In the next 800 words we summarize the entire 15 billion year history of the current universe. That’s about one word for each 150,000 million year swath of time. So sit up and pay attention.
It all began 13 to 14 billion years ago with an incomprehensible explosion known as the Big Bang. No one knows what exploded or what existed before — probably nothing. Nothing exploded. After that, there was nothing but quantum foam which is unlike anything you can get on top of your coffee at Starbucks. By and by atoms started forming. Just Hydrogen and Helium though. Nothing else. Those atoms are still around and make up about 5% of all matter in the universe. All the other atoms of all the other, heavier elements make up much less than 1%. All the heavier elements were created when stars blew up in huge explosions only slightly less incomprehensible than the Big Bang. Those elements include everything you are made of. You are stardust. Everything else is stardust too, including the planet. Only hydrogen and helium aren’t.
About another 25% of the universe consists of something called Dark Matter. No one really knows what that is, only that it is out there and we can’t see it.
The rest, about 70% of the entire known universe, consists of Dark Energy. No one has a clue what that is, but it is out there too. In fact, dark energy is blowing the universe apart at an accelerating rate.
We are at about the half-way point in the life of this Double-Dark universe. For about 13 billion years, the expansion of the universe had been slowing, but now it is speeding up again and, in another 13 billion years or so the universe will lose all its energy and all its heat and all its light and all its life. In the meantime, just as we are learning how to see them, the most distant galaxies are beginning to disappear from view because they are now traveling away from us at greater than the speed of light.
Eventually, all we’ll be able to see is our own galaxy and the Andromeda Galaxy, just before the two merge. Then all we’ll be able to see is the stars in one merged galaxy. (What shall we call it? “The Milky Andromeda?” No. Too many other referents there. “Andromeda Way?” No. That sounds too much like a street name in a gated community. We’ll think of something.)
Moreover, the oxygen of our planet is also about half done. Microorganisms first gave us a good supply of that about 500 million years ago and it ought to last about another 500 million. That’s when the sun is going to get hot enough to evaporate all the hydrogen out of the atmosphere. No more water after that.
Piling coincidence on coincidence, our solar system — 4.5 billion years old — is just about half-way through its life. The sun is expected to explode in another 5 to 6 billion years. I once heard Tom Brokaw talking about that. He said, “And NBC News will be there to cover it live!”
And we’re still not through with these “half-way” coincidences, but this last one is of less importance. Beings the size of humans are approximately half-way on the possible size scale. We’re about half-way between the estimated size of the Cosmos and the Planck length. (That is .000000000000000000063 smaller than the diameter of a proton or .0000000000000000000000000000000001th of an inch. Imagine the state of Rhode Island, a proton, and a Planck length. The proton is larger than the Planck length by roughly the same factor as Rhode Island is larger than the proton. [Thanks to blogger Plato for the comparison.]Beneath that size spacetime ceases to exist and becomes something else. Strings, maybe? Quantum foam? Nobody knows.)
Actually, we’re a little unsure about the exact size of the Cosmos. That depends entirely on a number known as the Hubble Constant and our estimate of that number has been anything but constant. Right now we think we know it within a 4% margin of error, one way or the other. That would be like an airline pilot flying you from New York City to Sydney, Australia (9,933 statute miles) knowing only that it is somewhere between 9,500 miles and 10, 300 miles away, a margin of error of 800 miles. You wouldn’t feel confident about the plane actually hitting a runway when it landed.
In fact, everything you just read may be wrong; much of it might be and some of it almost certainly is. We just don’t know what parts. The only way it could be all wrong is if we are all wrong about the Red Shift, the phenomenon of light shifting to red wavelengths as it recedes from us, like sound lowers in pitch as it recedes. Of course, there is much evidence that the Red Shift is bang on and none that it is wrong; still, it is fun to speculate about the upheaval in physics and cosmology that would occur if a bright young graduate student someday walks into his professor’s office and says, “Now, Herr Professor, about this ‘Red Shift.’”
In a subsequent post, we’ll devote another 800 words to the history of the earth. That’s only about 5 and a half million years per word, so stay tuned.