[HN Gopher] Bright flash is a black hole jet pointing at Earth, ... ___________________________________________________________________ Bright flash is a black hole jet pointing at Earth, astronomers say Author : wglb Score : 198 points Date : 2022-12-05 15:33 UTC (2 days ago) (HTM) web link (phys.org) (TXT) w3m dump (phys.org) | 7373737373 wrote: | How wide is this jet here? Does it cover the entire Milky Way? | moloch-hai wrote: | 8.5 billion light years away, vs. ~100,000 light years across. | To cover the whole galaxy, from a point source it would need to | spread out just 1 part in 100,000. So, probably. | | Yes, technically our galaxy is a lot bigger than 100,000 ly, | but the part somebody looking out from Andromeda could see | isn't. | mensetmanusman wrote: | How many years advance notice would we have before we knew that | such an event was our fate? To be eaten by a black hole... | cuSetanta wrote: | Typically Active Galactic Nuclei (AGN) with the jets pointed | directly at Earth are referred to as Blazars. | (https://farm9.staticflickr.com/8300/7754600044_e7635a1c8f.jp...) | | But this event seems to be something a little different. Its a | lot closer to us than a lot of blazars typically are, and the | emission seems to infer a different source than is typically | seens for blazars. | | Quite an interesting paper, will be cool to see how this might | change our understanding of AGN and accretion of matter onto such | objects. | jcims wrote: | >referred to as Blazars | | For me, legitimately one of the best names for anything ever. | First time I heard the word it gave me goosebumps lol. | mongol wrote: | How about blazer? Any reaction to that? | zikduruqe wrote: | I'm partial to Thagomizer. | | https://en.wikipedia.org/wiki/Thagomizer | unsupp0rted wrote: | > The term thagomizer was coined by Gary Larson in jest. In | a 1982 The Far Side comic, a group of cavemen are taught by | a caveman lecturer that the spikes on a stegosaur's tail | were named "after the late Thag Simmons". | mattkevan wrote: | My 5 year old surprised me when she pointed to the spikes | on a dinosaur tail and said 'that's the thagomizer'. I | knew about the cartoon and that it'd been adopted as the | official term, but somehow wasn't expecting it to be | taught in primary schools as standard dino anatomy. | LegitShady wrote: | thagomizer is a lot more fun to say than something | technical like "distal tail bone spikes" or something | similar. | maxnoe wrote: | The name comes from BL Lacertae (the prototypical object) and | Quasar (A kind of Active Galactic Nucleus, that name is for | quasi stellar, which it really isn't...) | russellbeattie wrote: | So you could say they're... Star Blazars? | | _" We're off to outer space... We're leaving mother Earth... | To save, the human race! Our Star Blazers!"_ | | (OK, so the spelling is off. But since I'm going to be humming | this the rest of the day, might as well see if there's some 80s | kids out there that will join in with me.) | nathcd wrote: | paper: https://arxiv.org/pdf/2211.16537.pdf | gammarator wrote: | Here's the paper by the discovery team: | https://arxiv.org/abs/2211.16530 | subsubzero wrote: | Wonder if this burst could have been seen with the naked eye? | They mentioned it was visible on multiple spectrums. | wumms wrote: | > 8.5 billion lights years away--more than halfway across the | universe | | Why is it halfway across? The universe's diameter is 93 billion | ly. Shouldn't 8.5 billion be more like "ten percent across"? | yayr wrote: | universe is a relative word, and typically treats us at being | at the center (which in the whole of reality is somewhat | unlikely). So it only describes that part of reality observable | by us. 8,5 bn ly refers to roughly half distance to all of the | observable events in that observable reality at the time these | events occured. Since 3D space presumably expands, it would now | take much more time for any event in our observable "universe" | to reach from one end of the observation limit to the other... | | by the way - if you want to go down further that rabbit hole a | good place to start is to search for "levels of multiverse" | anotheraccount9 wrote: | (I'm not an astrophysicist). They possibly are referring to the | initial age of the universe times the speed of light (13.8 | billion light-years), as if it was static. | | Like you infer, "[...] stuff is everywhere, light goes at c, | stars and galaxies move, and the Universe is expanding." | | https://www.forbes.com/sites/startswithabang/2018/02/23/if-t... | nicksrose7224 wrote: | I think it's more likely they got it wrong and are referring | to what they assume the size of the universe is. It's hard to | grasp why the observable universe is 92 billion ly in | diameter | denton-scratch wrote: | > Typically, such bright flashes in the sky are gamma-ray bursts | --extreme jets of X-ray emissions that spew from the collapse of | massive stars. | | Is that right? Surely gamma ray bursts are gamma rays, not | X-rays. At least, shouldn't it say "extreme bursts of X-rays _and | gamma rays_ [...] "? | monocasa wrote: | GRBs start, as their name suggest, as a burst of gamma rays, | but have long tails of emiting of x-rays and other lower energy | photons that we're more likely to notice. | anigbrowl wrote: | > From a rough calculation, the flash appeared to give off more | light than 1,000 trillion suns | | Not a single astronomical photgraph | BlueTemplar wrote: | Overexposure issues... | freddealmeida wrote: | * blackholes are not confirmed science. It is theory and little | evidence supports the theory. * Math is not reality, it is a | description of reality that should require evidence * this could | be many other things including plasma | cthalupa wrote: | Little evidence? We've got pictures of them a this point, | friend. While we are not entirely sure on all of the specifics, | and some things, such as the singularity, are likely a bit | different than our current theories suggest, there's mountains | of evidence that support the existence of black holes, or at | the very least, something that is very very very very very very | very similar to them on the macro level. | wigster wrote: | it's the focused beam of tortured souls escaping the event | horizon that worries me. | ordu wrote: | Why do you think they were tortured? Maybe they were ejected | for heavy drinking while waiting in a queue to a paradise. We | do not know what is inside of a black hole, but funny ways of | matter around a black hole seems like a result of drunkinness. | How one can miss black hole while falling into it? Try to miss | Earth while falling on it. No amount of gin seem to be enough. | But they somehow managed to miss a black hole which is much | heavier than Earth. They used a tremendous amount of gin to get | into the right state of a mind. No wonder they were stripped of | their right to a paradise and ejected from a queue. | amelius wrote: | What is the probability of something so far away pointing | straight towards Earth? What is the angle in which this | phenomenon spreads out into space? | moloch-hai wrote: | The big untouched mystery is how these things collimate the beam | so exactly. | | In order for all the mass to end up going in exactly one | direction, so focused, something would have to get them started | off that way. Any sort of thermal phenomenon would need a | parabolic reflector/nozzle. | | Currently favored is some sort of electromagnetic process that | works like a particle accelerator, applying a linear electric | field to highly-ionized nuclei over thousands or millions of km. | | The "geysers" coming out of Enceladus would likewise need | parabolic nozzles to stay collimated, so must be similarly | electromagnetic. Unfortunately the notion was first promoted by | reviled "electric universe" enthusiasts, so astrophysicists need | to file the serial numbers off before they can acknowledge it. | beedeebeedee wrote: | Is this going to annihilate us? I didn't see them mention any | safety risks, but it sounds similar to a quasar to me (a non- | astronomer), and I think if one of those is pointing at us, we're | toast. If they just detected the light, and the matter is going | 99.9% of the speed of light, does that mean we're toast tomorrow? | Next week? Next year? | evan_ wrote: | If it is going to, would you even want to know? | Gh0stRAT wrote: | Well it seems like we've detected 3 other jets pointed straight | at us as the black hole devoured a star so it seems like a very | common event on a geological time scale. The fact that we | managed to evolve and are still here is a decent sign. | | >The team says the black hole's jet may be pointing directly | toward Earth, making the signal appear brighter than if the jet | were pointing in any other direction. The effect is "Doppler | boosting" and is similar to the amped-up sound of a passing | siren. | | >AT 2022cmc is the fourth Doppler-boosted TDE ever detected and | the first such event that has been observed since 2011. | | Also, I believe that as the universe's volume expands, the | probability and intensity of being in the direct path of any | particular such jet goes down. Then again, the frequency of | these events may (or may not) be increasing at a rate that more | than counteracts that. (I'm just speculating here, I'm not a | cosmologist!) | dotnet00 wrote: | Most of the threat from relativistic jets is from within ones | own galaxy (and at worst, its local group). So, yes as the | universe expands the risk from the latter should decrease, | the risk from the former wouldn't really change due to | expansion. The risk probably does still come down, but more | due to age as larger clouds of gas get used up and spread | around by supernovae, preventing enough mass from gathering | for the things that produce relativistic jets. | | One possible answer to the Fermi paradox is that we're early | because the universe may have only recently gotten calm | enough for life to survive long enough to develop | intelligence. | peeters wrote: | As far as I understand it, gravitational lensing would affect | the trajectory of particles travelling different speeds | differently. So it would seem entirely possible that the matter | wouldn't even be pointed at us. That assumes that either is | being significantly affected by gravity of course. | | Also bear in mind that though the light of 1000 trillion suns | has been pointed at us, it's not like we have a second sun in | the sky right now. It's really, really far away. | czbond wrote: | I'd believe the small percent of a percent of the sky we're in | for it to be pointing at us is still a large swath of trillons | of miles. | | And 850k years from now - our galaxy would have moved from it's | location anyways. Some other galaxy will probably waltz into | it. | snarf21 wrote: | Very interesting. Does this imply (assuming these jets have | been occurring for a _very very_ long time) that we 'd be | able to see the consequences of _other_ jets in other | galaxies /planets? Said another way, have we ever observed | something that could actually have been "... some other | galaxy waltzing into it"? | Gh0stRAT wrote: | One of Earth's past mass extinction events is hypothesized | to have maybe been caused by a gamma ray burst[0]. I don't | know enough to speculate whether it could have been caused | by one of these jets instead. | | [0] https://en.wikipedia.org/wiki/Late_Ordovician_mass_exti | nctio... | adgjlsfhk1 wrote: | It's 8 billion light years away. We'll be fine. | [deleted] | 317070 wrote: | If the matter is trailing at 99.99% the speed of light as | reported, it gives us 800k years. | cthalupa wrote: | The matter was traveling at 99.99% the speed of light in | the jet. While we generally consider space to be a | friction-less vacuum for something like a spaceship, that | isn't true for things like a stream of particles traveling | across the universe. Even if the Earth stood still in this | exact position for another 800,000 years (which it won't, | since our galaxy is not stationary, nor is the solar | system, and there is of course the expansion of space as | well), very little of the physical matter from this jet | would hit us. | zdyn5 wrote: | Wouldn't it give us way more than that? If it were | traveling at 100% the speed of light it would take 8 | billion years right? | sp332 wrote: | The light has _already_ taken 8 billion years to get | here. The particles have also been traveling for that | time and are only 800,000 years away now. | insanitybit wrote: | For now! | ck2 wrote: | Hmm. If an alien race a million years older than humans | eventually figured out how to make synthetic wormholes on demand | for FTL when no other method existed, can we theorize what the | endpoint might look like? | | (this is a "fun" but not kidding question) | dotnet00 wrote: | One idea is that they'd be one-directional, with a black hole | on one end and a white hole on the other end. But considering | that we haven't really seen any evidence of white holes | existing, such a thing probably isn't possible. | | Other than that, a simple traversable wormhole entrance/exit | would just look like a sphere where you see the other side sort | of 'mapped' onto the surface. | ck2 wrote: | Oh wow, were the Hollywood versions in Contact and | Interstellar vaguely based on that science? | | Will have to watch them again this weekend and double-check. | dotnet00 wrote: | I wouldn't necessarily say they're based on science since I | don't really think there's enough concrete science on | wormholes to say what they would look like precisely | (although Interstellar did put some effort into visual | accuracy: https://cerncourier.com/a/building-gargantua/). | | My reasoning is that just like a circle is formed on a 2d | surface when 'bridging' two parts of it (the pencil through | folded paper analogy), a bridge on a 3d surface should have | a sphere as the hole (or maybe since it's technically a | space-time bridge, it should be a hypersphere, which would | still appear as a sphere to us 3d observers). Then, to not | tear apart anything going through, it'd need to conserve | 'symmetry' (so something that goes in comes out unchanged), | so the light would go through unchanged, making it just | appear like the view of the other side is mapped to the | surface. | theGnuMe wrote: | Imagine this is the end of a wormhole and it fries any planet | at the exit. | hiccuphippo wrote: | The Vogons did tell us about the hyperspace expressway in | advance but did we listen? | ionwake wrote: | (I can give you a "short" but not short answer to this) | waltbosz wrote: | https://en.wikipedia.org/wiki/Old-fashioned_(short_story) | | An Asimov story about stranded astro-miners who throw rocks into | a black hole to generate x-rays with the hopes that they will be | spotted by observers back on Earth. The throws are timed to spell | out S-O-S. | Mistletoe wrote: | Sorry for a stupid question but I've seen it repeated on the | internet many times that we can never observe anything actually | falling into a black hole because it takes forever to actually | fall in due to time lengthening the closer it gets. Is that | true? It has never made sense to me, since we see effects of | black holes all the time. | lisper wrote: | > Is that true? | | Probably. We don't know for sure because quantum effects | might change things, and we don't yet have a theory of | quantum gravity. The event horizon of a black hole is pretty | much the one place in the universe where the effects of | quantum gravity are most likely to manifest themselves, so | one should hedge one's bets when making predictions in their | vicinity. | | > It has never made sense to me, since we see effects of | black holes all the time. | | Falling into a black hole is different from falling into a | regular gravitational field. All kinds of weird shit happens | before you reach the event horizon. Among other things, tidal | forces rip you apart, heat you up, and turn you into a | plasma. That plasma emits radiation, and that is what you see | (because all that happens outside the event horizon). | bmitc wrote: | It all depends on the size of the black hole. HUGE black | holes have weak tidal forces. | lisper wrote: | True, but the hole under discussion here is not one of | those. (And it's important to note that big holes have | weak tidal forces _at the event horizon_. They still | probably have pretty significant tides close to the | singularity, but God only knows what actually goes on in | there). | waltbosz wrote: | https://en.wikipedia.org/wiki/Spaghettification | | I think spaghettification is my favorite word, maybe it's | tied with defenestrate. | BurningFrog wrote: | So an observer near the black hole would see an eternally | accumulating number of objects falling towards it, but | crawling to a halt near the event horizon? | cthalupa wrote: | It depends on the sensitivity of the instruments. For human | eyes looking out the window of a spaceship, they would be | redshifted away to invisibility pretty quickly. | MattPalmer1086 wrote: | And the light getting increasingly red shifted until you | can't really see it anymore. | BurningFrog wrote: | I see. Another way to think of "redshift" is "lower | energy", so these things will disappear from sight | another way. | cthalupa wrote: | You'll never directly see them fall in, but you will see them | "disappear" pretty quickly as the light is redshifted past | the point of visibility, etc. | | The more sensitive whatever tool you are using to detect the | photons is, the longer you can watch, and something that | approaches infinite sensitivity would be able to see you for | a time period that also approaches infinity, but outside of | the realm of the theoretical, anything falling in to the | black hole will wink out of existence in a fairly large hurry | once it reaches the event horizon. | | But things like accretion disks and these relativistic jets | are happening outside of the event horizon, so they're not | subject to these same concerns to begin with. For example, | the accretion disk of Sagittarius A*, the supermassive black | hole at the center of our galaxy, has an accretion disk that | is roughly 1/100th of a light year, or about 25 times the | size of our solar system. The event horizon, however, is only | about 16 million miles - or a roughly 1/6th the distance | between the sun and the earth. (These numbers are based on | our current best estimates - and those estimates have changed | frequently over the past 20 years as we get better data, but | the general scale should be quite accurate) | szundi wrote: | AFAIK you never see it falling in as it just slows and | turns into more red, but slowly. | dotancohen wrote: | The object falling in has its time dilated to forever - it | will never actually experience the "getting there". Outside | observers, on the other hand, will observe the "getting | there" just as if the black hole were any other large mass. | | Or do I have that backwards... | WrtCdEvrydy wrote: | Yes, the outside observers can see the item falling into | the blackhole while the object experiences more and more | time dilation. | | If you were falling into a wormhole, you would die of old | age before getting there while outside observers would see | you fall in quickly. | OkayPhysicist wrote: | Like the comment you were responding to, you have that | backward. | alonmower wrote: | You would be ripped apart instantaneously while everyone | outside of the black hole would see the light you emit as | you're crossing the event horizon frozen in time. It's an | optical effect, nothing magical is happening to you as | you fall into the enormous mass | OkayPhysicist wrote: | You have that backwards. The person falling into the black | hole falls straight towards the singularity as if it was | any other massive object, straight through the event | horizon without noticing anything change. | | The far away observer sees the falling one infinitesimally | approach the event horizon, but never cross. | dylan604 wrote: | >The person falling into the black hole falls straight | towards | | I guess you're assuming zero velocity by that person. But | if there is velocity, wouldn't the fall not be straight | towards but in an ever shrinking/decaying orbit | trajectory? | he0001 wrote: | This "never cross" statement bends my mind. Doesn't it | also mean that if we are observers, observing a black | hole, we should not see an actual blackness as we should | only see things that are slowly falling into the hole? | Regardless of how much time that has been spent from the | beginning of time? I mean the event horizon is the | boundary but that never happen? | cthalupa wrote: | The light is increasingly redshifted, so for practical | purposes it disappears from view quite quickly. | | The more sensitive the instrument, the longer you can | observe, and this doesn't really have a limit - as | sensitivity approaches infinity, so does the length of | time you could continue to observe the object. | | But for practical purposes, we would not see a black hole | as some sort of weird psuedo-magnet with all sorts of | junk stuck to the edge of the event horizon. | OkayPhysicist wrote: | Because of time dilation, light emitted (or reflected off | of) objects very near the event horizon end up getting | spaced out over (almost infinite) amounts of time. | | For example, lets say you dropped a beacon that flashes | every second into a black hole. As it approached the | event horizon, you'd see the flashes only happen every 2 | seconds, 4 seconds, minute, hour, decade, etc. Meanwhile, | the length of those flashes are getting longer at the | same rate, while producing the same number of photons, so | the light gets dimmer and dimmer. | he0001 wrote: | Another factor, that other things are falling into the | whole, wouldn't that mean that the event horizon, | relatively, gets closer to an earlier object? Meaning an | object may reach the event horizon faster than it would | originally or is that constant relatively where the | object exist in its descend? | birdiesanders wrote: | Backwards | cryptonector wrote: | It is and it isn't true. Light from the falling object will | be red-shifted, and eventually you won't be able to see it, | but if you could see extremely long wave-length light, and if | you could observe it for a _really_ long time, you 'd see | light from that object asymptotically approach the universe's | size as its wavelength, and you'd never see the object go | over. But obviously it's not possible for humans to observe | extremely long wavelength light, so you'd just see the object | disappear when light from it red-shifts beyond the range you | can observe. | | The object, meanwhile, does fall in from its perspective. | rirze wrote: | There's a difference between objects falling into the black | hole versus material accreting on the black hole's horizon | that can generate high energy beams. | plonk wrote: | https://math.ucr.edu/home/baez/physics/Relativity/BlackHoles. | .. | | > So if you, watching from a safe distance, attempt to | witness my fall into the hole, you'll see me fall more and | more slowly as the light delay increases. You'll never see me | actually get to the event horizon. My watch, to you, will | tick more and more slowly, but will never reach the time that | I see as I fall into the black hole. Notice that this is | really an optical effect caused by the paths of the light | rays. | | > This is also true for the dying star itself. If you attempt | to witness the black hole's formation, you'll see the star | collapse more and more slowly, never precisely reaching the | Schwarzschild radius. | | I don't understand everything but it seems that the falling | guy tends towards the event horizon, getting slower and | slower relative to the observer, and never reaching it from | the observer's point of view? | | Edit: this applies when observing something falling into the | black hole. It doesn't apply to faraway objects that deviate | because of the black hole's gravity well, so we can observe | most of a black hole's effects. | Mistletoe wrote: | Yes they say this but how do we see the jet in the original | linked article haha? | wholinator2 wrote: | The types of highly visible bright lights coming from | black holes are not actually coming from inside the black | hole. The gravitational potential of the well is so | incredibly high that objects falling through it gain | immense amounts of energy, thus giving of very high | energy radiation, i.e. x-rays. | nine_k wrote: | Think about the tidal forces that a piece of matter is | experiencing near a black hole, but still far away from | the even horizon. They deform the matter very violently, | hearing it so much that its normal heat radiation goes to | the X-ray wavelengths. | Mistletoe wrote: | Ah I see. Thank you everyone that responded! | plonk wrote: | No source now, but I think I've read that the jet is | matter that's far enough from the black hole to escape | it, accelerated during its rotation. | | The wiki page isn't very clear about how the jet is | created: | https://en.wikipedia.org/wiki/Tidal_disruption_event | dcminter wrote: | As I understand it (based entirely on pop sci books and | articles) they're purely from the accretion disk i.e. | nothing inside the event horizon. I don't think the exact | mechanism is agreed upon beyond that. | [deleted] | rssoconnor wrote: | FWIW, I asked my physicist friend this question one time. He | said while an outside observer would never see a "massless | test particle" enter the event horizon due to time dilation | effects, real particles have mass and their own gravitational | field, and thus due to complicated stuff they can eventually | been seen passing through or otherwise somehow merging with | the event horizon. | ars wrote: | You are correct, and it means black holes can never actually | form, because it would take an infinite amount of time for | them to form. | | > since we see effects of black holes all the time. | | We do not, we see super massive objects, or black holes in | progress, but no actual black holes. | at_a_remove wrote: | Once a black hole -- a collapsar -- forms, and you want to | toss something into it, it is best to imagine _two_ | timelines. | | From the point of view of the object being hurled into the | black hole, things proceed more or less normally: you | accelerate as you fall, but light behind you becomes | curiously more blue and brighter. You eventually reach the | event horizon, which ought to be called EH-sub-0, because it | is only the _first_ event horizon. It might be helpful to | think of a black hole 's interior as infinitely layered event | horizons, event horizons "all the way down." You'd note a | restriction of movement -- "up" (away from the black hole) is | no longer a possibility; every direction is some variation of | down, perhaps down and to the left, down and east, whatever, | but always _down_. Eventually tidal forces take over | depending on the size of the thing -- you might notice them | before or after the outmost event horizon, and | "spaghettification" occurs even as you are pummeled with | X-rays and gamma radiation from behind (millennia of | impacting photons blueshifted and jammed into a smaller | timeline). | | From the outside, however, your astronaut or thrown Cylume | lightstick becomes more and more red, and dim, slowly | approaching that event horizon but you'll never see it get | there as it now emits infrared and not much of that. You | switch on your FLIR and you can see it, for a while, but it | grows dimmer and eventually disappears off of that. | Eventually it emits very weak radio waves, and you lose track | of the thing, but even if you spent a million years building | longer and longer antennae, you'd never see it hit. | | The effects you see of a black hole are 1) gravitational | lensing (photons bending in their trajectory around the | exterior of a black hole, just above the outermost event | horizon), 2) the formation of an accretion disc (as matter | swirls into it, growing hot from friction and compression), | 3) absolute blackness if you managed to get a "transit" of | something particularly large across a light path, 4) other | knock-on gravitational effects, like disturbed orbits. | bmitc wrote: | The visible effects we see for black holes are things from | well outside the event horizon, where black holes behave as | just another gravitational object. Things, i.e. gas, can | rotate and swirl around them. Since the black hole can be | rotating and the gas being slung around violently, it can | emit radiation. If I understand correctly, the jets for | supermassive black holes can extend out to sizes comparative | to the containing galaxy's diameter. | | Here's a nice simulation showing this in action (article in | description): https://youtu.be/g1aW8TDOm4A | | The YouTube channel Kurzgesagt also has some pretty good | illustrations and animations. | monocasa wrote: | The effects aren't limited to just falling in. Once you pass | the event horizon it's game over, but remarkably little | matter from, say a star falling in, will actually reach the | event horizon. For one example, a lot of particles get swept | up in the magnetic maelstrom surrounding spinning black holes | and are shot away from the poles at near the speed of light. | That's what we're seeing here. | freddealmeida wrote: | maybe? could be? possibly? Highly doubtful and impossible to | verify | habibur wrote: | > 8.5 billion lights years away--more than halfway across the | universe | | That was the first number I was looking for. | | Not a threat to earth. It's not even in our galaxy. | JoeAltmaier wrote: | I don't know, its pretty bright. Maybe this periodic flash-fry | is what created life on earth! | geeky4qwerty wrote: | "From a rough calculation, the flash appeared to give off more | light than 1,000 trillion suns." | | Can any space geeks chime in on this one? | | Does this mean the emission of light from the sun at a single | point in time x 10^15? My brain pretty much divides by zero even | trying to comprehend such a large number and I'm just trying to | grasp the relationship of the emitted light to our sun. | dylan604 wrote: | > My brain pretty much divides by zero even trying to | comprehend such a large number | | I've tried using this line in the wrong company that wasn't | math oriented, and it fell flat. | | It's also amusing your use of this phrase, as in a lot of the | astronomy circles I've seen/read, there's a joke that black | holes are where god divided by zero. So it felt very apropos to | me in this context too. | londons_explore wrote: | That would be assuming the same amount of light was emitted in | all directions. But we have no indication that that was the | case. | jvanderbot wrote: | I roughly translate this to 10^15 x more photons per square | meter of surface area at some standard distance. | yourapostasy wrote: | Whoah, this goes way beyond Sarah Connor: "Anybody not wearing | two million sunblock is gonna have a real bad day". | cuSetanta wrote: | As others have said, its not quite the same as the Sun's | output, but it is still an incredible amount of light. | | I have studied blazars fairly extensively in the past and you | are right that the brain cant really fathom the 'real world' | appearance of these things. I resort to just thinking in terms | of number of photons and avoid thinking about the rest, as it | tends to result in a lot of existential dread and drinking. | swamp40 wrote: | > jet speed is 99.99% the speed of light | | Does that mean a wave of particles is coming at us right behind | the light flash? | cthalupa wrote: | No. The light from these jets travels many many magnitudes | farther than the actual material. You wouldn't want to be | within a few million light years of it but these particles have | mass and will be slowed by all of the matter they interact with | in space. The vacuum of space still has roughly an atom per | cubic centimeter, which really adds up over the distances we're | talking about here. | | Edit: Left out a fairly important word. few million light | years* | Renevith wrote: | That was my first thought too. But even at that speed, we have | quite a bit of time. Since the particles are 0.01% slower than | the light that just reached us, the particles would arrive in: | 8,500,000,000 light years away * 0.01% speed of light = 850,000 | years. Humanity will be unrecognizable by that point. | grayfaced wrote: | Wouldn't the galatic rotation mean the earth will be | somewhere far away when the jet travels that far? | suzzer99 wrote: | Yes, that and both galaxies careening through space on | different trajectories. | garblegarble wrote: | That got me wondering how far we'd move - if my maths is | correct then in 850,000 years time our solar system will | have travelled 652 light years around the galactic core | (230 km/sec * 850,000 years)! | d0mine wrote: | How wide is the beam? (given how far it started) Light- | years? | | Is it still dangerous at this point? (If its energy is | spread over a giant area radius billions light-years) | [deleted] | mynegation wrote: | On the flip side that also means that we might flow into a | burst travelling through space without any warning (?) | JW_00000 wrote: | When doing such a calculation, would you need to take into | account the fact that space is expanding while the particles | are traveling? (And will have expanded a bit more in the time | it takes for the particles to reach us than in the time it | took for the light to reach us.) | swamp40 wrote: | A couple more 9's changes that drastically though. Maybe | someone just truncated at 2 decimal places? | [deleted] | 22SAS wrote: | If it is 8.5 billion light years away and was traveling at | the speed of light (100% instead of 99.99%) wouldn't it take | 8.5 billion light years? Wonder how you got to the 850K years | figure. | Victerius wrote: | By his logic, an object moving at 0% of the speed of light | would arrive instantly. | alanbernstein wrote: | An object moving 0% _slower_ than the speed of light | would arrive instantly _after the light arrives_ , yes. | monocasa wrote: | They're saying the difference between the time the light | gets here and the particles 'only' going 99.9% of C is 850K | years back of the napkin. | umvi wrote: | > wouldn't it take 8.5 billion [years]? | | Yes, if you are assuming the jet was emitted right now. But | the jet was emitted roughly 8.5 billion years ago. The | light in front of the jet has already reached us. If the | jet were also travelling at the speed of light we'd be dead | right now. But luckily it's travelling slower than light so | that's why we have 850k more years before the jet reaches | us. | 22SAS wrote: | > If the jet were also travelling at the speed of light | we'd be dead right now | | Does that mean, once the jet reaches us 850K years from | now, we can say that will be a mass extinction event, or | even the end of life on Earth? Compared to a billion | years from now when the Sun's luminosity increases. | cthalupa wrote: | No. The matter in these jets isn't like a spaceship where | the matter is all connected together. It's largely | individual plasma particles - over billions of light | years they'll run into other particles, be deflected, | slow down, etc. There IS friction in space. | | Matter decay will have significant impact on the mass of | matter ejected by the jet, as well, particularly over | billions of years. As it decays into a lower energy | state, mass will be turned into photons, and less and | less of it will be left to impact. | | Plus, we won't be in the same spot in 850k years anyway. | The solar system is moving around the galaxy, and the | galaxy is moving around the universe, and space in the | universe is expanding. | 22SAS wrote: | Interesting, thank you very much. | darawk wrote: | Would we actually? If so, doesn't this imply that the | probability of earth just having been destroyed by one of | these things was roughly a coin flip, and therefore gives | us a (much higher) rough estimate of how likely such an | event might be? | twawaaay wrote: | Not necessarily. Particles will all be charged plasma and it is | possible that those will be deflected by magnetic fields. But I | am not astrophysicist so you would want to check on it. | | Also, in contrast with the flash where all light has the same | speed, the particles will have different speed so it will all | be smeared in time (read -- much smaller in amplitude and hard | to detect) and arriving much later than the flash. | | Then from the point of view of observer on Earth surface, | charged particles will not be coming exactly from the source | but at a bit of an angle (due to magnetic fields present). | Again, I have no knowledge about the magnitude of the effect | and I also suspect that the people who know this shit have some | way to account for it... | baobabKoodaa wrote: | When they say "pointing straight toward Earth", is that | hyperbole? Or are they actually saying that by pure random | chance, out of all the possible directions this thing could have | taken, it just happens to be pointed directly at earth? | PKop wrote: | But there are a lot of black holes yes? Surely some of them | will point towards us. | Cpoll wrote: | Depends on the width of the beam. If it's as wide as a laser | pointer, the odds of it hitting anything are infinitesimal. | When something's a light year away, changing the bearing of | the laser by a degree will cause you to miss it by hundreds | of thousands of kilometers. Or to rephrase, to hit something | a light year away you'll have to get the heading accurate to | many decimal points. (Exercise left to the reader, it's high | school trigonometry, but I'm rather lazy). | PKop wrote: | It's also a statistical question that involves how many | black holes there are. Do you have a strong sense of that | number, because I sure don't? | | Quick search says there are a very large amount of black | holes but maybe not so many super-massive that produce | these beams of light so eh, who knows. | cogwheel wrote: | The beam is surely wider than the planet so there's a large | range of "straight toward" | dan_mctree wrote: | It should be at least broad enough to compensate for some | movement of the earth, considering it was observed for at | least some days | cuSetanta wrote: | Yeah this is pretty much the case. | | The important thing is that the light from the beam is | sufficicently bright that it is not possible to resolve the | surrounding region of space to see more detail. | baobabKoodaa wrote: | If I point a flashlight directly at you, that's different | from me pointing the flashlight at the person standing next | to you. Even though in both cases the beam will light you up. | dotnet00 wrote: | But that becomes effectively the same thing if the | flashlight is being pointed in your direction from 10km | away and it's reasonable to just describe it as pointing at | you. Coming from 8 billion ly away, the beam is probably | wide enough that it would appear to be pointed at the Milky | Way in general. | bombcar wrote: | It's 8 billion light years away, even if the beam was _very_ | focused by the time it reached us it is probably tens of | thousands of lightyears wide. | ricardo81 wrote: | I suppose the metric expansion of space over this scale would | also diffuse the light | bombcar wrote: | I tried to find a calculator (you can find ones for "laser | over meters") that would support supernovas over lightyears | and came up short. | umarniz wrote: | Want to point out how incredibly good the website phys.org is. | | I was first introduced to it over 15 years ago and remember | visiting it using dial-up internet from Pakistan as a teenager to | learn about the latest developments in physics. | | Gem of a resource that is still going strong. | ourmandave wrote: | Kurzgesagt just did a vid on black holes and how close they have | to be before we're f'd. | | _The Most Extreme Explosion in the Universe_ | | https://www.youtube.com/watch?v=q4DF3j4saCE | jschveibinz wrote: | "Pointing directly toward earth" ...hmmm. In what possible frame | of reference could anything be pointed directly toward earth for | longer than a moment in space and time? We are traveling through | space and time in multiple frames of reference at a tremendous | rate. This confuses me. | ddevault wrote: | We are incredibly far away from objects like this, so the | apparent movement is negligible. | peheje wrote: | haven't you got this backwards? the further the distance the | smaller movement an object would need to not be in the | trajectory? | winReInstall wrote: | If you could controll the direction of a black hole, you could | use it to "disinfect" the neighbourhood or send messages. | Victerius wrote: | It's 8.5 billion light years away. It would be like aiming a | water hose at Mars from low Earth orbit. | backtoyoujim wrote: | so given this tool we would either murder or flirt | | can there be anything so human ? | pigtailgirl wrote: | https://telescope.live/sites/default/files/styles/photo_w102... | | very bright ^^ | | https://telescope.live/blog/transient-flash-identified-dista... | dustingetz wrote: | ChatGPT has made contact ___________________________________________________________________ (page generated 2022-12-07 23:00 UTC)