Excerpt
Physics says you’re an impurity in an otherwise beautiful universe.
You’re almost unfathomably lucky to exist, in almost every conceivable way. Don’t take it the wrong way. You, me, and even the most calming manatee are nothing but impurities in an otherwise beautifully simple universe.
We're lucky life began on Earth at all, of course, and that something as complex as humans evolved. It was improbable that your parents met each other and conceived you at just the right instant, and their parents and their parents and so on back to time immemorial. This is science’s way of reminding you to be grateful for what you have.
But even so, I have news for you: It's worse than you think. Much worse.
Your existence wasn’t just predicated on amorousness and luck of your ancestors, but on an almost absurdly finely tuned universe. Had the universe opted to turn up the strength of the electromagnetic force by even a small factor, poof! Suddenly stars wouldn’t be able to produce any heavy elements, much less the giant wet rock we’re standing on. Worse, if the universe were only minutely denser than the one we inhabit, it would have collapsed before it began.
Worse still, the laws of physics themselves seem to be working against us. Ours isn’t just a randomly hostile universe, it's an actively hostile universe.
My physicist colleagues and I like to pretend that the laws of physics are orderly and elegant. Indeed, I just published an entire book, The Universe in the Rearview Mirror, about the beautiful symmetries of the universe. Programs like Nova or Slate’s own Bad Astronomy tend to focus on the knowable structure of how everything fits together.
The history of physics, in fact, is a marvel of using simple symmetry principles to construct complicated laws of the universe. Einstein quite famously was able to construct his entire theory of special relativity—the idea that ultimately gave us E=mc2 and explained the heat of the sun—from nothing more than the simple idea that there was no measurable distinction to be made between observers at rest and observers in uniform motion.
The long-overlooked 20th-century mathematician Emmy Noether proved the centrality of symmetry as a physical principle. And what is symmetry—at least as scientists understand it? The mathematician Hermann Weyl gave perhaps the most succinct definition:
“A thing is symmetrical if there is something you can do to it so that after you have finished doing it, it looks the same as before.”
Which sounds innocuous enough until you realize that if the entire universe were made symmetric, then all of the good features (e.g., you) are decidedly asymmetric lumps that ruin the otherwise perfect beauty of the cosmos.
The seemingly simple idea that the laws of the universe are the same everywhere in space and time turns out to yield justification for long-observed properties of the universe, like Newton’s first law of motion (“An object in motion stays in motion,” etc.) and first law of thermodynamics (the conservation of energy).
As the Nobel laureate Phil Anderson put it:
“It is only slightly overstating the case to say that physics is the study of symmetry.”
Everything is kinda the same? Every Friday night is like every other one? Sounds almost comforting. But it would be a mistake to be comforted by the symmetries of the universe. In truth, they are your worst enemies. Everything we know about those rational, predictable arrangements dictates that you shouldn't be here at all.
How hostile is the universe to your fundamental existence?
Very. Even the simplest assumptions about our place in the universe seem to lead inexorably to devastating results.
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