# Universe research

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## INTRODUCTION

Page being worked with. Please update now and then.

As the page we becoming to big, I moved the dark energy Brian Smith talked about in the video below, to a separate page.

My grandfather wrote a book published 1907 in Germany, where he mentions observations of world collisions. That was what he thought it to be. Today we know these were supernovas.  He mentions among other Nova Persei 1901 and  a supernova from 1885.  Read more in http://www.kinberg.net/wordpress/willy/100_years_later/#nebula

I found July 2021 a great lecture made by Brian Schmidt in 2012, who is “leader of the High-Redshift Supernova Search Team, Brian’s work on the accelerating universe was awarded the 2011 Nobel Prize in Physics, jointly with Adam Riess, Saul Perlmutter and the rest of the Supernova Search Team.

In his video Brian Schmidt “describes this discovery and explains how astronomers have used observations to trace our universe’s history back more than 13 billion years, leading them to ponder the ultimate fate of the cosmos. ” (Source : https://www.youtube.com/watch?v=55pcpTjd3BY )

# INDEX

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## The video

The video is from 2012 but is still very intresting and enjoyable:

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“Hello, 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 100 years of development over the past century.
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 7 and 1/2 times around the Earth each second.

So for example, when Neil Armstrong took his “one small step,” well, we found out about it 1 and 1/2 seconds after that event occurred. And the radio waves from his voice were transported right down the road here at Honeysuckle 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 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 pie (π). If it were a pie and sitting here in my hand, and we think of the sun being another pie, 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 our sun is some 30,000 light years from the center. And our galaxy is made up of not just one or two stars but a hundred billion stars like our sun. 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, are little satellite galaxies of the Milky Way. They contain 10 billion and one billion stars, respectively. But they’re tiny little galaxies that don’t amount to much.

The first real galaxy of any size is the Andromeda Spiral, about two 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.

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 5,000 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 one 32 millionth of the entire sky.

And so while the universe is huge, 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 maybe 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 leftover 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 were 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’s 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 a fingerprint where it emits an orangey-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 Slipher, in 1916, took the light of not stars but galaxies, spread 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-ward. And Slipher knew what that meant from something we call the Doppler shift.

So if you look at, for example, a police car that’s coming toward you, its 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 Slipher went through and saw that all these galaxies’ light was stretched, he realized that all of the galaxies in the universe seem 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 seemed 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 and 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, it appears four times brighter.

And so by judging how bright objects are in the universe, one can judge how far away they are.

Auth,
Brian Smith choosed to not mention

“Edwin Hubble used Leavitt’s period-luminosity relation, together with the galactic spectral shifts first measured by Vesto Slipher at Lowell Observatory, to establish that the universe is expanding” (see Hubble’s law).

Brian Schmidt:
So Edwin Hubble, in 1929, looked at the stars in Slipher’s galaxies, and he realized that the faster the galaxy was moving away, the fainter its stars were.

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, meaning 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 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 the
acceleration rate of
9.8 meters per second squared.
9.8 m / s2

A very simple thought, but a thought that took him 8 and 1/2 years to reconcile with mathematics.

The result, his field equations.
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 behaves on the largest scales. Now he did this in 1917, and he got a nasty surprise.

the cosmological constant Λ  – the fudge factor

You come up with a fudge factor. And his fudge factor was the cosmological constant

Auth. ΛEinstein’s cosmological constant, is the energy density of space, or vacuum energy, that arises in Albert Einstein’s field equations of general relativity. It is closely associated to the concept of dark energy. In 1931 Einstein finally accepts the theory of an expanding universe…”) WikiΛ=2.036×10−35s−2. This value of Λ is in excellent agreement with the measurements recently obtained by the High-Z Supernova Team and the Supernova Cosmology Project.” scitation.org ).

Brian Schmidt:
This is sort of like energy that is part of the fabric of 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 (Auth. I presume that he refers to Λ )

Auth. Some historical facts about the cosmological constant taken from Wiki:

• 1915 – Einstein publishes his equations of General Relativity, without a cosmological constant Λ.
• 1917 – Einstein included Λ “to counterbalance the effects of gravity and achieve a static universe” ( Wiki ).
• 1922 – Alexander Friedmann mathematically shows that Einstein’s equations (whatever Λ) remain valid in a dynamic universe.
• 1927,  the Belgian astrophysicist Georges Lemaître shows that the Universe is in expansion by combining General Relativity with some astronomical observations, those of Hubble in particular (Wiki
• 1931 Einstein finally accepts the theory of an expanding universe
• He called his static Universe idea “the greatest stupidity of his life”

Brian Schmidt:
So the idea of this stuff is you’d add some of it to counteract gravity because this stuff ( Λ ) causes gravity to push rather than pull.

And we’re going to come back to this later on.

So under Einstein’s 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 its time to reach us.
But the light, as it travels to us as a wave, is traveling through expanding space.
S
o it’s not so much that the objects are necessarily moving away from us. It’s rather that 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 red-shifted as it gets to us.

So imagine a universe that is expanding.

The opposite of 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 dense.

Auth

As mentioned above the Belgian astrophysicist Georges Lemaître did just that mathematically, showing that the Universe is in expansion by combining General Relativity with some astronomical observations, those of Hubble in particular (Wiki )  Lemaître was the first to provide an observational estimate of the Hubble constant. After lemaitres lecture 1922, Einstein who still did not accept the idea of an expaning Universe, said to  Lemaître
Vos calculs sont corrects, mais votre physique est abominable[18] (“Your calculations are correct, but your physics is atrocious” (Wiki ) Read more in my page about Lemaître.

Brian Schmidt:
So to 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 (Auth. Yellow straight line below) is the expansion rate of the universe, what we call Hubble’s Constant.

(Auth. This constant written as Ho is part of the  ‘Hubble flow’ equation v=H0 x D that “describes the motion of galaxies due solely to the expansion of the Universe” Source: astronomy.swin.edu.au This equation clearly shows that greater distance D, greater is the velocity v ).

Brian Schmidt:
So the steepness of this line (Auth. Yellow g line above) 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 the universe is expanding, you can figure out how old the universe is.

Now I thought this was a great thing.

the answer that I got (Auth. In 2000 according to his lecture) is that the universe is about 14 billion years old, or that’s a Hubble constant of 70 in current measurements.

(auth. Brian Schmidt said this in 2012. “Data from Cepheid variables and other astrophysical sources calculated the Hubble constant to be 50,400 mph per million light-years (73.4 km/s/Mpc) in 2016“.)

Brian Schmidt:
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, co-led by Professor Jeremy Mould, 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 common 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.

The age of Universe is 10 billion years or 12 billion years old?

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 nine 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 could imagine a universe which is slowing down. Here’s the universe. If it’s slowing down quick enough, we’ll reach a maximum size, halt, and then go into reverse, just like the ball that I throw up into the air.

So while both these universes start with a Big Bang, this second universe, of course, ends differently. It ends with a gnaB giB. That’s a Big Bang backwards.

All right, 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 weight of the universe. And that’s because Einstein’s 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.

Light Universe

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.

heavy universe

In the heavy universe, they add up to more than 180 degrees.
And if that doesn’t make sense, go out and try a 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 string.

(Image source: it.mathigon.org )

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-a 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 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 universe is expanding now, something I more 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. (auth. red line above)

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, if 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. (auth. under the dotted yellow line in the image above)

The other side of this line, gravity loses. (auth. above the dotted yellow line in the image above), 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.

Ia supernova

And for that, the universe gave us something, something called a type Ia

supernova, an incredibly brilliant, exploding star which to understand,

we need to first understand the life of a star.

the life of a star.

So the life of a star like the sun is that it was born. Our sun was born 4.6 billion years ago. And in about 4 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.

Binary star

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 puffs up next to another one, this other star, the smaller star, will survive. And it can go through the same process. And that process allows this white dwarf to grow in mass as it siphons off material. And when it reaches 1.38 times the mass of the sun,

it becomes a giant thermonuclear detonation, producing light five billion times brighter than our sun and synthesizing about 2/3 of the iron in the universe.

These objects take about 20 days to reach their maximum brightness, and then they fade away into oblivion over time.

Fritz Zwicky. Fritz Zwicky used a Schmidt telescope

So these objects, it turned 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.

Auth.
Supernova have been   observed long time. As I mentioned in the introduction Nova Persei 1901 and a supernova from 1885 was mentioned by my grandfather.

Brian Smith:
Now over 30 years, they gathered a lot of data.
And by 1968, they were able to make their version of Hubble’s diagram, shown here (auth. See image above) by the one that Charlie Kowal did in 1968.

And here, bright supernovae, 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 in 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 Calan-Tololo Supernova Search.

And I met Mario Hamuy, 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 Chile 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, a formula developed by his colleague, and one of my colleagues also, Mark Phillips, which was that the supernovae, while 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 (Auth. the short life Ia supernova on the left in the image above )make and synthesize a little bit of iron.

These (Auth. the longer   life Ia supernova on the right in the image above ) 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 here is 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.

Ia supernovae as distance indicators.

From this work, this group eventually found 29 supernovae. And these have provided the fundamental basis of using type Ia supernovae as 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, who 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 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 Suntzeff formed in 1994, who was competing with Saul Perlmutter’s group. We did talk about working together.

But the reality is we had very different ways of approaching the project at this time. 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 High-Z 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.

New technology

the Keck telescopes came online

In 1994, the Keck telescopes came online. These were the new 10-meter size telescopes, bigger than the four- and five-meter size 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.

CCD cameras – 4 million pixel detectors

The other thing that came along were these large-format, CCD cameras. These CCD…  came through the military, through astronomy, and were dispersed into civilian life by astronomers more than anyone.

And in 1994, we had the first 4 million pixel detectors, or 2K by 2K detectors as we call them. And these things are about 100 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, which typically has an 8 megapixel camera now, you have to realize in 1994, we were dealing with computers that were Pentium II, 150 megahertz.

And we were dealing with one gigabyte hard drives. And we were usually taking 20 gigabytes worth of data a night, and so the technological challenges of sifting through this data and finding the supernovae was very hard.

Now just to 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 ..  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 semitrailer at the bottom. And you see, this huge telescope has to be aligned to an 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. To show you that is really happening,

I was at the University of Arizona, where I was a undergraduate, which is making the mirrors. And here is the first mirror, 8.36 meters, polished to 19 nanometers– so a nanometer, a billionth of a meter across the whole surface. And that’s mirror one.

It’s done.

Mirror two, well, it came out of the oven, and here it is sitting there.

And mirror three goes in to be melting in the oven early next year.

And so this project is really coming online.

the secret enabler to astronomy.

So technology is the secret enabler to astronomy. So I think astronomy, with investments like this, has a great future in the future here in Australia.
T
he technology of 1994, as I said, was very challenging to go through and sift through data like this to find the exploding stars.

There are 5,000 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 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 Chile, to the CTIO four-meter telescope, where we are getting ready for a night’s observing.

Here we see Greg Aldering from the Supernova Cosmology Project silhouetted against the background because he’s the bad guy.

Nick Suntzeff here is leading the observations. Nick is a incredibly finicky astronomer. He 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 of 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 puts up and see if we are finding things that we can use for measuring distances.

My software is OK. 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 can get onto it with 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 too, of course, using the same facility.

We were both using the same facilities, the best facilities that were on offer to do this work.

So in 1997, Adam Riess contacted me. He was reducing and analyzing the data that wewere 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 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.

nearby objects,

And when I looked at these nearby objects, (auth, in the left ring)

these are the objects of the Calan-Tololo 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.

distant objects

These objects, the distant objects, (auth, in the right ring) 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 (auth, green in the image, above the horizontal line in the accelerating infinite sector) 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 universeis being accelerated by something unknown. In this case the question then was, hmm, what’s going on?

Adam Riess’s auth, in his ) lab notebookhe wrote down what..  he found, when he did the calculations by the traditional method, is the universe had negative mass, or effectively gravity was pushing rather than pulling.

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 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.

two teams

And because this work is really done not by three individuals who won 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 Supernova team,

dressed as we like to normally dress, in white bow ties and tails, here for the first time ever together at the Nobel Prize ceremony in Stockholm.

team dynamics

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.

About the visit in Stockholm and the Nobel prize ceremony

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