Big News about Black Holes!

This has been all over my inbox since the press release came out yesterday; it’s been on slashdot (thanks Brian), it’s been at space.com, and there’s a mediocre writeup on Universe Today. What’s the big news? Black Holes don’t destroy information after all!

What is this whole information thing, anyway? Take a look at all the normal stuff in the Universe: photons, protons, neutrons, and electrons, for example. They have lots of different properties each. They move around one another, they get bound and unbound from one another, they exert forces on one another, etc. They’re aware of one another, and they interact with one another, and they have many properties, both intrinsic and extrinsic. And when they come together, they make complex things, like atoms, which contain even more information than the individual particles do on their own:

But when you put all of this stuff into a black hole, all of this information seems to disappear. Black holes have only three properties: mass, charge, and spin. Everything else, all the information you put into it, seems to disappear. Doesn’t matter whether you put a bunch of neutrons in, or a bunch of human beings in: to a black hole, they’re the same things. Black holes don’t remember quantum numbers, they don’t remember how many quarks or electrons you put into it. All they care about is mass, charge, and spin.

Or so the story goes. That’s what Stephen Hawking has been saying for years, leading to his famous information paradox about black holes.

Well, it’s a paradox no more! A team at Penn State, led by Abhay Ashtekar (who’s pretty famous for his work on trying to formulate a quantum theory of gravity), has shown how all of that “lost information” can be recovered. The catch?

It means that space-time is not a continuum.

Instead, on the smallest scales, it has to actually be discrete, like little “chunks” of space-time strung together to create a giant mosaic.

The reason for this is that without a continuum, there can’t be any such thing as a singularity. Here’s what Ashtekar had to say about it:

Information only appears to be lost because we have been looking at a restricted part of the true quantum-mechanical space-time. Once you consider quantum gravity, then space-time becomes much larger and there is room for information to reappear in the distant future on the other side of what was first thought to be the end of space-time.

Wow. Now this hasn’t been verified or even published yet (May 20th, in Physical Review Letters), but this is really ground-breaking! Have a great weekend, folks, and don’t forget to swing on over to this week’s Carnival of Space at Altair VI, where you can read about lots of interesting stuff, including how to avoid Armageddon from incoming asteroids!

Comments

  1. #1 Fraser Cain
    May 16, 2008

    Ouch.

  2. #2 ethan
    May 16, 2008

    Sorry, man. When you just cut and paste from the press release, and simply paraphrase the rest, I can’t give out high praise.

  3. #3 Anna K.
    May 17, 2008

    Dumb question: if there is no such thing as a singularity for a black hole, what about the singularity from the Big Bang? Did the Big Bang still start from a singularity, or will this change our views of that? Or are the models for black hole singularities completely different from the Big Bang one?

  4. #4 mark a. thomas
    May 17, 2008

    Anna,
    More information just keeps coming even if it is only theoretical or mathematical. Some of the theory or math has a certain measure of “correctness” even though it may turn out not to be correct. An example is cosmic inflation which looks better every day even though there are obstacles. In a sense the singularity may just be a measure of our ignorance (where the numbers make no sense) and it does not matter from the black hole case to the Big Bang case. Tom Banks has a term for this which he calls “asymptotic darkness” which describes areas beyond which we cannot yet see. In the classical Big Bang there are now pre-bang scenarios which are pushing the envelope even further into a quantum gravity realm. Progress is being made here as well. On another note Stephen Hawking had relinquished to the fact that the Black Hole paradox has been solved (I think back in 2003?) and that information is not destroyed in the black hole because of the quantum unitarity stringy/cft nature of its evaporation.

  5. #5 ethan
    May 17, 2008

    Anna,

    That isn’t a dumb question at all! What it means is that there is no such thing as a singularity at all, anywhere, ever. We’ll still get incredibly large densities at the big bang, but if space-time is chopped up into little points, then there’s no such thing as a “singularity” anywhere.

    Here’s the problem: density is mass divided by volume. We know that there are point-like particles with masses. What this tells us is that if space-time isn’t a continuum, then it, too, is just a series of points. The whole problem of a singularity is that densities would be infinite. But if we look at any one point, and find that its volume is zero, then everywhere we have a mass has infinite density. So the big bang and black holes are no more singularities than the place where my butt is sitting right now. Good question!

    Ethan

  6. #6 Anna K.
    May 17, 2008

    Thank you, Mark and Ethan — your remarks were very helpful!

    Weeeeird. So it’s all granular?! So in art terms, we have a pointillistic Georges Seurat kind of universe?

    Then would that make what we think of as singularities, just a very crowded collection of points?

  7. #7 ethan
    May 17, 2008

    Anna,

    *If* Ashtekar’s formulation of this is correct, then yes. Just like what we think of as solids, liquids, and gasses are really just huge collections of point-like particles, what we think of as space, what we imagine as a nice, smooth surface, is also really just a collection of a huge number of points. So put a bunch of points atop one another, and from a distance, it looks like a singularity.
    I prefer Chuck Close to Seurat, but you’ve got the right idea!
    Ethan

  8. #8 Cris
    May 29, 2008

    Is it possible that the infinitly small and dense point, present prior to the Big bang was the “missing” matter condensed by a blackhole on some other “universal plane” or even our own.

  9. #9 Cris
    May 29, 2008

    ?

  10. #10 ethan
    May 29, 2008

    Cris,

    I don’t think so, because what we understand about the missing matter (now known as dark matter) doesn’t line up with exotic explanations such as that. It seems just like regular matter, except it doesn’t stick together in stars and planets and humans; but it still obeys all the standard laws of gravity without needing another universe to operate in.

    Ethan

  11. #11 Drew Teniuk
    March 5, 2009

    Hi I’m not sure what everyone is talking about like quatum gravity and stuff because i am a 15 year old boy who likes to get baked… Besides the point I have a few suggests of my own that i thought of when i was high, 1st when matter and information is sucked through a black hole everything seems to just vanish, you need to ask yourself what matter and what is actually being sucked through ? Its all simply giant amounts of energy stuck together, to form atoms and atoms stick together to create matter and so on… How ever when all that matter is sucked into a black hole is it possable that all that matter is simply broken back down to its smallest and simplest form of energy? And becuase you can not see energy it would seem that all that matter that has entered has just vanished…? But !!! in order for that to be true if we were able to keep cutting a atom in half how ever many times it took tell that atom was broken down its energy stage that peace of matter would not longer exsit proving my theory about what happens inside a black hole, obs that is unable to prove at this point but still a good guess…? let me know what you think

  12. #12 The Space Expert
    March 25, 2009

    I’m 14 yrs old but I know alot about space and the quantrum galaxy. I say that a black hole is a time of substance made from particles of “Dark Energy” when made into 1 big hole like structer the Black Hole is made.
    The inside of a black hole is massive even though the outside is not. I know alot about space and i study it my e-mail is: mewtwo_owen13@yahoo.com

    if you want to ask me any questions about space just e-mail me.

    – The Space Expert

  13. #13 ethan
    March 25, 2009

    Owen,

    I’m glad you’re interested in space, galaxies, black holes, and dark energy! I’m happy to help you learn about this all you like; keep in mind that there are a lot of things you have yet to learn about how black holes work and are formed!

    Best,
    Ethan

  14. #14 Sili
    April 11, 2009

    That is indeed awesome.

    I’ll make no pretense of having any knowledge about the matter (I want to understand my book of Riemannian geometry, though, and buy Sean Carroll’s book someday), but I’ve liked the idea of space-time being a discontinuüm for a while. It seems more ‘neat’ when everything else is quantised, too.

    Not that I have any idea what that means for ‘motion’. Is it a kind of tunnelling from quant to quant?