July 15, 2004

The Great Escape. Stephen Hawking has changed his mind, and lost a bet. He now believes it's possible for information to escape from a black hole.

"Quantum theory says any process can be run in reverse, so starting conditions can theoretically be inferred from the end products alone. This implies that a black hole must somehow store information about the items that fell into it.... How could that information ever escape? The answer lies in one of Hawking's greatest discoveries: that black holes slowly evaporate into space by losing particles from the very edge of the gravitational precipice at their rim, called Hawking radiation. The black hole eventually shrinks to a tiny kernel, at which point a growing torrent of radiation begins to leak out, potentially carrying the lost information with it."

  • I think we should check Hawking's math before changing our own minds.
  • at certain locations in space, matter collapses into an infinitely small and dense point How can a point be infinite? Doesn't a physical point necessarily mean it ends? I liked A Brief History of Time but I knew the part about things going backwards in "The Big Crunch" wasn't going to work. This - and probably only this - is why I'm the world's greatest thinker.
  • Time is an illusion we practice on ourselves.
  • werd up, bees.
  • Infinity is a concept used for dealing with limits so I'm not sure what the technical meaning of "infinitely small" would be. I could guess it simply refers to a point at which current physical models no longer hold. Who here is a theoretical physics whiz?
  • If the infinite smallness of the point is hard to wrap your head around, just forget about it and consider that the density of it is infinitely high. Essentially, the operations of space-time as we know them become so warped under these conditions that even our ability to describe or measure anything about, or possibly even locate the experimental environment simply goes away.
  • To say a density is infinite, however, seems little different than saying, "I have an infinite number of puppies." It doesn't make sense; infinity is not a number. Of course, this is all mental masterbation of a layperson.
  • A thing is infitely small if there's no finitely small cage that can't enclose it. Mathematically. Something is infinitely small if you can't make any measure of it's size that has no positive error, ie. your measure will always be bigger than that you are measuring up.
  • measure of it's size or length.
  • Also, something infinitely small is always longer than zero. But it's limit is on zero. nontheless.
  • I'm not a theoretical physics whiz, but I'm reading a book by one, and here's what he has to say about infinity: "In practice, the incompatibility between general relativity and quantum mechanics rears its head in a very specific way. If you use the combined equations of general relativity and quantum mechanics, they almost always yield one answer: infinity. And that's a problem. It's nonsense. Experimenters never measure an infinite amount of anything. Dials never spin around to infinity. Meters never read infinity. Calculators never register infinity. Almost always, an infinite answer is meaningless. All it tells us is that the equations of general relativity and quantum mechanics, when merged, go haywire." -Brian Greene, The Fabric of the Cosmos, p335.
  • The reciprocal of an infinitely large value.
  • FREETHOUGHT! you have an infinite number of puppies??? you are soooo lucky! and the obvious person to open our patent-pending Room O' Puppies. or, should i say, Room O' Infinite Puppies. heh.
  • Further: "...although most things are either big and heavy or small and light, and therefore, as a practical matter, can be described using general relativity or quantum mechanics, this is not true of all things. Black holes provide a good example. According to general relativity, all the matter that makes up a black hole is crushed together at a single miniscule point at the black hole's center. This makes the center of a black hole both enormously massive and incredibly tiny, and hence it falls on both sides of the purported divide: we need to use general relativity because the large mass creates a substantial gravitational field, and we also need to use quantum mechanics because all the mass is squeezed to a tiny size. But in combination, the equations break down, so no one has been able to determine what happens right at the center of a black hole. "...For physicists, the existence of a realm in which the known laws of physics break down -- no matter how esoteric the realm might seem -- throws up red flags. If the known laws of physics break down under any circumstances, it is a clear signal that we have not reached the deepest possible understanding. After all, the universe works; as far as we can tell, the universe does not break down. The correct theory of the universe should, at the very least, meet the same standard." -Ibid., pp336-337.
  • "Let us first consider the case of an infinite number of puppies". May we then proceed to infinite monkeys or books? Good quotes JoeChip. There is an assumption that a perfectly accurate model of the universe is expressible in terms of our symbols and formal systems, but I guess if physicists (and mathematicians) didn't make such assumptions, they wouldn't have anything to do.
  • Hey hey hey - you linked puppies to a math problem! Have you no decency sir?! just kiddin' - i hateses me some math, tell you whut
  • Any news or announcements involving Stephen Hawking will forever be tainted by the ignobility of knowing he is being physically abused by his wife. In fact, I think every article that makes reference to him should have to include a paragraph at the end saying something to this effect: "PLEASE DON'T LEAVE STEPHEN ALONE WITH HIS WIFE, THX, -SCIENTIFIC COMMUNITY"
  • P.S.: Joe Chip, have you read The Elegant Universe, by Brian Greene? One of the most common criticisms of Fabric is that it is dumbed down for a more general audience. The general ideas are there, but illustrated allegorically. If you've seen his PBS specials, you know what I'm talking about.
  • On a side note: a friend of mine is an astrophysicist. He has had many milestones in his career--getting into grad school, getting his Ph.D., etc--but he really knew he had arrived when he started getting letters from random nutcases who had a BRILLIANT NEW THEORY, which was being IGNORED by the establishment, and PERHAPS YOU COULD HELP??? I bet this new Stephen Hawking/black hole thing sparks a new round of letters.
  • so he HAS been receiving my letters!! they must have gotten to him too . . .
  • Daniel, I haven't read The Elegant Universe but I did see the PBS special. I have no problem with allegorical illustrations for a general audience. Otherwise us laypersons are left to suffer through stuff like this (the abstract of Hawking's upcoming talk): "The Euclidean path integral over all topologically trivial metrics can be done by time slicing and so is unitary when analytically continued to the Lorentzian. On the other hand, the path integral over all topologically non-trivial metrics is asymptotically independent of the initial state. Thus the total path integral is unitary and information is not lost in the formation and evaporation of black holes." Clear as day, wot?
  • Yeah, I do appreciate accessibility, but I think Elegant Universe is perfectly understandable without sacrificing critical information. Cosmology and theoretical physics is complicated stuff. It should be hard. Not everything can be reduced to easily digestible bits. But that's certainly not to say science writing has to be hard to read. I thoroughly recommend Elegant Universe as the perfect example of a very well written, and intellectually rigorous book for non-experts.
  • there is no spoon?
  • Stephen Hawking doesn't actually exist. I like the idea that blackholes are really gravastars. This neatly avoids all that bullshit. Quantum Mechanics, while vastly interesting, must be broken because there are so many theories to explain the indeterminacy principle (the idea that it's not possible to measure energy & time/location & vector accurately) - even then it doesn't fit with General Relativity. Plus the Standard Model is incomplete, as recent studies on neutrinos seem to show. Stephen Hawking is proof that the Universe has a twisted, ironic sense of humour. I mean, think about it. He's Davros.
  • Greene's PBS special is worth watching, if for no other reason, for each utterance of the word "sparticles". Theoretical physics needs more words that sound like candy.
  • FREETHOUGHT! you have an infinite number of puppies??? The whole truth is that I have an infinite number of meowing things, but only half the necessary litter.