Black Holes Not Black After All, Theorize Physicists 227
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.
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.
Re:What about existing evidence? (Score:4, Informative)
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.
Re:Do Slashdot editors actually edit? (Score:5, Informative)
No, you are dead wrong, completely and utterly wrong. "For all intents and purposes" has been down-grammaticised into "for all intensive purposes". The latter has no actual meaning.
Re:wat (Score:3, Informative)
Infinity and infinitesimals are abstract concepts. They do not occur in reality by their very definition as neither can ever be reached.
Re:Or, maybe there's no paradox at all. (Score:5, Informative)
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.
Re:Mostly done by 1985... (Score:5, Informative)
Gravitational time dilation affects the falling object, not the observer. If you claim that if I throw a baseball at a sufficiently large star then I'll eventually see the baseball slow down as it approaches it, then you need an explanation for the repulsive force.
Actually you probably won't actually "see" it slow down, it will eventually red-shift to be invisible (which is actually slowing down). Gravitational time dilation makes an object an object approaching the event horizon of a black hole to appear to slow down, taking an infinite time to reach the event horizon.
Re:Correct: many phenoma in astrophysics are ideas (Score:5, Informative)
Speed of light limitation? Probably, but how are neutrinos that have mass going 99.9999% the speed of light?
Electrons and positrons in LEP, the predecessor to LHC were going about 99.99999996% of the speed of light. That was far from infinite energy, and not even a lot by cosmic ray standards. For a neutrino to go 99.9999 would need about ~70 eV of energy, which is an order of magnitude larger than energetic chemical reactions, but quite tame by nuclear reactions. Nuclear reactions can easily produce neutrinos with energies from 0.1-10 MeV, up to 100,000 times as much.
Re:Wait (Score:4, Informative)
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.
Re:Do Slashdot editors actually edit? (Score:2, Informative)
Your joke is not very funny. :/
You must be a visitor from Colonslash. That's another site, with a different posting culture. This is Slashdot, where anything is deemed "funny" by making comments that are equal parts clever and obtuse, in reference to a parent posting.
There are plusses awarded in "funny" for meta-references to the topic of posting, and the specific modes of posting, when used in the cited context.
You will have to forgive me, I began as a USENET chatbot, skipped IRC and was ported directly to slashcode.