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Black Holes Not Black After All, Theorize Physicists 227

Posted by Unknown Lamer
from the lemon-chiffon-hole dept.
KentuckyFC (1144503) writes Black holes are singularities in spacetime formed by stars that have collapsed at the end of their lives. But while black holes are one of the best known ideas in cosmology, physicists have never been entirely comfortable with the idea that regions of the universe can become infinitely dense. Indeed, they only accept this because they can't think of any reason why it shouldn't happen. But in the last few months, just such a reason has emerged as a result of intense debate about one of cosmology's greatest problems — the information paradox. This is the fundamental tenet in quantum mechanics that all the information about a system is encoded in its wave function and this always evolves in a way that conserves information. The paradox arises when this system falls into a black hole causing the information to devolve into a single state. So information must be lost.

Earlier this year, Stephen Hawking proposed a solution. His idea is that gravitational collapse can never continue beyond the so-called event horizon of a black hole beyond which information is lost. Gravitational collapse would approach the boundary but never go beyond it. That solves the information paradox but raises another question instead: if not a black hole, then what? Now one physicist has worked out the answer. His conclusion is that the collapsed star should end up about twice the radius of a conventional black hole but would not be dense enough to trap light forever and therefore would not be black. Indeed, to all intents and purposes, it would look like a large neutron star.
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Black Holes Not Black After All, Theorize Physicists

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  • by disposable60 (735022) on Thursday July 24, 2014 @12:42PM (#47523731) Journal

    Or just not quite as dense as we thought.

  • by MrKevvy (85565) on Thursday July 24, 2014 @12:46PM (#47523765)

    Frozen Star [google.ca] by George Greenstein had as a central theme that due to gravitational time dilation that we could never see a star collapse beyond its own event horizon: it would asymptotically approach it as arbitrarily close as we liked given unlimited time but never cross it. So as a natural consequence there was always a tiny but measurable probability that trapped light and thus information could escape.

    Although this is a layperson's work, it is based on his published papers which provide a mathematical background.

    • by swillden (191260)
      Interesting, but not surprising. It's unlikely that any new idea in cosmology (or anywhere else) is actually truly "new" by the time it garners sufficient support to warrant widespread serious consideration. The process by which knowledge is created -- conjecture and criticism -- almost precludes it. Ideas, even correct ideas, assuming this is and assuming that Greenstein actually had the same idea, not less-correct variant, nearly always come before the knowledge needed to identify them as correct, or at
    • by smooth wombat (796938) on Thursday July 24, 2014 @01:28PM (#47524095) Homepage Journal
      there was always a tiny but measurable probability that trapped light and thus information could escape.

      Isn't that the same thing as Hawking Radiation? I'm sure Dr. Hawking proposed and submitted work explaining the same thing.

      In fact, here is what I am talking about [ucr.edu].
      • by Gamasta (557555)

        No, these are different things.

        The "Hawking radiation" is a mechanism, by which a black hole would not be completely black. Hawking proposed that two particles created outside the black hole with opposite velocities (to conserve momentum), one of these particles could escape the black hole if it's velocity was high enough (the other one would be captured). The energy for creating the two particles would be from the black hole itself.

        He calculated that the probability of this happening is inverse to the mass

    • by ceoyoyo (59147) on Thursday July 24, 2014 @02:45PM (#47524651)

      Physicists originally called black holes "frozen stars" because the flow of time stops at the event horizon. Nothing can fall past an event horizon in outside time because that would take an infinitely long time to happen. It also can't happen from the perspective of an observer falling in, provided the outside universe has a finite lifetime. So you can never get a singularity.

      I'm not really sure why that idea doesn't get more attention from today's physicists.

  • by K. S. Kyosuke (729550) on Thursday July 24, 2014 @12:46PM (#47523771)

    physicists have never been entirely comfortable with the idea that regions of the universe can become infinitely density

    I'm pretty sure that editors outside of /. have never been entirely comfortable with that idea either.

  • Orange? (Score:5, Funny)

    by Sporkinum (655143) on Thursday July 24, 2014 @12:46PM (#47523773)

    Orange is the new black...hole...

    • uhm? Was that a reference to Josie and the Pussy Cats?

      • by sconeu (64226)

        Netflix series. "Orange is the new black".

        • doh! I've not seen it but i watched Josie and the Pussy Cats with my niece last night... if you haven't seen it it is a comedy about subliminal messages in pop music every time a new song comes on what's cool changes orange is the new black or blue is the new orange and all the kids run to the mall to buy all new clothes that color.

    • What's that you say? Orange Star is the new Black Hole?

  • by Joe Gillian (3683399) on Thursday July 24, 2014 @12:50PM (#47523807)

    I know that Black Holes aren't supposed to be observable - but I thought there were observations of other things, such as things being eaten by black holes and the interactions between a black hole's massive gravity well and the environment around it. If this study is right, shouldn't the astrophysicists who first observed the by-products of black holes have been able to see them?

    • by suutar (1860506) on Thursday July 24, 2014 @01:17PM (#47524005)

      they may not be truly black, in that electromagnetic radiation can actually escape from the surface, but that radiation can still be redshifted heavily and have insufficient energy to be detectable by us.

      • by Bengie (1121981)
        Another orthogonal explanation.

        Any light emitted from the "black hole" itself could also be dwarfed by the noise of all the other em coming from the accretion disk, making it nearly impossible to detected remotely.
    • Re: (Score:2, Interesting)

      by Anonymous Coward

      The best picture [nationalgeographic.com] we currently have of an exoplanet is about 6x6 pixels.
      The closest black hole is heck of a lot further away.
      Any observation we have of a black holes are extrapolations from gathered data.

      Discoveries of stellar bodies are often presented as facts in the news but the discoveries themselves are little more than "This example would explain the data, together with a hundred other possible scenarios."
      Next time you see a headline about discovering a star made entirely out of diamond or whatever, re

    • Black holes and neutron stars are both examples of stellar remnants, where fusion has stopped, so they're not emitting nearly as much energy as previously, just residual effects of temperature, magnetism and gravity. In the case of black holes, we've been assuming that the radius had collapsed to the point where the escape velocity was greater than the speed of light, hence, "black". Even if that isn't the case, they're not necessarily going to be easy to spot.
    • by mysidia (191772)

      Unless the objects weren't black holes but a massive amount of dark matter which is invisible across the visible light spectrum, and maybe our telescopes saw nothing, but there actually is a finite mass which does not emit light.

    • by Chalnoth (1334923)

      Obtaining observations that are close enough to the event horizon for this theoretical model to make a difference are really really difficult to perform. For instance, our current best estimates for the radius of the supermassive black hole at the center of our galaxy are only able to nail it down to smaller than five and a half times the Schwarzschild radius. So I'm pretty sure that this model is well within current observational limits.

      It probably won't be long, however, before we have observations that

  • by WormholeFiend (674934) on Thursday July 24, 2014 @12:53PM (#47523825)

    following the convention for naming stars that are not dense enough to ignite "brown dwarfs", we could name these new, less dense, singularities... "brown holes".

  • by NoNonAlphaCharsHere (2201864) on Thursday July 24, 2014 @12:56PM (#47523845)
    Now how is Michio Kaku going to portray black holes as marauding monsters that travel around like itinerant serial killers, gobbling up everything in their path?
    • by gmhowell (26755)

      Now how is Michio Kaku going to portray black holes as marauding monsters that travel around like itinerant serial killers, gobbling up everything in their path?

      I suggest bringing in a robot sidekick named Maximillian to improve ratings.

  • by gstoddart (321705) on Thursday July 24, 2014 @01:00PM (#47523893) Homepage

    Indeed, to all intents and purposes, it would look like a large neutron star.

    WTF does a large neutron star look like then?

  • by Cro Magnon (467622) on Thursday July 24, 2014 @01:06PM (#47523935) Homepage Journal

    physicists have never been entirely comfortable with the idea that regions of the universe can become infinitely density.

    They've clearly never been to DC. I'm convinced that regions of the universe are infinitely dense.

  • The paradox arises when this system falls into a black hole causing the information to devolve into a single state.

    Or... maybe it doesn't devolve into a single state at all. We can't actually see what goes on inside of black hole... but if our assumptions about what actually happens appear to create a paradox, then maybe it's our assumptions aren't valid, rather than the original basic concept of what a black hole supposedly is. I believe that the concept that black holes are necessarily singularities may be flawed. Space is so distorted by gravity in their vicinity that straight lines which intersect their event horizon never exit it, but I do not think that means that all of a black hole's mass is necessarily at its center, or even necessarily collapsing inexorably towards its center. Its center is just its center of mass.

    And yeah, I know that astrophysicists with a vastly more qualifications than I have came up with these ideas, but in the end, an argument from authority does not make one actually right.

    • by dunkindave (1801608) on Thursday July 24, 2014 @01:50PM (#47524269)

      And yeah, I know that astrophysicists with a vastly more qualifications than I have came up with these ideas, but in the end, an argument from authority does not make one actually right.

      This is actually one of my nits with these kinds of articles. When someone says "Now one physicist has worked out the answer", the use of the phrase "the answer" means in English that the question is now closed. He has found THE answer, meaning the one and only answer, hence the use of the word 'the' instead of the word 'a'. In reality, the article should say "Now one physicist has worked out a possible answer". What he has presented is a theory that he believes is consistent with known physics and observations. That is all it is.

    • The paradox arises when this system falls into a black hole causing the information to devolve into a single state.

      Or... maybe it doesn't devolve into a single state at all. We can't actually see what goes on inside of black hole... but if our assumptions about what actually happens appear to create a paradox, then maybe it's our assumptions aren't valid, rather than the original basic concept of what a black hole supposedly is. I believe that the concept that black holes are necessarily singularities may be flawed. Space is so distorted by gravity in their vicinity that straight lines which intersect their event horizon never exit it, but I do not think that means that all of a black hole's mass is necessarily at its center, or even necessarily collapsing inexorably towards its center. Its center is just its center of mass.

      And yeah, I know that astrophysicists with a vastly more qualifications than I have came up with these ideas, but in the end, an argument from authority does not make one actually right.

      The theory of black holes did not come from any observations of physical phenomenon, it came from studying Einstein's theories. The math suggested the possibility of singularities, but at first no one thought they would actually exist in our universe. Of course now we know that black holes DO exist, so those theories are validated. Now we're just trying to figure out how to reconcile with OTHER theories.

    • But that's exactly what they are saying.
      You need to differentiate. Blackholes are NOT singularities. A blackhole is the collection of phenomena and objects in an area of spacetime. It is believe that at the center of the blackhole is a singularity. What this new theory suggests is that there is not a singularity there, but instead that it just behaves very similar to one.

      • by mark-t (151149)
        Can you explain to me, therefore, why information should collapse to a single state inside of a black hole? Because I can't think of one unless you assume that a singularity is at the center of every black hole.
        • why information should collapse to a single state inside of a black hole?

          Information does not want to be free, after all?

  • by Triklyn (2455072)

    can some explain why information can't be lost? this is slightly confusing and that assumption makes it seem like they're building a lot of theory on a pretty shaky foundation.

    • Not quite, they're building it on presumption.
    • Re:Wait (Score:4, Interesting)

      by Anonymous Coward on Thursday July 24, 2014 @02:42PM (#47524623)

      1) Information is another term for entropy.

      2) Thermodynamic says that potential energy and entropy are inversely proportional in an isolated system.

      3) Thermodynamics furthers says that the entropy of an isolated system always increases until it reaches a minimum potential energy state. Why? If the entropy of a system decreases, that implies that potential energy is increasing. But if it's an isolated system, where did that potential energy come from?

      Because black holes exist within an isolated system that is the universe, if they were able to decrease the entropy of the universe then that would imply that they're generating potential energy. Remember that capacity for work is the same as potential energy, so black holes would then be the equivalent of perpetual motion machines because the expenditure of potential energy (i.e. work) creates more entropy, which would be swallowed by a black hole, which would generate more potential energy, ad infinitum. That state of affairs just wouldn't seem to mirror our larger understanding of the universe.

      Also, consider that what we call "time" is effectively the same as an increase in entropy. That is, the universe is evolving to a minimum potential energy state, which is the same as "aging". If you could decrease entropy you'd effectively be making time go backward.

      Of course, all this is premised on our definition of information, entropy, potential energy, etc. But as far as we know they're extremely solid and coherent concepts, and it makes more sense that some supposed phenomenon which violates that model is more likely to be false than those concepts are.

      Anyhow, I'm not a physicist. I don't even play one on TV. I hope real physicists correct my mistakes.

    • by Whorhay (1319089)

      I think it's an extrapolation of the idea that if you had a perfect knowledge of a system's current state and the laws governing that system you could then predict any future state and any prior state.

    • Re:Wait (Score:4, Informative)

      by Charliemopps (1157495) on Thursday July 24, 2014 @03:18PM (#47524999)

      can some explain why information can't be lost? this is slightly confusing and that assumption makes it seem like they're building a lot of theory on a pretty shaky foundation.

      It's actually not as mind bending as you might think.

      Quantum mechanics is "Time Symmetrical" meaning that, the laws of physics work the same irrelevant of the direction of time.
      This is only at the quantum scale so real world stuff doesn't work so hot.
      But take a quantum particle falling into a blackhole...
      If the blackhole consumed it, destroying all information about it... if you reversed time, the particle would never exist, and never be ejected back into space.
      If, however, time slows as it approached the blackhole and the particle never actually crossed the event horizon... then if you reverse time, time would speed up and the particle would eventually be flung away.

      This all depends on you accepting the standard model, and the current interpenetration of quantum physics. They are becoming more rock solid every day however, it would take some pretty amazing discoveries to break them.

      • by Bengie (1121981)

        If, however, time slows as it approached the blackhole and the particle never actually crossed the event horizon

        Can someone please explain this. It seems to be accepted that not only does the object's time slows down as it approaches the event horizon, but it's velocity does also. I don't get that. If an object is moving away from me at 0.9999c, I could expect is to actually be moving away from me at that speed, not slowing down relative to me. If from my perspective an object has stopped moving, then it is no longer moving relative to me and its time should be pretty much the same to my reference.

        I seem to be miss

  • by QilessQi (2044624) on Thursday July 24, 2014 @01:25PM (#47524071)

    IIRC, string theorists have also proposed the idea that there are no singularities. In their model, the gravitational collapse of a star of sufficient mass causes all the strings of its component particles to coalesce into one highly-energetic string, sort of a super-particle. The information content of the original matter would be preserved in the vibration pattern of the final string.

  • What's this about radius of a black hole? Circumference or surface area makes better sense to us, radius of an object with such intense gravity is difficult to comprehend due to the relativistic effect on distance, so comparing radii is not helpful to most of us.
  • Dark Energy?

    Would a 'negative energy' zone potentially produce Dark Energy, which is the repulsive force accelerating inflation?

    Does this explain why inflation is increasing? More 'black-hole-type' objects with more of this negative energy space in existence... creating more Dark Energy...

  • "My name is George McFly, and I am your density."
  • There's a Vaz difference in the region between the Schwarzschild radius and the radius of the star's observed dust ball?
  • In fact, this makes perfect sense. Consider that we *know* black holes evaporate via Hawking radiation. I haven't read the paper, but unless I miss my guess, what he's effectively suggesting is that the evaporation starts as the star collapses, and becomes stronger as it grows more dense, to the point where a balance is reached, *above* the Schwartschild Radius.

                      mark

  • .... this all revolves around the notion that the information paradox is real. It could very well be that what they think of as "information" is nothing more than a layer (or multiple layers) above what the real "information" is. The universe has a habit of proving our ideas need more work... pretty much every time we have a technological advance.
  • I should have tried harder in high school and college so I could really understand all this space stuff.
  • IANAA (I Am Not An Astrophysicist) but I was under the impression that black holes have a non-zero Schwarzschild radius (and therefore volume). Together with a finite mass, how does one get infinity for density?

    Yes, there are things about warped space that may give odd local answers frome a classical physics perspective. But using the term 'infinie density' seems to be an over simplification that is misleading.

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