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Black Hole Evolution Traced Out with Loop Quantum Gravity
- melling 8y agoIf you’re interested in black holes, Shep Doeleman’s efforts might be of interest. Taking a Photograph of a Black Hole https://youtu.be/RTKIZvDQ6Jk https://youtu.be/RTKIZvDQ6Jk Einstein’s Shadow: https://www.amazon.com/Einsteins-Shadow-Black-Astronomers-Unseeable/dp/0062312022 https://www.amazon.com/Einsteins-Shadow-Black-Astronomers-Un...
- branislav 8y agoI also highly recommend this [1] episode of the Omega Tau podcast which touches on black holes, holography and quantum gravity. [1] http://omegataupodcast.net/191-string-theory/ http://omegataupodcast.net/191-string-theory/
- nabla9 8y agoIf I understood the article correctly: 1. Black hole gradually evaporates (Hawking radiation) until it's Plank size. 2. Quantum transition and Plank star. 3. White hole is formed and "the collapsed star is bouncing back". I Always thought that black hole evaporating energy as Hawking radiation contains all the energy that went into the black hole when the evaporation is complete. This theory assumes that there is energy left. How is the total energy that went in is distributed between the Hawking radiation and the white hole that follows the evaporation? Are all white holes equal in size and does Hawking radiation account for the black hole size difference?
- enkid 8y agoMy understanding is the transition to a white hole exists instead of a singularity at the interior of the black hole, and is therefore hidden by the event horizon. When the event horizon shrinks to the Planck length, the white hole is exposed.
- nabla9 8y agoYes, but the event horizon shrinks by emitting Hawking radiation, right? When the white hole is exposed, what it looks like? Is it just hole in the space that does not emit anything? Nothing exits (because Hawking radiation already emitted all of the energy) and nothing can enter. What is the radius of the white hole?
- ianai 8y agoI think Roger Penrose’s explanation here is appropriate, but I don’t know if the similarity between a black holes evaporation and the eventual entropy death of the universe are similar enough: https://youtube.com/watch?v=z2_6h15UCMg https://youtube.com/watch?v=z2_6h15UCMg. If so, I think it would mean a Plankt scale black hole would have a significant probability of spontaneously evolving a white hole?
- nabla9 8y agoI just listened Sean Carrol's podcast interview wit Penrose and I think they are different. https://www.preposterousuniverse.com/podcast/2019/01/07/episode-28-roger-penrose-on-spacetime-consciousness-and-the-universe/ https://www.preposterousuniverse.com/podcast/2019/01/07/epis... In the loop quantum gravity there is a bounce because at the lowest level spacetime is discrete and can't be compressed. The big bounce theory of relating to big bang in the loop quantum theory might be similar to the black hole/white hole theory. In Penrose's theory it's the gravity/mass that is creating time and clumping things together between the big bang and the heat death of the universe (you need mass to create clock and time). At the beginning of the universe temperature was so high that masses did not matter, at the end of the universe there is no mass, just massless particles (after googol or so when the biggest black holes have evaporated). Massless particles (photon, gluon, graviton) don't experience time so they in a sense fly into the the end of the eternity instantly. Then there is something geometrical I don't understand and the ends meet and the new universe matches the end of the previous across timeless eon. Penrose thinks you could perceive the ripples caused by the massive black holes from the last universe in the background radiation of our universe.
- tylerjwilk00 8y agoAgreed. It's seems like it must be either Hawking radiation OR white hole bounce not both. If Hawking radiation evaporates the black hole then there should be no matter or energy left for white hole to ouput in the future.
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- SiempreViernes 8y agoRovelli himself wrote this more popular account and didn't manage to state a clear physical reason for the bounce, so the title is overstating the result. I take this to be an interesting technical advance for a theory whose relevance in general is still an open question.
- acd 8y agoIf white holes exist that are the inverse of black holes. The universe could exist forever. Black holes would suck matter in and white wholes on the other side would create new matter on the other side. Black wholes and white holes would then be gateways to other universes. Multi verse https://en.wikipedia.org/wiki/Multiverse https://en.wikipedia.org/wiki/Multiverse https://news.nationalgeographic.com/news/2010/04/100409-black-holes-alternate-universe-multiverse-einstein-wormholes/ https://news.nationalgeographic.com/news/2010/04/100409-blac... https://en.wikipedia.org/wiki/Wormhole https://en.wikipedia.org/wiki/Wormhole
- nyc111 8y agoAre Gray Holes next? When a White Hole and a Black Hole merge a Gray Hole will emerge as predicted by the Chromatic Theory of General Relativity.
- nyc111 8y agoI was wrong! Grey Holes have been invented already! http://adsabs.harvard.edu/full/1993AAS...182.5507B http://adsabs.harvard.edu/full/1993AAS...182.5507B
- foobar1962 8y agoMy quick summary of white holes, which I thought were a product of science fiction: Predicted by some solutions to relativity. They have not been observed yet but recent theories suggest that some burst of gamma rays may be markers. Other theories suggest that the expulsion of matter from a white hole may occur very quickly, almost instantaneously, so unlike say a supernova you’d need to be looking at the right place and the right time to see it happen. White hole mass may be behind a horizion that makes them dark = dark matter. Our Big Bang may have been a super-massive white hole event, so we are a universe-within a universe.
- featherrust 8y agoHas anyone tried sending information into black holes using lasers yet? It'd be convenient if ET's only lived in black holes, although perhaps a little lonely, too.
- maxxxxx 8y ago"Has anyone tried sending information into black holes using lasers yet?" We would need one at a pretty uncomfortably close distance to perform this experiment in acceptable time and without needing insanely large amounts of energy. Makes me wonder how close the next known black hole is. The center of the milky way?
- CGamesPlay 8y ago> The closest black hole we know of is V616 Monocerotis, also known as V616 Mon. It's located about 3,000 light years away. [1] So no, because we haven’t had lasers for 3000 years yet, and the black holes we can create here on earth last for microseconds. [1] https://phys.org/news/2016-03-closest-black-hole.html https://phys.org/news/2016-03-closest-black-hole.html
- mokus 8y agoWe can create black holes here in earth? I’d love to read more about that if you have any starting points
- featherrust 8y agoIs there evidence for or against the interior of black holes being similar to distinct separate universes? Is that a popular idea at all, in physicists' circles? How much (and _what_) would I need to read and understand to get a feeling of the nature of black holes? I'm a total layman when it comes to physics and it would put some distant worries of me to rest. I'd rather measure a lot of Hawking radiation while throwing bottles in flasks into a black hole. However, I'm currently preoccupied with figuring out why my mouth keeps talking when I'm not thinking of anything.
- Larrikin 8y agoWelcome to the Universe is an excellent book for understanding the basics
- czbond 8y agoPBS Spacetime is a great series, and delves deep enough for interested layman as well as practitioners to be interested. I find the videos really good. Here is a link to one of many on black holes. https://www.youtube.com/watch?v=vNaEBbFbvcY https://www.youtube.com/watch?v=vNaEBbFbvcY
- beaner 8y agoOne thing I never understood is, how does a black hole evaporate, even via hawking radiation? Doesn't the matter it ejects just fall back in?
- JabavuAdams 8y agoMy limited understanding is that the Hawking radiation is caused by virtual particle-antiparticle pairs spawning just outside the event horizon. The event horizon is by definition the surface on or inside of which not even light can escape. This seems to imply that outside the event horizon some non-zero mass objects can still escape, if they're on a favourable trajectory. E.g. aimed directly away from the event-horizon isosurface.
- SomeHacker44 8y agoMy layman's understanding mirrors this. Because one part of a pair of virtual particles crosses the horizon, and the other one does not, they become separated by said horizon and cannot recombine and disappear. The particles become actual and not virtual, but one is lost to the hole. Hence, it looks to the external world as if a particle was emitted by the hole. Note that to my (layman's) knowledge, this has not been actually observed, but does seem to be a modern consensus and involved a paid bet.
- InclinedPlane 8y agoThere's lots of different ways to approach explaining the phenomenon of hawking radiation, PBS space time does a good job here: https://www.youtube.com/watch?v=qPKj0YnKANw https://www.youtube.com/watch?v=qPKj0YnKANw Ultimately, hawking radiation does not come from within the event horizon, so it can escape into the wider universe.
- Baeocystin 8y agoOversimplifying, but the majority of the particles created are massless particles (usually photons), and a photon outside the event horizon can, by definition, escape. For a more detailed answer with references, see the last answer here at https://physics.stackexchange.com/questions/89983/how-many-of-which-particles-are-in-hawking-radiation https://physics.stackexchange.com/questions/89983/how-many-o... .