Hawking radiation

20/04/2021 को प्रकाशित
Do black holes radiate? How is the "temperature" of a black hole defined? What paradoxes does Hawking radiation bring to light? All these answers in 16 minutes!
0:00 - Introduction
1:39 - Relativity of the vacuum
7:22 - Hawking radiation
11:58 - Conclusion
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Alessandro Roussel,
For more info: www.alessandroroussel.com/en
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  • A precision about what happens at 7:05 : the particles observed far away are the same as those created near the horizon. Far away, no particles are created since both observers are in free fall. But still they receive the particles created near the horizons that escape the black hole's pull

    • @Steven Jones i guess they percieve the particles to appear further away from the horizon

    • Why blackhole capture only negative virtual particles?

    • Actually the surface temperature of a black hole is related to the temperature of the Unruh effect for an observer falling into a black hole.

    • Even curvatures have a straight line. Obviously energy is changing from one form to another at different intervals. Just how it is doing this is the mystery at this stage. But not out of the ordinary

    • I'm a bit confused. If we trace the in-falling observer's world line back in time till he is very far away, isn't he still in the same frame of reference as when he will cross the event horizon? Does he detect the radiation when he's very far away from the black hole, and only begins to no longer detect them as he gets closer? That seems counter to what I understand about frames of reference. Or would he not detect them, but his buddy a few parsecs over that will merely orbit the black hole would detect them? Similarly, would objects following world lines orbiting near the black hole detect particles? Thank you for your excellent videos.

  • Or You can just consider the Infinite Effects of the Singularity as the Entanglement breaker via Divergent Probabilities of Remaining tangled XD.

  • You say large black holes radiate less than smaller ones, because gravity doesn't pull as strongly near the horizon, due to their sizes. But should the pull between objects be equal, considering the pull is defined by the objects' mass and distance?

  • When nothing, no even light can escape a BH, I fail to see how Hawking radiation can escape.

  • Here's a question for the more familiar with big bang cosmology. Does the big bang model what would happen as a mega ultra super massive black hole evaporates into nothing, and the cosmic inflation is spacetime returning to an undeformed state relative to a black hole massive enough to contain the visible universe as the energy is spread out by the rapid evaporation?

  • Great video and I have a question, what is the difference between negative and positive waves ?

  • Your animations deserve much credit, congrats

  • I assume there are multiple space time which is connected to one subject and yet to discover.

  • Hawking radiation is Unruh radiation

  • Hey your explanation is great! I was thinking that if it is possible can you please make a playlist on tensors and tensor calculas. I was not having a great time in learning tensors at my undergrad level. None other youtuber explains as you do. Please help! I am hoping a lot from you!

  • New subscriber 🥰🥰

  • Since the video bothers to credit proofreaders, they should know that there's a grammatical error at 7:00. Should be "farther," not "further," when referring to physical distances.

  • Hypothetically, virtual particles may not form inside the event horizon of a black hole

  • “Negative energy”, uhm...

  • Hi Alessandro, great presentation. However I am still a little lost about the part at around 5:50. Why is it that negative waves are the ones that are trapped in the black hole but not the positive wave? Why is it that the observer hovering above the event horizon only observes particles, but not anti-particles?

    • @ScienceClic English Good stuff. I really appreciate that you take your time to answer my questions! I look forward to your future videos

    • It's a bit difficult to represent visually in space when to really see the difference between positive and negative waves one should look at a spacetime diagram. But the idea is that the negative waves can exist inside the black hole (because in a sense the spacetime grid flows faster than the speed of light) but not outside. Beware, the negative waves are not antiparticles. Or rather, they can, but they can also be particles. It is a common misconception, Hawking radiation does emit as many antiparticles as it emits particles. The only thing it does not emit is negative energy particles (or negative energy antiparticles). Yes precisely, as it crawls out of the gravitational well, the radiation gets redshifted. But this is due to time dilation near the horizon. In the local frame of reference which is shown in the video at 5:50 this effect is not visible. The only thing we see is that for the accelerating observer, inertial waves are subject to an increasing Doppler shift.

    • And why do the wavelengths of the waves become shorter as they go away from blackhole? Shouldn’t they become “redder”? i.e. longer wavelength.

  • Can we please take moment to applaud the visual side of these videos 👏🏻 they are so smooth and poetic, they flow along in a way that is so hypnotic it embeds the ideas discussed so well.

  • Great videos, great explanations. Thank you!

  • Great channel! I "ate" all your videos in one sit. Perfect, quite intuitive and interesting visualisation, especially for those, who just like me, are not natural scientists. More content is needed! How about making new series on dark matter, dark energy, supersymmetry, string theory, theory of quantum gravitation?

  • explain the maths paradox ' Sky Scholar Black Hole Geometry Analyzed!' Jun 9, 2018, explain the maths paradox ' Sky Scholar Black Hole Escape Velocity?' May 14, 2018 explain the maths paradox 'David LaPoint The Primer Fields Part 1' Dec 18, 2012 between this lab demonstrated electromagnetic 'Primer Field' & the hypothetical maths electromagnetic Black Hole what other US NIST calculations are -intentionally?- wrong

  • I like how he uses the pronoun "she" for imaginary person

  • 12:47 Time as an imaginary number which loops back on itself. MIND = BLOWN

  • Great video! It's a bit funny that you used blue to represent low temperature and red for for high temperature, but as a designer I understand your choice xD

  • Why/how do the negative particles subtract mass from the black hole once they fall in?

  • Sir, your content is amazing and explains these concepts better than any I’ve seen. You desperately need an outro on your videos. I think your channel would be growing faster if you just had better branding. I keep forgetting what your channel is, and I think that would be helped a lot by just reminding people who you are at the end of the video. Just something simple like, “you’ve been watching SciClic. Subscribe to explore more science topics in the future.” with your logo displayed again.

    • Even though I hate "outros", I agree with you.

  • Its just awesome...cant find words to describe...crystal clear explanation of concept, mindblowing bgm, engaging baritone voice....OMG! Its freaking amazing....This video deserves an oscar for its VFX 👌👌👏👏👏

  • 한국인들 모여!!

  • I find the explanation in "the brief history of time" much more easier to understand.

  • You answered so much at 8:40! Thanks, but now I need to go figure out what you mean by the reversal of space time...

  • Starting a petition to ban the term imaginary numbers. There's nothing imaginary about them!

  • Science fiction

  • does every positive particle have a negative counterpart? and if so, does that mean every single particle in the universe was spat out of some black hole, and that it's pair is still trapped inside that black hole?

  • One thing that I never understood about this topic is how one of the virtual particle simply escapes from the black hole. Is one thing to be outside the event horizon, but wouldn't the gravitational field pull the particle back? I suppose the particle would have a LOT of energy, and then how a virtual particle gets that much energy anyways? Not only that but all the animations of virtual particles show them appering at one point and then collapsing together at another point, always in a continuos path, like they were pushed from one another at the start and them they attract each other until they collapse. So I always asked myself, how 2 particles would have this type of motion and one just "escapes" from the loop with enough energy and in the right direction to escape from the black hole. Sorry if I wasn't clear enough with my doubts, english is not my native language.

  • So far there has not been established any concrete evidence to maintain the existence of Hawkins radiation, so it must perchance remain just that a theory.

  • Man! I discovered your channel by chance and I am completely in love with it, the quality of your videos are so good that are difficult to describe. I really enjoy learning new things, or at least trying to, since these topics are a bit hard. Anyway, great work, keep it up!

  • my puzzlement comes from the fact that time dilates as gravity increases, and at the horizon its infinitely dilated. which means that from the perspective of the leaving particle, the falling in one NEVER crosses the horizon. now, yes, the infalling one does cross it from its own perspective. but as it crosses it the outside universe would seem to speed up more and more like a movie played faster and faster. so when it actually crosses, the universe is ending already, and also the outside particle would looooong before that had an interaction that would destroy the connection between them. so i guess my question is: why is this a problem if the infalling particle never really enters the black hole, but rather just stops at the horizon? the connection wouldnt have a problem continuing because both particles are technically outside the horizon and can communicate. i might need to watch it again

  • Really awesome video

  • Why is there not an equal amount of positive energy virtual particles entering the black hole to counteract the negative energy ones entering and thus eliminating the effects of Hawking radiation

  • 9:00 you explain Hawking radiation here by negative particles being captured by the BH. What I dont understand is: if all virtual particle are created in pairs, and when a negative particle is captured a small piece of the BH "vaporizes", wouldn't a positive particle add extra mass to the BH? Or is there some broken symmetry that a negative particle has a bigger chance of being captured than a positive particle?

  • If a black hole can only radiate it's horizon, that would mean that a black hole would go forever, since it would take infinite long time to shrink infinity small, like a singularity.

  • Could you possibly cover electromagnetism? I struggle to grasp the concept.

  • This channel is great but now I’ve got some sort of question and I don’t know if it’s stupid If light cannot escape a black hole’s gravitational pull then if you were pulled on by a black holes gravity would you move faster than light?

  • What incredible graphics! Einstein and Hawkins would have loved their ideas being illustrated so clearly for ordinary persons. Thanks.

  • This blew my mind

  • Im subbed to so many science channels, don't know why it took the algorithm so long to bring me to you. Glad it did though, this video explained hawking radiation better than any other channel Im subbed to

  • now this make sense.... Make videos like this suuch that normal people who have basic knowledge in physics undersrtand. thank you so much for this video.

  • hawking was overrated

  • in maths

  • They don't have hair.

  • naice

  • 👍OK. Now I finally get it. Thanks.

  • What does it mean that the notions of time and space are reversed

  • Great video as always.

  • U r the most underrated channel ever.

  • I really love how you make pauses so the listener can realize the what are you trying to explain and everything then fits together.

  • Black holes, the VPN of the universe.

  • One thing that always puzzles me about hawking radiation: Those quantum field fluctuation particles come in pairs. Why does always the particle with negative energy fall into the black hole and the other escapes? It should be that 50% with negative energy fall into the black hole and 50% of negative energy escapes and correspondingly 50% with positive energy fall into the black hole and 50% escapes. Why doesn't it happen this way? (Maybe indeed it does, because nobody has observed hawking radiation yet, maybe hawking radiation doesn't happen at all.)

  • Nice

  • fcking awesome dude !!!!! you made my day you're one of the few people who explain the beauty of the universe with equations, and I love equations

  • The entanglement hypothesis for preservation of the information is not accepted by R. Penrose. According to him the gravitation breaks any entanglement.

  • Finally the video i had been waiting for. You guys are killing it. Holographic Principle coming up. I hope

  • 12:57 alright I'M OUT, SEE YA!

  • Finally, you reached 113k, I am damn sure you will get 1 M this year or the other. Love from India.

  • 11:05 bilyensen! i thought I heard trump lol

  • 8:59 why is the negative energy particle the only one captured?

  • Hawking radiation, while sounding logical, is untested, and untestable. There isnt any proof it actually happens.

  • I don't have huge background credentials in physics, but can 8:45 not be considered a plausible cause for the disparity between anti-matter and matter? The beginning of the universe was a singularity, similar to a black hole. Also everything could really just be relative, moving forwards in time and possibly moving backwards as well.

  • Wouldn't the universe be increasingly positively charged then? is there evidence of this?

  • For every action there is an opposite reaction. There you have it a simple explanation. Just about explains everything. Jimmy's radiation Theory. LOL

  • I have learned more from this channel than I have in several year's worth of schooling. I can’t believe this is free content. Thank you so much. WORLD'S BEST CHANNEL

  • I think this channel is the best physics channel on INplans.

  • I come into these videos with the presumption that I already know and understand the concepts being explained, but *every single time* I walk away with new insights and understanding. Your videos are so thorough I'm consistently amazed. The pacing is perfect. The explanations are simple. You need 10x more subscribers.

  • Believe me it's the most underrated channel on youtube.... Just want say one word "WOW" .. never saw explaining that much deep concepts with such simplicity...

  • I've heard this explained to me before, but not as like this. I now have a much better understanding of Hawking Radiation because of how clear your videos are. Keep up the good work!

  • this is the best channel ever..

  • This is so wonderful! I've been a big fan of watching numerous physics videos and usually fall back on PBS Spacetime (which is amazing! Complex info in relatable analogies, and Matt O'Dowd is a treasure 😊). This is just as amazing, and gets into the deeper end of the pool of these incredibly complex subjects in a way I've been hungry for! New subscriber now, and gonna spend the rest of my week watching all y'all's vids and eagerly awaiting the next. :)

  • I wonder how small a black hole would need to be to perfectly bake a frozen pizza (if the pizza was somehow orbiting a black hole) 🧐

  • There's no such thing as 'negative energy'. You must be thinking of negative charge. If there was 'negative energy', we could make warp drives.

  • Hawking radiation to cause black holes to evaporate requires a deterministic process at the event horizon where only negative particles are absorbed, releasing only positive particles into space. Why would not equal number of positive and negative particles be captured by the black hole and escaping into space? Such random capture and escape would result a random fluctuation in black hole size around the size of ordinary mass falling into the black hole. The black hole would radiate positive and negative particles with no net change inside or outside the black hole. Conclusion black holes radiate positive and negative particles and do not evaporate.

  • I really love the neon look of the little particle waves. It gives the v i b e s

  • There were multiple points during this video that I had to pause as I was running up against what I thought I already understood. I’m sure I’ve heard explanations of HR that didn’t break my mind so much, meaning either they lacked something or you have put it in such approachable terms that I’ve been more able to see at which point my understanding breaks down. I’m sure it’s the latter. Awesome video! I can’t wait to check out more

  • everything is fine on this channel even timestamps exists but i am not sure who is the man in the comments we talking with , Alessandro Roussel or Octave Masson?

  • Why is the equivalence principle so crucial when it is true only locally? I mean, acceleration and gravitational field are not in general equivalent since in one of them I can measure the tidal force, but not in the other.

  • Having skimmed through most of the comments (as of 4/22), I see two issues questions raised more frequently than others. People want a more in-depth presentation of 1) how particles are split (+/-) at the horizon and 2) the reversal of space and time inside a black hole. I hope ScienceClic will provide a video to that end and clarify some of the other concepts that the questioners asked about.

  • Im a serious consumer of science based channels on youtube and your videos are certainly some of the best, I really love your explanations! This channel has so much more potential, I would seriously suggest doing collabs or something with other science channels, im sure they'll love it and it will really help you popularize your channel, and anyone would love to work with such quality as yours. I only discovered this by chance but im so glad I did. Good luck and keep up thee great videos!

  • Ow! So the temperature of the black hole, which produces the radiation, is the reason we don't know what is happening inside it?

  • Hawking radiation seems off to me. Doesn’t make sense

  • Waiting for this channel to blow up.

  • could gravity be generated by neutrons? one up and two down quark. could this difference generate an imbalance capable of generating this "force"? Thanks

  • Paradoxes abound with black holes in this way. Here's one for you. They SAY that time's arrow is not present in the laws of physics, that they're all time reversible, and the 2nd law of thermodynamics is just a statistical rule. But they're forgetting one little thing for which that is not true. I can shine a beam of light into a black hole. What is the time reversal of this? It's not a beam of light being produced via hawking radiation and a stroke of great luck. Because that light actually goes THROUGH the horizon in the original direction of time. Its time reversal would literally be someone inside a black hole shining a beam of light that gets out and is received by me. But that is not possible, now is it? There you go. Once it involves event horizons, and only then, gravity suddenly loses its time reversibility. Here's another paradox. Does someone in freefall not see the hawking radiation then? Surely that is not the case, because if I was 20 feet away from a microscopic black hole that was blasting out terawatts of nasty gamma ray radiation, I would barely feel its gravity, so surely just turning off the incredibly weak jetpack I had running to keep myself from getting pulled toward it would not stop me from detecting the massive radiation coming from it, correct? So I surmise that one in freefall still sees the hawking radiation from a black hole, that it is not correct to see it as merely being caused by the unruh effect by the acceleration you need in order to keep your distance from it. Well in that case, someone falling into the black hole, should get a closer and closer view of the hawking radiation as he gets close to the event horizon. It in a sense, is only cold for a massive black hole because it is so redshifted in the act of getting away from the black hole, but the closer I get to it, the less redshifted it is in getting out to me, and what's more, as I fall in in freefall, the more blueshifted it is by my velocity in approaching the black hole in addition to that. The conclusion I see is that the temperature of the hawking radiation will rise as I fall into the black hole, and reach the planck temperature as I reach the event horizon. Which would utterly demolish my reference frame, and make it so that indeed you would die when you hit the horizon, and there IS no "inside". So I'm inclined to agree with the "firewall" idea. In fact I wonder if it was my messages to a certain group about this around 2005 that inspired the idea for it in the first place.

    • Beware if you shine a beam of light in the blak hole, or drop an object, from the outside you will never see the beam / the object cross the horizon (due to time dilation that becomes infinite near the horizon). The time reversal of this is therefore very well defined. Actually the time reversal of a black hole is what we call a white hole.

    • Well, the 2nd one wasn't really a paradox. But it contradicts the notion that spacetime actually even exists inside the black hole.

  • I feel guilty about the fact that this channel is underrated despite providing the best stuff.

  • Apparently, this video has a 10% approval rating (2700 likes / 26349 views = 10%) I CAN'T Approve this video because I have no method of validating its statements! 349 comments

    • And you only have 0,8% dislike compared to like.

  • In my opinion, both theories of Einstein and Hawking have explained the BH rather good. By Einstein's law, every mass will pull toward the BH and will follow the momentum of BH with speed and energy (the path will not required as circle). If the Einstein's theory is only explanation for the BH, every thing should keep spinning down to center of BH infinitely as their energy must be exist at the center. In fact, there is no energy at the center and Hawking's theory once may explain this well with quantum theory.

  • As always, enlightment!

  • 5:42 "some waves never reach him" .. Why are the waves never reaching him only negative? Shouldn't same amount of positive waves never reach him as well? Therefore cancelling each other ?

    • or in the alternative explanation, why does the blackhole absorb negative particles but not the same amount of positives as well..

  • HEY Calling photons massless is debateable I take offense

  • Well this is a MUCH better explanation than I've seen others give. Maybe PBS spacetime did it right too, they seem to be accurate too. Most of the "science" videos on youtube are just plagiarized material from individuals that don't actually understand what they're quoting.

  • This must have occurred to Mr Hawking in a moment of ecstasy on Epstein island.

  • 5:00 why particles/waves of predominantly positive energy have to exist then? If the detection of particles is a side effect of moving fast in spacetime through the quantum fluctuations that spawn virtual particles of positive and negative energy equally, why then particles of mostly positive energy have to be detected in this case? 8:59 if quantum fluctuations create virtual particles of negative and positive energy equally, why then the mirrored effect when the black hole captures *+E* particle to grow and radiate *-E* to cancel out Hawking radiation doesn't cancel out the entire story? Is there some law that prevents such a thing from happening and forces black holes to swallow predominantly *-E* particles and thus radiate *+E* particles? 11:59 is it?! I thought a month ago Hawking radiation was finally detected in microscopic lab-grown black holes, and the results were published here: www.nature.com/articles/s41567-020-01076-0

  • If the Gravitational Wave Background proves stable, can we infer the nature of these sorts of functions of extreme spacetime?

  • Please make a video on covariant derivatives of a tensor.