Depicting the physicists addicted to finding solutions of Einstein equations as cats eating some herbs is stunning.

@SabineHossenfelder

2 ай бұрын

creativity inspired by limitations of stock footage is an underappreciated phenomenon

@PlanetEarth3141

2 ай бұрын

​@@SabineHossenfelder It's the seizure of unsound minds.

@louisrobertson9215

2 ай бұрын

😂😂

@mcnaugha

2 ай бұрын

I’ve been saying for a while now that “solving Einstein’s equations” is nothing but video games by another name. The whole lot of it is video gaming and idea popularity contests. None of it reality. It is a shame the publications of these leads so many to proverbial war against one another’s beliefs… like history repeating itself, again and again. So, much of it so conveniently unfalsifiable… at least not within our own lifetime. As such, there is never anything truly risked.

@hugegamer5988

2 ай бұрын

It’s catnip. It’s cannabis for cats.

do physicists think singularities _exist,_ or is it more an "our math is messed up but we don't know how to fix it yet" marker?

@SabineHossenfelder

2 ай бұрын

I don't know any physicist who thinks that singularities are physically real. Then again that doesn't mean those physicists don't exist!

@VikingTeddy

2 ай бұрын

Most scientists don't really believe in a singularity. But any guess as to the size and composition of the object (if any) within would be a guess, so they don't talk about it. All they know for sure is "this is what the math says".

@francoislacombe9071

2 ай бұрын

I'm pretty sure that whenever singularities appear in a model, that model is either wrong, or incomplete, or both.

@PlanetEarth3141

2 ай бұрын

​@@VikingTeddy If math proved it we wouldn't be asking questions. Thinking humanity knows any math is as insane as a pig flying. Logically any math we depend on that doesn't support all math means we don't know any math or that there is no math. Math is a human invention like all we do. Humanity can not prove any knowledge isn't flawed or represents reality.

@Llortnerof

2 ай бұрын

That's kinda the problem. We don't know which it is.

Doctor: Wide Sabine does not exist, she can't hurt you Meanwhile wide Sabine: 👁️ 👄 👁️

@Broockle

2 ай бұрын

It's us who become wide relative to Sabine as she passes the event horizon 😆

@AnujFalcon

2 ай бұрын

@@Broockle Age old 'frame of reference' issue. Good one.

@michaelwinter742

2 ай бұрын

Beware “wide not” counter-Sabine

@marcoottina654

2 ай бұрын

I laughed mute then I would never admit

@MichaelOfRohan

2 ай бұрын

Hahaha wow an actually funny comment 💪🌏🫸 🦵🦵

1:37 stuff like this is why I love this channel

Sabine: Black Holes = Hotel California

@Notsogoodguitarguy

2 ай бұрын

Welcome to Hotel Blackholifornia

@sjzara

2 ай бұрын

They break the laws of physics so that wine becomes a spirit.

@anuragb.9349

2 ай бұрын

You can check in anytime you like but you may never leave...

@vincentkinequon4631

2 ай бұрын

Did the " scientists " even consider the notion that nothing can enter a black hole. Surely someone has, they didn't just assume that Matter falls into a black hole do they? I can go on and on. Did the inflationary hot big bang really happen as we think it did. And ultimately, are our finest thinkers going down endless rabbit holes that may take them exactly to where they started. Like I said "on and on". But anyway, I love science and the conceptions of these wonderful people, whether right or wrong. 😊

@Spiegelradtransformation

2 ай бұрын

A lot of talk noone knows!

Sabine, I just wanted to say that in your ad read, when you mentioned how much probability you had forgotten, that really warmed my heart. Sometimes it's embarrassing to feel proficient in a field (for me, Biostatistics) and to realize how much of another field you have forgotten. If a smart person like you can forget stuff, then maybe there's hope for the rest of us!

@Farming-Technology

2 ай бұрын

Agreed. Every time I learn someone's name; I worry I'll forget how to tie my shoelaces. 😮😅

@neglesaks

2 ай бұрын

You might be surprised how often that PhDs and Professors have to look up formulae in thei compendiums. We're human, not machines.

@xmuzel

2 ай бұрын

I forgor 💀

@margodphd

2 ай бұрын

With increasingly narrow specialties, the path to becoming an expert is inevitably going to include a lot of forgetting. It's only human, y'know? Now, if we could control whether we forget Something Important that will Inevitably Come Up or That Embarrassing Preschool Situation...

@joshua43214

2 ай бұрын

This is a good thing (fellow biomathematician here). I could not get rid of the mind poison of probability fast enough once I graduated.

"Disappointingly Human" is a new favourite of mine.

@Thomas-gk42

2 ай бұрын

hihi

@greatPretender79

2 ай бұрын

Agreed! Will use frequently.

@Thomas-gk42

2 ай бұрын

@@greatPretender79 We need a collection of Sabine´s "best of"

@Rudxain

2 ай бұрын

It feels like something Glados would say

Thank you, Sabine, for making the fine subtle point that there's a difference between things that could exist according to the solutions to Einstein's equations and things that actually exist. I might that add that for things to actually exist, there must be a physically allowed process or series of steps to arrive at that final state, it's not enough for the final state not to violate the laws of physics to actually exist.

@whiteeye3453

2 ай бұрын

Like there isn't proof that gravitational waves exist

@olbluelips

2 ай бұрын

@@whiteeye3453there isn’t proof that any physical object exists. Doesn’t mean there isn’t evidence for it

@whiteeye3453

2 ай бұрын

@@olbluelips and evidence is ither fake or hoax

@olbluelips

2 ай бұрын

@@whiteeye3453 and what's your worldview, exactly

@whiteeye3453

2 ай бұрын

@@olbluelips no gravitational waves don't exist

Hearing Sabine say "prof" is the highlight here. Publish or perish is such a thing. Thanks for getting us the real facts. Knowing is half the battle. Brilliant may be the other half.

So, our math professor gave us an example of how math can be used to calculate the "real world", but if one isn't careful with where limits are placed and so on, then you get things that are mathematically correct, but has nothing to do with reality. His example was with derivatives concerning car breaks. They could simulate how the car would behave while breaking by...I've forgotten already, it's been like 6 years, but, basically, the car's speed would start approaching zero, then dip bellow zero, then back over, and oscillate like that until it approaches zero (imagine a sinus wave, but slowly converging to zero, that's how the graph looked like). And his student presented the graph to him proudly, cause it was apparently a tough calculation. The professor looked at it and then asked - "If you step on the breaks while driving, do you start rocking back and forth until you stop completely?" Is it possible that something like this is happening here as well? There's a mathematically sound solution with these gravistars that doesn't actually conform to reality? Like the "mathematically correct" solutions to warp drives that require negative energy densities and more power than the entire universe can generate?

@zinken255

2 ай бұрын

If you step on the breaks while driving, do you start rocking back and forth until you stop completely? No, not at the start, but possibly at the end, at least for the occupants.

@Notsogoodguitarguy

2 ай бұрын

@@zinken255 hehe

@garethdean6382

2 ай бұрын

Yes, that's correct; the solution is stable,like a pencil balanced perfectly on its point, but there's no real way to produce it naturally. It could exist,if you could magically make it, but we don't know HOW it might be made. Whereas 'regular' black holes will just happen.

I just love the cool names they come with: gravastars

@TheRABIDdude

2 ай бұрын

Sounds like a gravy brand

@suicune2001

2 ай бұрын

@@TheRABIDdude I was thinking more like Space Jam.

"👏👏👏 Sabine, what are you doing!?" 😂

I never imagined I would get to experience a Sabine & Flextape crossover but I am glad I did.

Fascinating stuff indeed! Thanks, Sabine! 😃 Stay safe there with your family! 🖖😊

You have an episode from two months ago, explaining Kerr's new paper, which I suspect answers many of the questions raised here. First, in practice, there are no known black holes with zero angular momentum. Not only is it difficult in practice to get mass to stop rotating completely but also quantum mechanics implies that the ground state of any particle having angular momentum is nonzero. If I understand correctly, Kerr's paper suggests that angular momentum turns the Schwarzschild point of singularity into a ring. Matter tends to follow toroidal paths that take forever in proper time to approach the singularity. I never specialized in any of this, so I can't say much more useful.

@Ken-1

2 ай бұрын

That is how I understood it. Importantly, he suggests that the centrifugal throw of rotating black holes can counteract the pull of gravity within their event horizon, potentially creating an inner region where matter and light are free to move almost normally (thus avoiding the supposed "ring singularity"). That's the interesting region. Perhaps said gravastar (or a baby universe even) could exist within it. I do like this more sensible approach to explaining black holes

Thank you sharing such an interesting concept. Certainly worth thinking about. We have so much to learn.

I've always thought a black hole is named for its appearance, not for what it actually is, there is no doubt the gravity culminates from a huge amount of trapped material, so no way is it a porthole to another dimension/realm. Actually you could say It's behavior is the opposite of a star, a star emits energy, a black hole consumes it, for all we know the colour of a black hole could be Ultraviolet or Grey, unfortunately the gravity will never let us see, I think a black mass would be a better description.

@j.f.christ8421

2 ай бұрын

John Mitchell was the bloke who first thought of black holes (way back in 1783), and he called them dark stars. Reading his wiki he also thought up the balance used in the Cavendish experiment. Also into earthquakes & magnets, smart dude.

Ok but what if.. they’re not stars, but superatoms

@JJEMTT

2 ай бұрын

👀

@mahshshsrklingfa7031

2 ай бұрын

Or cheesecake

@reddragon7030

2 ай бұрын

No.. as is they have less in common with stars, and more in common with atoms. Follow electron shell theory, and the event that strong force collapses space.

@TheRABIDdude

2 ай бұрын

I think you just described a neutron star my dude.

@reddragon7030

2 ай бұрын

I mean.. you could be correct! The theory came from stacking matter (theoretically) over and over until you collapse the electron shell, and then searching for a comparable observation. At some point the object gets so dense photons do not emit, and what would you call that? Note* KZread wiped my first attempt to respond

Your videos are delightful and amazing Good job !

Once more, as the rest of all of your posts, loved it.

Isn't it the case that the analysis of gravitational waves uses statistical methods and filters that are trained on our expectation of black hole mergers and we'd have to redo analysis from raw data against a gravastar statistical model to really be sure?

@garethdean6382

2 ай бұрын

Sort of. To find merger candidates data is filtered to look for the 'chirp' expected of a merger, a signal rising in intensity and frequency that appears at both LIGO detectors at the right time. In this way only merger signals that fit the general pattern of what we expect will be processed,something which can be said to be limiting. On the other hand a lot of work has been done on identifying any other signals present, for novel processes and to try and find ways to eliminate noise. So we know we're not missing any significant weird signals. The LIGO detections require gravitational wave emission from two inspiralling dense masses,but not necessarily black holes.(For example we have at least one neutron star merger on record.) So we should be able to identify mergers of things that are like, but not black holes. We can also predict what signal other kinds of merger would produce and check LIGO data for that. Which is what's been done with the gravistar model; there's a big enough discrepancy there that we know LIGO should detect it and it shouldn't resemble a black hole merger. The difference is just too great.

@davestorm6718

2 ай бұрын

I would say yes, though, I doubt resources will be spent to study anything that strays this far from the main stream.

Really loved the speed ticket joke

Could this be extended to a continuous solution? Instead of nested shells of matter, each right where an event horizon would normally form, you could have a continuous distribution of matter that's right at the edge of forming an event horizon at every point within itself. If increasing the number of nested shells improves the stability, would this type of continuous distribution be perfectly stable?

Awesome as always! Saw you interview with the philosophy show from the swiss. Would love , if you would do a special series, where you dig deeper into the questions about whats the matter of the universe, does free will exist and all that. Maybe you could even interview other scientists too.

I have no formal education on any of this. I always thought since the universe started in a super dense state, black holes were just returning to that state. Maybe the stars that collapsed were formed of larger chunks that didn't become stable enough. Simplistic I know.

"It's full of stars." --David Bowman, about to get shredded

I love the humor in these videos. The cats with the catnip was just *chef's kiss*

Very cool. Reminds me of the models of rotating black holes which have a doughnut shaped ergosphere and an inner event horizon, PBS Space Time did an episode a couple years ago on this.

Loved the Eagles reference! Well done!!!

Great stuff. More please.

Check out anytime. Since it takes forever to hit the center, perhaps Rovelli is right, when it gets down to a quantum squeeze size, perhaps it bounces back out?

I had professor (quite famous in IEEE circles) who used to say that forgetting the old is as much important as learning the new. His argument was that there's only so much space available in our heads for all the things that we keep crammed in there, so one has to forget something old to be able to learn something new. I agree with that assessment of his, but it turns out that he was right in more ways than just that one. People, especially scientists, tend to get stuck on what they "know" (assume to be true), and that makes them increasingly rigid (over time), and (eventually) unable to learn anything new. I guess this is just another way of saying what Max Planck expressed so long ago -- science does indeed advance one funeral at a time, as those who "know" the old (assume it to be true) either abandon their (wrong) "knowledge" (which doesn't happen that often) or die (of old age, which, thankfully, happens quite regularly), freeing some space (in the collective human mind) for the new to replace the (now-forgotten) old. I think that this problem of getting stuck on the old (pretty much always) stems from not learning how to deal with self-importance first (and it's cardinal rule to learn that very thing first), as those who do not learn how to keep their self-importance in check tend to fall prey to the cost sunk fallacy. In other words, having invested so much of their time and energy into something that has already taken a big chunk of their lives, they (practically always) have trouble letting go of that which is "obviously wrong" (that is, obviously wrong to everybody else but them). Anyway, this dance between forgetting the old and learning the new is one of the main reasons why scientific breakthroughs usually (when they don't happen by pure accident) come from outsiders to the field. Einstein was a perfect example thereof... but he, himself, did eventually fall into the same trap of refusing to let go of what he "knew" (assumed to be true), and then ended up trying to fit his perfectly-crafted round peg (of a theory) into the square hole (of reality) for the rest of his life. Having recognized that trap myself, I like to avoid it by occasionally "forgetting" (putting aside) everything I "know" (assume to be true), and then amuse myself by coming up with all kinds of "crazy" models of reality (that still fit all of the observations of that reality). I guess that's why I still haven't completely ruled out the simulation hypothesis (which is indeed very hard to rule out, and that's what makes it so appealing even to some physicists out there). I have, however, realized that simulation hypothesis is a non-problem to begin with (to genuinely inquiring minds), because any hardware that this (presumed) simulation would be run on would have to exist in a universe that's just as mathematical as this one. That other (presumable) universe might have different rules (laws of physics) than this one, but I've also concluded that all possible mathematical models can always be mapped to each other. In other words, for any two mathematical models (or mathematical universes), there will always exist a mapping function (also mathematical, obviously) between them... which, if you are following my logic, means that all mathematical universes are fundamentally (that is, generally, if not in exact details) equivalent. What this means is that the only real difference between any two forms of... existence (as to not limit ourselves with the term 'universe') is in whether they are finite (in at least one aspect) or infinite (in all of their aspects). This existence that we're all sharing right now is obviously finite in at least one aspect (otherwise, quantization of anything in it would be impossible), and this finite existence is, therefore, fundamentally equivalent to any other finite existence (that may or may not exist out there), and fundamentally different from any infinite existence (at least one of which must exist out there), which is what makes the simulation hypothesis such a non-problem to begin with. But, I'm now digressing, and moving too far away from the subject of this video. Star-within-a-star-within-a-star-within... huh? I can't imagine how that would work (in practice), but I'm always intrigued by any fractal (self-resembling) structures. This universe is undoubtedly fractal in nature, but that aspect of it would be the consequence of the fact that this universe is being... generated (for the lack of a better word) from "simple" (nothing simple about it) recursive (self-referencing, mathematical) rules. I now wonder what the limit of this star-within-a-star-within... etc. model would be. Singularity at the center of it all (which would defeat the whole purpose of the model, namely, trying to avoid black holes and their singularities)? Or an empty (holographic) sphere of some "volume" (that is, occupying certain region of space of certain volume), but with no actual space inside of that sphere? Those would be the only two options (that I can think of) for a black hole as well, so... what exactly is this model bringing to the table (that's actually new)? I guess... it would solve the problem of needing extra (never observed) dimensions of space(time) if you could have a black-hole-within-a-black-hole-within... etc. (if it works for stars, it must work for black holes, too) in just 4 dimensions. In other words, it seems to me that this model (using only 4 dimensions for its fractal structure, by decreasing the size of the structure in each iteration) is (mathematically) equivalent to a model that uses hyperdimensional space and then embeds (in that hyperdimensional space) the same (that is, mathematically equivalent) fractal structure by increasing the number of dimensions by 1 in each iteration. Then again, if one started with infinitely divisible space (which is [mathematically] equivalent to having infinite number of dimensions to work with), any finite number of dimensions could be constructed out of that (infinitely divisible) space, and no one existing inside of those (finite) dimensions would ever be able to detect all those (infinitely many) other "dimensions" (which aren't really dimensions, it's just how mathematics sees them), so having any finite number of (whether observable or not) dimensions in a physical model is... a non-problem to begin with. Hmm... In any case, there are certainly some interesting ideas in this model, regardless of whether the model itself has any correlation with (this, physical) reality or not.

@YummyFoodOnlyPlz

2 ай бұрын

It seems like you think the new is always more good and correct, the old that got forgotten should righteously disappear. That's an extremely dangerous bias to hold. Nature doesn't care about the chronological order of the gained knowledge and insights.

Thank You! Stéph.

OH wow. This is so interesting to me right now . I've been very interested in gravity among many other things lately. Your videos are superb. Thanks Sabine!🤓🙏✨️

Hello Sabina, as always, your videos are very interesting. Could you someday talk about the theory that suggests black holes could actually be quark stars? It's proposed that after the level of gravity resistance of neutrons, there could be another level of nuclear resistance in quarks. Regards

FINALLY Sabine touched on my favorite black hole theory!

I enjoyed the humor in this video. Thank you!

always a great video! and funny! and wise.

I've always pictured black holes as shells of frozen time. Objects seen falling toward the horizon approach light speed, so appear shorter in the direction of travel and are never seen to cross. As they approach c, length becomes zero and forms a shell, preserving information about it at the EH surface. Frozen time prevents a singularity as viewed from the outside Universe. The increased mass means the horizen moves a tiny bit away from the center for the next shell. When the black hole evaporates, information in those shells imprints on the Hawking radiation, preserving it.

@aadilnaqvi4399

2 ай бұрын

That's quite neat.

@krox477

2 ай бұрын

What is time??

@starman2337

2 ай бұрын

@@krox477 I think I know what time is until someone asks me to explain it. Then I know not.

@starman2337

2 ай бұрын

@@aadilnaqvi4399 And since time in the outside Universe goes by increasingly faster near the EH from the infalling object's point of view, the black hole evaporates before it has a chance to reach the center to form a singularity.

Wonder-full times 😂🎉 your videos have just been getting better. I can see the bottle-neck opening, this year is gonna be wild!

I like the idea your Proff gave of making two predictions, one for the thing and one for the exact opposite. This complies with how I view a similar idea in statistics where you make a hypothesis (a thing is a thing) and a "Null" Hypothisis (a thing is not a thing). I feel testing an idea and the exact opposite of that idea helps lead to evidence for and against the idea.

Sabine always with the fun.

Are those gravastar layers *turtle* shells? I mean, it could be turtles all the way down 🐢.

I'm so glad that you pointed out that the singularity in a black hole is a purely mathematical entity. If the Schwarzchild solution is correct, we can never know what is at the centre of a black hole. Of course, I have to acknowledge that the Schwarzchild solution is for a non-rotating black hole, which almost certainly cannot exist unless someone finds a way to break the conservation of angular momentum.

You are quite inspiring...not always totally easy to follow but still...🙂

I had a "prof" grade 7 science teacher like that, he had great answers but i never found out what they were. As soon as I asked a question, I always had the leave the class, sit outside and stare into space. Thats why i like it so much.

Ms. Sabine, I was wondering if you'd heard of the recent statement from Kerr regarding the singularity issue and any thoughts you might have. Love the work ♡

I think I came up with something like this years ago. I wonder if it's similar. I said in large dense objects like a planetary core, if the thermal pressure overwhelmed gravitational pressure, there could be a relaxation through the inducement of a quantum state, primarily lowering the energy via degeneracy... it was a pretty approximate idea, kind of a Linus Pauling. I had put it out on Twitter, I wonder if it was annoying because it was smart or stupid. I'm just a chemist

@AB608052

2 ай бұрын

Right, and the # of quantum states would increase as you went closer to the center. Layers maybe.

@starventure

2 ай бұрын

Ah, but what of the old "what would happen if I fell to the center of the earth?" problem? If the center of ANY mass is where gravitation is cancelled out by the surroundings, should not a black hole obey the same laws? Instead of a singularity at the center, a near singularity as a shell around the center with either normal matter(super high elements?) or absolutely nothing?

@AB608052

2 ай бұрын

It's been a long time since I thought about this, and I'm not a physicist, but I think you did a perfect 180 @@starventure

@AB608052

2 ай бұрын

Actually, that might be a quantum mechanics with gravity in it. Hey, maybe you're the smartest man in the world@@starventure

@starventure

2 ай бұрын

@@AB608052 The power of alcohol...

Sabine, I have been watching your excellent videos for years and I love them (however, that doesn't necessarily mean I understand them). I have noticed recently, that you appear to have developed an English sense of humour - Bravo!! Is this something you've always had or is it part of your ongoing 'development' as a brilliant content creator? Kind regards, Jim - England x

@3:33 😂😂" quantum something and gravastar" got me hard

Thanks for the great explanation! You’re funny, I love it ❤

From EHT observations, the exterior of GR black hole solutions has been tested to decently high precision. However, a significant bit of discomfort I have with black holes is that the interior of GR black hole solutions is an untestable prediction, so I'm inclined to believe that the existence of black holes with GR-conforming interiors is as much an article of faith as any of the alternatives. Eventually near-horizon effects should let us determine if there are exterior deviations from GR, though, but depending on how close the QG corrections to GR are to the Planck scale, we may, for any given black hole, have to wait for approximately one evaporation timescale before any differences are observable.

The final stage of a black hole's evaporation, depending on its initial size, could leave behind either a tiny black hole or a stable, dense object resembling a "dark star". Suppose a quark star or neutron star is in the center of a 'Black Hole' with special matter (Infinite compression is not decided by zero) and particle-antiparticle pairs near the Event Horizon. In that case, one particle falls In, and the other escapes. If the negative energy particle escapes, then the laws of energy and matter conservation are resolved. Also, the resulting mass from the 'Dark Star' or dead star which has an evaporation leaving a dead star, could account for some of the lost mass attributed to dark matter. Dark energy, or the dark particle escape from the 'Black Hole', accounts for some of the 'Dark Energy' and would probably be stronger nearer a 'Black Hole.'. I think if we can find the remnants of a 'Black Hole' or dead star with extreme density mass, we could work backward from that.

1:37 I wasn't ready for this lol

What a great channel !

Uhm, what is the name of the following theory? I'll describe it. This theory is where black holes are just simply empty shells of ultra-dense matter and light and pretty much everything that can get stuck on them because everything stops due to time dilation at not the event horizon but where time is at a stand-still (or just infinitely slowed) and that's also the reason why black holes can grow by bloating up as a bubble of empty void since it's the shell that grows. The shell itself has a shared gravitational point at the center (like celestial objects of similar mass in binary systems orbit each other around a point and not one or the other) where the gravity of the shell concentrates but also this point has no mass, nothing that would stop it from acting like a singularity, it's just a pure shared gravitational field. Again, an empty shell can also spin as well as orbit around that point at its center. It is similar to the holographic theory which suggests that black holes have all the information plastered on their event horizon but what I'm saying is everything is literally just plastered on the time-stop shell if you will. This is the most simplistic view I can think of on black holes and I would like to know if anyone is actually pursuing this idea.

Sabine I’m not a physicist but I am doing thought experiments of timeless physics and now I have a promising result that has potential unify physics, specifically cosmology with quantum mechanics and statistical mechanics. I was able to show how conservation of energy emerges from very simple fundamental principles. What do I do now? Do I self learn deeper until I’m at the level of a master degree? Or do I reach out to someone who can help me develop this proper? My idea shows how universe can manifest physically from a conceptual space, it shows how the universe got its boundaries etc. It all started by reimagining gravity as the least action through a mass-energy field

Been saying this for years. Black holes are stars that are in dark mode vs glow mode. It’s replicated in the lab, meaning dark mode vs glow mode plasma.

@starventure

2 ай бұрын

Red Supergiant - "I am strong" Neutron star - "I am stronger" Black Hole - "Who do you think you are kidding? I freaking bend light!" Supermassive Black Hole - "Dude...I sit at the center of galaxies...how strong do you think I am?" Sun - "I exist..."

@duroxkilo

2 ай бұрын

there are so many ppl saying so many things (and that's fine) but it appears it's extremely difficult to build a coherent working model of sorts at this point. at some point someone will achieve a breakthrough and maybe the solution will be elegant and 'simple' to grasp...

Somethings that bothers me about the typical blackhole model (and I'm no expert, so wouldn't mind having someone correct me if I'm wrong) is that we say someone falling in to a black hole, especially a super massive one, wouldn't really notice they're falling it, but there's two things they *would* see, and that's time-dilation causing both the light coming from the universe to blueshift, and hawking radiation to also "blue shift". That someone falling in to the blackhole would never enter it within the lift-time of the external universe, so the blackhole would evaporate before the object would pass the horizon. So it seems like passing the event horizon is purely theoretical thing that would happen under a static, unchanging blackhole. But from a more wholistic perspective, the object would be fried by gamma rays and extremely high energy hawking radiation, it's quite possible the hawk radiation would apply outward pressure too. The only time the blackhole would truely grow is if matter outside the blackhole could cause the horizon to expand outward. Also one of the spacial dimensions becoming "time-like" seems rather crazy and I hazard a guess that would be fairly observable phenomenon as well. So I've been very intrigued by alternative models.

Sabine, would you mind doing a video to explain the following to us like we're 5 years old. Here is the thought experiment: 1. Let's say we have a star or mass that is slowly gaining additional mass by consuming nearby planets and/or stars 2. As it gains mass it's density and gravitational force increases and it's diameter would either grow or shrink (please explain which is correct) 3. At some point it's gravity reaches the point at which light passing close by would be refracted (lensing) 4. Then the gravity reaches a point where light from the surface can no longer escape 5. At this point it's still just a mass that is still just absorbing masses that get drawn into it 6. So effectively this is what's referred to as a black whole, but underneath the event horizon it's just a large mass with large density and gravity 7. There should be nothing that dramatic occurring that would all of a sudden reduce the inner mass to a singularity where all the mass just magically disappears 8. So isn't this a simple explanation for how black holes form and what they consist of? Again, please explain why not like we're 5 years old. Thanks so much. Peter

@garethdean6382

2 ай бұрын

There's a whole bunch of problems with this. A minor problem is that as a star gains mass it increases its fusion rate, its temperature and thus the outward force of radiation and matter. Larger stars resist adding more mass, above about 100 sun's worth a star can't grow larger feeding on gas. Above about 300-500 sun masses it's actively ejecting entire sun's worth of mass as a powerful solar wind. (Incidentally this means that more massive stars get larger, not smaller as they gain mass, but their cores get smaller and more dense.) The major problem is that as more mass is added, objects in the star must move faster to avoid compressing. A star so massive that light cannot leave its surface will have particles just under its surface that need to move faster than light to avoid collapse; no matter can do that without having more than infinite energy. So all the particles in the star will be too slow to avoid collapse and will all collapse inwards forever. Creating a 'traditional' black hole. Before this though there are other processes that will kick in. Core-collapse Supernovae happen when a star's core gets too heavy and collapses, forming a black hole or neutron star,Type1a supernovae happen when a white dwarf gets too massive and instantly fuses,vanishing in a blast of energy. Pair-instability supernovae happen when a star's core gets too hot, creates antimatter and collapses. We've even seen a few neutron star mergers, where two neutron stars collide, fracture and form a black hole with the release of a massive blast of energy and heavy elements.

@danielh.9010

2 ай бұрын

I'm not able to give a simple answer. However, there are classical examples in astrophysics where matter accretion occurs, e.g. en.wikipedia.org/wiki/White_dwarf#Binary_stars_and_novae . About the conditions for the creation of a black hole see en.wikipedia.org/wiki/Black_hole#Gravitational_collapse . About question 2: That's difficult to answer and depends on which object we're talking about. For example, en.wikipedia.org/wiki/Stellar_evolution#White_and_black_dwarfs states that higher-mass white dwarfs have a smaller radius than lower-mass ones. About question 3: Light is always "refracted" by gravity. It's just that the effect is normally so small that it's barely observable. But stars are massive enough to cause measurable gravitational lensing. And black holes even more so. About question 4: At that point a black hole has already formed. Matter always undergoes gravitational collapse, and if there is no physical process that is able to generate enough pressure to stop the gravitational collapse, then it will collapse into a black hole / singularity. Typically, in stars the process that generates the pressure to stabilize the star is the fusion reaction inside the star. Once that fusion reaction fizzles out the star quickly collapses. If during that collapse it becomes dense and hot enough to allow fusion of heavier elements then that fusion process will halt the collapse until the fusion reaction fizzles out again, and so on. In the end the star's core collapses either into a white dwarf or a black hole or something more exotic (e.g. neutron star), depending on the mass. If at some point an event horizon forms (i.e. light can't escape) then the black hole has already formed and the matter inside of it is quickly collapsing into a singularity. About question 6: For all we know that mass is concentrated into a singularity. The mass limit at which matter collapses into a black hole is the Tolman-Oppenheimer-Volkoff limit, and is somewhere between 2 and 3 solar masses. About question 7: Wrong, see 6. Also, the mass doesn't disappear. It's part of the singularity. We don't know any laws of physics that would prevent the mass from quickly collapsing into a singularity. We just expect that there are unknown laws that prevent if from being concentrated into a point.

@danielh.9010

2 ай бұрын

By the way: here is high-quality animation of the visual effects while falling into a black hole: kzread.info/dash/bejne/ZqaI2JuwptnHpJs.html . Yes, the event horizon is not "magical" and the laws of physics still work normally inside of it.

I remember first hearing about gravastars several years ago. And MECO's. You need to do a vid about these too.

When something is uncertain or unknown, I think it is good science to consider and idea and its opposite, and make contrary predictions based on each.

Came for the science, stayed for the dry humor. Thanks Sabine

Greiner's Field Quantization is my favourite introductory book about Quantum Field Theory

"The fact that it's an answer to the equation doesn't mean it actually exist" But does that mean that it might be able to exist, even if it doesn't happend naturally? (In an artificial/experimental setting for exemple?) I guess it could also show that there is some constraints missing?

The density of a black whole goes to infinity. Infinity is a place holder for "Our math and physics does not work here, yet." Think of infinity as a TODO in physics.

Sabine, I went to the Black Forest to visit my ancestral village but in fact it is a very green place. I demand an explanation for this!

The best explanation I have is that a Black Hole is the next step of Neutron Star in terms of density... The more dense a star gets the smaller it is. (Neutron star is smaller than Earth and white dwarf is Earth sized). Therefore the Black Hole is probably a dot.

I recently learned what the “nothing can escape a black hole not even light” means. It’s the escape velocity that is greater than the speed of light and since matter can’t travel faster than light is unable to ever get past that high escape velocity. That’s a big point I didn’t understand. But past the event horizon if you had some way to travel faster than light, you could possibly escape. That’s a bit exotic and I think probably not possible but I like the idea.

Very very very very very very INTERESTING!!!

Everything has a singularity if you squash it enough. An object big enough to rip stars apart does not need to be infinitely small. It simply(?) needs to be dense enough for its gravity to trap light.

"Gravastar" to me sounds like: "It looks like a duck, it walks like a duck, it quacks like a duck, but it's not called a duck!"

Have I actually heard the argument that "physicists have not yet observed impacts on the surface of a black hole/gravistar"? However, there is currently no Tesekop that has the necessary resolution. Strictly speaking, no black hole/gravistar itself has been observed yet, only secondary effects. That's why all solutions to Einstein's field equation are always just theories of what could exist, but not yet confirmed reality. A difference that has been often forgotten lately.

A variation of a question by Frank Zappa: Does humor belong to physics ? Gravystar

"Scientists can be disappointingly human." Sabine, you're freakin' awesome.

Hey right on, cool video😊

Ever since I learned about black holes and the big bang I wondered if the big bang was the product of a black hole in another universe in a multiverse. I felt that this would solve two problems. 1. there’s no need to theorize a singularity and 2. This would solve the issue of the loss of information in a black hole. Our big bang would be opposite of a black hole, a white hole spewing forth into a new universe matter swallowed up by a supermassive black whole in another universe in a multiverse.

@bestaround3323

2 ай бұрын

But the mass isn't gone, and the information may not be lost

Interesting video Sabine. What I want to know is what separates the layers in these so called dark stars? 🤔🤔

I don't think there is a star in the black hole. In the video at [5:11] you will see the picture taken by the event horizon telescope. If you pause the video and look at the very center of the doenut shaped (EHT) picture. You will see curved space-time and the black void. The curved space-time concaves down and looks like the edge of a cliff. And looks like the edge of a cave downward, before it goes dark. Also, it looks like a waterfall concaving down. But, I think it's the hot plasma at the very edge of curved space-time, the event horizon. Professor Sabine once said in another video that gravity isn't a force, its curved space-time. Maybe a black hole is like a cliff, like a cave like a waterfall. But its not a force, a force, it's curved space-time.

love this

To cite Stephen Hawking from the event horizon Wikipedia page on the topic of the (non-)existence of black holes: "One of the leading developers of theories to describe black holes, Stephen Hawking, suggested that an apparent horizon should be used instead of an event horizon, saying, "Gravitational collapse produces apparent horizons but no event horizons." He eventually concluded that "the absence of event horizons means that there are no black holes - in the sense of regimes from which light can't escape to infinity."[3][4] Any object approaching the horizon from the observer's side appears to slow down, never quite crossing the horizon.[5]"

The problem with using binary black holes as a measuring device means they have a unique problem of having to orbit a barycenter. So they are likely not really acting as black holes until they complete their merger at which point we STOP seeing the gravitational waves which means the black holes are NOT rotating when they're individuals.

There's no better place to grow your knowledge than Brilliant? Not true! Stay scientific, dear Sabine.

Finally some sense in black hole research.

You have the best science channel on All of Youbtube. Respect on your name !.

The major problem is; people have forgotten that mathematics is a language. It is not the "backdoor to the codebook of the universe" What I mathematics? The greatest language that humans have ever come up with. It allows us to communicate in such a precise way that it eliminated the miscommunication of lesser languages. But.. as with any language; it only says what you tell it to say

@Woxhergaztor

2 ай бұрын

Why are you so sure about this one?

Aaawwww kitties eating catnip, noice!😊

Sabine, I apologize if my question makes no sense--I'm a physician, not a physicist. As an object crosses an event horizon to be torn "apart" (by tidal forces?) what do we mean by "apart"? By that I mean (I think!) that as the object accelerates across the event horizon, and even as it approaches the theoretical singularity at the center of the black hole, will it not experience a radically-changed space-time coordinate "reality" that we think, from our frame of reference, imposes these "forces"? Maybe it only comes "apart" in our thinking because we are retaining our "outside the event horizon" space-time reality? As the falling object's space-time changes, it changes too? Will it experience any disruptive "forces" at all, from its perspective? Does this make any sense? (probably not!)

@garethdean6382

2 ай бұрын

Tidal forces apply outside the horizon in exactly the same way that the Earth-moon system experiences tides. They are felt by all objects and are not dependent on reference frame. An object falling into a 'small' enough black hole will be shredded to atoms in all perspectives, including its own. Inside a black hole the relation between an objects time and our time becomes indistinct. In that way we might be able to claim that no further disruption really happens. However from the object's perspective spacetime curvature becomes more severe closer to the singularity. In its own perspective it will continue to be disrupted. (Assuming that singularities are a real, physical thing.)

@Spherical_Cow

2 ай бұрын

Close to the singularity, the gravitational gradient becomes extreme. That means, for instance, that if you're falling feet-first, the acceleration of your toes is much greater than that of your head. This difference in acceleration across the dimensions of any macroscopic object becomes large enough to overcome the electromagnetic and even atomic forces holding that object together. Thus macroscopic structures, then molecules, then atoms, then nuclei, and finally even nucleons and quarks are torn apart as you get closer and closer to the singularity.

@rdjinaz

2 ай бұрын

Thank you for responding to my questions. You've expressed my understanding of this scenario. I was just curious to know if the "space-time" BETWEEN the molecules (or, even their component atoms) might not be proportionately distorted in radical space time curvature so as to mitigate the tidal forces?@@Spherical_Cow

@Spherical_Cow

2 ай бұрын

@@rdjinaz when matter is in freefall (such as, for instance, in orbit around the Earth, or falling through a black hole), it is moving within spacetime - but spacetime isn't really moving together with it (particularly if we ignore frame-dragging, which for any masses that aren't at least planet-sized, is minuscule to the point of being completely negligible.) Indeed, spacetime is the very embodiment of a coordinate system, through and within which motion is defined to begin with. The space between molecules or subatomic particles within the infalling object, IS the curved space inside the black hole: all these bits and pieces are each attempting to independently follow their individual, geodesic trajectories through that curved space - trajectories that would be completely defined only by instantaneous position and momentum, if it weren't for mutual interactions (such as electromagnetic, weak, or strong) between these particles and components. Near the singularity, the inertial trajectories of nearby particles begin to deviate so strongly that the particles are pulled apart from each other despite any forces that were trying to hold them together.

@rdjinaz

2 ай бұрын

@@Spherical_Cow Thank you. Something tells me our understanding of black holes is a "spherical cow". Great "handle"!

Im saying this for years. Singularity is just mathematics but not reality.

Sabine, does this mean that black holes are behaving as atoms do? Exhibiting properties similar to the electron shells and the nuclear shell model?

Great. They took out the coolest 2 things about a black hole, event horizon and singularity. This is why we can't have nice things

The singularity in a black hole is a mathematical convenience with inconvenient implications. We model normal Newtonian masses as point masses, which are singularities, but nobody thinks there is a singularity in the center of the Sun or the Earth.

Haven't some physicists at one time or another argued that GR can't be quite correct because the equations allow solutions that include singularities? Some QM equations "blow up" and you've got renormalization to sort of take care of that. In GR maybe someone might come up with a renormalization procedure that will avoid a singularity. Infinities and singularities usually point to a problem somewhere. Unfortunately, mathematical tricks don't seem to tell us anything about nature.

@nathanoher4865

2 ай бұрын

Yes, in fact, basically every physicist, including Einstein himself, are aware that general relativity is incomplete. Incomplete doesn’t mean incorrect, as general relativity produces some of the most accurate predictions ever, and is one of the most well-tested theories ever developed, to date not having failed a single experiment. Incomplete refers to the fact that singularities should not exist, that it is incompatible with the behavior of objects of microscopic scale, and that it operates under an assumption that is not proven. That assumption is that the speed of light is constant. We have proven that the speed of light is isotropic to an incredible degree and there is little reason to assume the speed of light isn’t constant, but it is taken as a postulate by the theory of relativity. It’s not proven. Some theories of spacetime are based on a speed of light that was faster in the early universe but has slowed down to its current stable value today. There’s a lot of unanswered questions that remain, but the theory of relativity is by no means incorrect, just not the whole picture. Einstein’s anecdotal “last quest” was trying to come up with a way to reconcile his theory with quantum field theory. He wasn’t able to, and no one else since then has been either.

It's a very strange coincidence, as for me, that this video was posted today. Today I got stuck with a spoon of peanut butter at breakfast. I was digging some butter, and then watching it slide back off the spoon. Thick, thinner, thinner, until if was so thin it could no longer hold its own weight, and dropped. "Looks like a singularity to me" - I thought - "Imagine if singularity works the same in black hole, but then the singularity expands to droplet and should be contained somewhere... What if singularity is just a new start for matter, a weird way to recombine, and there could be cascades of them, because mass isn't going anywhere..." And now I see this.

let's all remember it's called "singularity" because nobody can really prove for sure what it is. at the same time, describing its observable properties, while very useful, is not synonymous with knowing

One of the few things we can learn from history is that if there is a mathematical solution of gr then it exists somewhere. Iirc schwarzschild solution was initially discarded on the basis of being unphysical

@EinsteinsHair

2 ай бұрын

It was unphysical. Schwarzschild was solving for a non-rotating star. Of course it had an infinity at the center, but even Newton's equation had that infinity, but we knew all of the mass of a planet or star was not actually at the center, so we knew this was unphysical. Einstein and Schwarzschild noticed the odd radius, but since most of a star's mass would be outside the radius, clearly it was some sort of mathematical artifact. Neither of them proposed that there could be a new type of object where all of the mass was inside the radius.

I liked the subtle reference at the eagles hotel California.

coming from a math background this is so interesting. i have hard time narrowing down my question, how do scientists and physicists know when the math is too good to be true

Black Holes reminds of Death, you can't go in & come out, you can't Die & come back, and you can't tell what's on the other side for both Scenarios.

1:54 what are the pieces made of?