Original subtitles

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a lot has changed in the last 50 years

especially in our understanding of the

cosmos the last 50 years I think have

been the most exciting ever our entire

understanding of the universe just

turned upside down welcome to the Dark

Universe where powerful yet invisible

dark matter holds Cosmic sway shaping

even the very Galaxy we call home dark

matter is four times or five times more

abundant than the stuff we can see it is

fundamentally

disturbing what we're on the hunt we're

entering Discovery

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territory and the Darkness doesn't end

there a ghostly form of dark energy

dominates the universe dry its expansion

maybe even choosing its fate I don't

think we possibly could have grasped

just how profound it was this is a huge

Discovery it remains a total Enigma we

have absolutely no idea what dark

energies the more we learn about our

universe The

Stranger it becomes this is something

that can't just be wished away that's

where to look for the next breakthrough

it's potentially no prize winning

decoding the universe right now on

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Nova as an american-based supplier to

the construction industry Carlile is

committed to developing a diverse

workplace that supports our employees

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car.com September 5th

1977 3 2 1 and we have Li off a Titan

Centaur rocket carrying the space probe

Voyager 1 launches from cap

canav the Voyager spacecraft to extend

man's senses farther into the solar

system than ever before the Voyager

program would become NASA's longest

mission to date I Absolut remember the

coverage remember watching the launch it

was really exciting and I had no sense

of the scale of where that thing was

heading to where no human built things

had ever gone

before in 1979

Voyager One flies past

Jupiter about a year and a half later

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Saturn though it will continue its

journey in 1990 it sends its last images

looking back at the solar

system earth is just a tiny

Speck in Carl Sean's words a pale blue

dot the pale blue dot it's telling us

we're incredibly small at the same time

it also tells us that we've gone

incredibly

far I mean in cosmology we're looking

we're looking at Supernova we're looking

at other galaxies we're looking at the

beginning of the universe but there's so

much more than is to be done

during Voyager 1's nearly 50 yearlong

Mission our scientific understanding of

the universe has grown

immensely and even radically

changed the last 50 years I think have

been the most exciting ever our entire

understanding of the universe has

changed it's just turned upside down

over the past 50 years there's really

been sever several Revolutions in our

understanding of the universe we can

both be proud of how far we've come but

also be excited about how much we don't

know looking back the discoveries of the

last 50 years are remarkable in the

1970s Luke Skywalker's home twine was as

close as we got to seeing an alien

planet in the

1970s we knew of precisely zero planets

outside of our solar system and and in

the decades since then we've moved that

number up into the

thousands we've discovered planets are

incredibly common in our galaxy there

are more planets out there than there

are stars so go out and look at the

night sky for every one of those stars

there are probably several

planets and in recent decades we've also

learned our Milky Way galaxy isn't even

one in a million

a fact made evident by this astonishing

series of images taken by the Hubble

Space Telescope in

1995 just about every single bright

point is a

Galaxy scientists now think galaxies in

the universe may number in the

trillions the Hubble pictures tell us

that the universe is the same everywhere

it's also a reminder that we're

definitely not the same center of the

universe one of the most shocking

discoveries of the last 50 years was

made in our own Cosmic

backyard in

1998 astrophysicist Andrea gz and her

team surprised the world when they

revealed evidence of a super massive

black hole at the center of our own

Milky Way from watching Stars orbit the

center of the Galaxy the mass that we

infer is 4 million times the mass of the

Sun that is the proof of a black

hole astronomers now believe that just

about every galaxy has

one black holes are crucial to how we

understand galaxies that is a huge new

role for black holes in our

understanding of

them but perhaps the biggest discovery

of the last 50 years is just how much we

don't

know somehow we've missed much much more

than we've

discovered there's some new form of

matter out in the universe and it is

four times or five times more abundant

than the stuff we can see and so that is

the shocking truth of Dark

Matter Dark Matter only accepted as real

during the last 50 years and now one of

the biggest mysteries in the history of

science so far its effects have only

been detected on the cosmic

stage but understanding it may hold the

key to the very structure of the

universe my mom is always like you know

why do we have to care about D matter

and and the truth is that without D

matter we simply wouldn't exist dark

matter is in part the story of why and

how we're here

and yet in recent decades scientists

have uncovered evidence of something

that today is even more powerful than

dark

matter I just I don't think we possibly

could have grasped just how profound and

how much it would change our view of the

universe it would be like as though you

had only ever experienced land and then

one day you discover the

oceans it's called Dark Energy

scientists now believe it's the most

power power ful force in the universe

expanding its very fabric pushing

galaxies apart and it may even be

driving the universe's ultimate

fate but it remains an enigma we have

absolutely no idea what dark energy is

to this day how did our vision of the

universe get completely overturned in

just a few

decades and what new surprises might Li

just over the horizon

ni the past 50 years of astrophysics has

shown that the universe is

extraordinarily creative and what is out

there and it's very determined to

consistently subvert our

expectations we are so struggling to

figure out the nature of our Cosmos and

that's very humbling very humbling yet

very empowering it's a it's a strange

combination of the two things

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together since Voyager 1 left

Earth astrophysicists and astronomers

have overtaken the Intrepid

probe reaching farther and farther out

into

space to gather data written across vast

expanses of time and on colossal

scales and Stars

nebulas

supernovas distant galaxies and Galaxy

clusters here's the Galaxy we're at the

object and in the

1970s it was just such data meticulous

observations gathered by an

astronomer that forced scientists to

confront the idea of dark matter the

astronomer's name was was Vera Reuben

you'll get a guide star I'll set up for

the

observation Reuben was born in 1928 in

Philadelphia from a young age she was

hooked on the Stars by about age 12 I

would prefer to stay up and watch the

star of draria sleep there was just

nothing as interesting in my life as

watching stars there me not I do I

wanted to be an astronomer

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in

1963 Vera Rubin traveled here to the kit

Peak National observatory in the shuk

doic district on the th atham

Nation 56 Mi Southwest of Tucson

Arizona despite having Advanced degrees

for over a decade Reuben had never been

able to collect her own

data astronomy had few women and many

observator weren't

welcoming some officially did not allow

women but the national Observatory at

kit Peak had just recently

opened and accepted her

application she would return to Kit Peak

several times over her

career as she began to focus more on

Galaxies so Vin really was what I would

call a true observ ational astronomer

she L to go to the telescope do the

observation take it to her office and

analyze them and try to see what it told

her about the

galaxies today in more ways than one

Stanford cosmologist Risa Wexler follows

in Ruben's

footsteps so this instrument behind me

is the 84 in telescope at kit Peak your

Ruben started using it in 1968 when she

started making measurements of the

Andromeda galaxy and looking at how

different regions in Andromeda were

moving Reuben wanted to check a common

assumption among astronomers about

galaxies the presumption was Stars near

the center of a galaxy would be orbiting

very rapidly and stars at the outside

would be going very

slowly that idea came from the way the

planets in our solar system orbit our

massive

sun because the attractive force of the

Sun's gravity falls off with distance

the farther away from the sun a planet

orbits the slower its orbital

speed astronomers assumed the stars in a

galaxy would behave the same way like

the sun in our solar system the bright

star packed center of a galaxy appeared

to hold most of the Galaxy's Mass so a

Galaxy's orbiting Stars should act like

the planets with orbits slowing toward

the Galaxy's outer edges but no one had

done the work to know for

sure partly it was a technical issue

which Ruben solved by teaming up with

instrument maker Kent Ford he had

developed a device that enhanced a

telescope's light

sensitivity making it possible to

finally see the faint stars on the far

edges of

galaxies and what they saw was

surprising they found that the regions

of Andromeda that were quite far out

were still rotating quite fast faster

than you would have expected by the

amount of light that was there it was a

strange

observation what was keeping those fast

moving outer stars from flying

off during the 1970s Reuben and Ford

along with other astronomers gathered

more and more data from more and more

galaxies

almost none showed the speed of orbiting

Stars dropping as had been

expected still it would take years for

the astronomy Community to accept the

astonishing explanation that Reuben and

others

proposed that there was a vast amount of

hidden matter surrounding each Galaxy

gravitationally holding it

together aside from that effect it was

undetected detectable if you didn't have

some invisible mass in the Galaxy the

Stars would not be bound in this in this

orbit they would fly

out we now know that in every Galaxy we

study the stars at very large distances

are orbiting with very high velocities

and that tells us that there is a lot of

matter at very large distances from the

center so we see a lot of matter where

we don't see very much light and that

has led to the con cep of Dark

Matter Dark

Matter astronomer Fritz zi had proposed

the name in the 1930s to describe an

unseen Mass to explain some puzzling

observations of a nearby Galaxy

cluster but the idea had been largely

ignored until Reuben and Ford came

along today scientists estimate There is

five times more Dark Matter than

ordinary matter in the

universe it's arranged in a vast webike

structure of filaments and

nodes in the early Universe those nodes

through gravity attracted regular matter

which eventually evolved into

galaxies but what is dark matter over

the last 50 years

this question has become a guiding

question for huge swads of the physics

Community we've had some of the smartest

people in the world banging heads

against the wall for decades this is a

really hard

problem there aren't many

Clues aside from its gravitational

effect Dark Matter appears to interact

very little with normal matter and can

pass right through it it also emits no

electromagnetic

radiation no

light they're forms of matter that

simply don't glow like stars do but

actually they're also not responding to

light so they are invisible except

through their gravitational force it

probably is something quite exotic it

isn't any of the ordinary stuff so who

are the suspects for dark matter

there are the machos the massive compact

Halo

objects like primordial black holes

black holes that go back to very

earliest eras of the universe could be a

major component of dark

matter for a primordial black hole to

fit the bill as dark matter it would

have about the mass of an asteroid and

be about the size of an

atom and there are Aion

minuscule particles theorized by

physicists an Axion if it exists

interacts only very infrequently with

light and it does have some Mass so it

could be dark

matter but the suspects who garnered

early fans were the wimps weakly

interacting massive

particles the search for wimps leads

here

to the Black Hills of South

Dakota Native Americans have long

considered the area

sacred and the fort laramy Treaty of

1868 included the Black Hills in the

great Sue

reservation but just a few years later

the discovery of gold and an influx of

miners led to the great Sue war of

1876 the US government seized the area

and forcibly relocated its Sue

inhabitants the dispute over the broken

treaty remains

unresolved today in the town of lead a

retired Gold Mine houses the Sanford

underground research facility

CH cor God a professor at University

College London is a founding member of a

team of researchers drawn from

universities around the world that's on

the hunt for dark matter in the form of

wimps to get down a mile um it takes a

bit of

time why build a dark matter wimp

detector so far

underground so a mile of rock above us

here in the Black Hills of South Dakota

that Shield us from cosmic radiation

that is bombarding us all the time and

being underground we're able to reduce

that by factors of millions so this

experiment up on the surface just

wouldn't be able to run at all it's just

far too

sensitive and then go ahead hop on the

Chain ready y to the 10-minute ride down

it's on to a battery-powered locomotive

followed by a brief

hike to get to the cavern that holds the

lab of the Lux Zeppelin or LZ detector

experiment the core of the experiment is

Zenon it's liquid Zenon it's Zenon gas

that's been condensed and we've got to

keep that clean and we've got to keep it

cold and so much of what we'll see

around here is all for that

really here is the main experiment at

its Center is a container of 7 metric

tons of very pure cooled liquid

Xenon the concept is

straightforward the cooled xenot is

extremely

sensitive even just a single collision

between one of the theoretical wimps and

the nucleus of a Xenon atom would cause

the atom to collide with others emitting

a flash of ultraviolet light which would

be picked up by the detectors at the top

and bottom of the

tank the interaction would also liberate

electrons they drift up to the top and

emit an even bigger

flash so we get two flashes of light

here and based on how these two signals

look relative to one another we can tell

whether this was background radiation or

if this was a dark matter particle that

came in and hit the nucleus of a Zenon

atom LZ isn't the only experiment using

cooled

Xenon but it now leads the pack in

sensitivity it's the front runner now

and so we're entering Discovery

territory direct Dark Matter detection

experiments go back to the

1980s xenon-based experiments similar in

design to LZ to the

2000s so far all the experiments

combined have

detected

nothing we can see them crushing but the

process constantly Narrows down what

Dark Matter could possibly be we do see

the S and currently LZ has time on its

side the plan is to acrew a total of

three years worth of data

hopefully there'll be a direct detection

and we'll start to understand the nature

of it it could be that dark matter isn't

a simple one size fits all wimp it could

be that there's multiple different types

of dark matter different species of this

stuff and we started to understand the

Dark Sector as more of a

zoo I'm deeply interested in trying to

make some Headway into the unknown so

the bigger the unknown the better for me

so you know dark matter being 8 5% of

the mass of the universe that we have no

real clue about what this stuff is but

it is profoundly

important it's been a striking

transformation in the past 50 years

thanks to Vera Rubin and others dark

matter has become an essential

scientific building block at the

foundation of our understanding of the

universe there is no way out of dark

matter if you believe in general

relativity in Newton's law if you

believe in that no way out of dark meow

you have to have dark

metal in 1998 as Voyager 1 traveled to

the far reaches of our solar system it

surpassed the record of a previous space

probe Pioneer 10 as the most distant

human maid

object it was 6 and2 billion miles from

Earth 1998 was also the year of one of

the greatest discoveries in the history

of science what seemed to be a force

that literally creates new space out of

nothing today's issue of the journal

science reports new information about

the evolution of the universe a lead

author of one of the studies was

cosmologist Adam Ree thanks for being

with us thank you why did some

scientists react with what one called

amazement and horror to these

conclusions why was it such a shock to

them so we were hoping we'd find a more

simple explanation something mundane um

but but instead you found a new force in

the universe well it would appear that

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way one of Baltimore's hidden gems is

the George peab budy library at Johns

Hopkins

University it has been been called one

of the most beautiful Library spaces in

the

world these five tiers hold 300,000

volumes including astronomical Works

written over the centuries that try to

answer a question that has troubled

humankind perhaps

always when we look up at the night

sky what is it we are seeing

and has it been there

forever Adam Reese an astrophysicist

from Johns Hopkins played a key role in

formulating the current scientific

answer to that

question

wow this is really the original Earth

Centric model like many in astronomy he

has a deep appreciation that he stands

upon the shoulders of giants this is

really my favorite

here cap cernus puts the sun in the

right

place this is progress in

science but Reese has also added to our

understanding of

cosmology sharing a Nobel Prize in 2011

with Saul pearlmutter and Brian P

Schmidt for a discovery that profoundly

changed our view of the

universe here's somebody after my own

heart taking the observations Tao

each of these influential thinkers from

prior to the 20th century have

contributed to our understanding of the

heavens and here comes Isaac Newton who

really develops the mathematics and he

really lays out how gravity

works but they all shared something in

common whatever the heavens were they

seemed Eternal Earth may be at the

center surrounded by Celestial spheres

or the sun may be at the center with the

planets orbiting

it comets may come into view and

disappear but all of these took place on

a gigantic but static

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stage even Albert Einstein initially

agreed by the early 20th century he had

already revolutionized the Newtonian

view of the world

by connecting space and time into one

concept he called

SpaceTime and then theorizing that

gravity was the warping of that

SpaceTime fabric by mass and

energy in

1917 he applied his new ideas to the

entire

universe but he already had a final

result in mind the one generally

accepted by astronomers

Einstein's Universe would be a largely

static and unchanging one though gravity

posed a

problem Einstein had kind of a a puzzle

in his mind because if the universe was

static and yet all the matter in it was

attractive gravity would pull things

together how did it stay static what

kept it static and he made a remarkable

Discovery in his theory of general

relativity the gravity of matter can be

attractive but that the gravity of empty

space could be repulsive he called this

the cosmological constant and he thought

it was a possibility that these two

kinds of gravities the attractive and

the repulsive kind from two different

kinds of aspects of space were causing

this kind of

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stalemate Einstein's solution didn't

stand for long and here at the Mount

Wilson Observatory outside of Los

Angeles is where astronomers gathered

some of the data that led to its

fall these days you may be lucky enough

to hear a woodwind quintet playing in

one of its stored

domes the Acoustics are

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exceptional and it is an inspiring place

for theoretical physicist and graphic

non-fiction author Clifford Johnson to

let his mind

explore in the

1920s this Observatory produced two of

the most important discoveries about the

nature of the

universe both by astronomer Edwin Hubble

the same Hubble the famous Space

Telescope is named for Hubble changes

our entire view of what the universe is

and how vast it

is at the time a debate raged in

astronomy was the Milky Way the entire

universe or was there more to the

story in

1925 Hubble settled the issue by proving

that the Andromeda nebula existed

outside of the Milky Way it along with

other distant nebulas were renamed

galaxies

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the whole notion of a galaxy started to

become a thing only in the mid1 1920s

people started immediately get

interested in what these things

are especially Edwin Hubble he began

measuring the distance from Earth to

various galaxies and when he combined

his work with that of other astronomers

he discovered something deeply

mysterious it had to do with the Doppler

effect we typically think of the Doppler

effect in terms of

sound a siren coming toward you has a

higher pitch because the sound waves

catch up to each other and become

compressed a siren heading away from you

sounds lower because the sound waves

stretch

out a similar thing happens with light

waves if the source of light is headed

toward the Observer the light it emits

will be shifted toward blue if the

source is moving away the light is

shifted toward

red in fact astronomers working parallel

to Hubble encountered exactly

that the light coming from almost every

Galaxy they observed was shifted toward

red indicating that galaxies were moving

away from

Earth and when Hubble checked the red

shifts against his own distance

measurements he discovered not only were

the galaxies racing away from us but the

ones farther away were racing away

faster what did that

mean given that we're not in a special

place in the universe we're not at the

center of the universe the conclusion is

is that the whole universe is expanding

everything is moving away from

everything else this is another huge

discovery about the nature of our

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universe some astronomers like Belgian

cosmologist and Catholic priest George

ledra were already exploring the

implications of an expanding

Universe if you rewind the expansion

like a

film where does the Universe start does

it have a

beginning the idea is that there was

some earlier phase in the universe where

everything was much closer together some

very dense early phase of the universe

and something happened to begin to push

things

apart that line of thinking led to the

theory

labeled by its detractors as the Big

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Bang it wasn't until the mid 1960s that

observational evidence quieted the Big

Bang

critics when two astronomers Robert

Wilson and Arno penus using this antenna

in homedel New Jersey stumbled across

one of its predicted

artifacts after the big bang it took

hundreds of thousands of years for the

universe to cool enough to Transit light

that initial burst has left a faint

residual

glow today we call it the cosmic

microwave background or

CMB Cosmic micro background is actually

a remnant of the big bag it's the

radiation from that big bang that we can

observe from when the universe was about

380,000 years

old later ground and space-based

experiments would study this fossil

radiation in ever finer

detail because its extremely slight

variations shown here in different

colors can reveal insights into the

structure of the early

Universe by the

1970s thanks to the CMB most astronomers

had accepted the Big Bang Theory and

that the Universe was

expanding but they also thought the

expansion was likely slowing because of

the attractive force of gravity on

matter matter decelerates the expansion

it deer cerates it either a little bit

if there's only a little matter and the

universe expands forever or it

decelerates it a great deal halting the

expansion at some point in the future

and causing the universe to

collapse measuring how fast the

expansion was decelerating would reveal

the fate of the

universe and the key to doing that was

this

one of the brightest explosions observed

in

space when a star becomes a

supernova there are two types of

supernovas and distinctions within those

but a type 1A

Supernova is fairly common about a

quarter of all

supernovas incredibly bright sometimes

brighter than a entire

galaxy and remarkably

consistent that makes it an excellent

candidate to be what astronomers call a

standard

candle a kind of cosmic measuring

stick if enough of them could be

found so that was the goal of the newly

formed highz Supernova search team Adam

Reese was a

member they planned to discover distant

type 1A supernovas compare them to

nearby

ones and definitively answer how much

the expansion of the universe was

slowing down but they weren't alone

there was another team the Supernova

cosmology project which had started a

number of years before us they were more

particle physicists and we were more I

would say Supernova

astronomers but both comp meeting

realistically for the same telescope

facilities which were very precious

Commodities to get to do this

research by

1997 the highz team had collected a

large enough sample of

supernovas to get a first read on the

universe hey look at that but initially

the results made no

sense so we went from saying you know

this has got to be wrong to like this

looks like what the data says we have to

report that

in early

1998 both teams announced the same

shocking

conclusion the universe was not slowing

in its

expansion it was speeding

up like an invisible hand some

undiscovered force was at war with

gravity and pushing the universe apart

faster and faster

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from what we can see there's really uh

not too much left besides the

possibility of this repulsive force does

that mean that the Universe could just

keep on expanding forever if you take

this result at face value if this is

really true the implication is yes that

the Universe would expand

Forever The Mysterious repulsive Force

came to be known as dark

energy dark energy is really the name we

give to our ignorance of what's causing

the accelerating expansion of the

universe it's a pushing out that it does

it's a pressure and outward pressure

that the gravitational force is pushing

against overall the universe is

accelerating in its expansion because of

this dark energy

effect today scientists estimate it is

overwhelmingly the most prevalent form

of energy in the universe

we thought we knew the constituents of

the universe and how it was evolving

over time all of a sudden we found out

that no we didn't know because the

biggest component of the universe wasn't

Dark Matter it was dark

energy so what exactly is dark

energy one of the simplest ideas is that

it's actually a property of space and

time

itself scientists had always assumed the

energy level of a perfect vacuum was

Zero but what if it wasn't what if as

the universe expanded and created more

space a repulsive energy inherent to

that space grew as

well on massive scales it would oppose

and maybe even overcome the

gravitational attraction of

matter and ironically that's exactly the

kind of thing that Einstein had come up

with long ago when he was trying to make

the universe

static in his formula to describe the

universe Einstein had added a

cosmological constant to perfectly

balance the attractive effect of gravity

and create his static

Universe when astronomers in the 1920s

and 30s concluded that the Universe

wasn't static at all but expanding he

dropped his cosmological constant and is

said to have called it his biggest

blunder but with the discovery of an

accelerating expansion cosmologists

revived the term makes absolutely no

sense in fact it was an idea Adam Reese

turned to early in his

analysis after convincing myself I

hadn't made a mistake uh I introduced

that possibility into the analysis that

Einstein's cosmological constant existed

and the fit grabbed on to it and said

yes this you know a pretty high

confidence this is indeed part of the

recipe of the

universe so how did astronomers miss

this most consequential of

phenomena perhaps a reason we hadn't

noticed it before is because the way you

measure it is in terms of how much is it

per unit of SpaceTime perhaps a little

chunk of uh uh space right here so you

have to divide the entire effect by the

volume of the observable universe so

that makes it a very small number

imagine the energy released by a match

head

burning the estimated equivalent in dark

energy is spread across a cube of empty

space with an edge about 7 and a half

miles long or the amount of space

contained by about 1 and 1/2 million

astrodon so it's small and maybe in the

early history of the universe when it

contained a lot less empty space not

even that important if we were in a

period of time much much earlier in the

history of the universe Dark Energy was

a very very small component of the

universe and it wouldn't have

necessarily been

noticeable but that changed about 6

billion years ago by then the universe

had grown big enough for dark energy to

overcome the attractive force of gravity

and start speeding beating up the

expansion today Dark Energy dominates

the universe and it may even

determine its ultimate fate now we are

in the dark energy era of the universe

which means that the universe is

expanding at an accelerated rate if the

universe would keep on expanding and

expanding and expanding then we seem to

be looking at a a a far distant future

in which the universe is basically empty

it's been diluted of all the stuff that

we otherwise can see lighting up and and

and dancing around us galaxies would

just continue moving further and further

apart from each

other our nearest galaxies will go

beyond our visible Horizon beyond what

we can see in the universe space would

stretch even faster than light could

catch up to tell us as a Galaxy over

there eventually we will not be able to

see the light coming from another galaxy

we can't see any other Galaxy anymore

because dark energy and the expansion of

the universe has driven this all away

that would be kind of sad we might not

be S of um uh torn apart we just become

extremely extremely lonely the end of

the universe will be very cold and very

dark and and we won't see the nearby

galaxies and so on that's the future

expansion of the

universe if it makes any anyone feel

better there is still a lot of

uncertainty about Dark Energy especially

whether it has been consistent over

time at the moment we think it's been

consistent but it's potentially Nobel

prize winning if it's been changing over

time and so secretly not so secretly

cosmologists are really hoping to find

something different because that'll be

really

exciting a cosmological constant that

isn't really constant could be the

solution to another vexing mystery which

some have called a cosmological crisis

this is a real problem there are some

tensions in what we're seeing this has

been a great challenge for us in the

last 10 years this is something that

can't just be wished

away it has to do with how fast the

universe is currently expanding that's

known as the Hubble

constant to calculate it scientists have

mainly used two different approaches one

is based on the baby picture of the

universe the

CMB which itself has been measured in

ever increasing detail three different

generations of specially built

satellites in the sky to just do this

one thing measure the CMB to my mind

mindboggling Precision the measurements

that we have from the cosmic microwave

background right now they are the gold

standard in our field so high quality

that when you make measurements from it

they are extremely high

precision meanwhile other groups

including one led by Adam Reese have

calculated the Hubble constant using

measurements of distant

supernovas distant things from us but

not nearly so distant as the cosmic

micro background phenomena that are old

in Cosmic history but not quite so old

we call them late

Universe two different techniques one

based on the early Universe the CMB and

the other on the late universe

using

supernovas we have the ability to

bookend the universe to essentially see

how fast the universe was expanding at

the beginning and how fast it's

expanding now we're measuring the same

universe whether we're measuring the

cosmic microwave background or a

population of supern to see if you can

go from one to the other if you can

predict how fast the universe ought to

be expanding and there's all kinds of

reasons to think that either one of

these kinds of physical systems should

give the same answer it essentially lets

us test our standard model over Cosmic

time and and that sets up a very

beautiful robustness test for does this

model

work but as the accuracy of each

approach has grown the estimates for the

Hubble constant the speed the universe

is

expanding have diverged a problem known

as the Hubble tension many of us are

quite fascinated by the implication that

we could be missing something still in

our understand of the universe or this

might be another clue about the nature

of some of these unknown parts of the

universe the dark matter the dark energy

things like that when we get mismatches

we get pretty excited about it in our

field because these tensions tell us

that maybe something is not quite right

in the model maybe that's the hint of of

where to look for the next breakthrough

this is where we find new physics this

is where we find Discovery is it just

measurements being made wrong is it

modeling being made wrong or are we

fundamentally not understanding

something about our universe we don't

know yet but it's telling us that

cosmology is still very

exciting 3 2

1 so the jury is still out but more data

is on the way the European space

agency's uclid Space Telescope launched

on July 1st

2023 it's design to look 10 billion

years into the past with unprecedented

accuracy and uid is not alone in its

pursuit of

answers it will soon be joined by NASA's

Nancy Grace Roman Space

Telescope which will measure distances

and positions for millions of

galaxies but perhaps most fitting will

be the work done done here in the soon

to be completed Vera C ruin observatory

in

Chile it will house the Simon survey

telescope that will photograph the

entire night sky every few nights using

the largest digital camera ever

constructed I think it's wonderful that

the Vera SE Rubin Observatory has been

named after Vera ruin she was Fearless

and undaunted she just kept going my

number one belief is that the universe

is for everyone we all have this right

to understand our place in the universe

and how the universe works and I think

that's really A fitting part of her

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Legacy in 2012 Voyager one left our

solar system in the sun's protective

heliosphere sending home the First

Direct observations of interstellar

space today the space probe continues on

its lonely

Journey as it likely

will long after we're

gone since the days of the Voyager

launch about 50 years ago much has

changed about our fundamental

understanding of the

universe but what will happen in the

next 50

years the last 50 years was about posing

some of these very big questions I think

the next 50 years is going to be about

answering them now we're left with the

very very hard problem to solve trying

to understand what dark matter is trying

to understand what dark energy is those

are not going to be easy to

solve it's a hugely exciting time to be

involved in physics astronomy cosmology

all the things that are now coming

together to help understand our universe

at large we're doing the experiments now

that might allow us in 50 years to say

wow there was another revolution in the

mid 2020s or around the time

2030 that gave us a whole new way to

look at the

universe dark matter is going to be the

most exciting thing that's going to

happen in the next 50 years because

either they're going to find it or it's

going to be incredibly exciting because

they're going to not find it and then

people are going to tear their hairs out

because what are we going to do

now it really is truly hard to imagine

what's our model and what our thinking

will be we will find new things it's

undeniable what I would love to learn

more about if I had a time capsule Zoom

forward right now is to ask what are the

questions we didn't even think to ask

today what what's really going to

surprise us that we didn't even wonder

to wonder about

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