I would like to tell you as a thespian the entire history of the universe from the beginning to end,
I have only half an hour so it will be brief.
So thank you for inviting me to come and telling you this amazing story.
Astronomers have actually made tremendous progress on this
and we are still guessing about many of the things I'm going to tell you.
Many of the things are probably not true, but you will find out later, as we all will, as this comes to be discussed.
So astronomers are now working on this question of how did we get here.
Just as Jack and Ada were talking about, we are very interested in the origins of life.
So astronomers have the easy part, I think, we have the challenge of describing the physical universe
that leads to the conditions where life could exist here on the planet earth.
We have a story about the Big Bang, we have a story about how galaxies are made from the primordial material.
How galaxies change with time, how stars are made within galaxies, how planets can be made around stars.
And eventually, how the conditions for life may come to exist here and perhaps many other places.
So we are as astronomers working on the physical universe part and then we say, okay, biologists, you have the next step.
So first I want to show you about the expanding universe.
Back in 1929 this chart was made by Edwin Hubble.
He plots here each dot as a galaxy.
A galaxy as you know is 100 billion stars orbiting around each other.
On the horizontal axis is his estimated distance, on the vertical axis is the speed that he measured from the Doppler shift.
So the immediate conclusion from this chart in 1929 is that the universe is expanding.
The most distant galaxies are going away from us at speeds approximately proportional to the distance,
and that means that you can calculate the approximate age of the universe by dividing the distance by the speed.
So in those days he had wrong estimates for the distance, so we had a very confusing picture for a time,
and the universe appeared to be younger than the oldest objects in it.
So that mistake took several decades to correct, but at any rate it was corrected.
Now we have this story which we call Hubble’s law, it’s not just a theory, it´s the law.
And, by the way, also in 1929 it was discovered, that the worldwide economy could collapse.
So it’s a good thing to remember that that’s the year we also discovered that the entire universe could expand.
In 1929 this was a very large surprise.
I will show you pictures of some of the people who thought about this.
In the middle there you see Albert Einstein, and he is the man who told us
that space and time are not absolute but are mixed together in order to have special relativity.
Special relativity is the set of formulae that explains
how it is possible that the speed of light would be a constant regardless of whether we are moving or not.
So it turns out that’s the unique solution to that particular problem.
In 1916 he generalised this theory to include the forces of gravity
and he said that space and time are curved by the action of gravitation.
And this then gave us for the first time the ability to calculate the force of gravity across an infinite universe,
because his equations are differential equations and not just what Isaac Newton had given us.
When Isaac Newton thought about this problem of gravitation across the universe, the result was infinities.
So it was not possible to come to a definite conclusion, but Isaac Newton already was aware that there was a problem.
In 1929 this was still a surprise.
Now I want to tell you about the work of the two people here on the left,
Alexander Friedmann in 1922 applied Einstein’s equations, and he said “I think the universe is expanding”,
and he gave us the right equations for how to describe it.
In 1925 he died, so he didn’t get to see that he was correct.
In 1927 George Lemaître here, who is shown next to Einstein, wearing his Belgium priest´s collar,
who was a mathematician and a Belgian priest, derived the same equations and said “I call this the primeval atom”.
And in both cases Einstein said this is mathematically correct but physics is abominable.
So he was quite sure, Einstein was, that the universe could not possibly be expanding.
How would he know? Well he asked his friends and the friends said “everyone knows the universe is not expanding”.
So Einstein had included in his equations a constant of integration, which we now call the Lambda constant,
and his idea was that the Lambda constant was a force of repulsion,
which would balance the force of contraction that gravitation would produce.
So Einstein was greatly surprised in 1929 to find that his constant was not needed in the expanding universe,
and he had to apologise for being rude, as well as for making a great mistake, which he supposedly called his greatest blunder.
So that’s in the early part of the 20th century.
In the middle of the 20th century George Gamow, who is shown here, was a Ukrainian physicist
who came to the United States to work.
After the war was over and people know about nuclear reactions much more,
they were able to calculate the processes that should have occurred in the early universe.
So they said “what if we calculate the properties of the Big Bang?”.
So they were able to say
“we know what the reactions should be, the rate of reactions of neutrons with protons could be estimated,
and the lifetime of the neutron was known”,
so it was realised that the primordial material should make hydrogen and helium in the first few minutes.
And then after that the neutrons would be gone,
so the cosmic abundance of hydrogen and helium was set in the first few minutes of the expanding universe.
He also said the universe should be filled with radiation, cosmic microwave radiation,
which would have a temperature of a few degrees, about five degrees above absolute zero.
And this was not possible to measure at that time.
It would have been a very difficult measurement.
Now we know that it´s possible for a determined high school student to measure it with equipment from television receivers.
In 1948, when they calculated these things, it was not possible.
They tried quite hard but it was not measured, until it was discovered in 1965 by two of the Nobel prize winners,
who actually are here today, Arnold Penzias and Bob Wilson,
and so the discovery of this cosmic radiation was a tremendous surprise as it turns out,
even though some people had already been thinking about it decades before.
I’ll point out that this radiation is incredibly bright, although it’s difficult for us to measure
- it amounts to about one microwatt per square meter –
in that order of magnitude it´s very bright and in fact if you tune your television receiver between channels,
about 1% of the snow flakes you see on a TV screen come from the cosmos, come from the Big Bang radiation itself.
So if you knew what you were looking at you'd say “aha now I understand the Big Bang!”.
I have two other pictures here.
On the bottom on the left are Alpher and Herman.
They were working with George Gamow and they were the ones who actually did these calculations in 1948.
They are shown here as they appeared when they came to the launch of their satellite
which made a more precise measurement and earned the Nobel prize.
On the right hand side we have Sunyaev and Peebles, who are two modern theorists.
This is a reminder that no theorist has earned a prize yet for the Big Bang, but many observers have now.
I want to point out that a consequence of Hubble’s Law, the straight line on his graph,
is that there is no measurable centre or edge of the universe.
You might say “well, I see all the galaxies are going away from us here on earth, doesn’t that mean that we are at the centre?”.
And the conclusion of the calculation is here,
each of these astronomers would conclude that he or she is at the centre of the universe.
Therefore there is no centre that we can determine.
Astronomers have of course been very busy looking for a centre or an edge for many generations and we have not found one.
There is of course a practical edge.
You cannot see past the time that we’ve been allotted, if we have existed here for 13.7 billion years,
that means you can see 13.7 billion light years in every direction and that’s as far as we can see,
because we are looking back towards the beginning by looking at most distant things.
We look back in time as we look at distant objects.
So the practical fact is, there is a small part of the universe we can see,
and there is probably much more universe beyond that that we cannot see, because we have not existed long enough.
So to wave my arms very vigorously we imagine there was some primordial material.
Possibly infinite in extent, possibly not.
Some small volume of it began expanding by some strange and bizarre quantum mechanical process.
One of the great challenges of modern physics is to understand this initial period of time
when we believe that quantum mechanics and gravitation must be merged into some kind of quantum gravity theory.
And we do not have yet a successful theory.
Many people are still working on it.
At any rate not only did material start flowing away from other material in the expansion
but we picture that space itself has been expanding.
Now space is not necessarily a substance we do not know what space or time actually are for themselves,
but perhaps when we get a theory of quantum gravity, then we will have a better idea.
At any rate this early universe began expanding exponentially rapidly.
It doubled in size about a hundred times in a very, very tiny instant of time and kicked off the expanding universe of today.
Now we say “well, we look around and we do not see our local universe expanding”.
The solar system is not expanding, the galaxy is not expanding, nearby galaxies are not all of them going away.
So what is it that has made possible the non-expansion of our local part? How can we exist if the whole universe is expanding?
So the idea is that some parts of the early universe were more dense than others,
and they would have enough self attraction through their own gravitational forces to combat the expansion rate.
And so this is the story, the initial material had to be slightly inhomogeneous, some parts denser than others,
so that the gravitation could stop the expansion in those volumes and fall back and make stars and galaxies.
Of course after a star can be born, then we can have the nuclear reactions inside this star that produce the other elements.
I told you earlier, that we had only hydrogen and helium from the Big Bang, so where did the chemical elements of life come from?
They come from stars that have, a previous generation of stars that have burned their nuclear material
and exploded and distributed the chemical elements back into space.
So we ourselves are already recycled material from inside stars.
If you look in the mirror in the morning, and you see the chemical elements of life, you have to remember,
they were not there in the Big Bang.
They were formed already inside stars.
So you can be doing your cosmology every morning when you are doing your cosmetics.
So I have a short chart to summarise the early history of the universe,
we have a picture of the Big Bang as measured with microwaves.
We have an idea that galaxies are formed by small objects merging together to form large ones.
Just as small streams flow together to form large rivers.
We have a picture in the lower left of our nearest large neighbour galaxy, the Andromeda nebula,
which you can see with binoculars quite nicely.
It’s about as big as the full moon but not nearly as bright.
So in the beginning we have a story which was –
the Big Bang by the way was renamed the "Horrendous Space Kablooie" by our American cartoonist of Calvin and Hobbes.
So I like the name actually better than the “Big Bang”, because it suggests that there is something strange
that happens about space itself.
So it´s compatible with the idea that there’s an inflation and space itself may be expanding.
Since we don’t know what space is, that’s a little bit tricky, but it’s a different point of perspective.
So the original material gave us the chemical elements of hydrogen and helium,
it started off the universe with the expansion, it gave us a dark matter, which is important.
We would not exist without dark matter.
And that all happened 13.75 billion years ago with a very small error bar.
We are now in the era of precision cosmology.
So I mentioned earlier that the helium nuclei, that were made in the first few minutes,
then the universe expanded and cooled when it was about 389.000 years old,
the electrons found the atomic nuclei and the primordial gases material became neutral.
Before that it was opaque as a plasma, and after that it was neutral,
and the photons of the background radiation could propagate to us.
The universe became transparent.
So then hypothetical events on the chart, the first generation of stars, we imagine they were very different from the sun,
and much more massive, and that they would burn out very promptly in a few million years.
Then galaxies were formed and then at the end, here I point out,
that about 5 billion years ago the universe began to accelerate again and to go faster and faster.
This is a tremendous surprise of the last decade of astronomy,
and it tells us a little bit about what may happen at the end of the universe.
We see now that the universe is accelerating and going faster and faster, that means that in a number of billions of years,
the distant galaxies will be so far away that most of them will be invisible to us.
Their velocities of recession will continue to increase and in 100 billion years or so almost all of them will be invisible.
Not only will the stars go out, but the galaxies will be too far away for us to see.
So we have a few billion years before we have to move.
This chart illustrates very briefly why we talk so much about the microwave background radiation.
It is the strong remnant of the primordial material, it is a material that we can measure very precisely in every direction,
and at the right hand side of the picture is one of the space probes that is out there currently measuring the radiation.
And the properties of this microwave radiation turn out to be extremely informative.
I don’t have time to tell you details.
I do want to show you one picture of the first satellite that was built to measure this radiation:
this was the cosmic background explorer or COBE Satellite.
At least for me the idea came from the failure of my thesis project,
which was an attempt to measure the cosmic background radiation with a balloon payload.
The balloon payload failed for a number of reasons, and I concluded that this subject was much too difficult,
I would leave the subject.
But a few months later NASA solicited proposals for satellite missions, and I said to my advisor
“my thesis project didn’t work well, but it would have went much better in outer space”.
We had no idea how hard that project would be, but here it is, it was launched fifteen years later.
And here it is as an artist would see it in space.
It carried instruments to measure the microwave radiation and to look for the light of the first galaxies.
So I’ll show you just a few things from it.
Here is the spectrum of the microwave radiation.
The frequency of the waves, the cycles per centimetre on horizontal axis, brightness in the vertical direction.
You see all the little boxes are exactly on the curve as it should be if the Big Bang theory is correct.
So we received a standing ovation when we showed this to the astronomical society.
I was a little surprised, because I knew this was the right answer.
The astronomers were assembled.
They had been quite worried that the Big Bang theory might not have been correct.
So this was a tremendous relief for people.
Now this little picture is in all the text books.
Our second discovery was this set of maps of the sky, the one to focus on is the Ellipse at the bottom of the picture.
This is a map after taking out all of the local effects that we know and the blobs, the objects on the map,
are primordial temperature variations.
The tiny variations of the temperature of the microwave radiation from place to place.
As it turns out the cold regions on this map are the ones which are more dense in the early universe,
and those are the volumes which are going to develop into galaxies and clusters of galaxies.
And the bright regions, the pink ones are the ones which are going to turn out to be empty,
where the gravitation will pull the material away.
Stephen Hawking saw this picture.
He said it was the most important scientific discovery of the century if not of all time.
I was appreciative of his good words but of course I think there have been some other discoveries as well.
So on the other hand, if those blobs were not there, we would not exist, so maybe it´s important.
Years have passed, we have now a great deal of activity in characterising the statistics of those objects,
that you see in those maps.
And this is a theoretical curve which has been used and interpreted
to determine many cosmological parameters down to the percent level of accuracy.
I don’t have time to explain the details, but I just wanted to show
that there’s a tremendous amount that can be learned from the shapes of those objects on the microwave map.
Now time is short, so I will not actually give you all the details of anything else either.
This is a picture of three people who discovered that the universe is accelerating,
and we named the cause of this acceleration Dark Energy.
Now that means that we do not have any idea what it is.
So in a few years maybe somebody will have the correct description, but right now it´s only a name.
There are a few mysteries remaining for us, astronomers would say we know that there is only matter in the universe.
There are no anti-matter galaxies.
Particle physicists want to know why this is true.
I told you there is dark matter out there, there´s a lot more of it than there are atoms and molecules.
The question of what is the dark energy, what is it beyond, just a name? Everyone wants to know from astronomers,
is Einstein right about relativity? And of course we are busy testing it but we are not there yet.
And we would certainly like to answer the question of our own history.
How did the earth come to exist and how did all those things come to be that we can live here?
Are we the only living things in the universe? Is it possible, of course, in the remote possibility,
that you could communicate with other living things and of course for our own history what would happen next?
So astronomers are now pursuing the infrared region of observations in space.
I will show you the project I'm currently working on.
We would like very much to be able to study infrared radiation from outer space.
And it’s a very difficult project because infrared does not come well through the earths atmosphere,
and because telescopes emit infrared radiation of their own.
So on the other hand, it´s interesting because of that same factor objects at room temperature emit infrared radiation.
Your body is emitting about 500 watts of infrared radiation, as each of us are sitting here in the room.
So the telescope we are currently building is called the James Webb Space Telescope and named after the man at NASA,
who organised us to go to the moon, and did it successfully.
This telescope is being now built by a partnership with a European and Canadian space agencies with my agency, NASA,
in the United States.
We are well along in the process of building it, which was started fifteen years ago.
This telescope that you see here does not look like an ordinary telescope.
It looks more like a solar energy concentrator.
Actually think of it as a galaxy energy concentrator, bringing light from the distant universe
to concentrate and be focused by the giant hexagonal parabolic mirror down into the instrument package.
The large blue system that you see underneath is a umbrella, a sun shield to protect the telescope from the sun and the earth,
and allow it to become cold.
The telescope will operate at a temperature of about 40° Kelvin and it is also much larger than a rocket.
You see that it is a structure, not just a tube, so I don’t have the video for you
but it actually will unfold after launch from the Ariane 5 rocket.
And we are hoping to launch it in 2014 with luck.
So I’ll show you just a few of the scientific topics that we hope to address with it.
I wanted to assure you that we are learning how to focus the telescope.
the Hubble Space Telescope, as you all know, was imperfect when it was launched and it was repaired by astronauts.
Our telescope is going to be much farther away, a million miles away from the earth and it cannot be fixed.
So we have to get it right the first time, so we are practicing.
We have this small model and then we will take the telescope that we will fly to this giant test chamber in Houston, Texas,
where the Apollo astronauts actually want to practice being in a vacuum.
A few things to illustrate about our scientific program.
One of the remarkable discoveries is that as Einstein told us it would happen, gravitation can bend light.
So you can barely see in the upper right corner of the picture that there is a pink arc
and the pink arc is actually the image of a very distant galaxy that has been magnified and distorted
by the gravitational field of these other galaxies that you see in the picture.
So Einstein’s gravitation is helping us see even farther into the distant universe.
We have the capability of understanding how galaxies were formed, not by watching them do this, but by simulating them.
So in the lower right we see a computer simulation, that for a moment matches the picture of real galaxies
- they are seen in the middle at the top - and then you see what happens when galaxies collide.
They completely change their appearance as they merge together.
By the way the Andromeda nebula is coming towards us and it is going to do that to our galaxy in about 5 billion years.
We have these projects in front of us.
We will watch stars explode occasionally.
This is an image, on the right is an image of a star that will explode in the next few hundred thousand years quite nearby to us.
On the left there’s a concept of how it may work.
Anyway we have seen something like this happened.
Well, this is a rare case but probably like the earliest stars in the universe as they explode.
Once in a while a star blows up and has a jet of material that comes out and is aimed at us.
This is a jet of material moving at nearly the speed of light, and once in a while, when it is aimed at us,
we receive a burst of gamma radiation that lasts for about two seconds.
And just in the last few years it was recognised that these are the sources.
These are stars exploding at the edge of the universe and just happening to be aimed at us we can get these gamma rays.
So all of these things are mysteries we will pursue to try to understand.
Another closer target for us is the Eagle nebula.
If we could lower the lights a little bit this would really help with these pictures.
But in any way this is a very famous picture from the Hubble Space Telescope, it shows,
where you see these beautiful images of a star forming region, stars have been born inside these dark clouds of material.
And the Hubble Telescope even cannot see inside because the dark clouds of dust are opaque.
Now if you can use infrared light, you can see through the dusty material inside
and see where stars are being born these days.
So we have a chance to learn much more about the formation of stars like the sun,
as we look at clouds nearby where it is currently happening.
It was mentioned earlier by Jack that we are now able to take pictures of planets around other stars,
and we have a picture here that illustrates this.
We have hundreds of targets eventually, maybe thousands, and the possibility, which I will now illustrate in the next chart,
that we can learn about the chemistry of the atmospheres of those planets.
The movie shows a planet going in front of a distant star,
and you should imagine that a little bit of the starlight is going through the atmosphere of that planet
on its way to our telescope.
That means we can do spectroscopy, we can determine the chemical composition of the atmosphere of another planet by doing this.
And we do not have to have a telescope that makes a separate image of this planet,
we can have a telescope that just watches the change of light as the planet intercepts some starlight.
So once in a while even the opposite occurs as well, the planet will be obscured by this star.
And both of these have already been done with telescopes in space, with our new telescope we hope to do better.
It is not probable that our telescope will be able to do this for an earth-like planet around a sun-like star,
but for a future generation of observatory that would be built just for this purpose.
We should be able to learn whether a planet around another star has an atmosphere like the earth with oxygen,
and that would be a clue that there’s life.
So there’s a little paperback book which has been published, that summarises or story, and it´s available from Amazon.com.
And of course there are plenty of websites that convey the general information of our story.
So anyway, thank you very much for hearing the story of the universe and appreciating the mysteries that are still in front of us.
Applause.