BIG
BANG
Version 1.0
by Patrick
Grant & Charles Liu
with input from Brian Schwartz
It is Today and we are Here.
Albert Einstein once said, “The most incomprehensible
thing about the world is that it is at all comprehensible.”
This, the Universe and our consciousness of
it, isn't impossible. It's just so incredibly improbable that this
thing came together and that we can experience it.
It's amazing that we are even talking about
it right now.
We don’t know what
is happening at this moment far away in the universe. The light that we see from distant galaxies
left them millions of years ago, and in the case of the most distant objects that
we’ve seen, the light left more than 12 billion years ago.
So when we look
at the universe, we are seeing it as it was in the past.
What makes things hard to understand is not
how big they are but how complicated.
Inside a star, for example, everything is
broken down to its simplest constituents.
It's the same for the Big Bang.
If you know that the Universe is expanding
it means that it wasn't this big yesterday and it will be bigger tomorrow. That's where you really get the idea of running
back in time.
That's why we say, "Yes, the Universe
was probably small."
If you think of the Universe as something
like a gas, thinking of the stars and galaxies as gas particles, then when you
push them together they'll get hotter and hotter.
When we’re contemplating our place in the
Universe, a metaphor is always useful. Here’s
one:
Ever see a film of somebody playing on a pool
table and how all the balls go apart? Well, if you run the film backwards all
the balls would come together.
As it turns out, just like that film, we can
conceive of the universe going both forward and backward in time. So we can get back to where we were by reversing
the film.
That's how we can conceive of the Big Bang.
=====================================
2. Running
the Film in Reverse
We’re living now in an era where stars and
galaxies are important.
The biggest structures in the Universe are
superclusters of galaxies.
Matter is spread out in a huge web, and at
the nodes of the web are collections of thousands and thousands of galaxies.
It's Gravity playing itself out through Time.
It’s been more than 13 billion years since
the Big bang and things have grown bigger and bigger into larger structure.
But going backward in time, we see everything shrinking.
I'm going to take you back to where there
is no Space, there is no Time, and then I'm going to take you forward much more
slowly, through all the evolutions of the past until I get you back to where we are.
As you move further and further back in time
those clusters of galaxies are more and more separated and unstructured, more
and more uniform as you move back in the time that Gravity has been able to affect
them.
As you go further back, you see that
the clusters aren’t quite so big; and further back still, you see that the clusters
aren't really there at all.
Even further back, some 13 billion years ago,
there are no galaxies as we know them today.
There are clumps of matter, containing maybe
millions of stars, but nothing like the hundreds of billions in our Milky Way
galaxy now.
Go back even further and you wind up with
a Universe of individual stars that were huge, much, much bigger than our current
Sun, but they're still just stars. They’re the biggest structures in the cosmos.
Before that there aren't even stars. There's
just swirling gas that seems to be making snake-like patterns throughout the Universe.
Then you go back in time some more, and now
the gas is locked in tight with the photons – a blinding, glaring fog that light
cannot shine through.
Then from there we go through a period before
separation where all this matter and energy are tied together.
Before that you lose all distinction.
You can't even tell the difference between
matter and energy they're so interchangeable, they become one another so readily.
The Universe has shrunk and is so hot and
so dense that particles and anti-particles are annihilated in creating energy
and the timing of that is so rapid that the distinction between the particles
is lost.
Eventually
matter cannot exist because it's so hot and dense that you just have a tight bundle
of pure energy, infinitely dense and infinitely small.
This is the Planck Time, where the density
of the Universe was 1097 times greater than that of water.
Before that Time and Space don't exist
at all and the Laws of Physics as we know them totally break down.
=====================================
3. The
Quantum Gravity Era: Time=0
If someone asks, "What happened before
that?," then it becomes a question which has no meaning.
Time was created then. Space was created then. So we can’t answer that question, even though
it’s perfectly logical to ask it.
We have duck the question by saying, "It
didn't exist."
This is the Quantum Gravity Era, modeled by the idea Zero Point Energy
- a uniform quantum sea, in which bits of matter come together and fall apart
on a multitude of tiny, tiny scales.
Some of those quantum events could cause flashes of light, but most
are much, much smaller.
We can't go back to Time=0 but we can go back to Time=10 to the minus-43
second. That's the movie running backwards, and we can do that.
All the Laws of Physics, all that we know,
do not break down until that point.
At some moment, something goes out of whack – and that’s why the
Universe begins to exist - the equilibrium has somehow been broken.
Could it have been the result of parallel Universes bumping into
one another?
Could it have been Chaos? Like
where a water drop bounces off the surface of water in a pail, instead of just
falling in?
It’s something so unlikely that it’s a total surprise. It doesn't
make sense in the ordinary scheme of things.
Was this whole thing, our Universe, even meant to happen?
Or is it a part of a much greater cycle?
Who knows?
But amongst all the possible things that could have happened, this did.
=====================================
4a. The Big Bang:
10-43 seconds
[sound effect: Boom!]
At the Planck time, the smallest observable unit in we which we can
describe the Universe, the cataclysm we call the Big Bang generates space and
time, matter and energy
At this moment Gravity separates as the first of the Four Forces
that define our Laws of Physics. It’s a puny force compared to its future compatriots,
but the reach of its power is infinite.
For an incomprehensibly small fraction of a second, the universe
is a nearly infinitely dense, nearly infinitely hot fireball.
Then the Strong Force breaks off to become the second of the Four
Forces. Its power is tremendous – but its reach is incredibly small, only as far
as the sizes of the sub-nuclear particles it binds. We learned of its strength
when we first split the atom.
The remaining two forces have still not yet come into their own.
4b. The Inflationary
Period: 10-32 seconds
Then, all of a sudden, the Universe increases in size by a factor
of at least ten trillion trillion. It inflates!
Things that were once close together are now spread so far apart
that it might not even be possible that they could ever communicate again before
the end of the Universe. Even light traveling at its maximum speed may never get
from one end to the other in that time.
It’s now that big.
And, it all happened within one millionth
of one billionth of one trillionth of a second.
How do we know inflation happened?
The Universe has a flat geometry today – and a super-fast expansion like
this is one of the few ways that could have made it so. But nobody really knows why that is yet. It's
still a model in search of a theory.
Imagine an explosion and think of the light from that explosion as
the inflation of our Universe. Now think of the sound from that explosion as light
in the Universe. Even after the inflation
stops, the light may never catch up.
So Space itself expanded everywhere, and in every single spot, there
was that same infusion of energy.
Now, you might think that the Big Bang occurred and that for 13 billion
years things have been expanding out, and that these 13 billion years are all
that is.
It’s as if I turn on a light, and let that
light travel for 13 billion years in all directions, and that marks the whole
size of the Universe. Well, that's actually
only a very, very small part of the Universe.
No, the cosmos is way bigger than that; it's
much richer than that.
Let's
put it this way: if you and I were right next to one another and then inflation
occurred, we might be carried so far apart that, 13 billion years later, I would
have a big bubble of space around me that I’d
be aware of, and you would have a big bubble of space around you that you’d be aware of, but we'd still be so far apart that Time would
have to go on for a long, long, long while before it would even be possible that
we could communicate.
It’s as if this room were the size of the
Universe, and we could only see this much of it (makes a circle with fingers),
a small bubble of space 13 billion light-years in radius – that's tiny
compared to this room.
That’s it!
That’s the smallness of this tiny piece of the Universe that we can see.
What’s out there, beyond our reach, is so big that it’s almost indescribable,
almost incomprehensible. Almost…
…Wow, 10 trillion trillion. That’s a big number!
=====================================
5. The Universe Takes
Shape: Up to 10-6 seconds
The inflationary expansion fades away almost as quickly as it began.
After inflation ends, less than millionth of one billionth of one
trillionth of a second after the Big Bang, the universe continues to expand –
but not nearly so fast.
At this time, the temperature is still so high that everything is
still pretty uniform. Everything behaves basically the same.
All this energy is just slamming into itself. Nothing can take hold.
As the cosmos expands and cools, it also becomes less dense – more
spacious.
It becomes a thick soup of quarks and gluons and other sub-atomic
particles, but it’s still too hot for them to form anything yet.
There is just about as much matter as there is anti-matter.
Nothing can form.
The Universe keeps expanding and cooling down.
Then, the Weak Force and the Electromagnetic Force break apart.
They’re the third and fourth forces which govern our Universe today.
The Weak Force’s range of power is also very small. It governs some
nuclear processes, such as beta decay.
The Electromagnetic Force has, like Gravity, a range that is infinite.
We know it in many manifestations: it holds together atoms and molecules.
It is heat. It is light – visible and invisible.
The Universe comes closer and closer to the way that it works today.
Things have cooled down enough now that the
Four Forces begin to show their individual powers and begin to create the stuff
of which our Universe is made.
One second after the Big Bang the universe
is made up of fundamental particles and energy: quarks, electrons, photons, neutrinos
and less familiar types.
These particles smash together to form protons
and neutrons.
Particles and anti-particles form and begin
to annihilate each other.
For some reason, though, for every billion
and one particles of matter there were just a billion particles of antimatter.
And when the mutual annihilation was complete,
that billionth bit of matter was left – that's the stuff of our universe.
=====================================
6. Formation of Basic
Elements: 3 seconds
Things
have cooled down now to the point where protons and neutrons can come together,
and start to form the nuclei of simple elements: hydrogen, helium and lithium.
It
will take another third of a million years for electrons to be captured into orbits
around these nuclei to form stable atoms.
Now, I bet you learned in elementary school
that like-electric-charges dislike each other, they hate each other. They repel.
North repels North, and South repels South.
Now, helium has two protons. Of course there are neutrons involved too, but
for the moment, let’s consider the two protons.
The protons are positively charged.
How can two protons which want to repel each
other, be fit into one nucleus and be so
close together?
How could I get them together? To stay together
as Helium?
This is where the Strong Force comes in –
and a very strange force it is.
Only when I get the protons really close together
– to within a trillionth of an inch of one another – then !snap! They suddenly come together.
The Strong Force overcomes the repulsion even
though the protons are still trying to push themselves apart.
So without the separation of the Four Forces,
the quarks would not have pulled together to form protons, atomic nuclei, protons,
and all that.
Now, photons – particles of light – are the things that squirt out
when the electromagnetic force acts. Photons
carry the electromagnetic force, and they’re everywhere. But there is still no visible light yet.
Nothing shines. Nothing shines.
The fog of matter is still too thick for it to push through.
But at least, the basic building blocks of matter as we know it now
exist.
=====================================
7. The Radiation Era:
10,000 years
The Radiation Era began just minutes after the Big Bang and lasted
for more than 300,000 years.
This is the true start of the atomic kingdom.
The ratios of the early elements that existed then, are almost exactly
the same as those that exist in our stars today.
This
major era in the history of the universe is one in which most of the energy is
in the form of electromagnetic radiation – gamma rays and X rays; ultraviolet,
visible, and infrared light; microwaves and radio waves.
This
energy is the remnant of the primordial fireball, and as the universe expands,
the waves of radiation are stretched and diluted.
For the rest of the Radiation Era the Universe remains fully ionized, and
continues to expand.
The entire universe
is plasma, the so-called “fourth state of matter” – freely moving electrons and
atomic nuclei, the same as in the stars today.
Photons scatter off
these electrons and ions, reionizing any atoms that might form.
There are no electrons
orbiting a nucleus, because the heat is still so great that any electrons are
automatically stripped away.
During the Radiation
Era, then, the entire universe was sort of like the heart of a single gigantic
star.
During this period
the universe was in thermal equilibrium, and opaque to radiation.
Any free radiation
was scattered away by all the free electrons whizzing around.
=====================================
8. Beginning the Era
of Matter Domination: 300,000 years
At this moment, the energy in matter and
the energy in radiation are still equal.
But as the relentless cosmic expansion
continues, the waves of radiation – that is, of light – are stretched to lower
and lower energies, while the matter spreads thinner and thinner throughout space.
Now, neutral atoms form as electrons link
up with hydrogen, helium, and other atomic nuclei.
The cosmic background radiation hails
from this moment, and thus gives us a direct picture of how matter was distributed
at this early time.
By the way, disturbance from the cosmic background
radiation is something we have all experienced.
Tune your television to any channel it doesn't
receive, and about 1 percent of the dancing static you see is accounted for by
this ancient remnant of the Big Bang.
So the next time you complain that there is
nothing on TV, remember that you can always watch the infant universe.
By now the Universe has created all the matter
it will create. But only a few percent
of it will ever be visible to us.
The rest is Dark Matter. What is Dark Matter?
Oh… let’s say that the headlights of an oncoming 18-wheeler
are visible; that’s the visible matter.
The rest of the semi-truck, the big rig, is
the Dark Matter.…and that can slam into you just as well, whether you see it or
not.
We astronomers have found gravitational irregularities
in galaxy motions that show us that there is a lot of stuff out there that we
cannot see.
That is, we either think that the Laws of
Physics are correct, and that dark matter is there, or we have to believe that
our understanding of those laws is seriously flawed.
Time should tell.
In any case, the fog of matter is too thick.
Photons can’t get through that fog. It’s all still dark.
Nothing shines.
Yet.
=====================================
9a. Birth of Stars
and Galaxies: 300 million years
Gravity amplifies slight irregularities in the density of the primordial
gas.
Even as the universe continues to expand rapidly, pockets of gas
become more and more dense.
Stars ignite within these pockets, and groups of stars become the
earliest galaxies.
Now it shines. Now it shines.
Brilliant visible light shoots out and fills the Universe.
Now with fusion in the stars all of the elements get created.
9b. Birth of the Sun:
5 Billion Years Before the Present (BP)
As the Universe expands, it becomes more complex, more interesting,
more varied.
The sun forms within a cloud of gas in a spiral arm of the Milky
Way Galaxy.
A vast disk of gas and debris that swirls around this new star gives
birth to planets, moons, and asteroids. Now,
if you’re worried about something, consider this:
"Every second in the Sun 600 million
tons of hydrogen are being converted to 596 million tons of helium, and 4 million
tons disappear – converted into energy according to the formula E=MC2.
This has been going on for nearly 5 billion
years and will go on for another 5 billion years.
This star is one of hundreds of billions in
our galaxy and there are tens of billions of galaxies - and you're worried about
something?" Think about it.
Earth is the third planet out in our Solar
System.
Beyond the other specialties like the stars
and planets, Earth brings with it the ultimate specialty: Life.
=====================================
10b. Earliest Life:
3.8 Billion Years BP
The most wonderful thing we know about in
the universe is life. It’s the most complicated
emergent phenomena we know of.
Sure,
the Big Bang is complex. But it’s much,
much more difficult to understand even the simplest living organism.
I’m
always amazed when we study the simple beginnings of life.
We need to understand, not just how the necessary chemical elements have
been made but how they’ve forged themselves into something complicated enough
to develop into life as we know it.
Why is there life here? There are lots of
fundamental factors that have to be just right for life to exist: how stars form,
how planets form, how close this planet is to this star, and so on and so on.
If the numbers that represent any of those
factors were "off" by even a little… then this whole world would be
very different.
We can keep working the formula, as best as
we know how, until we get a very small number representing the probability of
the occurrence of life.
But, this very small number, when multiplied
by the billions and trillions of stars in the universe, makes it almost certain
that there is life elsewhere.
On this planet, the very first life forms are microscopic
living cells which begin to evolve and flourish in the early Earth's watery, volcanic
environments.
10c. Primitive Animals
Appear: 700 Million Years BP
These
are mostly flatworms, jellyfish and algae. By half a billion years before the
present, large numbers of creatures with hard shells appear. Eventually evolution
leads to the era of the dinosaurs.
10d. The First Mammals
Appear: 200 Million Years BP
The very first mammals, our ancestors, evolved from a class of reptiles
that evolved mammalian traits often becoming nothing more than sustenance for
their evolutionary forebears.
10e. Dinosaurs Become
Extinct: 65 Million Years BP
An
asteroid – or it could have been a comet – slams into the northern part of the
Yucatan Peninsula in Mexico.
This world-wide cataclysm brings to an end the long age of the dinosaurs,
and allows mammals to diversify and expand their ranges. Otherwise, intelligent
life on our planet may have evolved from reptiles making it even less possible
that we’d be here right now.
=====================================
11a. Homo Sapiens
Evolve: 600,000 Years BP
Our earliest ancestors evolve in Africa from the primates and spread
out over the world.
According to the 2nd Law of Thermodynamics,
entropy is always increasing –everything is slowly losing its distinctiveness
and becoming more and more chaotic.
That's only true on the largest scale.
On the small scale, counter to the increase
of entropy, we evolve. Over the millennia,
we build societies. We invent language,
philosophy, art, and science.
11b. Galileo Builds
the First Telescope: 1609 A.D.
Galileo builds his first telescope. He sees mountains on the Moon,
the phases of Venus, the moons of Jupiter, and the stars in the Milky Way.
11c. Isaac Newton
Describes Gravity: 1665 A.D.
Isaac Newton realizes that gravitational force accounts for falling
bodies on Earth as well as the motion of the planets in orbit around the Sun.
This realization extends the principles of earthly behavior to the realm of the
heavens.
11d. Albert Einstein
Publishes Theory of Relativity: 1905 A.D.
Albert Einstein recognizes the speed of light as the absolute speed
limit within the universe and unites the previously separate concepts of space
and time into a unified spacetime.
General relativity replaces Newton's model of gravitational force.
Gravity is now understood as the response of bodies to distortions in
spacetime which matter itself creates.
11e. Edwin Hubble
Discovers that the Universe is Expanding: 1929 A.D.
Edwin Hubble discovers that the universe is expanding in all directions.
This shows that the universe is not static,
but dynamic – continually changing – continually evolving.
We now know that
our galaxy is only one of perhaps a hundred billion, with each galaxy itself containing
millions, billions, even trillions of stars.
11f. Discovery of
Microwave Background Radiation: 1964 A.D.
Scientists working in New Jersey discover the cosmic background radiation
that bathes the earth from all directions in space. (Imagine that: New Jersey!)
This radiation is the afterglow of the Big Bang.
11g. Hubble Space
Telescope Launched: 1990 A.D.
A twelve-ton telescope, equipped with a 94-inch mirror, is sent into
orbit by astronauts aboard the space shuttle Discovery.
Evidence gathered
with the Hubble Space Telescope suggests that the universe will probably expand
forever – or at least, anyway, that the universe won’t recollapse for at least
ten billion years.
By that time, assuming
that we haven’t evolved as a species and colonized well beyond our Solar System,
humanity will long since have died out, extinguished along with our Sun.
The words of Carl Sagan ring truer than ever: “Our planet is a lonely speck in the great
enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint
that there is anyone who will come and save us from ourselves.”
11h. Big Bang Confirmed:
1990 A.D.
The new Cosmic Background Explorer satellite is used to measure in
detail the spectrum of the cosmic microwave background radiation.
The results show that the radiation is in nearly perfect agreement
with the Big Bang model of the birth of creation. At last, the Big Bang Theory is confirmed!
=====================================
12b. The Stellar Era
Ends: 100 Trillion Years in the Future
As long as it keeps on expanding and does not recollapse under the
pull of its own gravity, the universe will gradually fade away.
During this era, most of the energy generated by the universe is
in the form of stars burning hydrogen and other elements in their cores.
12c. The Degenerate
Era: 100 Trillion to 1037 Years in the Future
Most of the mass that we can currently see in the universe is locked
up in degenerate stars, those that have blown up and collapsed into black holes
and neutron stars, or have withered into white dwarfs.
Energy in this era is generated through proton decay and particle
annihilation.
12d. The Black Hole
Era: 1038 to 10100 Years in the Future
The only stellar-like objects remaining are black holes of widely
disparate masses, slowly – oh-so-slowly – evaporate away.
12e. The Dark Era:
Times Later than 10100 Years in the Future
At this late time, all protons have decayed and all black holes have
evaporated.
Only the waste products from these processes remain: mostly neutrinos,
electrons, positrons, and photons of colossal wavelength.
For all intents and purposes, the universe as we know it is gone.
A universe that came from nothing in the Big
Bang has disappeared into nothing.
Its glorious existence not even a memory.
=====================================
13. Epilogue
It is today, and we are here.
Our universe is very unlikely and unique, but we do have this Universe and if we're going
to have any universe at all, it's kind
of neat that we have this one.
The
Big Bang theory describes how the universe developed from an almost featureless
explosion to something that's been broken up into huge clusters of galaxies and
huge empty spaces.
The Big Bang
Was neither big Nor did it bang
Within or Without.
For outside,
There was no Time & Space
To
carry the sound -
And inside
There was never any silence
To know
there was sound.
“It is Today and we are Here.”
For most of us, this statement will hold true
for tomorrow.
But will it in a week? In a year? In a century?
All things are finite, it seems, even the
Universe in which we live, at least as far as we understand it. Today.
So what then? Will the Universe contract to begin the cycle again?
And again?
Who knows?
Here’s one thing we do know:
The questions we’ll
have to answer are the ones we have yet to ask.
[MUSIC STOP]
Any questions?
THE END
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