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Physicists observationally confirm Hawking’s black hole theorem for first time
- lennoff 5y agoSo black holes can't evaporate? How does Hawking radiation works if the back hole are has to stay the same?
- SiempreViernes 5y agoI think it's more a case of the press release people wanting to call it a unqualified "law", as far as we know black holes do evaporate slowly. But there remains is a statement about how the final area relates to the area of the two merging black holes.
- edem 5y agoThey _do_ evaporate, but they also absorb CMB, and right now CMB > evaporation. Later, when CMB fully dissipated they can evaporate in practice.
- kstrauser 5y ago> Later, when CMB fully dissipated That's one of the most understated uses of "later" I've heard.
- jfengel 5y agoBlack holes can't evaporate now because the cosmic background radiation is too hot. The black holes are colder the CMBR, so they absorb heat and grow (albeit very, very slightly). Eventually the CMBR will cool down and the holes will be able to evaporate, but not for an insanely long time.
- __MatrixMan__ 5y agoI imagine this holds only for black holes that are massive enough to be stable? All those itsy bitsy ones created by the LHC, they've evaporated, yes?
- wruza 5y agoI believe that LHC has no chance ever to harvest enough energy to create a sensible-sized black hole. It’s still mc-squared (give or take an order of magnitude and my layman mistakes), so 1g BH takes about 1e14 joules or 5 minutes of average EU electricity output. Also, there is no sea nearby to cool it off afterwards. Also, a planck-sized BH weighs 1e-5 g. A mass similar to Mount Everest[13][note 1] has a Schwarzschild radius much smaller than a nanometre.[note 2] Its average density at that size would be so high that no known mechanism could form such extremely compact objects It seems that at energies available to us they are basically either virtual or non-existent. This contradicts the common notion that cosmic rays create microbhs occasionally, but I guess we have to wait for a physicist to clarify this.
- jfengel 5y agoIn theory, it might have made a black hole. It would have lasted a ridiculously small period of time, but be quite recognizable by the energy it gave off. Instead of the usual decay patterns, it would give off a spray just of photons, like a black body at a recognizable (and very high) temperature. We didn't see that, and in fact theory predicted that it was insanely unlikely that we would. But there's nothing wrong with the possibility of a black hole much, much, much smaller than a gram, with a radius smaller than the Planck length. If we had seen it, it would have been insanely informative. But it wasn't ever gonna happen.
- eximius 5y agoAlright, I'm confused. How does this square with Hawking radiation? How can a black hole shrink without shrinking? The article mentions both in the context that they are reconciled but not how they are reconciled.
- rakkhi 5y agoExactly what I came here to ask. Is Hawking's theory that the area never decreases or that it does not decrease in a black hole merger as was tested here. "central law for black holes predicts that the area of their event horizons — the boundary beyond which nothing can ever escape — should never shrink" this seems to imply the former to me. Does that mean with Hawking radiation the black hole effectively evaporates by loosing mass (?) from the inside without the boundary area never shrinking?
- jleahy 5y agoThey're not reconciled, it's just garbage reporting. The 'area theorem' they are referring to was by Bekenstein and others, not Hawking. It's basically the equivalent of the second law of thermodynamics for black holes (dA/dt>=0 instead of dS/dt>=0). Hawking's insight was that this formula was wrong and the area could decrease due to radiation.
- aliasEli 5y agoIt is a pity about the reporting. But it is a fascinating area of research. I never expected that we could measure gravitational waves in our life time.
- Cthulhu_ 5y agoI'm amazed - to the point of skepticism - that with such minute forces they can extrapolate so much information and prove theories. I mean I'm no astrophysicist, I like the "pop sci" bits, but when I look closer I'm seeing a lot of small numbers and statistics that imply something - e.g. exoplanets based on minute wobbles and brightness variations, water on said exoplanets based on spectrography. It's theories based on tiny but statistically significant data. The pop sci then comes in and makes statements like "second Earth found!11", which is like, whoa hold on, when you look closer all they found is a wobble or dimness variation that kind of implies there might be a planet at a certain distance from its host star. Anyway I don't dispute the findings or that there are exoplanets or whatever, I'm just impressed that they are able to make confident claims on what little information we can receive from here.
- realYitzi 5y agoAnyone can think of any practical effect this might have or is this something that at the moment seems to have only scientific relevance.
- eru 5y agoWell, if the result had turned out the other way, we might have seen some practical effects, because it would overturn some well-established theories that we also use for predicting more practical things.
- 867-5309 5y agoso they're 95% sure.. how do they even come up with a figure like that? they didn't bother saying. might be equivalent to 'give or take a few trillion tonnes'
- Cthulhu_ 5y agohttps://www.zmescience.com/science/what-5-sigma-means-0423423/; https://www.zmescience.com/science/what-5-sigma-means-042342... 95% means 2-sigma, when it comes things like the Higgs boson, they announced the results with 5-sigma certainty, which is a very good indication of statistical significance and confidence.
- wyager 5y agoIt’s more that p-value is a bad indication of anything (since it’s vulnerable to p-hacking and all kinds of other issues), so physics just picks a really extreme publication threshold to avoid getting inundated with spurious developments.
- mhh__ 5y agoIt will say in the paper how they went about the error analysis. These estimates are however, subjective. There is a good paper on this called "Bayesian methods in particle physics" (something like that).
- edem 5y agoNote that by the time black hole evaporation would be significant the CMB will be long gone because of dark energy (universe expanding). All this means that evaporation is delayed till there is nothing else left apart from black holes (because of the faster than light recession of space itself).
- Ankaios 5y agoHere's the paper: https://journals.aps.org/prl/accepted/36074Y8aM291c462a4e264336d883136eb53c122b https://journals.aps.org/prl/accepted/36074Y8aM291c462a4e264... https://arxiv.org/abs/2012.04486 https://arxiv.org/abs/2012.04486
- louloulou 5y agoThank you! It drives me crazy that news articles about a paper never link to the actual damn paper.
- notorandit 5y agoIf you have BH evaporation you cannot keep the horizon surface constant.
- ordu 5y ago> There are certain rules that even the most extreme objects in the universe must obey. A strange way to put it. The more object is extreme the harder it would be for it to disobey laws. If we try to imagine what forces are involved, all we'll find is that our imagination has it's limits. I'd be less surprised if some quark disobeyed laws, because it small, forces are minuscule and... who is to notice? Maybe they disobey laws all the time, just scientists fail to catch them red handed.
- justinboogaard 5y agoI don’t think the quote is saying objects have to obey laws because they are extreme (and therefore easy to notice) I think it’s saying all objects have to follow the established rules of physics, regardless of how unusual they are. It’s an interesting idea though! Known, “extreme” objects may be less fruitful places to study unknown forces because they have qualities that overwhelming drown out smaller less known forces.
- steve76 5y agoFor something to exist, it must be able to interact with surroundings. It also must be independent. As it interacts the surroundings see the same thing, even if it's very small or for a brief moment. Why? If the surroundings interact, and without delay something changes, there's no independence. It's just the surroundings. Very few things interact with a black hole. With relativity and the photoelectric effect, black hole internals are an unticked watch. Or a film strip with one opened frame. There's not enough in the surroundings that can make it move. All interactions resist. That black hole is on that one tick or that one frame. It has yet to occur, and there's not enough in everything that exists to make it occur! No ability for interaction is the same as two interactions canceling each other out. One of those two interacts with a black hole. It looks like the black hole is emitting and interacting with the surroundings. Surroundings interact with the internals. It's permissible to model internals far more complex than what surroundings see. Humans see space and can visualize brightness as heat transfer across different clockspeeds. Nature has no mind, and does what is asked without question. Nature does things like: - See the inverse of an electron moving backwards in time as the same as an electric current. - See the inside of a proton, the counterbalance to electromagnetism or interaction via internal state, as three poled electricity, positive, negative and something else along with neutral, at least to a very accurate degree. - Transfer mass while leaving temperature and ionized bonds alone, as in nuclear decay and radiation If it's easier, nature will do it. Surroundings see something much more simple than the complex internals on which interactions occur. The idea that black holes are two dimensional consisting of just the surface brought forward this principle. Something enters the black hole, it doesn't go into a volume. The surface area is the amount of surroundings it's interacting with, and they all say send heat there by changing internal clock.