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Physicists identify the engine powering black hole energy beams
- wpasc 5y agoWould any knowledgeable HNers mind providing an ELI5 for this discovery?
- prichino 5y agoQuanta magazine is not a journal and is meant for general public divulgation; it is written in a very accessible style, starting from the title.
- arbitrage 5y agosome people do not speak English as their native language.
- omrjml 5y agoThere has been lost of theories to explain how jets from black hole systems form. New observations of light polarization from M87 jet show twisting magnetic field lines which suggest one of the theories might be right. That theory says that spinning black hole's energy can be extracted by these twisting magnetic field lines and therefore power these jets.
- ISL 5y agoFor many decades, people have observed jets of hot gas spewing from the centers of some galaxies. There are multiple theories as to how those jets form. Radio astronomers got together and built a synthetic telescope the size of the Earth in order to be able to take a picture of the gas near the black hole at the center of a nearby galaxy, M87. When they did, and looked at the polarization of the light, they saw twisting lines, which agreed with the prediction of one of the most-favored theories for how these jets are produced.
- FredPret 5y agoThings like the above makes me so grateful to be alive in this day and age
- hi41 5y ago>> “The black hole in M87 is about the size of our solar system,” Issaoun said, yet it produces a 5,000-light-year-long current of white-hot plasma Do both jets put together have a length of 5000 light years or does each of the two jets have a length of 5000 light years making a total lenght of 10000 light years? Can someone please clarify. I have had this question for a ling time and it is eating me up. Edit: grammar.
- omrjml 5y agoThat's just one of the jets. In fact, I think only one side is observable as it pointed close to our direction, making the other side very difficult to observe.
- wumpus 5y agoYes. The forward jet is already faint despite being enhanced because it's pointed towards us. We can't see the backward one until it's way way outside the galaxy.
- deleted 5y ago[deleted]
- vmception 5y agoHow does one get to be the "artist" in astronomy article "artist renditions"?
- kryptn 5y agoLooks like they have a position open for an Interactive Web Developer [1] but it seems like the header animation is sourced (and attributed) from a youtube video from 2018 [2] [1] https://www.quantamagazine.org/about/ https://www.quantamagazine.org/about/ [2] https://www.youtube.com/watch?v=S4a45z36EU4 https://www.youtube.com/watch?v=S4a45z36EU4
- wumpus 5y agoThat animation was made by an EHT collaboration scientist, Andrew Chael. The EHT has outsourced some animations to a firm named CrazyBridge, but only occasionally.
- mhh__ 5y agoIf you've read Brian May's (of Queen fame) PhD thesis, he is the artist of his own pretty sketches
- RosanaAnaDana 5y agoWell if its anything like biology, your first bet would be to get a degree in astrophysics. Doesn't necessarily need to be an advanced degree, but enough to know how to ask the right questions of those doing the work. Second step would be to maintain a continuous love for art/ drawing/ illustration. Third step is to get your work out there/ build a portfolio. Several colleagues of mine have ended up down the road of scientific illustration in biology. Most of them had BS in biology, botany, zoo, etc.. Also: https://work.chron.com/become-scientific-illustrator-17160.html https://work.chron.com/become-scientific-illustrator-17160.h...
- eevilspock 5y agoIf these jets are narrow, and if the radiation is directed in the same direction as these jets (That's my understanding. Am I wrong?), how do we (1) see these jets in the first place and (2) if the answer is that we only see the ones pointed at us, how do we know they are (narrow) jets since we can't observe them from other angles?
- gotstad 5y agoPerhaps reflection from other bodies? Or simply some kind of radiation emitted from the jets?
- FredPret 5y agoI’m speculating, but maybe it lights up a conveniently located dust cloud
- ISL 5y agoI believe that this is generally correct. Relativistic particles impinging upon even dilute gas will have bright signatures in many bands.
- omrjml 5y agoThe radiation is not pointed in the same direction as jets like a laser. There is bulk motion of the plasma in a given direction, but the radiation is emitted from particles that are moving in a different directions within that plasma. So the radiation spread is wider than the jet direction. Interestingly, depending on if the jet we are viewing is pointed towards us or not can impact on the radiation signature in the form of blue shift and red shift. If the orientation is just right, bits of jet appear to move faster than to the speed of light, but it's just a geometric effect.
- btilly 5y agoHow do you see the beam of a flashlight in the dark? Because it hits stuff in the air and bounces off. And the particles previously in the beam that already hit something are likely to hang around and be candidates for being hit themselves. And eventually they wind up as part of a big glowing cloud that you can see in the pictures. See https://d2r55xnwy6nx47.cloudfront.net/uploads/2021/05/cyga_v1.jpg https://d2r55xnwy6nx47.cloudfront.net/uploads/2021/05/cyga_v... linked in the picture for what it looks like. And for evidence that we can still see the beam when it isn't pointed directly at us.
- lsllc 5y agoThe spiral picture appears to actually be a "photo" of a black hole, from this article linked in the OP: https://eventhorizontelescope.org/blog/astronomers-image-magnetic-fields-edge-m87s-black-hole https://eventhorizontelescope.org/blog/astronomers-image-mag...
- wumpus 5y agoThe spiral is an overlay telling you which way the magnetic fields point.
- ineedasername 5y agoUnobtainium. Probably literally.
- arbitrage 5y agoi mean their hypothesis is pretty convincing. have you read the article?
- ineedasername 5y agoYes, and my assumption is that light-years long jets of plasma shot out both ends of a black hole will be fairly unobtainable in any practical way. At the same time, the energy levels involved would be massively useful if they could be harnessed. So, we have a potentially valuable resource that is difficult-to-impossible to obtain. Pretty much the canonical use of the term unobtainium. So my post was a bit snarky, but also likely accurate
- eloff 5y agoNoob question: if not even light can escape from a black hole, magnetism can't either, right? So these fields must be produced by matter falling into the black hole, but before it crosses the event horizon?
- nostromo 5y agoAnother noob question I've never heard explained in a way I can understand: How does gravity escape from a black hole? It, like light, travels at the speed of light. So if light cannot escape, how does gravity?
- curtainsforus 5y agoFrom the perspective of an outside observer, nothing ever reaches past the event horizon- it just asymptotically approaches it. The same goes for the whole mass of the black of hole- from an outside perspective, it's smeared across the surface. There isn't an object that messes with the warping of spacetime- the black hole IS the warp in spacetime. If changes in spacetime couldn't propagate away from the black hole, it wouldn't exist.
- simonh 5y agoI understand that from an external POV things that fall into a black hole never seem to reach the event horizon, but there must be material that is inside the event horizon. When the original star collapsed and the black hole formed, there was material inside the volume enveloped by the new event horizon. Also as more matter accumulates in the accretion disc of the black hole the event horizon will expand. With these enormous super-massive black holes, with event horizons the size of earth's orbit, there must be something inside the event horizon. Or is that wrong, and everything just smears out even more finely as the event horizon grows?
- bollu 5y agoAs best as I understand: light travels in space. Thus, if space is scrunched up, light can't escape. Gravity IS space. The scrunching up IS gravity. There is no "escaping", because gravity is literally the substrate.
- eloff 5y agoSimulation theory speculation: If the universe is a simulation, when there gets too much matter in an area to simulate all the interactions, a black hole is the way programmers fixed that - it gets turned into a singularity and isn't simulated anymore except as one point source of gravity (or in a more complex way if black holes preserve entropy - jury is still out on that one.) Silly and untestable, but fun to think about, like the rest of simulation theory. It would be required to do something like that if you're running a simulation with finite resources. You couldn't just keep piling matter into a finite area without bound, eventually you'd overwhelm what you can compute. Same reason one might want a hard speed limit like the speed of light. Interestingly this is a not a discrete function, time slows near large masses, which would allow the computer to keep up as matter in an area increased, much as you'd expect in a simulation.
- infogulch 5y agoAgree! This is my favorite crazy pet theory: spacetime is simulated on a flat 3d substrate with constant compute and memory per volume, which runs at a fixed rate in time (c) [1], and to account for a high density of mass requiring more compute the simulation is slowed down proportionally. Then, black holes are just the extreme end of this slowing down of the simulation. [1]: You always move at a constant speed: the speed of light. But that speed can be broken down into two component directions which you can trade off: time and space. You typically move near the speed of light in the time direction, meaning your speed through the space direction is comparatively low.
- shaded-enmity 5y agoMy crazy pet theory: computational bandwidth is constant for any spacetime coordinate. According to Bekenstein bound the lower the temperature of the system the cheaper it is to flip a bit of information. As time progresses the CMBR gets colder, so it's cheaper to flip a bit, but conversely, as time progresses our Hubble volume gets smaller, limiting our total available energy budget to perform a bit flip.
- goldenkey 5y ago
- hcrisp 5y agoI want to know if the jets are made up of material that is swirling towards the black hole from the accretion disk but get caught up in the magnetic helix (a) before it reaches the event horizon, or (b) after it passes the event horizon. If the former, then it's not as impressive since then nothing can escape a black hole except via Hawking radiation. If the latter, then this seems like quite a novel mechanism to prevent infinite black hole growth. The illustrations in the article don't provide an answer, though, since the details ends right where it ought to provide insight. The article does mention that the new paper puts doubt on the idea that nothing can escape a black hole, but I still didn't see any direct mention of the event horizon question.
- db48x 5y agoNothing can return after having crossed the event horizon. Gravity bends space and time, and in particular it changes which direction the time axis points. In a black hole, the time axis is bent all the way over so that it points directly at the singularity. All paths that enter the black hole must end at the singularity, because to do otherwise would require going backwards in time or faster than the speed of light.
- hcrisp 5y agoCan you then explain what the author means when she says, "a voltage that draws energy up and out of the hole and along the helix. This, they claimed, is the jet — and a big asterisk on the naive notion that nothing escapes black holes"?
- wumpus 5y agoBlack holes have spin, and this process is expected to slow the black hole spin, which takes energy out of it. It's not the only known way to slow black hole spin.
- db48x 5y agoThe statement doesn’t mean anything because it was written by a reporter and reporters generally don’t understand what they are writing about, especially in the modern era, and especially in regards to scientific concepts. The magnetic fields can accelerate matter from the accretion disk and turn it into a jet headed away from the black hole, there’s nothing wrong with that. Maybe matter can be created by photon–photon interactions in the photon ring, and that matter can be accelerated into a jet by the magnetic field. Either way, no matter has exited the black hole; the jet is made of matter that avoided entering the event horizon. Black holes have only three macroscopic quantities which are observable from the outside: mass, rotational kinetic energy, and electric charge. Since it would be pretty hard to arrange for matter of only one electric charge to fall into a black hole, the charge of the average black hole is believed to be pretty much neutral at all times. The mass of the black hole is inaccessible, because it is concentrated at the singularity. Or possibly in the firewall, if black holes have firewalls. That leaves the rotational kinetic energy as the source of the energy that powers the jets. The jets would last until the rotation of the black hole slows enough that the magnetic fields aren’t twisted enough to maintain them.
- nvader 5y agoThis reminds me of the Hairy Ball Theorem: https://en.wikipedia.org/wiki/Hairy_ball_theorem https://en.wikipedia.org/wiki/Hairy_ball_theorem
- kovek 5y agoAt the center of a black hole, is there another universe?
- Justen 5y agoWould be cool to see an estimated thrust. I would guess it isn't perfectly counteracted but wonder how much that serves to push the galaxy through space.
- deleted 5y ago[deleted]
- mikevm 5y ago"Black hole" is a racist term, it should be renamed to "Hole of Color".
- JoeAltmaier 5y agoThe author throws in "and a big asterisk on the naive notion that nothing escapes black holes." Not true. The jets are from the plasma surrounding the black hole. And we see that already, meaning photons escape it all the time. Since the jets didn't start below the event horizon, they were never "in the black hole" at all?
- bashinator 5y agoYeah that was a bit of clickbait for sure.
- z_ 5y agoAnother helix formation from Cambridge? Hrm.