidation of this system
639
00:43:12,535 --> 00:43:16,755
has ended 50 years of
scientific controversy.
640
00:43:28,724 --> 00:43:31,942
Minoru Oda contributed to
the first ever discovery
641
00:43:31,943 --> 00:43:33,694
of a black hole.
642
00:43:33,695 --> 00:43:37,432
His concepts and inventiveness
turned the impossible
643
00:43:37,433 --> 00:43:39,101
into the possible.
644
00:43:39,102 --> 00:43:42,795
That legacy continues to inspire.
645
00:43:47,742 --> 00:43:50,845
Can one see a black hole
with the naked eye?
646
00:43:56,552 --> 00:43:59,220
Scientists on the cosmic
front are now trying
647
00:43:59,221 --> 00:44:03,295
to undertake direct
observations of black holes.
648
00:44:11,333 --> 00:44:13,368
But can that be done?
649
00:44:13,369 --> 00:44:16,671
With formulas derived from the
General Theory of Relativity,
650
00:44:16,672 --> 00:44:20,108
Rohta Takahashi tried to
deduce mathematically
651
00:44:20,109 --> 00:44:23,811
what a black hole would look
like when directly observed.
652
00:44:23,812 --> 00:44:27,739
It took him four years
to arrive at a solution.
653
00:44:50,410 --> 00:44:53,708
This is how Cygnus X-1
is currently imagined
654
00:44:53,709 --> 00:44:55,876
based on observed data.
655
00:44:55,877 --> 00:44:57,778
The black hole is deep in the bottom
656
00:44:57,779 --> 00:45:00,481
of that dark center area.
657
00:45:05,731 --> 00:45:09,403
If one could see it with a
sufficiently powerful telescope,
658
00:45:09,404 --> 00:45:12,561
this is what it would look like.
659
00:45:15,540 --> 00:45:16,797
The gases that have been sucked
660
00:45:16,798 --> 00:45:18,966
into the black hole are superheated
661
00:45:18,967 --> 00:45:22,703
by that violent friction
and shine brightly.
662
00:45:22,704 --> 00:45:25,473
That bright light makes
the invisible black hole
663
00:45:25,474 --> 00:45:28,676
appear to take the form of a black ball.
664
00:45:28,677 --> 00:45:32,580
This phenomenon is called
a black hole shadow.
665
00:45:32,581 --> 00:45:34,501
The bright light to the left of the ball
666
00:45:34,502 --> 00:45:36,663
is from the superheated gases
667
00:45:36,664 --> 00:45:40,711
which are forming a disc,
spinning at high speed.
668
00:45:42,091 --> 00:45:45,326
Even some background light
is visible at the fringes,
669
00:45:45,327 --> 00:45:47,962
despite the gravity induced invisibility
670
00:45:47,963 --> 00:45:51,057
of the black hole itself.
671
00:45:52,567 --> 00:45:54,735
Unfortunately, says Takahashi,
672
00:45:54,736 --> 00:45:57,405
Cygnus X-1 is too small a black hole
673
00:45:57,406 --> 00:45:59,073
to be observed more directly
674
00:45:59,074 --> 00:46:01,698
with today's technology.
675
00:46:03,912 --> 00:46:05,579
A black hole that is easier to view
676
00:46:05,580 --> 00:46:08,048
has been found however, right in the middle
677
00:46:08,049 --> 00:46:12,016
of our own Milky Way Galaxy.
678
00:46:12,017 --> 00:46:15,490
Equivalent in mass to
four million of our Suns,
679
00:46:15,491 --> 00:46:18,492
this is a monster black hole.
680
00:46:20,662 --> 00:46:25,335
Its event horizon radius
exceeds 10 million kilometers,
681
00:46:25,336 --> 00:46:27,834
so large that it would look quite different
682
00:46:27,835 --> 00:46:31,626
from a small black hole like Cygnus X-1.
683
00:46:34,742 --> 00:46:36,944
Assuming it could be observed from Earth,
684
00:46:36,945 --> 00:46:40,422
Takahashi envisions it
as looking like this.
685
00:47:21,497 --> 00:47:23,190
Takahashi has calculated
686
00:47:23,191 --> 00:47:25,526
just how strong a telescope would be needed
687
00:47:25,527 --> 00:47:29,161
to observe this black hole from Earth.
688
00:47:32,467 --> 00:47:34,235
It would have to be powerful enough
689
00:47:34,236 --> 00:47:36,593
so that from Tokyo, one could make out
690
00:47:36,594 --> 00:47:38,972
the baby hairs on the
face of someone standing
691
00:47:38,973 --> 00:47:43,445
on the summit of Mount
Fuji, 100 kilometers away.
692
00:47:45,834 --> 00:47:49,064
The attempt has already begun.
693
00:47:51,820 --> 00:47:56,290
MIT's Haystack Observatory
in the suburbs of Boston.
694
00:48:02,898 --> 00:48:04,699
Sheperd Doeleman has been cooperating
695
00:48:04,700 --> 00:48:07,908
with the National Astronomical
Observatory of Japan
696
00:48:07,909 --> 00:48:11,596
in the effort to observe
a black hole directly.
697
00:48:18,747 --> 00:48:22,229
Here, data from radio
telescopes all over the world
698
00:48:22,230 --> 00:48:25,373
are combined and analyzed.
699
00:48:29,891 --> 00:48:31,619
They may not have a telescope capable
700
00:48:31,620 --> 00:48:33,861
of seeing from Tokyo, the baby hairs
701
00:48:33,862 --> 00:48:36,283
on someone standing on Mount Fuji,
702
00:48:36,284 --> 00:48:39,733
but they can emulate that power.
703
00:48:39,734 --> 00:48:43,861
Actually I think it's running
now, so you can see.
704
00:48:43,862 --> 00:48:46,641
And to get the high angular resolution
705
00:48:46,642 --> 00:48:48,442
that you need to see the event horizon,
706
00:48:48,443 --> 00:48:50,201
the boundary of the black hole,
707
00:48:50,202 --> 00:48:53,157
we create an Earth-size virtual telescope
708
00:48:53,158 --> 00:48:57,784
using radio telescopes
spread all around Earth.
709
00:48:57,785 --> 00:49:00,821
And we tie them together to make a picture
710
00:49:00,822 --> 00:49:02,457
as though we had a telescope as large
711
00:49:02,458 --> 00:49:05,926
as the Earth itself.
712
00:49:05,927 --> 00:49:09,196
At the US National Radio
Astronomy Observatory,
713
00:49:09,197 --> 00:49:12,613
they have an array of
27 parabolic antennas,
714
00:49:12,614 --> 00:49:16,103
each 25 meters in diameter.
715
00:49:16,104 --> 00:49:18,205
The diameter of the remote telescopes
716
00:49:18,206 --> 00:49:22,469
is determined by the desired
resolution of the image.
717
00:49:24,189 --> 00:49:27,331
By combining data from
multiple remote telescopes,
718
00:49:27,332 --> 00:49:29,369
one can emulate the capabilities
719
00:49:29,370 --> 00:49:31,786
of one giant telescope,
720
00:49:31,787 --> 00:49:35,540
and obtain high-resolution images.
721
00:49:39,260 --> 00:49:41,762
To obtain the highest possible resolution,
722
00:49:41,763 --> 00:49:44,899
in their effort to capture
a black hole shadow,
723
00:49:44,900 --> 00:49:46,326
Doeleman and his colleagues
724
00:49:46,327 --> 00:49:49,315
used submillimeter telescopes.
725
00:49:51,372 --> 00:49:56,047
This technology is called Very
Long Baseline Interferometry.
726
00:49:57,012 --> 00:50:00,281
The plan calls for linking
three submillimeter telescopes
727
00:50:00,282 --> 00:50:03,316
in Hawaii, California and Chile
728
00:50:03,317 --> 00:50:07,421
to emulate one gigantic
Earth-size telescope.
729
00:50:07,422 --> 00:50:09,290
We really hope that in five years,
730
00:50:09,291 --> 00:50:13,694
we have started to make
a very good progress
731
00:50:13,695 --> 00:50:18,293
on actually making an image
of the black hole itself.
732
00:50:22,471 --> 00:50:23,972
In the near future,
733
00:50:23,973 --> 00:50:27,909
we will be able to peer
directly into a black hole.
734
00:50:40,656 --> 00:50:43,074
The invisible black hole,
735
00:50:43,075 --> 00:50:46,026
at first it was a theoretical proposition,
736
00:50:46,027 --> 00:50:48,462
but its reality has been confirmed
737
00:50:48,463 --> 00:50:51,410
and a consensus has emerged.
738
00:50:53,601 --> 00:50:57,073
Actual observations have
produced scientific proof
739
00:50:57,074 --> 00:51:01,053
that black holes exist in our universe.
740
00:51:03,441 --> 00:51:05,746
The same inexhaustible curiosity
741
00:51:05,747 --> 00:51:08,585
that led to the discovery of black holes,
742
00:51:08,586 --> 00:51:12,215
powers an ongoing quest
to view them directly
743
00:51:12,216 --> 00:51:15,991
and to behold the wonders
they will surely reveal.
57901
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