In a recent talk at Britain's The School of Life, Lawrence Krauss discusses the grand scope of the history of the universe and our relatively insignificant role within it.
And, in fact, this tongue-in-cheek (but still true) approach helps illuminate some of the biggest problems in the world, because they tend to come from humans having an over-inflated sense of self importance. Krauss humorously alludes to this in his opening to the presentation:
"You're here because you want to escape reality and that's one of the things that science is good for, to take us out at least a bit beyond our petty worries and concerns of the day."
How will he do this?
"I want to try to ... take you beyond this brief moment in cosmic history, to realize that all of this isn't important, that the really important stuff is far grander. The next time you're depressed, you can think about the fact that we're really, in fact, completely insignificant.... You are much more insignificant than you thought."
Krauss then proceeds to do what he does best: explain the history of the universe as a compelling narrative.
Because, as he says, the most poetic fact that scientists have ever discovered is this:
We are all made of stardust.
As gravity draws stellar hydrogen together to form stars, the power of gravity forces the atoms together with enough strength to bond the nuclei together through nuclear fusion. When all the hydrogen is fused together, it begins moving on to the higher elements, until eventually the star becomes nothing but a giant ball of iron. Krauss describes the death of a star (one bigger than our own sun) this way:
All the hydrogen burns into helium in 10 million years.... All the helium burns to carbon in 1 million years.... Again, the star starts to collapse, because there's no more fuel. But then it heats up and the carbon starts to burn ... to form neon and nitrogen. And all of the carbon in the star burns in 100 thousand years.... And you get to oxygen. Oxygen ...? burns to silicon in 10 thousand years. It's getting hotter and hotter and hotter. Less efficient. And then when all the oxygen burns to silicon, you're in the last day of the star because, remarkably, it is so hot at that point that all of the silicon in the center of the star, many thousands of times the mass of the Earth, burns to form iron in one day.... Iron can't burn to form anything. Iron is the most tightly-bound nucleus in nature. So once that's happened, there's no more fuel... When all the silicon has burned to iron, suddenly the star realizes there's no place left to go and that interior of the star, which has been held up by the pressure of nuclear burning, collapses. That whole collapse happens in one second.... There's a shock wave and that shock wave ... spews out all of the atoms that were created during the life history of a star. The carbon, the nitrogen, the helium, the iron. And that's vitally important, because every atom in your body was once inside a star that exploded.... The atoms in your left hand probably came from a different star than in your right hand, because 200 million stars have exploded to make up the atoms in your body.
How do we know this? Because we've seen these supernovas happen. How frequently do these things happen? Stars explode once per hundred years per galaxy.
Sounds like it's kind of hard to find these things, doesn't it? Consider this:
If you took a dime, held it up into a dark portion of the night sky, you'd be pointing your dime toward about 100 million galaxies. Many of these galaxies can be seen by our best telescopes. This means that we would expect, in a given year, to see about a million galaxies that are having a supernova in it. If you take this reasoning further, there should be about 2,739 supernovas per day, or 114 supernovas per hour, or almost 2 supernovas per minute ... just in the region that you're able to cover up by holding up a dime.
Now, we aren't going to see all of those supernovas, but this gives an idea of how common these things are. Again, in the words of Krauss:
Rare events happen all the time because the universe is big and old.
You can check out a video of the talk or, if audio is more your thing, it is also available on the Science Weekly podcast, which you can find through our physics podcast list.
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