Tuesday, October 18, 2011

It's All in Your Point of View

Today Sean Carroll started blogging for Discover Magazine, and he wrote a pleasantly short article about multiverses, namely asking if there are any and if we'll ever know. As I read it, I got a sidebar advertisement for funny Schrodinger's Cat t-shirts. Also, my cat Caesar jumped up on my keyboard, strutted in front of the monitor, and finally settled for raking my back with his claws. And suddenly my point of view had changed about those t-shirts: putting a cat in a box sounded like a genius idea, absolutely funny. I began to formulate a theory that Schrodinger must have been a cat owner, and maybe his cat kept jumping up on the counter when he was trying to think, and thus a metaphor was born. "I'm going to put that cat in a box," I pictured him thinking, "there's no telling what crazy thing it will do next."

But, back to the article. It also starts with point of view:
The extent of what astronomers can see is frustratingly limited by the speed of light: one light-year (about six trillion miles) per year. When we look far away, we are looking into the past, and that past doesn’t stretch forever. Everything we see emerged 13.7 billion years ago from the hot, dense state known as the Big Bang, so we cannot observe anything more than 13.7 billion light-years away. If there is something so far away that its light couldn’t have traveled from there to here in the time since the Big Bang, we cannot observe it. [bolding my own]

Wow, did that sentence blow your mind? I had to read it like six times to understand it, of course, but wow. There's a ton of stuff out there that we're never going to be able to see! Or maybe there's nothing out there past the 13.7 billion light-year limit. But that's it: there's a limit, our telescopes just can't fly off into infinity and beyond.

And if we can't observe it, then we can't make any theories about it. Because listen, anti-evolution theory people, there's no such thing in science as a theory that hasn't been proven by observation. It's like that old cartoon "How a Bill Becomes a Law." Until we really look at something, it's only sitting on the steps moping, wishing it was a theory but it's only a prediction instead. Hey, do you think if I made a cartoon "How a Prediction Becomes a Theory," it would help quiet down the anti-evolutionists?

So, that's it, then. Beyond 13.7 billion light years from here, we have no theories and no way to get them. Could there be other universes out there? Maybe. Sean Carroll puts this better:
Science depends on being able to observe something, but not necessarily everything, predicted by a theory. It’s a mistake to think of the multiverse as a theory, invented by desperate physicists at the end of their imaginative ropes. The multiverse is a prediction of certain theories­—most notably, of inflation plus string theory. The question is not whether we will ever be able to see other universes; it’s whether we will ever be able to test the theories that predict they exist.

So the question of the day is what exists beyond 13.7 billion light years from Earth. Nothing? Other universes? More of the same? "Nothing" just seems so limited, like we're living inside a glass sphere. Really, don't you feel in your heart it has to go on forever? But in fact our point of view always has physical limits, whether you're an astronomer or just someone trying to pry a cat off her back. Sean Carroll ends the article by noting that the fun questions are the ones we can't answer, and I suppose he's right, but really, I find it annoying that we have this limit I didn't know about yesterday. Oh, wait, we can't just keep looking? No. No, we can't.

There's a story in here somewhere about trying to see beyond 13.7 billion light years, I'm thinking something along gothic horror lines. You have peered into the abyss and you must die! Or perhaps it's the magic talisman that introduces us to the Vulcans, but writing that kind of story wouldn't be as much fun.

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