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Practice English Speaking&Listening with: The accelerating Universe: Nobel Laureate Brian Schmidt

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everyone my name is Brian Schmidt and

today I'm going to tell you about the

accelerating universe now the

accelerating universe is not a story

that is just my own it really is a story

about cosmology and the hundred years of

development over the past century and so

let's first start with a tour of the

universe and the first thing I want to

say is that the universe is big now to

understand just how big we're going to

use the speed of light as our tour guide

and the fact that it travels 300,000

kilometers per second that's seven and a

half times around the earth each second

so for example when Neil Armstrong took

his one small step well we found out

about it one and a half seconds after

that event occurred and the radio waves

from his voice were transported right

down the road here at hunting cycle

Creek and then transported around the

world you may not realize it but the Sun

is five light seconds across so much

bigger than the Earth Moon system the

reason the Sun is so small in the sky is

because it's so far away about eight

light minutes in distance now our Sun is

only one of many stars in the sky the

nearest of star stellar systems is Alpha

Centauri the brighter of the two pointer

stars to the Southern Cross Alpha

Centauri is a star not dissimilar to our

own Sun and I want you to imagine it

being a pea if it were a pea and sitting

here in my hand and we think of the Sun

being another pea where would the Sun

have to be to be the right scale well

about Sydney 270 kilometers away

everything in between is empty space and

so you can see why we call space space

there's a lot of it out there so if we

look out to our own galaxy we see we're

sour Sun is some 30,000 light years from

the center and our Sun is made up of not

just one or two stars but a hundred

billion stars like our Sun and so it's a

very exciting part of the universe but

only a small part of it looking further

afield we can see the nearest galaxies

the large and small Magellanic Clouds

right down here our little satellite

galaxies of the Milky Way

they contain ten billion and our 1

billion stars respectively but they're

tiny little galaxies that don't amount

to much the first real galaxy of any

size is via dramatis spiral about 2

million light-years in distance it's a

galaxy that's a little bigger than our

own Milky Way but just the tip of the

iceberg where here we are looking only

in the nearest part of our own universe

the most distant image that we have been

able to take of our universe thus far is

with the hubble space telescope and this

is the image we call the Ultra Deep

Field in this image there are about 5000

galaxies each of these galaxies is not

dissimilar to our own Milky Way

containing hundreds of billions of stars

and so this part of the image this part

of the universe very small is 132

millionth of the entire sky and so while

the universe is huge it at least the

part we can see is not infinite we take

32 million pictures like this and we've

seen it all and the reason we can see it

all is because the universe although

very big and may be infinite is not

infinitely old if we look back 13.7

billion years ago

we see a picture of the sky that looks

like this this is an image taken in

microwaves and shows not stars and

galaxies but little ripples of sound

left over from the Big Bang each one of

these ripples is a sound wave which

eventually forms tens of thousands of

galaxies and before that of course we

have the time of the Big Bang all right

so let's go to the beginnings of

cosmology and figure out how we learned

all of this I really see the beginnings

of cosmology when we are able to take

the light from stars spread them out

into the colors of the rainbow something

we call a spectrum and a spectrum of a

star reveals what the star is made out

of because every element has a

fingerprint a fingerprint of

light and color which it absorbs and

emits so for example sodium has

fingerprint where it emits an orange

yellow color which you can see in for

example lights around airports or in

other places that have sodium lights

neon has a similar fingerprint that

gives you the fingerprint of a neon sign

well Vesto melvin Slifer in 1916 took

the light of not stars but galaxies sped

them out into the spectrum and he saw

that these galaxies looked a lot like

stars but with a difference and that

difference was that their light was

stretched red word and Slifer knew that

what that meant from something we called

the Doppler shift so if you look at for

example a police car that's coming

towards you it's sound waves are

compressed by its motion and when you

compress sound waves you raise the pitch

of sound as that star as that car goes

past you well then you're seeing the

sound waves which are stretched rather

than compressed and when you stretch

sound waves you make the sound lower

pitch now light is a wave and so it is

affected by the exact same process and

that process for light is when you

compress light so an object moving

towards you the light is made bluer and

when you stretch light well the light is

made redder and so when Slifer went

through and saw that all these galaxies

light was stretched he realized that all

of the galaxies in the universe seemed

to be moving away from us there are a

few nearby objects which are actually

coming towards us but very very few only

a handful and so this was a big mystery

in 1916 why would all the galaxies in

the universe be moving away from us it's

saying you seem to indicate that we were

a special place in the universe a

seemingly very unpopular place in the

universe which everything else was

trying to get away from so trying to

unravel this mystery took some time and

it took being able to measure distances

now measuring distances in astronomy is

not easy

we cannot lay down a ruler between

us in the nearest star or galaxy instead

we have to resort to how things appear

so for example a candle or any light

source appears fainter the further away

it is on the other hand a ruler of

course appears smaller the further away

it is so Edwin Hubble was able to use a

law that Newton had come up with that is

the inverse square law which says that

for example if you have a light bulb and

you move it to half the distance that

appears four times brighter and so by

judging how bright objects are in the

universe one can judge how far away they

are

so Edwin Hubble in 1929 looked at the

Stars and slifer's galaxies and he

realized that the faster the galaxy was

moving away the fainter its stars were

or in other words the further the galaxy

was the faster it was moving away and to

show you his data here is his data from

1929 and we have plotted here brighter

stars meaning nearby distances fainter

stars meeting further distances and then

on this diagram these are the bottom

part of the diagram is slow moving

objects

fast moving objects and from this data

he said wow there's a relationship the

further away you are the faster you're

moving and he said in 1929 this means

that the universe is expanding and to

give you an idea why Hubble said that

let's make a little toy model of the

universe so here we have a universe full

of galaxies which thanks to the power of

a computer I can expand and when I

expand those two images and look what's

happened I'm going to overlay them from

a reference point in the center you can

see that nearby objects have moved a

little bit distant objects for example

have moved a lot here here and here and

so you can see the further away you are

in an expanding universe the faster you

move just what Hubble saw and

furthermore it affects all the parts of

the universe the same

so if I overlay those images at a new

spot I see exactly the same thing we

aren't a special place in the universe

now it's nice to think of this toy model

but you really want to understand things

in the universe with a theory and our

theory comes from Albert Einstein widely

respected as one of the greatest

physicists of all time in 1907 Albert

Einstein had a revelation that

acceleration due to motion and

acceleration due to gravity were

indistinguishable that is imagine you

were in a box and you are in on earth

and you don't know where you're at and

you feel yourself being accelerated by

9.8 meters per second squared the

gravity of Earth Albert Einstein's

thought was that you cannot tell using

any physical test whether or not you're

on earth or in a rocket ship that's

speeding up at that acceleration rate of

9.8 meters per second squared a very

simple thought but a thought that took

him eight and a half years to reconcile

with mathematics the result his field

equations and it predicted many things

including curved space and allowed him

to do something for the first time

something that Newton was never able to

do that is solve for cosmology how the

universe is behaves on the largest

scales now he did this in 1917 and he

got a nasty surprise he found that the

solutions for the universe were dynamic

that meant that the universe had to be

in motion had to be expanding or

contracting and in 1917 that was twelve

years before Hubble made his great

discovery and so Einstein did what any

good theorist does when they have a

theory

which they're sure is right but doesn't

quite fit the observations you come up

with the fudge factor and his fudge

factor was the cosmological constant

this is sort of like energy that is part

of the fabric at space itself at least

that's how we think of it now of course

it was realized later on in his life

when Hubble discovered the expanding

universe that the universe really is in

motion

and that Einstein could have predicted

it from the basis of his theories along

with everything else he predicted but it

also turns out mathematically the

universe wouldn't sit still even with

the addition of this stuff so the idea

of this stuff is you'd add some of it to

counteract gravity because this stuff

causes gravity to push rather than pull

and we're going to come back to this

later on

so under Einsteins view of the universe

things are a little different when we

looked at distant objects we're looking

back into the past because light takes

us time to reach us but the light is it

travels to us as a wave is traveling

through expanding space and so it's not

so much that the objects are necessarily

moving away from us it's rather they're

expanding they're traveling through

expanding space and the further the

object is away the more it has to travel

through expanding space so the more it

is redshifted as it gets to us so

imagine a universe which is expanding

let's put it in reverse things get

closer and closer and closer until voila

you get to the time of the Big Bang the

time when everything in the universe is

on top of everything else and so the Big

Bang is sort of a natural consequence of

an expanding universe having a time when

everything was on top of everything else

very very dips so think of this

graphically imagine I have two galaxies

separated by some distance at some time

and if I go through and I run the

universe back with this line and this

line is the expansion rate of the

universe what we call Hubble's constant

so the steepness of this line tells you

how old the universe is and the

steepness of this line is the value

which we call the Hubble constant the

rate that the universe is expanding

today so by measuring how fast universe

is expanding you can figure out how old

the universe is now I thought this was a

great thing to know back when I started

my PhD in 1989 at Harvard and so three

years 11 months and four days later but

who's counting Here I am showing my PhD

supervisor professor Bob Kirchner at

heart

my result for the expansion rate of the

universe and you can see I'm very

excited about it and because the answer

that I got was that the universe is

about 14 billion years old or that's a

Hubble constant of 70 in current

measurements now it turns out I was part

of a larger discussion throughout the

community that was figuring this number

out the eventual answer was decided

using the Hubble Space Telescope let

co-led by professor jeremy mold the

director of Mount Stromlo Observatory

and the man who brought me here to

Australia back in the end of 1994 so we

think the universe is about 14 billion

years old but there's an extra

complication when I showed you this

diagram that line is straight but what

if gravity is slowing the universe down

we expect by Einstein's equations and

just calm and intuition that gravity is

going to pull on stuff and so just like

a ball that I throw up in the air and

the Earth's gravity pulls and slows down

I expect all the gravity in the universe

to pull on the universe and slow it down

and so this universe you can see is not

as old as it might otherwise be indeed

if we went through and added a

reasonable amount of gravity to the

universe the universe instead of being

14 billion years old might only be 9 or

10 billion years old and that might be a

problem because we're pretty sure the

oldest stars in the universe are at

least 12 billion years old and we

cosmologists aren't too fussy but it is

useful for the universe to be older than

the stuff that's in it now when we look

at a diagram like this we can also

project into the future so imagine I

look at a universe which isn't slowing

down this is a universe which is empty

and coasting it just keeps on going at

the same rate gets bigger bigger and

bigger and bigger this is a universe

which goes on forever it is infinite

into the future on the other hand you

can imagine a universe which is slowing

down

here's a universe if it's slowing down

quick enough we'll reach a maximum size

and then go into reverse just like the

ball that I throw up into the air so

while both these universes start with

the Big Bang

this second universe of course ends

differently it ends with again AB Gib

that's a Big Bang backwards alright so

as a review the slowing down of the

universe affects how old we think the

universe is from the Hubble constant it

tells us the ultimate fate of the

universe and it turns out it tells us

the shape and way to the universe and

that's because Einsteins gravity bends

space so imagine I have a heavy universe

the weight of the universe bends space

onto itself and makes it finite this is

a universe if I start here today and I

head out this direction given enough

time I will eventually come back to

where I started on the other hand you

can imagine a light universe well space

is naturally hyperbolic as we would say

in geometry it's the shape of a saddle

it bends away from itself in this

universe triangles when you add up their

angles add up to less than 180 degrees

in the heavy universe they add up to

more than 180 degrees and if that

doesn't make sense go out and try but

globe and make a triangle a big triangle

on a globe and add up its angles and you

will see that on a globe the angles of a

triangle add up to more than 180 degrees

if you use string and finally we have

the just right universe the universe

precariously balanced between the finite

and the infinite a universe which is

just right also because the theorists

who study the Big Bang or right after

the Big Bang period which we call

inflation but that's a topic of another

lecture they think that the universe

must be right on this precarious balance

between the finite and the infinite for

their theories to make sense so when I

came to Australia at the end of 1994 I

was moving to a new land and I decided I

wanted to do something big so measuring

the age of the universe was once one

thing but measuring its ultimate future

seemed like the biggest thing I could

think of and so imagine the plan you go

through and you measure how fast the

universes expand

ending now something I wore or less did

for my thesis and then I look into the

past and I recreate that experiment I go

and I look at these objects a long ways

in the past so I'm looking a far far way

away and that allows me to see how the

universe changes over time if the

universe isn't slowing down well then

it's going to be coasting and it will

mean that the universe is infinite it's

empty it's going to go on forever on the

other hand if the universe has got a lot

of stuff in it it's heavy well there is

a trajectory in which gravity wins and

faster than this if the universe is

slowing down faster than this line well

gravity wins and the universe is heavy

and finite the other side of this line

gravity loses the universe is light and

infinite and so to do this test well we

need to be able to measure distances

across the universe's past and for that

the universe gave us something something

called a type 1a supernova an incredibly

brilliant uh exploding star which to

understand we need to first understand

the life of the star so the life of a

star like the Sun is that was born our

son was born 4.6 billion years from ago

and in about four billion years it's

going to puff up and eventually consume

the earth crash down to a tiny little

star called a white dwarf a star about

the size of the earth but the mass of

the Sun now if our Sun was instead born

not as a single star but as a binary

that same process happens but when a big

star pops up next to another one this

other star the first the smaller star

will survive and it can go through the

same process and that process allows

this white dwarf to be grow and mass as

it siphons off material when it reaches

one point three eight times the mass of

the Sun it becomes a giant thermonuclear

detonation producing light five billion

times brighter than our Sun and

synthesizing about two-thirds of the

iron in the universe these objects take

about twenty days to reach their maximum

brightness and then they fade away into

oblivion over time

so these objects that turn out were

first looked at by Fritz Zwicky Fritz

Zwicky used a Schmidt telescope Schmidt

telescopes are not named after me or any

of my relatives but they're a special

type of telescope that allow astronomers

to take pictures of large portions of

the night sky at a time and so by taking

photographic plates one night and then

looking a month later Fritz Zwicky and

his colleagues could go through and find

things that changed and they discovered

this class of objects supernovae which

they named that were appearing in the

nighttime sky and seemed to be these

powerful explosions now thirty over

thirty years they gathered a lot of data

and by 1968 they were mable to make

their version of Hubble's diagram shown

here by the one that Charlie Cowell did

in 1968 and here bright supernova faint

supernovae are plotted against their

redshift low to high and you can see the

same thing that Hubble saw the further

away you go

the faster you're moving or the more you

have redshift as we would describe it

and the scatter and this method was

relatively large about a factor of 30 or

40% but it was consistent with the

uncertainties in the experiment which

were very very large from this work

supernovae developed a reputation of

being perfect standard candles that is

almost all identical and to test that a

group in Chile formed in the early 1990s

the culantro supernova search and I met

Mario hem we here just above my head in

France in 1990 when I was just starting

my PhD and they were just starting this

supernova search and so they told me

about their plans to use these objects

as standard candles and when I visited

chewie in 1991 the group was very

depressed they had been lied to these

supernovae were not all the same three

years later when I was seeing Mario he

told me that actually there was a magic

formula formula developed by his

colleague and one of my colleagues also

Mark Phillips which was that the

supernova will not

all the same had a very specific pattern

and that pattern was that these ones

that rise and fall quickly are fainter

than the ones that rise and fall slowly

and we know from now that these things

may can synthesize a little bit of iron

these do a lot of iron and that process

we can understand why this pattern

happens in nature so in 1994 when mario

came and showed me his diagram and his

here it's his version of the Hubble

diagram you can see it looks a little

different than the other ones I've shown

you because all of the dots each

supernova lie exactly on the line and

that indicates that these supernovae

were giving distances accurate to 6% and

that is really good by astronomical

standards even today from this work this

group eventually found 29 supernovae and

these have provided the fundamental

basis of using type 1a supernovae as

distant indicate distance indicators so

in 1994 there were two breakthroughs

there was the one I've just shown you

about how to use these supernovae but a

group at Berkeley had been working since

1988 to discover distant supernovas in

the hope that they could be used to

measure precision distances had a major

breakthrough they went through and were

able to define in a period of three

months seven sent such objects and the

thing that really contributed to that

was a lot of hard work but also the idea

of technology enabling in the form of

computers and large CCD cameras which

I'll talk about in a second so that

started a race a race between a group

that worked on the supernovae which was

a group that myself and Nick sunset

formed in 1994 who was competing with

saw promoters group we did talk about

working together but the reality is we

had very different ways of approaching

the project at this time and so it

became clear that we needed to do the

projects in our own ways and this set up

a competition between two teams the

Heisey team and the supernova cosmology

project and here you can see Saul

Perlmutter the leader of the supernova

cosmology project and myself trying to

punch each other out

we had a spirited competition but I

think most of the time we were very well

behaved and certainly one thing is clear

science benefited from the competition

now I told you in 1994 we had these two

breakthroughs and the one breakthrough

that's implicit was technology in 1994

the Keck telescopes came online these

were the new 10 meter sized telescopes

bigger than the four and five meter

sized telescopes we had before

these were necessary to go through and

take the redshifts and spectra of the

supernovae that we needed for this

experiment the other thing that came

along were these large format CCD

cameras these CCD cameras you know on in

your digital cameras and video cameras

but they came through the military

through astronomy and worse pursed into

civilian life by astronomers more than

anyone and in 1994 we had the first 4

million pixel detectors or 2 K by 2 K

detectors as we call them and these

things are about a hundred times more

sensitive than the ones for example in

your iPhone and although 4 million

pixels doesn't sound very big compared

to your iPhone typically has an 8

megapixel camera now you have to realize

in 1994 weald dealing with computers

that were Pentium 250 megahertz and

we're dealing with 1 gigabyte hard

drives and so we were usually taking 20

gigabytes worth of data a night and so

the technological challenge of sifting

through this data and finding the

supernovae was very hard now just to

think make you think that we here at the

ANU are not sitting still in technology

the ANU through the Australian

Government for Australia has invested in

the next generation of telescopes and

these are called this new telescope that

we've invested in is called

the giant Magellan telescope a telescope

that is made up of seven 8.36 meter

mirrors and you can see these mirrors

all work together to give us both a

deeper and sharper view of the distant

universe the scale of this is

represented by the semi-trailer at the

bottom

you see this huge telescope has to be

aligned to incredibly precise accuracy

of better than a micron or a millionth

of a meter and it's a very

technologically challenging project that

we expect to reach fruition over the

next decade it is a project we are doing

in concert with the Carnegie Institution

the country of Korea

Harvard Smithsonian Texas A&M University

of Texas and the University of Chicago

and the University of Arizona so it's a

great project for the future and to show

you that it's really happening I was at

the University of Arizona where I was an

undergraduate which is making the

mirrors and here is the first mirror

8.36 meters

polished to 19 nanometers so I'm a

nanometer a billionth of a meter across

the whole surface and that's mirror one

it's done mirror to well it came out of

the oven and here it is sitting there

and mirror three goes in to be melted in

the oven early next year and so this

project is really coming online so

technology is the secret enabler to

astronomy and so I think astronomy with

investments like this as a great future

in the future here in Australia so the

technology of 1994 as I said was very

challenging to go through and sift

through data like this to find the

exploding stars there's five thousand

galaxies in this image and the key is to

find the needle in the haystack

the exploding star and that exploding

star is this little smudge right here

and the way we find this is not by

taking one image but by taking two and

separating them in time so for example

if we take an image and we take compare

it to an image taken in this case 24

days earlier we can see that nothing has

become something here this something a

supernova 5 billion years in the

universe's past a supernova which

exploded before the earth was formed

that is the power of cosmology being

able to look in the past

fortunately we can't look into the

future we can only speculate about the

future to give you an idea about how one

of these trips works I'm going to take

you to chew a to the

CTI oh four meter telescope where we are

getting ready for Knights observing here

we see Greg altering from the supernova

cosmology project silhouetted against

the background because he's the bad guy

Nick some stuff here is leading the

observations nick is a incredibly

finicky astronomer wants everything to

be perfect and well so because we only

get six nights a year because we have to

share this telescope of course with all

the other astronomers in the world Nick

makes sure that every image is precisely

pointed and is a perfect quality so that

my software can run on it and then a

team of people can go through and look

for the candidates my software what's up

and see if we are finding things that we

can use for measuring distances my

software is okay it's not perfect

there's a lot of junk and time is of the

essence because we have to go and look

at these things across the globe at the

Keck telescopes 36 hours later so we

have to process all that data as fast as

we can so we get on to these large

telescopes here we have Alex Filippenko

and Adam riess making sure that they get

spectra and of course there we're

sharing the telescope time also with the

supernova cosmology project Saul

Perlmutter there and they are - of

course using the same facility we were

both using the same facilities the best

facilities that we had were on offer to

do this work so in 1997 Adam riess

contacted me he was reducing and

analyzing the data that we were taking

for our next paper and he said well what

do you think of this and what I saw was

the following each supernova here is a

point and it has an error bar because

the supernovae have an uncertainty and

these error bars are essentially tell

you where 68.3% of the time the correct

answer lies so one in three chances it's

out of here but two out of three is it

lies within that error bar and when I

looked at these nearby objects these are

the objects of the kalam 200 survey the

chilean group who are actually part of

our team as well and you can see that

compared to this trajectory on average

you can't tell

what's going on that's why we had to

look a long ways away these objects the

distant objects though not a single one

of them is consistent with the universe

which is finite but on average you can

also see that they don't lie in the

yellow part of the diagram the part of

the diagram where the universe is

slowing down instead they seem to lie up

in the top part of the diagram the part

of the diagram which says the universe

is being accelerated by something

unknown this case the question then was

hmm what's going on people asked did you

say Eureka and the answer is no I think

we really thought geez what have we done

possibly wrong so here we have Adam

Reese's lab notebook where he first

written wrote down what this meant to

him and what he found when he did the

calculations by the traditional method

is we had the universe had negative mass

or effectively gravity was pushing

rather than pulling so I'm afraid there

was no Eureka there was a great deal of

hard work to figure out what was going

possibly wrong after the end of that

period we decided nothing seemed to be

going wrong it was a crazy result but as

scientists we ultimately have to report

what we see not what we like and so in

1998 we put a paper out and it turns out

that the supernova cosmology project was

getting the exact same crazy result at

the same time and so it wasn't one it

was two papers that came out pointing

towards an acceleration acceleration of

the universe and so these two papers are

what eventually led to the discovery of

the accelerating universe and to what

became the Nobel Prize of 2011 and

because this work is really done not by

three individuals who win the Nobel

Prize but by two teams I think it's very

important to point out the teams here's

the supernova cosmology project and our

own high redshift supernovae team

just as we like to normally dress in

white white bowties and tails here for

the first time ever together at the

Nobel Prize ceremony in Stockholm so

that sort of gives you an insight of

team dynamics this team had never all

been together in one place until the

Nobel Prize ceremony we all knew each

other we had all worked with each other

but because we were dispersed across

five continents we were never able all

to be in the one place at the one time

we had a great time in Stockholm and to

give you a sense of what Stockholm's

like when you cut off the plane if

you're a Nobel Prize winner they first

thing is they don't have you go through

security in the normal way instead they

give you a driver and they whisk you off

the airplane and in my case I came up

and my driver said hello my name is Stig

and I said Stig hmm and I thought I

think he's going to get us around the

streets of Stockholm just fine thank you

the other thing you get to do is you get

to meet the king so here the king is

presenting me the award and the Swedes

really wanted to know more than anything

not what came before the Big Bang what

is the universe expanding into nope they

want to know what did the King say to

you so in my case the King said

congratulations on behalf of cicada me

for the Nobel Prize in Physics and thank

you very much for the bottle of wine

because I'm a winemaker among other

things and I presented him a bottle of

wine before the ceremony so I hope he

liked it and the final thing that they

give you in my case at least was a

princess and Here I am escorting

Princess Victoria at the banquet and

when I look at this photograph when I

first saw it I said to my wife I said

geez I woke so glamorous with the

princess on my arm and that's a

turned-out she didn't appreciate that as

much as I had hoped

turns out she also had the Swedish Prime

Minister a tall handsome guy so she

didn't completely miss that all right so

what is pushing on the universe well we

only have to look to Einstein for the

answer his cosmological constant the

energy that is part of space itself well

that turns out can actually provide us a

way to make gravity

push rather than pull this stuff if it

exists makes gravity push as the

fundamental way that gravity works in

his theory rather than pull so by adding

some of this stuff to space we can go

through and get the universe to speed up

now we're not sure that Einsteins

version of this is correct and so we

give it another name and that name is

dark energy now whenever astronomers use

the word dark it's because we can't see

it and that means since astronomers look

at things we don't understand it very

well so dark energy is really stuff we

don't understand very well energy so if

you do a detailed analysis of our work

you come to the conclusion that the

universe is a 30% mixture of normal

stuff pulling on the universe and 70%

pushing on the universe so we really

need a little bit of pull a little bit

of push to make our observations make

sense now when we release these in 1998

the community was justifiably skeptical

I was skeptical I couldn't believe the

universe could be so crazy but I knew

that our measurements were fundamentally

correct that the supernovae were too

faint to make make sense except for

something crazy were going on so a

series of experiments were made and the

first one was done or one of the first

ones was done here in Australia where a

group using the anglo-australian

telescope an Anglo Australian group made

a map of the nearby universe out to

about a billion light years making a map

of 221 thousand galaxies and you can see

that the galaxies aren't smoothly

distributed they sort of show this

cosmic foam and that foam is caused a

signature of gravity and so they turns

out by looking at this foam and how

galaxies are moving and the the nature

of this foam they would be very out they

were able to very precisely measure the

weight of the universe in gravity as it

attracts so actually essentially - whoa

- way attractive gravity here and so the

amount of gravity pulling on the

universe by their measurement was 20

7% of the amount of stuff necessary to

make the universe flat so astronomers

way the universe typically relative to

the amount of stuff necessary to make

the universe just right to bring it to

that precarious position between finite

and infinite the amount of stuff in the

universe was 27 percent of the way there

at least the stuff that has makes

gravity pull the other experiment that

came sorry

the but the other thing I need to

mention is that this well not enough to

make the universe flat was still 5 times

stronger than the gravity we could

account for by the number of atoms that

were in the universe and so this stuff

of course the shortfall is what we call

dark matter or in the vernacular before

I don't really understand matter this is

stuff which we're hopefully going to get

an insight into over the next couple

years but we think it's some

undiscovered particle that like a

neutrino can pass right through the

earth so it has gravity just like atoms

but is essentially invisible that's at

least our hope what this stuff might be

so the other experiment that was able to

be done was using the Cosmic Microwave

Background this image of the universe

taken right after the Big Bang 380,000

years after the Big Bang

so these sound waves splashing around

the universe have physics which is very

similar to what we can do here on earth

very accurately and so the physics tells

us exactly how long these sound waves

are so for example one of these sound

waves right here is about 450 thousand

light years long and if you remember how

big something appears depends on how far

away it is but it turns out it also

depends on the shape of the universe if

you look at things in a curved space the

light waves get bent and so not

dissimilar to a car objects for example

in curved space that's finite appear

larger than in a flat universe so we can

use that to make a precise measurement

of the geometry of space and when you do

this you find that those little bumps

add up to being exactly what you expect

for a universe which is geometrically

flat that is has a hundred percent of

all the stuff necessary to be flat now

the geometry of space doesn't care if

it's made up of stuff that makes gravity

pull or push it's sensitive to

everything and that allows us to do a

little bit of subtraction so if we add

up everything we have a hundred percent

we subtract off the stuff which is

attracting 27 percent and that leaves us

with 73 percent mystery matter the same

mysterious stuff that the super novae

found is pushing the universe apart so

what does that leave us well it really

leaves us with a mess a universe where

four and a half percent of the universe

are atoms the stuff we know and love and

are made out of

we represent a very small minority of

what's in the universe the rest of the

stuff is dark matter and dark energy

dark matter

pulling dark energy pushing dark matter

pulls along with the atoms and almost

exactly the same way now you might think

well if we only understand 4% of the

universe we have to make up 95 and a

half percent of the universe we just

don't know what we're doing and that may

be a good call but this model of the

universe has been asked to predict many

many things and over the last 13 years

everything it has been able to predict

we have been able to go out and measure

and show to be true and that is how

science works reality is what the theory

predicts you know when a theory predicts

something to be true that is the reality

of the day now it may be that there's

something wrong with this model and

we're getting lucky on being able to

predict things but the things we predict

are sufficiently complicated now that I

think most people think that this model

has essentially the truth embodied in it

and while it's probably not a perfect

the universe it is a model like Newton's

gravity which works very very well at

describing the universe we live in crazy

yes messy yes but it seems to be the way

the universe is constructed so dark

matter as the universe expands the

amount of matter and atoms stays the

same so Dark Matters density and

gravitational effect gets smaller as the

universe expands on the other hand dark

energy is tied to space itself as the

universe expands the dark energy gets

created with the created space and so it

becomes stronger relative to dark matter

over time so this sets up a battle for

domination of the universe dark energy

versus dark matter well after the Big

Bang the universe was expanding dark

matter would have been very dense and

very strong it would have been slowing

the universe down as the universe gets

bigger and bigger Dark Matters

domination is dropping and at some point

about five or six billion years ago it

turns out the universe got sufficiently

big before Dark Matter could slow it

down that dark energy took over and so

the future of the universe well the

future of the universe seems to be dark

energy the more space expands the more

dark energy can push against gravity

creating even more space and even more

dark energy leading to a runaway process

eventually the creation of space can

happen even more quickly than light can

travel and so galaxies we see today will

literally be lost as their light goes

through and is stranded in the expansion

of space between us and those galaxies

in the first and one of the in the

oldest picture of the universe I showed

you taken with the Hubble Space

Telescope those galaxies that we see

back 10 to 12 billion years ago the

light they admit today we'll never reach

us they will be those photons will be

stranded in the creation of space

between us now just

a allows some of your fears attractive

gravity has defeated dark energy in our

part of the universe you are not

expanding the earth is not expanding the

Milky Way is not expanding and that's

because our part of the universe dark

matter and atoms overwhelmed the

expansion of the universe thirteen

billion years ago and so all part of the

universe quit expanding and collapsed

and there's a little sphere ball of

material where there was enough mass to

do that and that's what formed our own

part of the universe however that part

of the ball of the universe is

gravitationally bound and will

eventually merge into what we will call

a super galaxy and so we believe the

Andromeda galaxy which is one of the few

galaxies in the sky that's coming

towards us will eventually merge with

the Milky Way and three or four billion

years in the future and we're going to

have this spectacular change in the

nighttime sky from first to milky way's

effectively in the sky finally merging

into a big ball of stars is something

that would look more like an elliptical

galaxy as we call them but the rest of

the universe beyond that bound ball will

be accelerated out of sight we will look

out onto stars and nothing else the rest

of the universe will be empty and that

will leave cosmologists such as myself

who study the distant universe and

galaxies out of a job because there'll

be nothing left for us to look at but

the reality is until we understand what

is accelerating the cosmos anything is

possible

one of the most speculative ideas

involves how dark energy might be a

little different than Einsteins view you

know when anything's possible this dark

energy can change over time and

potentially even accelerate the cosmos

at a faster rate than Einstein's version

and this leads to the potential and I

should say this is very speculative of

something called the big rip if dark

energy gets created

work quickly than the creation of space

that is if I have a box and I double the

size of the box by the expanding

universe I get more than double the

amount of dark energy then that leads to

a runaway that is able to penetrate to

every part of the universe including

your own body and your atoms and E and

even down to breaking the universe down

into essentially subatomic particles and

this point is the universe expands more

and more quickly the density of this

dark energy Rises and it eventually

approaches infinity allowing the dark

energy to eat in to where the universe

is already collapsed and so this really

has almost a human time scale up to it

as the galaxies disappear that happened

a long time ago suddenly the stars in

the Milky Way will start disappearing

eventually the Sun would disappear and

then sometime later move every atom in

your body taken far enough away that

light cannot be transported between any

of the atoms and even the atoms

themselves broken apart into quarks and

electrons so a very exciting end of the

universe and that leaves nothing well it

leaves something it leaves an infinitely

dense universe which is expanding very

quickly and that has a certain synergy I

think with a big bang so I kind of like

it at some level but it doesn't mean

it's true so this is one of the things

we can go out and try to see if the

universe is doing at this point there

was no evidence unfortunately that this

is going to happen and I should say as

far as a theory of the universe it has

some real messiness associated with it

having this energy getting created more

quickly with space however that aside

really unless dark energy suddenly

disappears the universe will in an

ever-increasing rate

expand and fade away in front of our

eyes so that people like me 50 billion

years in the future have nothing less to

do thank you very much

you

The Description of The accelerating Universe: Nobel Laureate Brian Schmidt