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How do black holes swallow stars? (2021)
- NKosmatos 4y agoNice write up, with a good explanation of how stars are “eaten” by black holes but the page is full of ads.
- sandworm101 4y agoI do like the evolution of black hole illustrations. They change every few years, mostly based on depictions by hollywood, the latest being Interstellar. The current trend, the symetrical ufo-shape, is scientifically more accurate than the previous whirlpool but isnt perfect. It doesnt show the red/blue shifting. If you were actually looking at one with human eyes, you would probably see a rainbow effect. One side would be blue/white other red/black, with variations inbetween. But every attempt at such rendering just doesnt look as intimidating or magnificent. It is like dinosaurs on TV. Over the years they have gone from naked lizards, to having feathers, to being almost furry, and now back to naked again as hollywood balances science with audience expectations. This sort of thing. https://twitter.com/redshift3d/status/1156595374183854080?s=20&t=KyFvc4ShBNFLaYVLqUDC9Q https://twitter.com/redshift3d/status/1156595374183854080?s=...
- somewhereoutth 4y agoIncredibly beautiful - I wonder how (and how long) it will be that we can get better real images of black holes, the most extraordinary objects we know to exist.
- spaetzleesser 4y agoIt will be very tricky to get better images. Black holes are very small and very far away.
- Ralfp 4y agoCurrent best bet is using our sun as gravitational lens, but with current technology it would take 2-3 decades to get satellites far enough (few times further than New Horizons is currently) for that to be possible.
- sandworm101 4y agoGravitational lensing is one option, but another is the Terrascope concept whereby the Earth's atmosphere would be used as a refractive lens. In theory, any atmosphere would do. It may even be possible to use Jupiter's outer atmosphere. As refraction is stronger than gravitational lensing, such schemes would not require multi-decade trips out focal points at edges of the solar system. https://arxiv.org/abs/1908.00490 https://arxiv.org/abs/1908.00490
- deeg 4y agoCan you explain why gravitational lensing is important?
- sandworm101 4y agoIt allows for star-sized telescoped, lenses bigger than stars that can focus objects very far away.
- deleted 4y ago[deleted]
- sandworm101 4y agoThe best bet in our lifetimes will be by luck. There is a chance that gravitational lensing of a distant object might give us a glancing view of a black hole if thing line up just perfectly. But the chances of this happening, and that we actually are looking at the right place/time, are very very small.
- aardvark179 4y agoThey did do some test renders for Interstellar with better fidelity. You can see some in this article [1] or in the paper they wrote on their renderer. They were simulating film response rather than human retinal response, but it’s probably close enough. [1] https://cerncourier.com/a/building-gargantua/ https://cerncourier.com/a/building-gargantua/
- bmitc 4y agoThe idea that Interstellar "taught" us what black holes look like is way overblown and oversold. John-Pierre Luminet and others were drawing black holes back in the 1970s. https://blogs.futura-sciences.com/e-luminet/2018/03/07/45-years-black-hole-imaging-1-early-work-1972-1988/ https://blogs.futura-sciences.com/e-luminet/2018/03/07/45-ye... https://blogs.futura-sciences.com/e-luminet/2019/05/23/40-years-of-black-hole-imaging-2-colors-and-movies-1989-1993/ https://blogs.futura-sciences.com/e-luminet/2019/05/23/40-ye... https://blogs.futura-sciences.com/e-luminet/2019/06/12/40-years-of-black-hole-imaging-3-from-kerr-black-holes-to-eht/ https://blogs.futura-sciences.com/e-luminet/2019/06/12/40-ye... > The current trend, the symetrical ufo-shape, is scientifically more accurate than the previous whirlpool but isnt perfect. It doesnt show the red/blue shifting. A bit of a technicality, but the frequency shifting would only occur for rotating black holes but not non-rotating black holes. However, as far as I understand, non-rotating black holes are assumed to not exist in reality.
- sandworm101 4y agoIf we are getting an image, it is a rotating black hole. The light we see came from somewhere and didn't fall straight into the event horizon. Therefore it imparted some rotational energy as it dipped in and out. Therefore, any black hole emitting anything more than hawking radiation has at least some angular velocity.
- codethief 4y ago> Therefore, any black hole emitting anything more than hawking radiation What else does a black hole emit besides Hawking radiation? > Therefore it imparted some rotational energy as it dipped in and out. You're bringing up an interesting point. So any photon passing by a Schwarzschild black hole should actually set the BH in motion/rotation. Then again, I would expect these effects to cancel each other out, given a somewhat random distribution of incoming photons?
- JumpCrisscross 4y ago> idea that Interstellar "taught" us what black holes look like is way overblown Teachers don’t invent mathematics when they teach addition, they distribute known knowledge. Interstellar absolutely taught many people a more-accurate image of a black hole. They did not discover Doppler beaming or the accretion disk’s wrap around, sure, but I haven’t seen that claim made explicitly as much as heavily implied.
- vertnerd 4y ago"This relativistic jet was aimed directly at Earth — and astronomers were staring directly into the beam." Great. Something else to worry about. Seriously, though: are jets like these generally detectable and would we know if there are any of them making their way out from the center of our own galaxy?
- sudhirj 4y ago> Great. Something else to worry about. Anthropic principle applies here - the universe is huge and there's already tons of dangerous things pointing at Earth. The only reason we've evolved enough to notice the danger is because we have protection from it.
- ordu 4y agoWe rather had protection. Anthropic principle tell us nothing about our future. Only about our past.
- hiptobecubic 4y agoWell sure, but after many billions of years of the protection working and with no known reason to suspect that that's changed, it's not something I'm actively worried about.
- sandworm101 4y agoNope. They move at the speed of light. Our first detection of such a death start might be our oceans boiling. But the reality is that astrophysical jets come out at right angles from the rotational plane of the black hole. All the biggest black holes rotate in the same plane as their host galaxy. We are far away in the outer spiral arms, in the plane. Any dangerous jet will likely be at 90 degrees from us, missing earth by many thousands of light-years.
- AnimalMuppet 4y agoNit: Relativistic jets move at significant fractions of the speed of light, but not at the speed of light.