(sea-gulls)
What makes the sun... shine?
What does Albert Einstein's famous equation, "e = m... c... squared", tell us about matter and energy?
In this video, how the simplest element in the universe produces "sun"-"shine"...
The life and death of stars... and why stars cook up the elements of life...
And... how particle physics uses energy to reveal the building blocks of matter... and illuminate the origins of everything!
Main titles
Like these students, you're probably sitting down as you watch this video.
Believe it or not, your chair is mostly empty space... molecules of plastic, wood or metal held together by electrostatic forces.
If there's metal in the chair, it looks something like this... a long line of atoms in a crystalline structure.
Every atom is composed of still smaller parts...
A nucleus, making up most of the mass of an atom, composed of neutrons, seen here as grey...
Protons, depicted in purple...
And, around the nucleus, a cloud of electrons.
The number of protons in the nucleus determines what element it is... and the number of neutrons, what isotope.
Now we know that neutrons and protons, in turn, are made of still smaller particles called quarks.
So that's your chair...
What about your universe?
First off, let's zap across 150 million kilometers, from earth... to our local star...
On this magical trip, let's plunge right through the sun... and out the other side...
...to the very edge of our solar system...
...to the frozen world of Pluto and the comets, some 39 times the distance of earth from the sun.
Now let's place our solar system in context.
Our sun is one of more than 100 billion stars bound together by gravity in a giant spiral shape known as the Milky Way Galaxy.
Our galaxy is one of 30 galaxies known as the "local group."
Beyond that, on every side, in every direction, are more galaxies.
And the farther away from earth we get, the older the objects are.
But with the scientific imagination we can travel back farther still, and conceive of a time when absolutely nothing, as we know it today, existed.
In a fraction of a second a mighty eruption of primary energy burst into being.
At first there was just a sea of particles...
Then, in the first 3 minutes, the simplest elements-including a heavy isotope of hydrogen known as deuterium-formed.
But from hydrogen comes everything we see around us today.
About 300,000 years later, matter and energy separated... the fog lifted.
Over time huge clouds of gas clumped together through slight variations in density and gravity.
At the heart of these vast clouds of hydrogen, a process began which links physics... with chemistry... and biology... and which continues, today, in our sun.
Let's jump across time and space, through the birth of galaxies... the life and death of many giant stars... and arrive, some 5 billion years ago, in the vicinity of the cloud of gas and dust that is to become our solar system.
Once again, gravity makes the cloud fall together...
At the center, pressure and temperature becomes so great that our star turns on...
The early sun is a violent young star...
And the early solar system is a place of collisions, as little planets, asteroids and comets all smash into the larger worlds, leaving the craters we still see around us today.
Over time, our sun settles down into stable middle age... and nearly 5 billion years later we humans have emerged with our telescopes and scientific understanding to figure out what makes the sun shine.
The ultimate source of the light and heat on which we rely is found in the core of the sun.
Here temperatures reach nearly 15 million degrees, and pressure makes the gases many times denser than lead, though there's nothing solid here...
In the heart of the sun, protons-the nuclei of hydrogen-collide at such speed that they overcome the force of electrostatic repulsion, and fuse together.
Beginning with 4 protons, you end up with helium-the second most elemental gas in the universe-2 protons and 2 neutrons.
In the process, zero point seven percent of the proton's original mass is converted into pure energy-as expressed in Albert Einstein's famous E=mc2, which means "energy equals mass times the speed of light squared."
Every second in the sun, 700 million tons of hydrogen become helium-and 5 million tons are converted into energy.
That was one of Einstein's many breakthroughs... to realize that inside matter... is energy.
The sun's core, where fusion occurs, extends out about one quarter of the way to the visible disk.
This is the "photosphere", the region which releases visible sunlight which eventually-8.3 minutes later-reaches us here on earth.
We've seen that the universe began with hydrogen, and that fusion in a star produces helium.
But where did the carbon in your chair...
The silicon in your computer...
The iron in your blood, come from?
Amazingly enough, we now know that all the heavy elements were cooked up in massive stars which then died in tremendous supernova explosions, and recycled the elements we're made of throughout space!
Kathy Flanagan:
The star's mass which is determined essentially at its birth or perhaps later if it accretes matter, the star's mass determines its history.
Kathy Flanagan uses NASA's Chandra X-ray Telescope to study the life and death of massive stars.
Flanagan:
It'll determine effectively its color, its luminosity, how long it will live and how it will die.
Stars much more massive than our sun burn brighter and hotter... many reaching temperatures of more than 20,000 degrees... and appearing blue-white in color.
Their hydrogen fuel changes to heavier elements, first helium, as we've seen.
Then helium, in turn, fuses and creates carbon.
Finally all the lighter elements are used up, and only iron is left.
With nothing left to burn, the core implodes.
The star's outer atmosphere collapses... and we see what astronomers call a "supernova."
The gases fall in, bounce, and then explode outwards, creating shock waves in the material surrounding the star.
Flanagan:
Life on earth actually owes a significant debt to supernovae and supernova remnants. Turns out that many elements are manufactured only during a supernova explosion. And most of our heavy elements, chemical elements such as oxygen, neon, iron and others, are distributed by this supernova and through the supernova remnant.
The oxygen we breathe more than likely came from supernovae and supernova remnants that existed prior to our arrival here. So in fact there is a deep link between these events and life on earth, and our solar system as we know it.
We've talked of some pretty mind-blowing concepts in this program... the big bang, fusion in the heart of the sun, how life on earth uses elements cooked up in preceding generations of stars.
How do we know any of this is true?
Amazingly enough we have machines down here on earth that allow us to explore what matter's made of, and even recreate aspects of the big bang.
They're called particle accelerators.
They smash atoms to pieces to study what they're made of.
You could call it a form of "fission", or splitting the atom, for entirely peaceful purposes!
Maria Spiropulu:
We're at Fermi National Accelerator Laboratory, the highest-energy laboratory in the world today, and this is the area where all the acceleration begins.
And all the hundreds of people who work here to tackle cosmic mysteries use atoms of hydrogen gas, that simple element which makes the sun shine...
Maria:
So this is where it all begins. With a bottle of hydrogen, and this is in gaseous form, high-purity hydrogen. Now hydrogen is a very simple element: water is made of two parts of hydrogen, and a part of oxygen. If you take one hydrogen atom, and you stick an electron on it, it becomes negatively ionized, and therefore you can put it in a potential and accelerate it, and this is where the acceleration of all this laboratory, of all the protons and anti-protons, start.
As we go down now, what we are seeing is the structure that brings the voltage to 750,000 volts. This is done in stages, as you see there. If this was in operation now, we would be zapped, fried, really!
So now we are going to use this very high voltage to accelerate the hydrogen that we saw in the bottle, up in the dome.
So there we are, we are now down at the tunnel and we're traveling like protons, along the direction of protons. As we saw, the beam came from the linac pre-accelerated, and here at this tunnel is where the beam is actually getting at its final energy after going around and around for millions of kilometers. The particles are relativistic. They are going almost with the speed of light… 40,000 times per second the particles are going around the 4 mile ring.
We're expecting pretty cool results, after the protons and anti-protons collide at the collider detector, and other locations.
We're now in a controlled area. Before we enter the pit we have to have a key to enter the Collision Hall, and we have to have hard hat on because there is heavy equipment in there. Let's go.
Now if we look towards there, actual detector moves in, rolls in, and it takes a day. It's not very easy to move thousands of detector in there. And the beam is actually where, coming where the hole you can see on the wall is, and we're going to go over there and take a better look.
There we are, going now to the Collision Hall. And we're going to be at the very end stage of where this hydrogen bottle that we saw at the Cockcroft and Walton started. So we are going to have the protons coming that way, and the anti-protons, and the anti-protons coming the other way, the CDF detector in the middle, and we're going to detect the debris of the collision when the protons collide with the anti-protons, and there is a big "barra-boom", debris, we're taking with the cdf detector, and then another big journey begins, of analyzing the data, in order to extract all the physics that we need to understand matter, and to understand the universe, eventually.
Results from Fermilab, and data from our largest telescopes on earth and up in space have enabled us to see how matter becomes energy in the stars... and how energy can be used to probe deeply into matter.
We've not yet learned to recreate nuclear fusion safely, and economically, down here on earth.
But the same kinds of technology we see at Fermilab-giant magnets, sophisticated computers, teams of skilled engineers and scientists-are what we'll need to put fusion power to work.
And when we learn to use fusion and hydrogen power we humans will have harnessed the power of the sun, the process which makes the stars shine...
End
