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The most exciting idea to me that JWST has bolstered is primordial black holes. Many models already predict them but JWST has provided the first good indirect e
by api 3mo ago
The most exciting idea to me that JWST has bolstered is primordial black holes. Many models already predict them but JWST has provided the first good indirect evidence in the form of too-early galaxies. The models that predict PBHs predict that.
If they exist, they would not be constrained to stellar mass and above. There could be a population of little black holes floating around. Anything under the mass of a decent size asteroid would have evaporated by now but anything that mass and above would still exist.
They are a dark matter candidate, and one that doesn’t require new physics. But even if they don’t account for a significant amount of dark matter they still probably exist.
The most exciting thing about PBHs is that one or more may exist in our solar system. They might have been captured over billions of years. Finding them would be incredibly challenging, especially if they are low mass, but if we did it means we could directly examine and experiment on a black hole.
It could be something with the mass of a large asteroid but the size of a hydrogen atom. We could only find it by its gravitational effects. It would be utterly invisible otherwise unless it encountered matter and even then there might only be a tiny gamma ray flash, a nano accretion disc that lasts femtoseconds. We might also find smaller objects that appear to be orbiting nothing and find it that way.
Directly accessing one could allow us to test theories of quantum gravity and things like string theory, and maybe more. A black hole could be like a Rosetta Stone of deep fundamental physics.
The film Interstellar involved using plot magic to visit a black hole and solve physics, but this would allow it for real. It would just be an itty bitty one.
- MichaelZuo 3mo agoDoes PBH theory also predict >1 billion solar mass black holes so early?
- api 3mo agoI believe it does, due to PBHs forming seeds for early accretion, but ask a non-armchair physicist (or a good LLM).
- pmontra 3mo agoOf course if we had a black hole in a lab (or one in a convenient orbit) we could run all sort of experiments, but which experiments exactly? We will start by throwing things at it and watch, obviously, but that's unimaginative. What are the smart experiments?
- typeofhuman 3mo agoI'm not sure anything after the event horizon right? Since no light == no information.
- cholmdomsky 3mo agoCan magnetic fields escape, if their lines intersect the event horizon of a black hole?
- muvlon 3mo agoNo, a classic GR black hole does not have its own magnetic field. It can have electric charge, along with mass and spin, but that's it. There is a somewhat fringe alternative idea called a MECO, which can have a magnetic field. Unlike some of the other fringe black hole alternatives, this one at least produces falsifiable predictions.
- cholmdomsky 3mo agoI suppose what I meant to have asked was, can an external magnetic field intersect with a black hole's event horizon and then escape? For instance, with these theoretical tiny black holes, what would happen if you held a powerful magnet close enough for the lines of flux to actually intersect the event horizon?
- typeofhuman 3mo agoI think not because light is also a field.
- JumpCrisscross 3mo ago
- scotty79 3mo agoMy pet theory is that supermassive black holes are older than the universe and they didn't grew much.
- tomaskafka 3mo agoWe could probably redirect budget for next gen particle accelerator to building an experimental platform orbiting the black hole, and get better results, right?
- JumpCrisscross 3mo agoI’m still convinced a muon collider is the best bang for the buck for a next-generation collider. It requires new engineering and could probe new physics.
- prairiedogg 3mo agoWhat could go wrong?
- api 3mo agoNot much. A black hole isn't a magic cosmic vacuum cleaner. It's a dense piece of mass. An asteroid mass black hole the size of a hydrogen atom would be... an object the size of a hydrogen atom with the mass of an asteroid. You could orbit it and the orbital calculations, at a reasonable distance, would be the same as orbiting an asteroid. You just can't get too close or you get into that steep gravity well and "become physics" (spaghettification etc.). It would have an insanely steep gravity well, but you'd have to get close to actually feel it. It would rarely interact with mass naturally. We could chuck stuff into it or fire lasers and particle beams at it to study it, of course, but to hit it we'd have to fire it at the right angle and velocity to negate the orbit and fall into it. Orbital mechanics still works the same way. If a black hole this size flew through the Earth at high velocity, it might not even do anything. It'd be like a bullet being fired through a puff of smoke. It might leave some kind of trail if you knew exactly what to look for and where to look, something almost analogous to the trails left by particles in a chamber. I've given this example multiple times because it illustrates the point well, I think. If you could magically transform the Moon into a black hole of the same mass, you would now have an object of that mass about the size of a BB or a small marble orbiting the Earth right where the Moon's center of mass orbited. The tides would continue as normal, since its gravitational effects on the Earth would be the same at that distance. Probes and other objects orbiting the Moon would continue to orbit it. You just wouldn't be able to see it anymore. If you focused a very good telescope on its location, though, you could probably see gravitational lensing of the star field behind it. The only risk might be if a large object actually hit it, in which case the accretion disc might temporarily emit enough X-rays and gamma rays to be harmful to Earth. Not sure though. It might not be that harmful at that distance.
- macintux 3mo agoAs is often the case (and I suspect you're already familiar with it) Randall Munroe tackled the moon->black hole question: https://what-if.xkcd.com/129/ https://what-if.xkcd.com/129/
- consensus1 3mo agoHow certain is the evaporation? Obviously Hawking radiation has never been observed, but is it tied in enough to other known physics that we can be reasonably certain it exists?
- api 3mo agoIt's a very strong consensus among physicists, but has not been observed. My understanding is it pops right out of the math. If it doesn't exist it means some new fundamental physics is in play, like quantum gravitational effects we don't understand at all right now. If it doesn't exist its also has profound implications for the long term fate of the universe, since it would mean black holes never evaporate.
- rolph 3mo agohawking radiation is a postulated mechanism for tempurature of a black hole. the whole thing started with information paradox, leading to the suggestion that a black hole would have to be associated with entropy, thus would have a temperature, but required an escape hatch to allow radiation, the thought experiment came to a thought solution when particle-antiparticle pair dissociation at the event horizon was postulated. We Knew Black Holes Have a Temperature. It Turns out They Also Have a Pressure[2021]: https://www.universetoday.com/articles/we-knew-black-holes-have-a-temperature-it-turns-out-they-also-have-a-pressure https://www.universetoday.com/articles/we-knew-black-holes-h... Black hole thermodynamics: https://en.wikipedia.org/wiki/Black_hole_thermodynamics https://en.wikipedia.org/wiki/Black_hole_thermodynamics