The Rare Gem Series: Meteorites (Part One: The Big Bang to Supernovae)

Timeline of the Universe. (National Geographic)
Timeline of the Universe. (National Geographic)

About 13.8 billion ago the lights turned on.  Or more accurately: THE Light turned on.  That is when scientists have estimated the Big Bang occurred; the singularity that began it all.  As an astronomer as well as a geologist I can go on for days about the fractions of a second in which our story began.  Instead, I will only go on for a few minutes… Or more, depending on your reading skills.  (Please note: if you really don’t want the literal History of the Universe, too bad, because I can’t talk about what meteorites are and where we can find them when I haven’t explained what asteroids are and where they came from, and to explain where asteroids came from I have to explain what they’re made of, and to explain what asteroids are made of I have to explain where matter came from, and to explain where matter came from I have to explain how stars formed and the extent of their lifecycles, and to explain how stars formed and how they die I have to take you back to the beginning of it all.  Thus, when you are finished with these articles, you will essentially have the equivalent of an Astronomy degree without the ability to do the math and physics that makes such a degree useful.  Satisfied?  Didn’t think so.)

For starters, all around us, matter and antimatter are going to war.  It’s an ancient war, the most ancient of wars.  It has been waged since the beginning of time, and possibly, since always.  It is a useless war, one that only ends in photons (nerd joke).  Basically, every second of every day, out of fucking nowhere, a piece of matter appears, and at that same moment, its antimatter counterpart appears as well.  The particles scratch their hooves like angry bulls and make a go at their nemesis.  They violently collide and as instantly and randomly as they appeared, they disappear.  Nothing to show for it but a single gamma photon thrust into the Universe as an orphan with random vector.  Why? Beats the hell out me.  It just does, and that is as good an answer as you will get from anybody.

Matter/Antimatter collision (NASA)
Matter/Antimatter collision (NASA)

So, this instant where the singularity, this infinitely dense, infinitely small point in an infinite Universe that did not even exist yet went *blamo*, the very moment when it all began, nothing but a hot mess could exist.   The amount of energy that was released was so unbelievably unfathomable that nothing bigger than a quark, gluon, or a lepton could exist.  In other words, atoms, the building blocks of matter, did not exist because the infant Universe was hotter than the melting point of atoms themselves.  Run that through your brain for a minute or two.  Hotter than the melting point of atoms themselves…

Atoms melt?

Well, when there is more energy present than either the strong or weak nuclear forces that holds the constituent particles together that form constituent nucleons of an atom the glue is melted and quarks run free!

OK, what’s a quark?

Fuck you. You figure it out.

Back to the message at hand:  This beginning, when the Universe was only 10^-37 seconds old (or 0.0000000000000000000000000000000000001 seconds), the greatest matter/antimatter war that will ever exist raged.  We are the only survivors.  Well, us and the 250 billion other galaxies in the known Universe (and the countless billions in the unknown Universe).  For some reason, yet to be explained by some supernerd (who is more than likely not to have even been born yet), there was more matter than anti matter that farted out of the singularity.  Something on the order of one extra quark or lepton in every thirty million particles.  Think about that.  All the matter that exists in the Universe is impressive, but at the moment of the Big Bang there was not thirty million, but SIXTY million times more matter in the Universe that just obliterated each other out of existence in just a few seconds.  *POOF*

We have no clue as to why there was more matter than antimatter.  There just is.  Maybe on the other side of the Universe there is nothing but entire reaches of space made up of antimatter with antipeople pondering why there is more antimatter than matter.  I don’t know, I am an not an interdimensional space traveler who can answer that for you.

As the nanosecond war of existence raged, the Universe became instantly less dense.  Combine this with the huuuuuge expansion of the nearly instant expansion of the fabric of space with the explosion of the Big Bang and things began to cool down.  At about 10^-6 seconds ( or 0.000001 seconds) temperatures dropped to a mere several billion degrees and the quarks, gluons, leptons, antiquarks, antigluons, and antileptons were allowed to combine into baryons to form things like protons and neutrons, and antiprotons and antineutrons who continued the war for survival even more violently.  By about 1 second (or 1.0 seconds) electrons and positrons sprang from the womb with their fists clenched and swinging.

A few seconds in and the war was over. Matter won and temperatures continued to drop.  A few minutes later with the Universe at a balmy one billion degrees the first hydrogen and deuterium atoms formed out of the protons and neutrons that were basking in the glory of their victory over their anti-selves (it was still too hot for the electrons to join in on the fun).  It took close to 400,000 years for things to cool off enough for electrons to happily orbit the nucleus of an atom, then we started really cooking with fire… er fusion.

Think of this early Universe as a giant, billion light year-wide cloud of particles.  Where the matter was more dense, the pull of gravity brought giant swarming clouds of particles into spinning giant clouds of particles and thus the earliest galaxies began to form.  Even denser regions of clouds inside these galaxies condensed into the first protostars.  At this time the Universe was about 75% hydrogen and 25% helium with no heavier elements.  As the clouds within the clouds began to collapse they got really warm from pressure forcing the particles of helium and hydrogen to bounce off of each other with ever more vigor.  As more particles were attracted to the growing center of mass of this cloud, the pressure became greater and things heated up even more.  Soon so much matter was inside these clouds that they began to glow from the pressure oven they had created giving off a bunch of infrared radiation.  The Universe was on the verge of is second light turning on.

The more mass one of these protostars had, the more gravitational pressure there was within the protostar.  If enough material gathered the hydrogen and helium atoms stopped having enough elbow room to really bounce around and they started smashing into each other, fusing their nucleuses of protons and neutrons into each other forming newer, denser matter.  This is how we got things like lithium (hydrogen + helium), beryllium (helium + helium), and boron (lithium + helium, or beryllium + hydrogen), and so on.  Whenever two atoms smashed together and fused, an insane amount of radiation was emitted.  Once fusion reactions began in the very dense core the protostar ceased to exist, for now it had become a man–I mean a STAR.

Inside a star (UC Berkeley)
Inside a star (UC Berkeley)

This star wasn’t that bright, literally; there was still a lot of gas blocking the light being emitted.  Inside the baby star as more and more nuclear reactions were taking place the high-energy photons being released from these reactions began to push the star out against the pull from gravity.  Gravitational pressure wants it to be a nice dense sphere, while radiation pressure wants everything to explode and scatter.  Eventually, the stellar winds of light being emitted by the new star blow away the remaining loitering cloud of gas lingering around, and the light is now able to broadcast the star’s existence to the Universe.  It is during this time when the star finally gets the hang of the battling pressures and finds itself perfectly balanced between the squeeze of gravity and the push of radiation it enters a state known as “hydrostatic equilibrium.”  The star has now begun the “main sequence” of its life.  Just learning the words “hydrostatic equilibrium” has now given you half of a bachelors of science in Astrophysics, by the way.  Good job!

Oh, how these were the halcyon days for our new star.  Happily smashing hydrogen atoms into helium, emitting light into the Universe, having no cares… until that fateful day.  That unforgettable, fateful day.  The day the hydrogen-fusion died.  After tens of millions, or even possibly billions of years of carefree atom smashing our star found itself old and not able to get it up like it used to all of a sudden. “I swear, this has literally never happened to me before!” Exclaimed the star to no one, because stars can’t talk and there wasn’t anything that existed yet who could listen to its cries.

You see, as the star was fusing all these hydrogen atoms into helium, at the very center of the star, the core, the newly formed helium began to pack into a dense degenerate ball of non-fusion.  As the star made more and more helium, this degenerate core got bigger and bigger.  Hydrogen is easy to fuse; it doesn’t take much energy (relatively speaking) to do it and you get a whole bunch of energy out of the reaction to do it some more.  Helium, on the other hand, takes a lot more energy to make them fuse together, and you are not going to get as much energy out of the reaction as you do with the hydrogen. When the core gets bigger and bigger, with more and more helium that refuses to fuse into anything, then the hydrogen fusion zone gets smaller and smaller.  Gravitational pressure is its greatest at the center of the star.  If the center of the star is full of a bunch of stupid helium then the only hydrogen fusion that is going on is at the outside of the degenerate core where gravitational pressure is weaker.  Soon, the number of hydrogen fusions that occur become less and less, and the radiation pressure gets lower and lower, and the star gets all limp and tiny as it begins to collapse in on itself.

There is a silver lining to this rather doomed state; as the star collapses in on itself the gravitational pressure starts to climb like it did when the start first burst onto the scene.  The degenerate helium core starts to feel the squeeze, starts to feel the pressure, and just can’t hold out any longer and *squish*.  A whole bunch of helium just fused into Boron, the star just experienced what is known as a “helium flash” as the core begins to switch to burning helium.  This causes the start to inflate and as it gets bigger it grows redder in color because the envelope of gas surrounding the star is cooler with more surface area.

Hydrogen burning leads to helium burning (University of Manitoba)
Hydrogen burning leads to helium burning (University of Manitoba)

If our star is really big, much bigger than our own Sun, then the core starts to fill up with carbon that was created out of fusing all sorts of combos of helium, hydrogen, and other light elements.  Just like before, the radiation pressure is weaker on the outside of the core where the helium is being smushed together, blah, blah, blah… Eventually *squish* we have a carbon flash.  Now the star is a geezer burning carbon.  If the star is really, really big, like nine times or more larger than our Sun, it will go through oxygen, neon, and silicon flashes.

Stars are born, they get old, and like all things, they die.  Sit down, clutch your security blanket, and steady your heart; it’s time to talk about death.  Stellar death can range from the most pitiful whimper to the greatest party in the Universe.  A teeny tiny star, like a red dwarf star, will never die.  The smaller the star, the more efficiently it burns its hydrogen and can last anywhere from 10 trillion to 100 trillion years or more!  A star like our sun will last about 10 billion years before it withers and does not have the mass necessary to fuse anything above carbon.  The star contracts under its own gravitational pressure, gets really hot, and the remaining gas inside the star either becomes part of a dense core or gets blasted away by the heat.  The star is dead.  This is death by white dwarf.

The exciting death, the only one anyone really cares about, is the death of big mutherfukkers.  Stars that are anywhere from nine to twenty five times larger than our own sun.  These guys know how to party.  A nine solar mass star might live 100 million years.  A twenty-five solar mass star may only last as little as 5 million years.  These idiots burn everything they’ve got as fast as they can.  They’ll spend about four million years burning hydrogen, one million burning helium, 500 years burning carbon, six months burning oxygen, a week burning neon, and maybe one day burning silicon.  The size of the degenerate core at this point is gigantic.  The moment the core itself is more than 1.44 times the mass of our own Sun it can’t handle it, and everything collapses like a house of cards.

Crab Nebula
The supernovae remnant known as the Crab Nebula

Imagine the core.  It’s dense, it’s hot.  There is no room to wiggle.  It’s basically the nuclei of atoms stacked on the nuclei of other atoms.  Just protons, electrons and neutrons chillin’ with nowhere to go.   Nothing but the weak nuclear force to keep them separated, and the strong nuclear force to keep them what they are.  Things are about to change.  The moment the core reaches 1.44 solar masses, known as the “Chandrasekhar Limit”, gravity has now become stronger than the weak nuclear force and the protons and electrons fuse to become neutrons (positive + negative = neutral).  This sudden collapse of the core draws in the remaining envelope surrounding it.  The instant and sudden gravitational pressure squeezes everything together and causes the star to burn upwards of 10% of it’s entire mass in one instant.  The star has gone supernovae.

When the star is just being a star, the heaviest element it can make through fusion is iron (26 protons), in a supernovae everything else is made.  Anything heavier than iron comes from a supernovae; radium, iridium, lead, gold, silver, krypton, everything else all the way up to uranium get blasted into existence by the intense explosion of a supernovae.  When a supernovae explodes it outshines the other 100 billion stars in its galaxy combined for an entire month!

This explosion can leave behind one of two things, if the star is big, but not freakishly so, a neutron star will be all that is left.  A dense dark ball of nothing but neutrons a few kilometers wide spinning really fast.  One spoonful of a neutron star would weigh hundreds of millions of pounds… If you could get yourself and a spoon close enough to the surface without somehow become nothing but neutrons yourself, of course.  The second option is the one that overwhelms the strong nuclear force that keeps quarks in their shape of something like a neutron.  If the envelope around the star is really massive when the core collapses at the moment of supernovae, an excess of material can be added to the core that overwhelms the neutrons and forces them to become an infinitely dense singularity, like the point of space from which the Big Bang began.  A black hole.

I’m not going to go into the physics of a black hole.  That would require another few months of writing to describe the mind fucks that go on inside one.  Another time, maybe (but probably not).

Stars die and make more stars (NASA/JPL)
Stars die and make more stars (NASA/JPL)

The explosion of a supernovae is tremendous.  If one occurred within 30 light years of Earth everything would die.  Everything.  Dead.  Forever.  Sanitized.  Even miniscule things like bacteria.  Gone.  EVERYTHING!  The blast wave from a supernovae will travel as fast as 40% the speed of light.  This wall of newly formed elements find themselves slamming into previously content clouds of gas in the galaxy and generate new bouts of star formation.  This time instead of the clouds only being made up of 75% hydrogen and 25% helium, they’re composed of 74% hydrogen, 25% helium, and 1% other things heavier than that.

After about 1300 generations of super giant stars going supernovae we find ourselves in the present where newly formed stars have as much as 5-10% elements heavier than helium.  It is these heavier elements that comprise the elements that make every rock you have ever held, every planet in existence, and every comet that has streaked through the cosmos.  Carl Sagan was right, we are nothing but stardust.

The next installment I will learn you on how the planets formed and just what the hell meteorites are made of.  Until then, revel in the fact that you just became an expert cosmologist.  You’re welcome!

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