The more I watch Sabine the more I learn.

@bobhoven3959

3 жыл бұрын

Nice that I can vissit your older u tube movie,s thanks I will use it as back up learning 🎯👍💖

@Mikey-mike

3 жыл бұрын

That is the best compliment one can pay a teacher.

One of those very rare Sabine videos where I can say "I knew that."

@nosuchthing8

3 жыл бұрын

That's why she made it perhaps..To let us join in

What happens at the horizon, stays at the horizon...

@will2see

4 жыл бұрын

That's why from our point of view nothing happens at the event horizon because it hasn't happened yet, but it will inevitably happen in the infinite future.

@devilyn76

3 жыл бұрын

Because of time dilation. Time slows as you approach the Event Horizon. And it slows more the closer you are. Technically, if black holes didn’t evaporate, you can never reach the black hole itself. From an outside view, you would fall forever. However, from your point of view, you would watch the universe age faster and faster. To you, you would reach the event horizon fairly quickly. But, you would see the entire life of the universe and see it die before you reached it...

@will2see

3 жыл бұрын

When you fall into a black hole (you are about to cross the event horizon) you see and experience things very differently than when somone observes you falling into the black hole. But don't worry about it too much...

@user-hr8pz6lh5w

3 жыл бұрын

Except for implicit randomness.

@Rancid-Jane

3 жыл бұрын

@@devilyn76 "But, you would see the entire life of the universe and see it die before you reached it..." Not quite as fun as being at The Restaurant at The End of The Universe, but still incredibly interesting.

Apologies Dr S. In my enthusiasm to ask this question I forgot to congratulate you on this video. The content of course is spot on and as I've said before, the presentation style is clean and does not overpower the message. More please.

Hi Sabine, I am an internal medicine physician who cares for the elderly. I really enjoy your vignettes on physics! Thanks for making such an abstruse topic accessible to the lay public.

@JiveDadson

2 жыл бұрын

I am the elderly, and I enjoy them too.

your videos are great, I really appreciated especially your explanation on what it means for black holes to lose information, and why that is an issue

You are simply fabulous. Such a pleasure to watch your videos. Concise, informative and delivered with a wicked sense of humour. One of the best educational channels out there. Bravissima!

Wow! I found your channel while searching for science and I loved it!

Thank you, Sabine, great video!

What I admire most of her is her presentation of science in a very honest way. Best wishes.

Happy birthday, SH! By the way, great video.

I can't think of anything in the entire universe that I am more interested in than black holes. I appreciated your video immensely, and hope to see more like it in the future.

Hypothesis and collapse... I just love your accent lol Keep up the good work. You're so important to humans with the work you do...thank you for your contributions

Hi Sabine, I just discovered your excellent KZread channel. A question which is in my mind for a long time, knowing that my understanding of physics is limited, I must have been miss understanding something: so if an observer in orbit around a black hole watches another observer moving in the direction of the black hole, the falling looks slower and slower, until it "freezes" and never reaches the horizon. The 2nd observer just keeps falling in his own referential and passes "normally" the horizon. Ok so this comes from general relativity if I understand correctly. So my question is: how is it that we see black holes evolve, merge, etc. if from our point of view nothing never passes the horizon? It's a bit confusing! Maybe you've already answered this question in your video, I've not watch it entirely yet! Thank you for this high quality channel. Hossein

@bearcb

Жыл бұрын

We don't see the black hole or anything inside it, just the effects it has on the surroundings: star trajectories, gravitational lenses, gravitational waves. There is even a photo taken recently of a star being sucked into one, stretching like pasta!

Wonderful.... Thanks, Sabrine.

I love this new Channel which I've recently subscribed to. What amazes me is how things have not changed so much since 1966 when the TV series Star Trek season one Epd. 20 on Netflix entitled "Tomorrow is Yesterday" written by my alma mater Dorothy C. Fontana and produced by Gene Roddenberry referred to a "black hole" as a "Dark Star" in the episode. The "Dark Star" as renamed by the scriptwriters presumed the "Black Hole" had such a high gravitational pull that even the Enterprise had to use all of it's warp engines in reverse just to escape the "black star's" gravitational pull. It is clear that Gene Roddenberry hired scientists, some from NASA to explain the events for the science fiction in the series back in the day. Even back in 1966 the term "Black Hole" was met with resistance. Similar to what Dr. John Wheeler met when he invented the term "Black Hole" for a paper he published which coined the term. The publisher initially opposed the term "Black Hole" but finally yielded to it for publication purposes. The term was considered derogatory in its nature at the time and still was as of 1966 when the TV series "Star Trek" had to call it a "Dark Star" instead. To this day, the term "Black Hole" offends some people. John Wheeler had to fight for the right to use the term in his famous paper, but he won. Dr. Wheeler was later quoted as saying, "black holes have no hair". Wow, what a thing to say back in the day. Was it another insult? No it was not. What John Wheeler was really trying to say was that "Black Holes" are completely "clean" at their "event horizons" . In the above video by Dr. Hossenfelder this is acknowledged. A Black Hole's event horizon has "no hair" according to Dr. John Wheeler. The event horizon is a place where there are no distinguishing waypoints. There is not point of demarcation from on inch before nor one inch after a black hole's event horizon. That is what John Wheeler was trying to say. If I have to cite my sources, I guess I can go back and look at all the audiobooks I've read this from, but anybody who knows anything about black holes knows that Dr. John Wheeler wrote about and said these things.

You want black hole questions? Here are some black hole questions: What does the evaporation of a black hole ultimately look like? Does it emit Hawking radiation until the point at which it has decreased to zero mass, or does Hawking radiation stop before then? Does a black hole's density decrease as it emits Hawking radiation over time? If so, can a black hole theoretically lose the requisite gravitational pressure for continuing its existence as a black hole (e.g. can it "unfold" into something like a neutron star or some other dense glob of matter before it evaporates completely)? Love your videos, Sabine!

THANK YOU for NOT saying "nothing can escape... not even light".

@hipphipphurra77

4 жыл бұрын

may be se forgot to say "nothing can escape, not even light"

@hadesdescent6664

3 жыл бұрын

Nothing but radiation? Is radiation faster than light, and wouldn't it be pulled back into the black hole? The scientists only speculate, and don't know nothing with certainty! Too many conflicting ideas....

@iVardensphere

3 жыл бұрын

@@hadesdescent6664 think of light as radiation. It is a part of the electromagnetic spectrum. And yes, it could certainly fall into a black hole. My OP was to thank the speaker for not using the same phrase uttered in nearly every single description of a black hole influence.

@iVardensphere

3 жыл бұрын

Oh... and Radiation is not faster than light

@hadesdescent6664

3 жыл бұрын

@@iVardensphere I understand that, thanks for answering, but that Hawking radiation would eventually nullified the black hole is absurd to me. Black hole is constantly eating, and that loosing radiation is greater than amount of what is falling inside is doubtful at best. How come that beyond visible universe, expansion of space is faster than light? And quantum physics vs General relativity is in conflict. I'm not competent enough to understand many of those things in physics, astronomy etc... But, it's a mess of pure speculation and theories of all sorts!

I looooove the strangeness of black holes. When I heard we detected their gravity and then got an image of one, I cheered so loud.

Sabine, i very much enjoyed this Video. Could you at some point do a video about why black holes are understood as being extremely cold, even though all this energy is dumped into them... is it because there is no room for particles to move?

If an outside observer watching something fall into a black hole sees the object freeze in time , then why don't we see everything that ever fell in frozen in time?

@hjs6102

4 жыл бұрын

That is the case. For the outside observer the light from the falling thing becomes a redshift (the waves will become longer and longer and so weaker and invisible) but the object never crosses the horizon.

@Jopie65

4 жыл бұрын

Yes, so all stuff off the black hole lives on the surface of the event horizon. So, what is inside it then, you may ask? My conclusion is, there is no inside of a black hole. I'm also trying to make a case that someone falling in a black hole, will also never cross the horizon. Because that person would see it shrink as he nears the horizon.

@DrunkenUFOPilot

4 жыл бұрын

@@Jopie65 No, the infalling tourist sees the horizon, the black hole, widen more then expected for approaching a typical spherical object. All that is visible that's not the BH, shrinks into a little spot, becomes very bright, very blue shifted. I think. I admit, I haven't actually tried to see for myself yet!

@Jopie65

4 жыл бұрын

@@DrunkenUFOPilot The reason that I think the tourist would see the bh becoming smaller is because, I think, seen from outside the (not so lucky) tourist begins to look bigger. Here's why: Imagine the tourist bringing Einsteins light clock. Every photon bounce between 2 mirrors counts as a tick. When the tourist nears the BH horizon, the external observer would see it's clock slow down until it (almost) stops at the horizon. Here's the thing: light has a constant speed in every reference frame. For the clock to tick slower, the mirrors need to be further apart! Eventually so much that they are wrapped around the horizon multiple times. Poor tourist merges with the surface of the BH. Seen from the tourist however, his clock doesn't run slower. But the clock of the BH starts to run quicker once he nears the horizon. Hence the horizon must become smaller. Follow my reasoning? Could you point me to a mistake?

Dr. Sabine. Firstly, I loved all the videos that you have made, that I have seen! So far, I have heard a lot of references to Einstein. This one references Hawking. Could you do a video just on Hawking and some commentary on his work. I think that would be great!

Very clearly stated information, I appreciated it. You made a truly great video. I recommended this video to a non physicist friend. He said to me: "They say at the beginning the black hole is black because the gravity is so intense that even the light can't leave from beside the horizon; but at the end of the video, they say the black hole emits a thermal radiation (he meant the Hawking radiation), so what gives? It is black or not?" I explained the discovery of the radiation happened at a much later time, while the name had already stuck, and this radiation is emitted *after* the horizon. May be repeating this detail (from where the Hawking radiation is emitted) later can eliminate any confusion.

Could you elaborate on what you said about collider blackholes? How come in order for them to exist there should be higher dimensions?

Just subscribed! Found you on a night I cant sleep and have been watching youre videos for the last few hours, I watch and read alot of info on the topics you discuss but you have a way making my feeble mind wrap around it a bit easier. Hello from Boston.

@xlnt2new

4 жыл бұрын

This happens to me more often than i like to admit (to my cardiologist mostly) - Hello from Sofia.

You are the brightness of my mind , your words touch my thirst and desire . For clear understandable knowledgeable knowing.

Thanks for all your work Sabine. Wondering if the "spooky action at a distance" would work if you place one part of an entangled pair into a Black hole.

@antonystringfellow5152

4 жыл бұрын

There are various interpretations of "spooky action at a distance", one of which is not really spooky at all. However, regardless of which interpretation is correct, the answer to your question is, "Yes", since this effect is not governed by distance (space) or time. Light, like all massless energy, travels at the speed of causality. It would be just as correct to refer to this speed as the speed of gravity, since gravity waves, having no mass, also travel at the speed of causality. This speed is the limit at which cause and effect can propagate through space. This is why no event that occurs beyond the event horizon can have any effect outside of it.

@amandayorke481

4 жыл бұрын

@@antonystringfellow5152 that sounds really interesting. As I'm a cultural historian I only have the beginnings of a terribly basic understanding of scientific and mathematical formulae and language. At various times I've heard carefully slow explanations of general relativity in English and briefly been able to follow them, but they've all focussed on why nothing can exceed the speed of light; what I've never heard before is what the speed of light itself represents. But of course I suppose the phrase "speed of causality" is actually the same thing turned around and examined from a different angle.

@aurelienyonrac

3 жыл бұрын

@@antonystringfellow5152 hello Antony. I wanted to ask you a question: if in the middle of a hypothetical hollow planet one experience zero gravity, then the same would apply at the singularity of a black hole. It would feel like zero gravity like in space. Am i missing something? Thank you.

Let’s forget about the black holes for a minute; that black shirt looks so elegant on you; specially against that starry sky background. 👍🏻

@MaoDev

3 жыл бұрын

@ilkldme lmao

Firstly, I'd just like to say thank you for making these videos. You're a real inspiration, and the work you're doing on group think etc is so valuable to the scientific community and scientific progress. I am so grateful for this. OK, so I have a question about black holes: If time runs slower as the gravitational effect increases in strength, wouldn't this prevent a true singularity from forming, as it it would take infinitely long for one to actually form, and instead wouldn't it be more accurate to say that it 'tends' towards a singularity but it is actually just 'extremely dense'?

@fjbayt

4 жыл бұрын

The time runs slower for the observer outside, the image of someone falling into a blackhole is redshifted in the horizon and freezes, for the one falling time ticks like always, so the individual clocks of the matter that fall into making one never stops from their perspective thus time doesnt stop the singularity from happening. Althouh the singularity is the name of something that is not yet explanable.

@ThePinkus

4 жыл бұрын

@@fjbayt That is the answer given by certain solutions to GR, maybe we can call them as "proper theoretical BH" solutions in that they extends geometrodynamics inside the horizon up to the singularity. What Marc Bali is asking can be stated as if those solutions are the physically relevant ones. The reason his question can be reworded like this is that the GR solution is determined by the energy-matter distribution: solutions resulting from all energy-matter accumulating on this side of the horizon are different than those for which energy-matter ends up inside the horizon. I think, and I might be wrong, that in a region void of energy-matter GR has no unique (well defined?) solution (yep, that region is sort of contradictory, surely looks suspect). The scenario where energy-matter wholly accumulates on this side of the horizon is that of a sort of gemetrodynamical cavitation rather than that of a "sink hole". In this scenario gemetrodynamics does not extend to the inside of a horizon (so that that suspect region is not actually there), perhaps no more than it extends to an hypothetical embedding geometry of the curved space-time. In this sense there would be no singularity. Also, in this scenario, there is clearly no information loss.

@pedrolmlkzk

3 жыл бұрын

@@fjbayt that's not really accurate, although their time would never stop someone that falls in to a black whole would suffer from extreme time dilation to the point that to reach the singularity he'd need to travel an infinite amount of time

Beautifully done. I feel as though I slept at a Holiday Inn last night. Thank you.

damn! you really know how to explain things! thank you

Amazing video as always! I always could not understand one thing: If time dilation is considered can a black hole even completely form for a distant observer? I assume it should take an infinite amout of time (at least for the distant observer) that the mass is compressed to the Schwarz-Schild-Radius or am I missing something?

It must be cold in her studio! Gets me excited!

What I still can't figure out is how black holes can exist if (from our point of view) nothing ever falls into them. Same for collisions of black holes.

@Jopie65

4 жыл бұрын

That's a good question. Purely intuitively I'd say that all mass of the bh seen from us, lives at the horizon. So there is no 'inside' it from our perspective. But what about seen from someone falling into a bh? My intuition says that that person would see the bh shrink. Because when there's time dilation, there's also length contraction. So from that person's point of view he'd also never reach the horizon cause eventually it's become a single point. But I never hear about that. And that's what I don't get. Why is length contraction never considered? It would solve all those questions about where the information is and what is inside a bh.

@istvanszennai5209

4 жыл бұрын

then you didn’t listen to the video. As she said the most common black holes are formed from depleted stars. Things don’t have to ‘fall in’.

@hjs6102

4 жыл бұрын

@@istvanszennai5209 Well, it is in deed not so easy. You are free to choose an observation point within the collapsing star. At which point the first horizon appears? Does it grow? You have to be very careful, from which point of view you start your calculations and care about not to change the view without transposing all the coordinates in space and time.

@istvanszennai5209

4 жыл бұрын

@HJ S: 😑 the star uses up all its fuel, explodes into a supernova, then it _might_ collapse into a black hole. You ask ‘at which point’; it depends on the star to begin with...the point is, that the Schwarzschild solution predicted it, and today we have definite proof. End of story.

@hjs6102

4 жыл бұрын

@@istvanszennai5209 You misunderstood what i meant. I wanted to say, that if you have an event horizon at some location and time and then you go back in time, does the horizon shrink towards zero or popped it into existence instantaneously exactly with the given radius. And this timeline has to be viewed from an outside observer and an observer inside the later event horizon. What would the observers see?

Great.Thank you.

When I stopped watching quantumn woo videos in favor of "actual physics" videos I was so amazed by the difference... then I found this channel. Where Sabine makes other physicists feel like woo doctors in comparison. I can't tell if I'm happy about this or not. Yet, I can't stop watching.

Sabine, thank you for putting your video's together. I have a question, which I will preface with another question--and please forgive my lay-man approach to physics and problem solving. When 2 bodies orbit each other, does the barycenter create or emit energy via the tugging/stretching of space/time. And leading from that, can black holes, or at least the black holes observed at the centers of galaxies, be nothing more than the barycenter of the entire mass of bodies within the galaxy?

Sabine, good video as always. I do have a question, is it posible to exists a black hole so big that its temperature will be near to absolute zero ??

Is not possible black hole will eat us up . 2020: ok, we'll see.

@brookscarpenter8327

3 жыл бұрын

Agreed. We still have time.

@thefaboo

3 жыл бұрын

The only catastrophe we managed to dodge 😂😭

Regarding #10, I think we wouldn’t get much warning from the effects on the outer planets if the black hole approached somewhat perpendicularly to the orbital plane.

How about a video titled, 10 things you should know about Sabine Hossenfelder. Your choice of what 10 things you want to tell us about yourself.

Good stuff.

strong message!

Thank you for this video. they're properties of black holes at dinner (!) and your video ("Let's see what Sabine says...") has resolved the arguments. My idea to use the event horizon of a small black hole in the kitchen as a pasta maker has been addressed. In a similar vein, my idea to use a black hole instead of a rubbish bin in the kitchen has also been addressed. (I'm sure everyone has been thinking of this application since black holes were first theorised.) I guess our family can now go back to quality time talking about prince harry.

Thanks Sabine - love your work - As a person is falling towards the event horizon their 'clock' will slow down to zero from an outside observer's point of view. From the viewpoint of the person falling what would they see happening? Would they not see time flowing by quicker and quicker until 'all of time' flicks by in an instant when they hit the event horizon?

@DavidBeaumont

4 жыл бұрын

PBS SpaceTime talks about this. See: kzread.info/dash/bejne/fZmEsMqOepXYlaw.html Short answer, no. The person falling into the blackhole might not even experience anything special at the event horizon.

@Jopie65

4 жыл бұрын

@@DavidBeaumont I saw that one too. But consider this: Suppose someone could really cross the horizon. Since the only path for light and any other thing inside a bh is towards the center, how can this person still see, or be aware of his feet when inside a bh? And if he can't, why then say that he would not be able to tell her crossed the horizon? I think a person could never cross it, cause from his point of view, the horizon shrinks. People seem to forget: When there is time dilation, there's also length contraction.

I love your videos btw

Couple of questions: 1) if black hole is "everything with radius smaller than the event horizon corresponding to the object's mass", then isn't every stable, free elementary particle a black hole on its own? If not, what is the radius of an electron? If yes, how come every elementary particle black hole doesn't evaporate immediately and leave a trace of stuff behind? 2) what is the kinetic energy distribution of the particles coming out of the black hole? I'm looking for something like S (E), similar to S(nu) for a black body. Is it spherically symmetric? Does it follow Lambert's cosine law? 3) if an observer outside of a black hole sees something falling in slowing down, seemingly taking forever, could we ever observe a black hole to grow due to infalling matter? How can we possible observe it, if all infalling matter suddenly slows down and takes forever (from our perspective) to fall in? 4) what is the position vs. time function of a photon, directed exactly at the event horizon from inside of a black hole? If it cannot ever escape, that means it has to "slow down" (in order to never get past the event horizon from the inside), but we know, that photons have a constant speed (in a vacuum - does it mean inside of a black hole horizon is not considered vacuum?) Or, since c dt - dr = 0 for a photon, then if dr has to slow down, then photon's time should slow down to keep this consistent.

Excellent video! But I have a little problem when I compared this video to your other excellent video: "Solutions to the black hole information paradox". In this video, you said at 2:19: “... but from outside it takes like it [to fall into black-hole and cross the horizon] take forever. On the other hand, one of the subject of that video is that if an object felt into black-hole (see 10:35 in this video too), then it’s information content must come out when the black-hole is still large / latest when it is evaporated. I.e. an outside observer must wait endlessly until an object falls into a black-hole (cross the event horizon) but the black-hole will evaporate within finite time from viewpoint of this outside observer (theoretically if the Universe just expanding forever). So, If the black hole is destroying itself before anything can fall into it, then why we ask what will happen the information of this object when it is felt into black-hole? Does it make sense? Or maybe I have caught your explanation in the wrong way.

A blessing for a black hole... "May God bless and keep black holes...far away from us!"😬

Thanks much, I enjoy your videos. You refer to "inside the black hole" many times, Is that synonymous to "beyond the event horizon" of the BH?

@JasperKloek

4 жыл бұрын

I think it is.

@jorgepeterbarton

3 жыл бұрын

I'm reasonably sure that is the 'edge' of a black hole, and that it's not quite referred to as an object but the 'hole' left by a much smaller one inside (singularity or similar dense mass)

I have watched several of these and find them fascinating even though I don't get much of it. Thank you for making them short and interesting (I have a very short ...what was I saying? oh yeah, attention span.) I would like to make one small suggestion however and that is that there is more than one picture of Stephen Hawking out there.

One more question (cant sleep) if the final parsec problem is indeed true, would the gravity waves moving at each other cancel each other out or have some sort of bounce? Im thinking back to the double slit experiment when particles behave as waves and dont the troughs cancel each other out? Thanks

How did this only get 4K likes? Was much more understandable than spacetime.

Two questions: 1. What percentage of supermassive black holes was originally dark matter that fell in? 2. Since distant observers see that it takes infinite time for an infalling object to reach the event horizon, why is there a paradox problem accounting for the quantum information the object contained? The info can't be lost if it never reaches the black hole.

@Sabine Hossenfelder, can you make a black hole to resonate with gravitational waves (and then make it so strong that the BH splits)?

Nice, more enjoyable than most blackhole vidues due to more accurate and recent theory. I'd suggest that a simple explanation for not understanding how some blackholes get so large, would probably make more sense if the 'big-bang' theory is changed with universe is constant theory. Too many factors point to that the universe age theory is not realistic, ancient blackholes might offer more proof to that end..

Sabine talks like a German John Battman. I'm riveted. I love it.

I would love to see what you think about Magnetospheric eternally collapsing objects.

Is our universe the inside of a supermassive black hole? There seem to be many parallels: black hole accretion/universe expansion, black hole formation/inflation, the horizon could contain enough information to describe a 3D universe inside via the holographic principle, etc; Is there a way to prove this is not the case?

Hey Sabine, question about black holes and special relativity. If I have a high velocity (outside of the milky way), and I see space more compact - will I observe that the milky way span over a smaller volume of space? If so - will I also observe the milky way having less mass? If not - is there a certain velocity in which I will observe the milky way has a large mass compacted in a relatively very small volume, and observe it as a black hole? Is it possible that we are actually moving at a high velocity and what we observe as black holes are actually regions of matter moving much slower than us and we only observe them as black holes? Also - in case an object have higher velocity - its observable universe will actually contain more space than an object having lower velocity, so it is possible that objects inside a slowly moving region of space will not be able to observe other far away objects while the far away objects *will* be able to observe them due the difference in their perception of space-time? So what we observe as the event horizon of a black hole is the limit of the observable universe from "inside" the black hole?

I enjoyed watching your video. Thank you. I have trouble understanding that if nothing, not even light, can escape from a black hole, then how it's it possible for a black hole to emit radiation?

@tonydarcy1606

3 жыл бұрын

Something to do with virtual particles popping in and out of existence, as they do all the time everywhere. On the event horizon, one pops in and the other pops out. The energy must be conserved in the form of radiation. I am bending over ready to have my bum whacked for such a stupid reply, but I am as ignorant of black holes as most people.

I prefer the explanation that says a black hole is a region where all paths lead to the center. It's a relativistic explanation, and when I first heard it it blew my mind.

@DavidBeaumont

4 жыл бұрын

It's explained really well in: kzread.info/dash/bejne/fZmEsMqOepXYlaw.html Space becomes "time like" and time becomes "space like". In the same way that outside a black hole, the direction of time is "forward only", inside a black hole, space is "forward only".

"Black hole sun, won't you come?" Another good video here!

Thank you for the lecture. 1) All we know about black holes will collapse if we detect electromagnetic emission from black hole mergers or observe episodes of energy emissions not from an accretion disk or from matter that falls in. 2) We assume that matter is destroyed in a black hole. That would imply a zero Einstein tensor and only a non zero Weyl tensor. It is not sure if it is even possible though I personally like the idea. 3) QFT relies on particle fields via spinors. An alternative approach is torsion operators and Geometric Chronon Fields where the building blocks are not particles but realization events of space-time. We don't know about particles but about their interaction events. In the Geometric Chronon approach, matter appears where these realization events or Causal Sets are misaligned. In mathematical terms, it is where the Reeb vectors of the gradients of the Geometric Chronon Field are not zero and thus prohibit geodesic motion. Gravity in this case is simply the controlling response of space-time.

@NaRhala

4 жыл бұрын

re: 3) w h a t but also v e r y i m p r e s s i v e

@eytansuchard8640

4 жыл бұрын

@@NaRhala The results of this model are more impressive. It allows unexpected gravity and anti-gravity by electric charge. That means Alcubierre - White warp drive is within reach !!!

I like that Sabine tries to simplify and mentions what I consider to be important exceptions to laws/rules. I've heard that black holes have infinite density,. Is this correct? Can a black hole's gravity force space out of existence? On a local level (I'm not sure what that means exactly) gravity and acceleration may be equivalant but there is more gravitational force on my feet than at my head while acceleration probably doesn't do that. When/where are 'local' effects equivalant and when/where aren't they?

Unless I missed it, noticed no mention of AMPS? In 2019, how can you not mention the Firewall when going over things to know about bh's? Btw, what if the firewall has the quantum data spread out on it (like 2-brane)? In such a case subatomic particles would be black hole quanta and there would be no information paradox, as there is no loss of quantum data.

AMAZING...! A question: the center of a black hole is a singularity, then hypothetically a white hole center is a Ubiquity, i.e. everywhere in the space out of the black whole? If this is true, can the particles created during quantum fluctuations the same particles that passed through the black hole singularity? Thanks....!

@333STONE

4 жыл бұрын

White whole would push and not pull. I think a black whole is the Reciprocating precessional hyperboloid gone over the limit of oscillation or spin and starts divergence and convergence in the form of the White Whole the inhale and exhale inhale=black exhale=white There is an intermediate blackhole in the sword of Orion in the middle is the trapezium open star cluster where the 5 stars form a cross the top of which is a binary . Now that's where the barnards loop starts. Which curiously looks like a fibonacci spiral, and if one follows said loop trajectory it leads to our solar system. That's probably why orions nebula is so important to ancient cultures the eye in the triangle

In your opinion Sabine, what combination of instrumentation and/or observations is required for us to find definitive answers to these questions re Black Holes? Any experiments that you are aware of on the horizon which may provide us with satisfaction? Is the human mind really capable of coming to terms with Infinities.....given that any kind of cosmological Infinities even exist at all? TNQ

Sabine, some people still think a black hole is a hole. Can it be mentioned clearly by a scientist that a black hole is not an empty hole but physically a spherical object like any stars, except that its mass is so dense that it doesn't permit even light to escape.

Could you please comment on the process of two black hole mergers? I'm interested to know how mass is transformed into spacial/time waves and could this be considered dark energy or matter? E=MC^2 but how does this relate to a black holes losing mass? How is the loss of mass conserved? Instead of solar panels could we ever have gravitational panels that produce some form of energy?

Way back in the eighties I bought the book of Misner Thorne and Wheeler "Gravitation". I think it is still the best textbook around - or has something better come up since? Also, in this book it is shown that many things in relativity can be explained by simple diagramms. What spacetime does is not that complicated, and for understanding things one can mostly ignore the tensor calculus. Why is this so? If you walk through a curved landscape (mountaineering), you also do not need math in order to understand how to go from A to B. - However, knowing some math does not hurt - beautyful or not.

@SabineHossenfelder

5 жыл бұрын

MTW is still one of the best references, simply because it covers pretty much everything relevant in GR. I myself also use it. (Though I want to complain it's starting to fall apart. The binding is miserable.) It is of course out of date now as with the cosmological data and so on.

@herwighuener3256

5 жыл бұрын

The first volume of "Berkeley Physics Course" is also a good reference for beginners. I mention that because the media tell, at this moment, that Charles Kittel is dead at 102. His books about Solid State Physics and Thermodynamics were, for me, essential in understanding physics. RIP - If physicists are admitted to heaven, that is.

@toddq6443

5 жыл бұрын

@@herwighuener3256 Nicely stated, I agree. TNQ

@toddq6443

5 жыл бұрын

@@SabineHossenfelder At least we all still appreciate the value of wonderful, useful texts. Each time I have had to move into a new home I question my sanity at having to relocate my massive library.....but then I select a volume, open it at random, take a deep inhale and begin to read.....suddenly all of the effort seems well worthwhile (even those with tattered bindings are a blessing). I have a 1955 Larousse Enclyopedia of of Astronomy in near mint condition which I value like a beloved pet! :) TNQ

@sbkarajan

2 жыл бұрын

So called stellar black hole, which started this entire black hole farce series, is impossible to begin with, as the sun is not really a hydrogen plasma ball. The black hole itself, where the definition is being continuously shifting to make common sense these days, probably don't exist after all. Think about this, about the closest star, and how little we know about it. 1. The density of the sun is 1.4 g/cc. The density of SOLID H and He are 0.076 g/cc and 0.2 g/cc respectively. The sun is probably not made of H or He. 2. The pressure and temperature of the sun's core is "modeled" to nearly equal, or exceed those of Hydrogen bomb's. If that's the case, H and He cannot exist in plasma state in the core any long term. Moreover, all of H in the core should have fused into He instantly when such pressure and temperature was reached billions of years ago. Yet' it's slowly and surely fusing H into He all this time.... Nope. 3. The radiation from the sun is that of blackbody. H and He plasma don't do that, they emit lines of spectrums, like neon sign does. 4. Looking at the solar activity close up from the telescope, they are not that of some gas or plasma, but of some magma... Did you know that even the clouds in the sky or smokes from chimney are mostly solid particles like water ice or shoot? Gases are very thin and mostly invisible. 5. Some stars repeat supernova explosions, again and again, never disappears, have you looked at such news? If not, google it.

Sabine, what is the actual surface of the BH mass? Does it exist like in planets? Is it the even horizon?

I just checked the other channel. I watched Talk to Me. Not less confused. I'm gonna stay here.

Sabine, with respect to the formation of black holes; what are your thoughts on the formation of (micro) singularities other than by collapsing stars? More specific, I refer to the hypothetical event whereby objects would be pushed to speeds beyond C (e.g. at the Big Bang) ? From the Lorentz factor we then get a length contraction that would render any object to appear smaller than the Planck length for any ST observer. Would such an object not get the physics of a singularity, which in mathematical topology would entail a collapsing torus shape inversing its grid denominators (see e.g. the collapsing torus animation on wikipedia). Extrapolating; are there any objections to the thought that our atoms would have formed this way , meaning they are actual micro singularities? This question is important as it would bring back symmetry to physics which was lost upon the introduction of QP of mathematical approximation of such a inverses grid structures...Thank you...

Yes, they're a bit scary. Did my thesis on accretion disk variability so I know a bit about them. A few comments; 1. the time delay effect for far observers when matter crosses the horizon may be observable, if the huge gravitational Doppler shift can be compensated for or very long wavelengths being used. 2. the Hawking radiation has zero practical influence as you mentioned, 3. one should not ignore the rotational energy of BHs, since that may become the only energy source in the far future when all stars have ended their evolution, 4. staying close to the horizon without getting killed may one day be used as a one way time machine into the far future. The question is what purpose such an adventure would have.

You look so much comfortable before the camera

I love that she recognizes that the inside of a BH is not understood because GR doesn't work in such a scenario (and a few others). But it seems Penrose/Hawking theorems affirm that BHs need to have singularities. Should we trust Penrose theorems? Or are those only valid if GR also applies to BH?

And I have my own paradox. The way you pronounce paradox. In this presentation, you pronounce it the way I would, but, in more recent videos, your pronunciation is quite different. . . That too, is a question of cosmic importance 😉

Regarding QM not allowing any information loss: Please comment on the situation of a light source emitting a photon that passes through a two slip apparatus with a screen detector. The position of the "detected" photon is random to a degree (modulo the interference pattern) but I would say that the process is not really reversible, at least as I understand the terms.

Are so-called active galaxies, those with huge jets and plasma bubble ejections, pre-cursers to having a black hole, or are these types mutually exclusive?

U R Inspirational

Excellent - lucid. As I, in my limited way, understand it, Hawking radiation arises from the spontaneous appearance in vacuum of particle pairs as a function of 'uncertainty' - i.e. quantum fluctuations in energy level. In the vicinity of a black hole, one of these particles, the 'anti-particle' falls into the black hole, releases its energy and reduces the mass of the black hole. The other particle, being short-lived, 'vanishes' again or 'hangs about'. (This all sounds like magick to me, but I have some faith in the math and empirical evidence). So the issue now is of conservation of information. Forgive my limited understanding, but at a classical level, we can write differential equations that play backwards and forwards in time. In principle, if we had infinite accuracy in the variable coefficients of our equations, we could replay the whole universe backwards and forwards (as Laplace thought). I practice, we do not have that exactitude and so chaos reigns - but in principle, no information is ever lost. I 'think' you are saying that the same applies at the tiny quantum level? So the problem is that we cannot ever recover information beyond the 'horizon' of a black hole. Now here's what puzzles me - why do we relate Hawking radiation to the processes and information inside a black hole at all? The particle pairs are created in vacuum throughout the universe (are they not?), So what is the connection between the absorption of one particle of a pair into a black hole and the information already in it? Are you saying that the absorption process itself destroys information? Pardon my poor understanding Dr, Hossenfelder - I'm an engineer, not a physicist and it's a privilege being able to as you these questions.

@SabineHossenfelder

5 жыл бұрын

The problem with information loss is not that the information in the radiation is lost. It's that the radiation causes the black hole to shrink, so that the information about what else is inside the black hole is ultimately destroyed. It is not the horizon that causes the problem. The horizon is merely the location where information becomes disconnected. What causes the problem is the singularity that ultimately destroys whatever touches it.

@keithrowley5520

5 жыл бұрын

@@SabineHossenfelder Thank you sincerely. Now I must go away and think!

@adrianconstantin1132

4 жыл бұрын

I believe Hawking radiation says the particle pairs that get separated by the horizon (after the spontaneous formation) can no longer re-combine, and so the remaining particle does not vanish back, but remains, and that is what makes the ratiation. I also believe there is no empirical evidence for this, it is just as thought experiment

Thank you,pretty Sabine 😍❤👍

Hi! As far as I know, space-time moves in a black hole at a faster-than-light-speed. So, when a particle falls into a black hole does it start to go back in time?

How would we know that the horizon can actually be crossed? Is it possible that things just float on the outside of the black hole? (Since time slows down infinitely to the outside observer does it not?)

When gravity make thing shrink, it happen in moving reference frame or non moving reference frame or for all reference frame? Could you answer this question please

excellent

From a phenomenological perspective, I think that it will be very interesting to have a video about the following point of view. When positive ions of an accretion disk fall under the Schwarzschild radius of a black hole, we may suppose that they cannot exchange photons anymore with any other particles and that, per consequence : a) this does not give a positive charge to black hole ; b) the electrons ejected previously by the powerful gamma rays of the accretion disk will then be liberated from the attraction of those positive ions and begin to distance themselves from other electrons ; c) after millions of years, around most of the galaxies, the leftover electrons should have dispersed in an approximate spheroid shape and generated an electric field approximately constant ; d) this should have observable consequence on the attractive force between galaxies and on the shape of the galactic plasma and disk, as suggested for example by the physicist Steve Reucroft. I have notice that it is easy to find recent papers on galactic-scale electric and magnetic fields.

Information loss paradox: either the random frequencies of the Hawking radiation contains the information, but we don't know how to decypher it or either (but less likely) it is gone in another baby universe, the blackhole been a gateway or either (more likely) we think we know all about information loss, but in fact we have made huge confusions when applying couple of theorems and obviously, they don't work for blackhole.

@juanausensi499

3 жыл бұрын

I think information does really disappear in the black hole, and if quantum mechanics have a problem with that, then, well, it's time to do some revisions.

I have a question, if I understand correctly from the perspective of someone falling into a Schwarzschild black hole, time outside the black hole flows faster and faster until all of the universe history has passed. But how does the black hole evaporation or the universe expansion affects the journey ?

I read that the biggest neutron star 2.16 stellar mass is 20 kilometres across and the smallest black hole 3.8 stellar mass is 24 kilometres across its event horizon. The densities of these two bodies are the same +/- 2%. Is it possible that as a neutron star gets bigger that the the radius of the event horizon simply exceeds its physical radius? In " The pressure distribution inside the proton", coauthors V. D. Burkert, L. Elouadrhiri, and F. X. Girod show that the the average peak pressure, near the center of the proton, comes out to 10^35 pascals: a greater pressure than neutron stars experience anywhere. Is this reason to believe that stellar black holes are just large neutron stars?

@SabineHossenfelder

5 жыл бұрын

If the radius of the event horizon becomes bigger than the actual radius of the star, then the matter can no longer be stabilized and it will inevitably collapse.

@toddq6443

5 жыл бұрын

I really admired this thought provoking question Mr Forbes. TNQ

@adrianconstantin1132

4 жыл бұрын

Neutron stars formation indeed requires a star of a size up to, but not quite, that of a black-hole forming star. Neutron star or not, as soon as an object size fits inside the diameter of the black hole corresponding to its mass, the black hole is created. So neutron stars always have a radius larger (but still close to) then that of the corresponding black hole of the same mass. Neutron stars can be observed (by telescope), black holes can not, so there is no confusion between them, not visible nor conceptual (theoretical). They are totally different.

@amedeofilippi6336

4 жыл бұрын

What makes me feel “ strange “ is that if ithink about densities of a BH , I see that the larger they are the less dense they become. M87 Supermassive BH has about 0.6 kg per cubic meter, much lighter than water while a 3.8 Solar mass BH has the tremendous density of about 4*10^24 kg per cubic meter. Believe that I would prefer to fall in a supermassive BH after all!

Liebe Sabine, was passiert eigentlich in dem Moment indem aus einer Masse ein schwarzes Loch wird? Ich meine wenn das zeitintervall immer kleiner wird auf den Moment hin, wenn die Region die Singularität wird. Davor kann Licht aus dem höchstwahrscheinlich noch sehr heißen Zentrum in allen Wellenlängen entweichen. Danach aber nicht mehr. Kann man sich das so vorstellen wie bei der chaostheorie, wenn alles streng deterministisch auf einen Punkt zu läuft nachdem man keine Aussage machen kann, wie die Endposition aussieht, also streng chaotisch? Aber eigentlich ist ein schwarzes Loch ja ein sehr geordneter Zustand, da ja nichts mehr raus kann sondern alles nur reinfâllt. Und von außen sieht ja das Reinfallen in das schwarze Loch extrem langsam aus. Bevor es ein schwarzes Loch ist, jedoch nicht. kann man sich das dann wie einen seltsamen dopplereffekt vorstellen? Viele Grüße, Bruno Kramm PS: Danke für Deine inspirierende Arbeit

2:18 I would not look this happy falling into a black hole

The amazing mysteries of life Sabine.

Why do black holes vanish? Given the fact that black holes evaporate over time, wouldn't they just become some dark dense object which does not have enough mass to be a black hole any more and therefore stops evaporation at some point in time (in mass).

@SabineHossenfelder

5 жыл бұрын

Well, that's one of the possible solutions to the black hole information loss which have been proposed. The problem is that since nothing can come out of a black hole, the horizon cannot vanish as long as general relativity remains valid. For that to happen, stuff that was previously inside would have to be able to then be outside. You can do it if you change something about general relativity.

When matter become denser inside black hole, does some of the density leak into another area or dimension as gravity?

When a star is pulled into a black hole is it's decay from being pulled into the black hole the same as the golden ratio.. if so what's the relation between the 2

the thumbnail reminds me of the 1982 cosmonaut timeline from the strokes music video for at the door

I love her teaching style and everything else about her. I got lost about how does anything go the wrong way out of the black hole and read the wiki. Magic, if you can't do the math. Ok. Maybe it'll make sense when gravity gets figured out

Dear Mme Hossenfelder, may I kindly ask you 3 questions about BH in german language? 1) Warum weist die gekrümmte Raumzeit eines SL nicht die Tendenz auf sich wieder zurückzustülpen so wie sich auch die Raumzeit um die Erde oder die Sonne wieder abflacht nachdem der Körper vorbeigezogen ist? Die Masse ist ja in der Singularität "verschwunden" und kann somit nicht mehr die SL-Raumzeit in ihrer Verkrümmtheit fixieren. Vielleicht hat die Raumzeit eine fixe Sollbruchstelle und ist nur begrenzt elastisch? 2) Wie kann es sein, dass SL unterschiedliche Massen, Größen haben wo doch alle ein und dieselbe Singularität aufweisen? Wie kann sich hineinfallende Materie auf die "äussere" Beschaffenheit des SL auswirken wo doch alles in der Singularität "verpufft"? 3) Kann es sein, dass im SL-Zentrum nicht Singularität auftritt sondern nur Raum der aber absolut frei von Quantenfluktution ist? Vielen Dank für Ihre so stark vermittelnde Art Physik zu erklären, sodass auch bei nicht Initiierten wie ich das Licht ab und an in der Laterne angeht ;-)