Wednesday, January 23, 2008

Stop me if you've heard this one before.

A physicist walks into a bar and says "Hey, I got this particle-wave duality thing all figured out". And his buddies look over the numbers, and sure enough, they parse. "But it's still bullshit," one of them says. "It has to be." And the others all nod in agreement.

"But the numbers," the physicist says.

The naysayer takes a moment to butter his nose. "Look, according to those, those numbers," he says, as the resident bar cat starts licking, "if you put this cat into that box over there, and put this radioisotope trigger in there with him, and closed the lid, why, why — according to your numbers the cat would be alive and dead at the same time!"

And everybody agrees that this is so fucking stupid that there must be something wrong with the numbers, even if they can't find what it is.

But here's the thing: almost a century later, they still haven't. That cat's still in there, in its indeterminate catly state, and the experts still don't know what that even means for sure. Except that a reductio ad absurdum once put forth to discredit a model has instead become an icon for it.

And you know what's even scarier? It's happening again, only worse.

If I'm reading this NYT piece correctly (and I'm trusting you guys to set me straight if I'm not), a theoretical consequence of dark energy is that quantum fluctuations following universal heat death could seed the spontaneous and probabilistic reemergence of a bunch of new universes. This would be fine except that probabilistically, simple things are more likely than complex ones to arise spontaneously. (The analogy they use in the story is Scrabble letters, spilled randomly onto a table; a word is more likely to arise from that happenstance than is an entire sentence.) And any subset of a universe, by definition, is less complex than the universe as a whole, and therefore more likely to arise.

So yes, while the spontaneous reemergence of new universes is certainly called for in some cases, in far more cases you'd just be getting pieces showing up. Cats in Space. Fully-functional yet utterly disembodied brains, floating in the void. Very small rocks. And since such iterations are more likely — and hence, more numerous — then the likelihood is that I'm just a disembodied brain imagining a universe where none actually exists, and the rest of you are — well, no. The rest of you aren't. Which makes me feel a bit better about not having got laid over the past few months, but a whole lot worse about pretty much everything else.

Of course, nobody takes this seriously. The whole Disembodied-Brain thing was cooked up specifically as a a reductio ad absurdum, to show how stupid the whole idea is. Everyone seems pretty much convinced that there's something wrong with the numbers, even if they haven't found what it is. And I think we should trust them, because after all they certainly figured out Schrödinger's — oh, wait...

At this point I'll just modestly clear my throat and suggest that the thematic punchline for the five-billion-year plot of Sunflowers (or Gerbils — still open to suggestions) will resolve the whole open-universe question much more elegantly, when I get around to it. In the meantime I can only invoke the spirit of the AI in John Brunner's Stand on Zanzibar, "bathed in his currents of liquid helium, self-contained, immobile, vastly well-informed by every mechanical sense: Shalmaneser. Every now and then there passes through his circuits a pulse which carries the cybernetic equivalent of the phrase,

Christ, what an imagination I've got."

Illo credit to Holly Stevenson.


Monday, November 26, 2007

Euthenising the Universe

This quirky and disturbing preprint (by a couple of astrophysicists with impeccable credentials) has been doing the rounds over the past week or so, and if I'm reading the commentaries right it's taking the Copenhagen Interpretation of quantum physics to its logical conclusion — specifically, that whole Schrodinger's Cat thing that says nothing actually exists until an act of observation collapses the probability wave and forces the universe to make up your fucking mind already. If you buy this interpretation, then a bunch of astronomers who looked at a supernova back in 1998 may have — by that very act of observation — shortened the lifespan of the whole universe. (The obvious question about whether the universe-altering observations have to be made by human astronomers — or even humans for that matter, given that at least a few photons from that supernova must have fallen onto the retinas of everything from cats to Cardassians long before now — was never addressed.)

I read this paper. More precisely, I ran my glazing eyes over each line and each equation in turn, while moving my lips. And even though I kinda recognised some of the Fourier transform stuff, it was pretty much all over my head.So I showed it to a biochemist I occasionally hang with; she got all squee-y because she kinda recognized the imaginary-numbers stuff, but she wasn't much help beyond that. Fortunately we happened to be in a bar with a couple of astrophysicists, who had been roped into this community outreach program where experts on various subjects fend off questions hurled at them by drunken patrons. One of these experts actually specialized in the whole dark-energy thing; the other was a former student of his. So I hurled this weird Krauss-and-Dent paper at them, and this is what what they said:

The Master said that the paper took quantum theory to its "logical extreme", and then kind of shrugged and said "But what are you going to do? It's not like we're going to stop looking." He also allowed that the whole thing sounded kind of like worrying that the elephant that supported the world was going to fall off the back of the turtle that supported the elephant.

His apprentice said "If in fact the astrophysics community has shortened the lifespan of the universe, I'd like to take this opportunity on behalf of Canadian astrophysicists to be the first to apologize." I liked that.

But neither of them said the paper was wrong. Neither pointed out any sort of fundamental error in the math or the conclusions. In fact Carlberg, for all his grousing about giant turtles, did grudgingly concede that the conclusions followed as a "logical extreme" of the theory. I find this disturbing.

Of course, the Copenhagen Interpretation does have competition. There's also the Many-Worlds Model, which in contrast to the nothing-is-real view, claims that everything is — that there is no probability wave, only an endlessly-proliferating infinity of parallel universes that spawn wholesale every time an electron has a choice between flipping this way or that. This theory also carries some profoundly ugly implications (it confers credibility onto Sliders, for one thing; also, nobody has explained to me where the extra mass for all these universes is supposed to come from), but it seems to be gaining ground amongst the theorists.

Still. Just to be on the safe side, it couldn't hurt if we all agreed to walk around for a while with our eyes closed. It might buy us some time.

Update 1715: OK, looks like a false alarm. Initial popsci reports were all causal-this and shortening-the-lifespan-of-the-universe that, but as AR has been kind enough to point out, Krauss is actually quoted in the article I linked to as saying he didn't mean to imply causality. Move along. Nothing to see in the comments. (Unless you want to see AR pointing out how credulous I can be...)


Wednesday, April 25, 2007

"It's 20 light years away. We can go there."

Now that's the kind of attitude I like to see coming from a legitimate authority-- to wit, Dimitar Sasselov of the Harvard-Smithsonian Center for Astrophysics, quoted in today's NY Times. He was talking about Gliese 581c, a potentially earth-type planet orbiting a dim red dwarf in the constellation of Libra. 1.5 time Earth's radius; 5 times the mass. Mean temperature somewhere between 0 and 40°C, solidly in the Goldilocks Zone for liquid water. A type of planet thought by Sasselov to be not only congenial to life, but more congenial than Earth.

Of course, you probably know this already. It's on boingboing, after all, and Yahoo, and and Nature, and a thousand other websites. (Science, my usual go-to source for this kind of thing, is still asleep at the wheel as of this posting.) What you probably don't know, however, is that there's a pretty specific real-world connection between Gliese 581c and Blindsight.

You see, we don't really know all that much about 581c yet. We got a mass, and we got a distance-from-primary, and we got an orbital period (11 days), and we got all of that by watching Gliese 581 wobbling slightly as its planets tugged gravitationally on its sleeve. We don't even know if 581c has an atmosphere, and if so, whether it's closer to ours or Venus's.

But there are plans to find out, and they involve the use of a suitcase-sized Canadian satellite called MOST (also known as "The Humble", by virtue of its teensy dinner-plate of a mirror). Despite its small physical size, MOST is well-suited for picking up the atmospheric signatures of extrasolar planets, and it'll be turning its glassy eye towards Libra in the near future. The Principle Investigator behind the MOST is a guy name of Jaymie Matthews, who acted as my unpaid astrophysics consultant (well, paid in pizza and beer, I guess) for Blindsight.

And now, after helping me chase aliens through my own brainstem, he's gonna be looking for real ones at Gliese 581. How cool is that?

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