What if Singularities DO NOT Exist?
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- Опубликовано: 21 фев 2024
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It's not too often that a giant of physics threatens to overturn an idea held to be self-evident by generations of physicists. Well, that may be the fate of the famous Penrose Singularity Theorem if we're to believe a recent paper by Roy Kerr. Long story short, the terrible singularity at the heart of the black hole may be no more.
Roy Kerr Paper: Do Black Holes have Singularities?
arxiv.org/pdf/2312.00841.pdf
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Roy Kerr, being almost 90 years old, had been looking at this debacle for half a century, and then said “fine, I’ll do it myself”. What a chad.
True
And Rodger Penrose is 92
Ageism be damned!
@@tylerknight99 true, but Penrose Singularity Theorem was published in 1965, when he was around 34.
Sounds like good news for monkeys.
Kerr is still shaking things up at 90 years old. What a beast.
Sorry to general public that is too old to do anything recently it seams.
That's because the young people are caught up in gender identity than physics. Neil Tyson for instance.
And being snarky about it! That sassy old bastard!
@@jonathandawson3091 stop making yourself look like a clown
@@jonathandawson3091you are not welcome in these spaces
10:45 It can’t be put into words how utterly disappointed I am that this isn’t called a Ringularity.
Both are technically correct terms
A thingularity
Nice one! Ringularity it shall be!!!
That has a nice ring to it
I accept your termination.
This is one of the best videos Space Time has ever produced. Technical, succinct, refers to sources, gives references, and great graphics. Whoa! Well done.
+1
That's EVERY PBS spacetime. Lol
@@astrophyz Nobody is perfect. On a channel almost a decade old, it's normal to get highs and lows. Some video were a bit weak and erratum were given afterwards. And more rarely some topics were too far from their field of expertise.
14:08 lol, though
Agreed
Man, he's 90 and still contributing to physics. That's life goals right there.
Thank God for boomers😂
Exactly!!!!!!!!!! Enough of the “retirement ‘communities’” already.
@philallsopp42 what I consider to be a good "retirement" would not mean at all that I would stop contributing to the world, but rather doing it on my own terms without having to chase after money all the time. I would be really much more productive. I don't think of retirement as stopping working. I think people would more say like an eccentric millionaire
@@emersonmsd Penrose is not a boomer. He's one of the few golden gen left in the world. Uncomplaining and tough as old boots 🙂
@@emersonmsd He was born in 34' so he actually predates boomers by more than a decade.
I read the paper with ever-increasing levels of incomprehension. Eventually I came to
"Since we had a preprint of Papapetrou’s paper we put the Kerr metric into his canonical form. The covariant form of the metric, ds2, is then a sum of squares of a suitably weighted orthonormal basis,
ds2 = Σ dr2 − ∆ dts + a sin2 θ dφs2 , ∆Σ
+ Σdθ2 + sin2θ (r2 + a2)dφs − adts2 (13) Σ
We stared at this metric for a very short time, gave up and went for coffee. "
I did the same.
XDD
There's a point where math becomes an alien language with all the variables. 😂
@@HichigoShirosaki1 Math has already become an alien language considering reality is "overrated" to them.
@@Grundrissewell, as someone that understands those words even though I can't see the formula because RUclips messed up with the formatting, they are words that are really close to the our daily lives. Orthonormal bases and covariant matrices are very important for Signal analysis like for wifi, MRTs, Bluetooth etc. And canonical forms are very basic university math.
Although all these mathematical operations combined on Einsteinsteins field equitions are far above my knowledge.
Just wanted to share that those words sound more complex than they actually are and any electrical engineer knows them
Came here to say similar - well said! - love PBS SpaceTime, I thought I mostly understood others I've watched, but this one completely lost me.Trying to retain my sanity; I was told a Singularity was where physics breaks.. infinities etc.. but maybe once things are close enough to the centre, the Uncertainty Principle means they can't be said to be AT the centre, ever, so, no Singularity? Also.. just MY take, but I think too many people assume things falling into a black hole somehow teleport to the centre.. if YOU crossed the Event Horizon, you wouldn't notice.. you'd just keep falling, or notice your altitude had dropped below the SchRad and say "Ohh shii.." but then maybe keep orbiting inside it, spiraling inwards maybe.. for a LONG time, especially with time dilation.. maybe nothing is ever "at" the Centre, just close to it? Also, if Physics breaks, it just means some rule we don't know yet will apply.
Here are some reasons I've always felt black holes are more genuine physical object than the romantic singularity that we apparently "need event horizons" to "hide" from us:
1) Black holes are physical objects. They grow, they spin, and they move through space and time, just like an extremely heavy star or planet
2) Rotations from black holes are to be expected when you consider that planets and galaxies have a 'spin' due to the summing rolling motion of colliding objects over time
3) The event horizon is just a blind spot where photons lobbed back out are too weak to escape the aptly named 'escape velocity' of the black hole's mass, we already know this. Even if there's a 'single point' in the middle of it, it would still be a degenerate mass correlating to the size and spin of the black hole itself as observed from the outside, wouldn't it? We have neutronium in our textbooks to suggest what pulsars are made of. Has anyone ever considered a black-holium degenerate matter? My point being, that violent mass would still be following some kind of compressed, ugly geodesic.
Unfortunately I was taught in school to not ask what if questions because they are endless and most instructors do not have the knowledge or time to tell you an answer. I LOVE PBS thanks so much for giving us these in depth analysis' on topics like this. It's really great seeing the scientific method being practiced real-time and gives you an inordinate amount of respect for all the beautiful minds thinking of these things.
Yeap, school is a horrible place for those who really like learning in depth or have fast pace for the topics approached in class
They still dont have the knowledge. They can try to explain things, but they truly dont know for sure. Its just a best guess. Its mind blowing to even have the concept of existence. Because if there is existence now, then there always had to be existence. And to think that there was never a beginning and there will never be an end can sometimes overload the mind to where it has to shut off for a second :D
There is no science that even begin to explain this because there is no way to test it. And that in itself is mind blowing.
I realised the uselessness of asking deeper questions when my mathematics teacher revealed that she had to study each new year's textbook to find out if there was anything new in them, teach herself the work, AND that she didn't do so until it got to the point where she had to teach that topic.
I wasn’t taught anything of that sort in school. Schools don’t teach things like that.
@@morlath4767So basically your teacher kept up on developments and you’re chastising them for doing their job… Great story…
Here's an observation that I think a lot of people here are getting wrong:
Many comments are saying "I didn't believe in singularities anyways!" and yeah, many physicists agree. It's been said even on this series that singularities are simply gaps in our math.
The point is that we didn't have a solution, and that's why this is important. Of course you didn't believe in singularities. But while the problem was obvious, the solution was not.
What the cited paper is saying is "What if singularities don't exist *even within the current theory*."
As stated in the video, everyone wanted to get rid of this problem, but assumed we needed a new Theory of Everything that combined GR and QM.
But this is a potential solution that shows that GR might still be functional. Is a new Theory of Everything still the goal? Of course. BUT, maybe GR and QM are not scrap that needs to be thrown out, but maybe 2 puzzle pieces that CAN fit together, to show the full picture. And even if GR is thrown out eventually, the more we refine it, the better our eventual understandings will be.
13:40
If there is a theory of everything eventually, it might result in the finding that neither the theory of relativity or quantum mechanics are fundamental, but rather emergent. If that turns out to be the case, then they don’t have to coincide.
@@user-me5eb8pk5vDon’t bogart that joint, pal.
@@melgrossI like that. Having a bit of faith, and yes it is strange.
I'm looking forward to the updated version of Bohemian Gravity when we figure this all out
Dear whoever edits/does music for these,
✨ PLEASE make the outro quieter! I love listening to these before bed and the last 15 seconds are so much louder than the entire episode. THANK YOU! 🙏 ✨
Sincerely,
A mom who just wants to peacefully learn and fall asleep to science
You got it! We're happy to help you dream of science. . .
Also consider watching How It’s Made for reliable fall-asleep material
@@pbsspacetime thank you!!!! 🪐 ✨ 🌌
I found the music, including the intro, rather loud. Matt's audio is absolutely on point for this one. P.s, I love cars, engineering and astrophysics. Even though I struggle to understand the latter at points 😭🤣 much love PBS crew 💗
@@thedownwardmachineI watch a lot from the Astrum channel! He even had a “sleep space” podcast 😅
It's great to see Kerr's thoughts laid out clearly at this point in his career. Some folks down my little branch of the physics family tree were with Kerr in Texas in the late 60s. As a grad student, I once had the pleasure of hearing him talk and then going to dinner. At the time I was struggling with the concept of singularities in the physical universe, but he provided an elegant model that broke down a mental barrier for me immediately. Thanks for bringing this paper to light, I doubt I would have seen it otherwise having been out for the game for quite some time. Cheers!
do you remember what that model was?
I'm glad PBS is still going after all these years. And still has decent content.
PBS FRONTLINE is pretty solid too. No agenda just straight facts and a story built on them.
"Singularity-free spacetime!" - Sounds like a great slogan for a T-shirt.
I would have said it sounds like a marketing gimmick, like "splinter-free toilet paper."
@@cbunn81 😂
Yes please, I’d buy one
Put me down for one of those
@@cbunn81 Maybe so; but with some of the lower quality 'eco friendly' bathroom tissues I've seen out there, splinters are a legitimate concern. 😬
Roy Kerr dropping papers like it's a rap battle, he is really cooking!
The Physicist Aussie O'dowd could captivate any large crowd, raise their minds higher by lighting their fire!
Physicists have rizz
nonsense...:) Sycophantic nonsense...:)
By the way, before you go up on your high horse, that is just a request for a scientific argument. You know what I wrote against Kerr's argument and the idea of a Singularity.
Typical aussie to bring nations into it. Grow up, dude. However, fyi, Kerr is a Kiwi physicist and is guessing a bit. Main guys in the equation here are Penrose and Hawking, both of which are/were English.
Why does this comment sound like it was written by ChatGPT...
@cerostymc That's because it's combined stolen comment by a bot-like user. The second half of the comment was posted by someone named @claritas6557 two days ago - you can find it by doing some scrolling. I'm guessing the first half of the comment is stolen, too.
I've seen this user with their copy-pasted children comments on some Skibidi Toilet videos and useless shorts before. So it's pretty clear to me that they are absolutely not interested in black hole physics or this discourse. They're only interested in accumulating subscribers for their "special" channel.
I don't have the mathematical knowledge to understand, but I do remember a physics professor making a couple of passing comments about the "woo" like nature of singularities, string theory, multiverses etc. and just how much bunk he felt was given undue credence. This was 13 years ago so...
It does make sense a black hole could be an extremely dense object that we can't yet conceive instead of a single point with some infinit density.
I'm really glad he more or less came out and said "you're taking the models too literally, it's probably just some kind of really dense star in there". Looking at a model throwing infinities and assuming the model is so perfect the universe must be breaking is a bit silly.
Another one that falls into this is the conclusion that any information propagation with an effective speed greater than c must constitute reverse time travel. The key assumption there is that it would be reverse time travel *from the perspective of an equally valid inertial reference frame* , an "inertial reference frame" being a non-accelerating one. The only way that a universe can have an infinite number of equally valid inertial reference frames is to LACK GRAVITATIONAL INTERACTIONS, something you may have noticed our universe does not. In a universe with gravity, the only valid inertial frame is the "co-moving" frame, the center-of-gravity reference frame of the universe, all others are accelerating.
Your opening line reminded me of the expression:
All models are wrong. Some of them are useful.
Does this also hold true for the tachyonic antitelephone? Is causality preserved in that instance as well? If so, how? I'm aware it's a silly thought experiment but I'm genuinely curious.
Not my area of expertise, but the idea of physicists taking models too seriously is something that I'm inclined to believe is more true than black holes actually being incomprehensible.
As a programmer it reminds me of coming to a conclusion when programming that fits strongly with your model of whats happening, only to realize that there was something entirely different happening that made your model not apply.
For example, suspecting memory corruption to explain a bug still existing in pointer-heavy code after making a change that should logically fix it... when the real culprit is that you've been building an old copy of the code the entire time. 😅
He's still using the same model, GR, just not throwing out as much of it
@@JudoGeoffall models are based on incomplete and erroneous mathematics. a perfect model can only be created if we already knew all, which we do not. but sometimes those errors are usefull allowing us to discover something new. so yeah, the statement isnt wrong.
This video has hit me harder than many others before it... and I am so grateful for it. My entire life I have balked at the idea of a 'literal' singularity in BHs - but I just assumed that people waaay smarter than me knew what they were talking about when they talked about 'collapses' and 'singularities', and whatnot.
The idea of the 'event horizon' makes perfect sense to me, it's just an emergent trait that is the byproduct of the extremes of gravity and light, but the idea that suddenly all this mass at the center - which was able to be 'squished' while in star (or neutron star) form suddenly cannot 'squish' anymore and instantly condenses down to 'nothing' but still has mass (and therefor gravity) has never made sense - yet it's just talked about by everyone in science community as if it's just another Tuesday.
This is the first time in my entire adult life I've ever heard from someone who actually works the in the astrophysics (AP) scientific community mention anything about the fact that most members of the community do NOT actually believe in a 'literal' singularity when talking about BHs.
This is a BIG deal that does not get talked about - it SHOULD be talked about - very publicly. I understand that we have no 'proof' in GR of the non-existence of literal singularities, but the entire science community would probably benefit from a concerted effort to stop referring to it just as a 'singularity' rather a 'mathematical singularity', or making a distinction between the common parlance of 'singularity' versus a literal singularity that I imagine 99% of the rest of the world just assumes it actually is because it's what they've been told ad nauseum - and thus, just take it on trust from experts/educators.
Honestly, it feels like a relief that I'm not a crazy person for questioning the existence of 'literal singularities' that has been parroted (even if unintentionally) by every speaker on the subject, either in a classroom or RUclips video, or that somehow I'm just too inexperienced (or dumb) in the specific mathematics to comprehend that particular truth.
This kinda feels akin to the whole 'Neptune and Uranus actually look the same' that happened late 2023. The members of that community already know and got so used to the idea that they forgot to remind the rest of the world that it's not actually the case and so entire generations of people have grown up to become scientists themselves and are then 'mindblown' when they learn later in their own studies that it's not actually a thing. For BHs, perhaps when the scientific community first started talking about it, they all understood that 'singularity' was shorthand for the 'mathematical singularity of GR', but that distinction seems to have been lost over time - especially when talking to and educating the public, at large.
Y'all need to send out a memo to the rest of the AP community, especially those among you who take the time to interface with the general public (thank you for that, by the way!) and make an effort to dispel the long-ingrained conception of a literal singularity and start referring to it as either 'mathematical' or some other way of helping to make the real-world entity distinct from the long-standing assumption of a mathematical construct made manifest in our own universe.
Anyways, thanks Matt (and the rest of the SpaceTime team) for everything you do week in and week out for the rest of us non-AP'ers!
A lot of theoretical physicists believe in dumber stuff than that. But a safe bet assumption I have heard from several AP's by now has been that infinities while useful in mathematics, do not occur in nature.
Tl;dr: If you don't struggle with reading bus routes never assume someone just knows better. Find out if they do.
I mean, I read every word, and best comment hands down, echoed a lot of my thoughts along the way. However it's the Internet after all, so I'm playing Mr funny guy.
Communication from academia to lay people is disappointingly scarce.
I feel like there is a similar thing going on with Sabine Hossenfelder's work on superdeterminism, where everyone seems to just accept the free will assumption required by Bell's theorem rather than discussing its validity. I didn't even know Bell's theorem relied on an assumption of free will until I saw her videos.
@@larrymunn5279 Except many will argue that the universe itself is infinite, that it stretches out infinitely beyond the observable universe.
People often forget that a spherical object has most of its mass on its outer layers. Just like you'd essentially be weightless at the center of the earth, a blackhole's center would be unable to reach singularity pressures because of all the mass around it pulling it in every direction. People also often don't realize that a blackhole's surface isn't actually at singularity densities either, it's just at a density high enough to keep light from escaping, which isn't just from the immediate surface facing you, but also every layer behind that shell too. So ironically, what we see when we're seeing a blackhole, is not even anything approaching a singularity. What's really happening with a blackhole is gravity becomes soo high that all the mass is essentially converted into the most basic building blocks of matter, with the outer layers being atomic parts and the inner layers being subatomic parts. It's that simple. All a blackhole can ever do is generate gravity and radiation, all other matter interactions essentially cease. If you created a blackhole out of matter that is made up of entirely a single element, it would be no different than another blackhole made out of a different element, the only difference would be the size, depending on the atomic weight of the element and how much of the element you used to create each blackhole. Ironically, blackhole's are actually pretty boring in the end. They do something you don't see elsewhere, but it's literally all they do, there's nothing particularly special after that. It's just a thing that happens when enough matter coalesces.
I'm really glad that the PBS channels exist, but especially Space Time. Physics has always been something that fascinated me, but I was forced to drop out of my physics class in high school in order to graduate on time (due to a slew of problems caused by my guidance counselor) despite being one of only 3 people who grasped the material we covered in the first month or so, and unfortunately I was never able to pick it up even recreationally in college due to scheduling conflicts with my required courses. This channel does a great job of breaking down complex concepts in a way that is easy to follow with a basic understanding of physics and allows to me to still be able to learn and understand more on my own time without shoveling money into further education. Seriously, thank you guys for taking the time and effort to make these videos and in an easily accessible way.
Although I barely understand 5% of the mathematics and physics behind it, I enjoy watching this show. Very relaxing! Thank you!
Like lying on a bed of nails.
Matt, many years ago, you did a video titled (something like) “how to build a black hole”. In that video you described adding mass to a neutron star to grow the event horizon beyond the stars surface. The implication for me was that the neutron star didn’t care one little bit that it had an event horizon inside it that gradually grew beyond its surface. After watching that video I was left with an image in my mind of black holes just “containing” a neutron star, happily existing, doing what neutron stars do, just that it now had an external event horizon. The discussions in this video bring me back to that idea.
this is what makes intuitively the most sense in my mind. Whatever is left inside the inside horizon is obviously an exotic object that we cant know but its fascinating to ponder what lies beneath
well if you add mass to an object, it doesn't really grow an event horizon that was already there as a physical object, it just grows the size that all of the mass of the object would need to be compressed within in order for it to form a black hole. for example, if an object with a radius of 100 km has a Schwarzschild radius of 50 km, that means that all of its mass would need to be compressed into that radius for it to form a black hole
He also brought up, that a 'singularity' could be a Planck star, as it could not get any smaller, in an earlier episode.
neutron star jail (it was caught evading taxes)
Yeah he also suggested this in his video, "Are we INSIDE a black hole"
It's a fascinating theory we can't disprove.
I’m not a physicist but I am a huge space nerd. When I’ve pictured a black hole, Kerr’s model seems to be the most logical. I’ve just always imagined a black hole is more of a spherical/ pancake shape just like in the model.
Great to see this!
We suggested that they were just super massive atomic nuclei within one of the theoretical stable zones.
That was in 2002. It was a mathematician from Hawking’s department, a Swedish PhD student and myself.
kerr is like 90 and still producing new ideas. what a g
To me a true singularity has to be the plank length or less.
But I'd still consider that black holes can exists.
@@ehsnilswhat are you even responding to
we literally have a photo of a real blackhole its not a debate topic anymore, they do exist
I agree ❤
@@ehsnils *Planck*. Look it up.
I had seen this covered by another youtuber, but your way of explaining in-depth, making the intuition from the maths easy to grasp, really made me feel like I understand what the big deal is now. Great Channel!!
This is exactly how my uncomplicated brain figured it worked. Things enter a black holes event horizon but never reach the center and at the center is the remanent of a dead star...
my idea has to do with time dilation. the gravity causes time to move slower and slower relative to the rest of the universe, as objects approach infinite density, the singularity. so in every blackhole time is moving so slowly, the universe restarts before anything ever reaches the singularity. i know it's probably super dumb but i do try my best hoping for the butterfly effect, possibly inspiring a real idea somewhere on this planet. i almost cant believe how much we've learned about the universe, but i want to know more
@@brandoloudly9457It sounds like a beautiful method by the Universe to prevent breaking down into something inconsistent or ilogical, which thus far has proved to always be the case, afaik
As you approach but not reach singularity time passing approaches 0 or in other words the time to reach singularity approaches infinity. Even if black holes do not evaporate there will never be enough time to reach singularity.
that's what i said bro @@donmead6751
This is one of the things I've been thinking for quite long time. The concept of the existence of a point where there's infinity density and infinity gravity sounds quite implausible. The center might be a place with unimaginable density but it doesn't mean it is infinite. The most obvious answer is that our mathematical models are not developed enough to comprehend what's truly happening at the center of a black hole. I am glad I found this video to shed light on this topic!!
I was giddy when I saw the new Kerr paper. Thanks so much for devoting an episode to this discussion.
Our local mad genius 80 year old JP Petit has been pounding this for years here in France (but he's been black listed from publishing for longer) I hope he'll find the fire to keep pursuing his cosmological model (he called Janus) with other people.
The closest thing to witnessing a singularity in my life is when I reached the bottom of an ice cream cone of a drumstick.
Yep ,not even physicists know what a singularity is just conjecture.
I mean ok ,in the end who cares how does it affect us humans in the end ?
There are many singularities you can physically put your hand on in robotics. Fun ones too. The basic rigid model does predict them, but reality has elasticity to avoid the Universe collapsing on itself into a folded paper.
And all there is at the bottom is a cone of chocolate
Did you begin orbiting or found you devoured it?
Dr. Matt -- as usual -- another fabulous and educational vid... I usually view them multiple times... keep on keeping on... best vid on the net!
Gemini summary of Kerr's argument:
Penrose's singularity theorem is based on null geodesics, which are the paths traveled by massless light speed objects. These paths are tracked by an affine parameter, which is a measure of the progress along the path.
Penrose's theorem shows that affine parameters for null geodesics are bounded inside black holes. This means that the paths must end at some point, which is interpreted as a singularity.
However, Kerr argues that affine parameters don't track time in a meaningful way. They simply measure the progress along the path, without taking into account the fact that light doesn't experience time.
Therefore, a bounded affine parameter doesn't necessarily mean that the path comes to an end. It just means that it has a finite length.
Kerr also argues that the singularity in the Penrose theorem is a mathematical artifact. It's a convenient way to represent the gravitational field generated by a rotating object, but it doesn't necessarily correspond to a physical singularity.
In the Kerr metric, which describes a rotating black hole, there is no point-like singularity. Instead, there is a ring singularity, which is a looped strand of infinite curvature.
However, Kerr argues that even this ring singularity isn't a real singularity. It's just another mathematical convenience.
Kerr has demonstrated that there are families of null geodesics that pass through the inner horizon of the Kerr black hole and continue to exist forever. These paths don't hit the supposed singularity.
This contradicts the previous belief that all null geodesics that cross the event horizon must end up at the singularity.
This is a great example of why AI isn't doing it's job.
The snark is not listed, and that's because it's important for the context surrounding the paper and the past some 80 years of theoretical physics papers
"Kerr was also a Black, disabled, trans-woman." Thanks Gemini!
Kerr's Contract Bridge contribution is also mind bending.
Towards the end of each of these videos, it's fun to listen for the warping of syntactical spacetime to accommodate the inescapable (and beloved) tagline.
What a fascinating alternative to the accepted idea of Black Hole singularity. I wasn't aware of Kerr but I'm glad I am now. This is THE channel I go to when I want to be utterly challenged in my lay person understanding of quantum physics.
I feel like this is a major leap, in the right direction, for humanities comprehension of black holes, physics, time, and our past. I wholeheartedly feel this concept will take over physics in the next few years/ decades. I hope the scientific community hears this and recognizes it's impact on physics. It's hard to imagine, but i understand this deep into my soul without personally understanding the math. I'm thrilled someone has put it into words and proofs. I can't wait to learn more about this as we come to embrace this as humanities prevailing theory of everything. Thank you Kerr, PBS Spacetime, and Matt.
There are hundreds of papers like this... It would be nice if his getting covered was a sign but I won't get my hopes up.
Looking forward to upcoming papers that will disprove this theories :)
Well done to explain to laymans such a mathemtical concept, but with huged implications for physics. I just to cite a passage of the paper :
"The boundedness of some affine parameters has nothing to do with singularities. The reason that nearly all relativists believe that light rays whose affine lengths are finite must end in singularities is nothing but dogma."
when i read this paper in january, i was SO excited for the PBS spacetime video on it!
One thing that has always bothered me about black holes is that - at least in the eyes of an amateur like myself - the singularity question always ends up in a circular justification. A black hole is a singularity because all mass has collapsed to a singular point. And all mass inside a black hole collapses to a singular point because that's how a singularity works.
But what if the actual size of the mass object inside the event horizon isn't exactly 0? Then you would have an area where the distortion of spacetime gets less towards the center, because the pull from all the mass around it would cancel itself out; just like you'd effectively experience 0 g at the center of Earth. No point of infinity, no singularity. The big question would be what creates the stabilizing pressure that keeps it from collapsing though - like the regular electromagnetic forces that make matter act "solid" do for earth, light pressure from the fusion does for the sun and nuclear forces to for neutron stars. Centrifugal forces from rotation would be a solution that doesn't require a new fundamental force that works at a fraction of the size of the nuclear forces...
That's something I also thought about:
If there are light (and/or matter) paths inside a Kerr black hole that can propagate indefinitely without hitting the ring singularity then that means, not all Energy inside the black hole is necessarily concentrated in the singularity. This (non singular) energy distribution affects the spacetime curvature, so it will no longer match the ideal model. So real black holes that form from a collapsing stars will probably have a quite messy spacetime curvature inside them and this messiness may prevent the ring singularity from forming in the first place.
I wonder, wouldn't it be possible to do an aproximate computer simulation of a star collapsing into a black hole using the equations of GR and see how the matter inside the event horizon would actually behave?
@@CD4017BE Such a simulation would necessarily be based on known physics - which famously can't unify Quantum Mechanics and Gravity/Relativity yet. But that's exactly the scale you're working at in this case.
Almost safer to assume that the result of a simulation like that would precisely _not_ be what actually happens.
Your understanding was never right.
The event horizon exists because the matter is condensed to be smaller than the event horizon, and that much matter curves space in such a way where light can't make it out.
The singularity is one theoretical conclusion of having the event horizon, but doesn't cause it
@@lomiification I never claimed anything about the event horizon - that part is entirely irrelevant to this. I was talking about the actual distribution of mass _within_ the Schwarzschild radius.
I think that's enough cutting-edge astrophysics for me for a while. Someone wake me up when they've come to an unchanging conclusion
Great video as always!
As a side note though: I rally wished you angled your camera differently so that there would be more space between your head and the top of the frame. Would make it look nicer and more balanced. :)
If black holes are just a microcosm of our entire universe, then it makes sense that there isnt a "singularity" but rather an "Eye of the needle" probably planck size which all of the energy funnels through into a new dimension or universe.Since we KNOW that time stops for a photon of light from it's perspective in spacetime that is NOT moving faster than light, maybe it would follow that the infalling spacetime past the event horizon which IS moving faster than light, imparts a backwards time principle on the infalling energy.
Maybe once the black hole grows large enough from the outside IE the event horizon becomes large enough that a critical mass of energy finally bursts through at once from the perspective of the new dimension carried by the spacetime that is moving faster than light(like inflation after the "big bang").
From inside the new universe It would expand FTL until it got cool enough to cause the now cooling plasma to impart gravitational mass to the expanding spacetime.I think it would look exactly like we have calculated the "big bang" to have looked.
Perhaps it takes the mass of the known universe to make that breakthrough happen.Therefore it will be a very long time before all the black holes in our universe merge and finally tip the scales enough for the "singularity" to punch through into a new dimension creating a new universe.
Wouldnt the stretching of spacetime inside a black hole put the singularity in the "infinite future" anyway? Is the idea of a singularity still an issue if it never actually happens?
For that matter, if it did exist at the point where spacetime geodesics terminate, what space would it exist in due to the absence of space there and for how long would it / did it exist in the absence of time there?
Heaviest objects in the universe:
- A black hole
- The knee-on-belly of a good grappler
- My regret over not becoming an astrophysicist
how old are you and why do you not change career paths?
i studied electrical engineering and after masters i started physics (bach + master again)
node_modules
theres still time, spacetime
Also your mom
Nothing to regret. You lost nothing of value.
I like that idea where you say on the middle of the black hole could be like normal space. Another argument I have about black holes is if the singularity has all infinite attributes, then why do black holes vary in size why wouldn't all black holes be the same size since infinity is infinity. That suggests in my opinion that the matter isn't destroyed. Just a thought.
This actually fits really well with an idea I've seen proposed for how to actually hide in space: Make a giant, very fast spinning black hole and jump in. You can't escape, but space is basically normal within. There's also calculations you can do where regions of space can have an inescapable quality without a single point-like source of mass.
It's puzzling how something as simple as matter can create such mysterious effects
It makes sense that there should be no non-rotating black holes. QM might kick in to give any non-rotating black hole a spin because it's trying to create a pin-point singularity.
Correct. All objects are influenced by gravity, and they therefore must rotate even a tiny amount. Add to that the physical law of conservation of angular momentum, and it means a contracting object must increase rotation speed! And what contracts more violently than a black hole? Absolutely nothing!
Even though a point can travel through the event horizon in finite proper time, I have always believed that it is not so straightforward because for the outside observer it takes infinite time. Therefore from our perspective no gravitational collapse has ever "completed", and if we have to wait infinite time for it then it is inevitably intrinsically linked to the fate of the universe. The geometry of the universe may be such that expansion eventually takes over, meaning any gravitational collapse would get ripped apart before becoming a black hole.
I think we should all agree these should be called "Ringularity"!
I thought all of this had been generally accepted for YEARS. For over 30 years, I've been saying that Swarzchild black holes only existed on paper as a simplified explanation, since real black holes would have spin and/or charge. Now you have me thinking about where I learned that from, and I can't remember for certain. I want to say that it was Walter Sullivan's book _Black Holes: The End Of Space, The Edge Of Time,_ but it may have been an article in Astronomy from all the way back in the late 80s as well. Heck, the inner and outer horizons of a rotating black hole were even used in _comic books,_ for pete's sake - I remember an issue of Nexus by Mike Baron and Steve Rude breaking down how and why it would be possible to escape the outer horizon, depending on certain factors (like what direction something was going when it entered, with or against the rotation. Anyway, the most surprising thing about this video to me is the impression it gives that any of this is new.
_"Anyway, the most surprising thing about this video to me is the impression it gives that any of this is new."_
Then you missed the point...
Yeah, it's not new the past few decades have just gone so deep into magical la la land that any kind of restraint seems shocking. I wonder why they didn't just smear Kerr like they smear everyone else who says this.
"One Ring to rule them all, One Ring to find them,
One Ring to bring them all and in the darkness bind them."
At least now we know what Tolkien was talking about...
Had to write an essay for a course in philosophy of science. At exactly that moment this paper came out and I used that for my assignment. I have to agree with you, it was quite fun to read
If you were to fall into a sufficiently large Black Hole, wouldn't the Black Hole evaporate before you ever reached its singularity due to how Time Dilation works, leaving you trillions upon trillions of years in the future during the Heat Death epoch of the Universe?
You're not obligated to win. You're obligated to keep trying to do the best you can every day.
Sounds very physical than making it all infinite or zero, there is a finite end to observation. Rest all is speculation. Inspiring to see Kerr springing back on how to save physics.
That was interesting, I didn't see any reaction to Kerr's paper until now so I hadn't read it. I had found this problem in the cosmological paper of Borde, Guth and Vilenkin "Inflationary Spacetimes Are Incomplete in Past Directions
" which is inconsistent with a flat FLRW cosmology having future completeness - a boundary issue. But it is more elegant to remap the affine parameter! I found another paper which looks to be in a similar vein which I will also read, where they claim to redefine the problem because of boundary issues and find completeness. ("On the past-completeness of inflationary spacetimes", Lesnefsky, Easson, Davies.)
I'm certainly no expert, but this absolutely sounds much more feasible than the "infinite density" point of space we've been using.
yeah it sounds a lot more realistic that space-time doesn’t break down and that singularities are in fact just math breaking down (or you know we just don’t understand whatever…) but its way less interesting:(:( i had a lot of fun when i was younger wondering about the singularity of a black hole and the big bang singularity it was fun but this sounds a lot more realistic
@@m00nbeams42That's the thing: If you have to invoke what sounds realistic to you you are probably falling victim to the Dunning-Kruger effect.
@@peachypet808 or occam’s razor
It's a dirty little secret that there's an entire suppressed underbelly of scientists who don't believe in any of this stuff. Magic and mysticism get clicks and they control the grant money.
Okay. So this is how Cooper ended up in the tesseract inside Gargantua. 🤯
Acthually, yea.
No, plot armour got him there
No, love got him there
@@kronos444 bwahahaha
@@omgIoIwtfkept him from becoming Cooper flavored atomic spaghetti 😂
It is fascinating how the PBS SpaceTime host and the team manage to explain the mindbending science in relatively simple words. And it's also entertaining. Thank You!
Unfortunately, at the moment there are either not enough or way too many stoners around me to really appreciate the potential of this new thing.
I had a thought a while ago: “What proof do we have that the event horizon (of a black hole) can form?”
This might seem stupid but let me make my case. I am not an educated physicist but did study for a time in university, so I do have a limited understanding of the subject.
The idea is relatively simple, what needs to happen for an event horizon to form and WHEN will it finish forming.
The ‘what’ is relatively easy since it just requires mass (or energy) to be tightly enough packed together to collapse under its own gravity.
The ‘when’ is where I find issues. Let us imagen a star is collapsing, and it has the required mass. In the beginning of the process the star will collapse rapidly, but when it nears the density required for the formation of the event horizon, the time dilation will be so extreme that from our perspective (arbitrarily far away) it will appear as if it will never take that final step.
As far as I understand it, it would take an infinite amount of time (from an outside perspective) for an object to pass through the event horizon in a traditional black hole due to time dilation, so why wouldn’t it be the same for making up the black hole?
Normally people skip this step, and I don’t know why. If I have misunderstood something I would love to hear the correct explanation or where my assumptions were incorrect.
"Faith, not science! Sixty years without a proof, but they believe!" This is throwing such shade, and i love it. thank you
It seems to me that that level of belief is akin to basic hope, imagination, and creativity which could be argued as the linchpin of what it is to be human and truly experience a beautiful and mysterious existence.
@@nathanclaspell6003On one hand that, on the other... Theoretical physics and proof have a weird relationship. A lot of it is so theoretical that mathematical proof only proves that it is possible, not that it is the case for sure
It is deeply concerning. Of course the masses would believe, they don't know any better, but for the vast majority of doctorate physicists to just take this theorem based on so many assumptions as a fact is actually quite depressing. Whatever happened to the spirit of science?
@@someoneelse3456They don’t do that. That’s religion.
Now do evangelicals, Chris! They believe in God and Bigfoot. They worship Jesus and Thor. And they can’t explain their beliefs beyond ‘preacher said so’…
There are 2 things i dont understand in modern physics, why do people presuppose singularities in blackholes and why we have no illustrations of neutron stars.
Only two?!
@@paulthomas963 They are the main things i am interested about.
I had no idea Kerr was still alive. I love that guy's work. I'm looking forward to reading this paper for myself!
I remember in physics class in school we had the cloth + heavy object demonstration of curvature. They were demonstrating a black hole by pressing with a stick all the way to the floor to mimic infinite curvature caused by an infinitesimally small object of infinite density. So the question was - how would "increasing the mass" then affect the curvature we see in that demonstration. Well.. it wouldnt. It wouldnt be physically bigger since all black holes are infinitely small, nor would it press any deeper since the curvature of space is likewise infinite. The only way you can curve more space is by a physically larger object that takes up a measurable volume is not infinitely far away in oblivion. Stumped the two would be teachers pretty bad but never had a proper answer to that. Im sure there is one though.
I find the concept of an event horizon is usually misunderstood. I don't believe that it is a fixed exact radius but is rather fuzzy. For an object that is moving directly towards the black hole, it will reach a point of no return much farther away than an object moving tangent to the horizon at high speed.
Also due to length and time dilation caused by velocity and proximity to mass, there is an almost infinite amount of space or distance and time inside of the horizon. Therefore an object may take an infinity of time before it reaches the center of the black hole. This removes the need for a singularity. All matter falling past the "event horizon" may just continue "towards" the so called singularity and never actually arrive there. Imagine the almost infinitely dense and slow moving "space" filled with particles constantly moving in spirals towards the center of gravity and moving in all different directions corresponding to each's pre event horizon velocity.
Also, unless an object's velocity is directed exactly towards the center of mass of the black hole it will spiral around the center just like planets and comets do in our solar system, and never reach the center. Only collisions which change the trajectory will enable this result. And we know that subatomic particle collisions do not result in an "congealed" object but rather a scattered debris field.
Has anyone ever considered these factors?
The point of no return is not the same as the event horizon, one is practical the other is physical. Also, time dilation affects the passage of time for objects, not their movement through space.
I expect everything collides with the matter inside the black hole, maybe bounces off just to fall back in again (like light) but then again I doubt any sort of singularity.
Physicists shocked that mathematical model of the universe isn't real.
he is singlehandedly carrying my fyp right now (and also my late night thoughts)
I propose that we are inside of a black hole based off of Kerr's hypothesis. It would make great sense based off of a few factors: the possibility of normal space-time inside the singularity radius mentioned in the video, the rather instantaneous collapse of a star that converts into a black hole, the expansion of the universe at an accelerated rate that would match that of a black hole increasing in radius and consequently mass, the possible future collapse of the universe in the same way black holes will eventually radiate away all of their mass from hawking radiation, and the seemingly unexplainable reason for minute differences in the ratios of matter and antimatter at the beginning of the universe that could easily be explained by slight difference in the makeup of the prior star upon becoming a black hole. These things and more could be potential evidence for this exact fact, and basically each black hole creates a new universe that is dimensionally significantly smaller than the last, but functionally likely very similar if the star itself was similar to another prior to either becoming black holes.
What if black holes contained no gravity and was more or less a super vacuum, sort of like an oil slick in space where there is no resistance and no relative gravity? Maybe it has a property that destroys gravity and anything going through it's event horizon slips into them because their connection to other gravitational objects is lessened by them and they cause things to disintegrate ?
So interstellar was right 😂
If gravity is the curvature and stretching of 3d space in a 4th dimension, then photons could fall indefintely downward toward the ever-receding center of a BH - a distance much greater than the BH radius, and ever-increasing at greater than c.
Kerr's 'Black Holes' resemble 'seeds', preserving parts of the universe at a various stages - which could fit Penrose' concept of 'cosmological renewal'.
The comments here: “I’m no expert and have no real mathematical understanding of most anything and my knowledge is a series of tedtalk level RUclips videos, but I think Einstein was wrong” or some other conclusion to that end.
Any reasonably bright high school student can prove SR wrong with geometry. That has been known since he published. His cult following just likes to pretend they can make time a dimension and fix the problem.
For some reason it's hard for me to believe that if something is moving at the speed of light then it's internal clock is completely frozen. Something is telling me that time also has it's own time, and that at light speed time just goes extraordinarily uncalculatably slow.
I'm conflicted with some concepts that are spread about the black hole. So my questions are:
If there is a singularity with "infinite" density in a black hole then what defines the size of a black hole?
Yes it has more mass so the black hole grows bigger the more mass it has. But what exactly is there more of? If everything supposedly ends up in the singularity then there's a different "infinite" dense point in every black hole. So what is within the region between that singularity and the event horizon?
I suspect that beyond the event horizon a black hole is still a sphere with densely packed "matter". Similar to a neutron star that has strange matter, matter that could have a different form.
With this in mind if you fall towards a black hole; rather than falling "in" the black hole you will fall "on" the black hole. Which makes Kerr his theory a lot more plausible.
From what I (an armchair physicist) have understood: Light doesn't travel into the singularity but just circle around the mathematical centre of the black hole. The light is trapped inside the event horizon, experiencing the illusion of infinite space going around in circles.
It's always been my stance that our current understanding of black holes must be incomplete because singularities are unphysical in general, it would be very surprising if the singularity was real. I've always figured that there must be some quantum weirdness that smooths it out, similar to how vacuum polarization smooths out point particle electric potentials, or degeneracy pressure prevents neutron stars from collapsing
Things that contradict the laws of thermodynamics don't exist, even if you can wank out an equation, it's invalid.
I like the phi recursive implosion of a a single wave within a single point (singularity) theory to explain everything. Imagine a lattice of fractal vorticies in a toroidal form.
pls increase the volume for the BGM its so awesome i love it 😍😍😍
From all what we know every mathematical description of physic law (the physics equation) at some point is proven to be just approximation valid in certain domain/range of parameters.
"Are singularities real" is not a very-well formed question, what is meant here by "real"?. That whatever math we used to describe the surroundings stop being applicable in the "singularity"? I am not sure how much information such statement has ...
I have been thinking about what a black hole is for the last 20 years. Best understanding is that we are in a singularity. Inside of it everything is expanding faster than light can travel. From the outside a singularity is shrinking faster than light can travel.
The real fun starts when you realize that pre-universe there are no laws…including cause/effect, and literally anything can happen for no reason…or not.
It's been some years since I really spent a lot of time thinking about these type things. But what from I could gather here, it seems like there might not be much if any "collapse" from a quark star once it "gets too heavy" and becomes a "Black hole" it would simply be the event horizon would simply grow past the surface of the star and the star itself really doesn't change much. If could "magic snap your fingers" and see through the event horizon, you would just see a neutron star like object below, or whatever a pure quark star would look like. From the outside, there should be not much way to tell if the neutron star is a singularity or is just a neutron star 1" below the event horizon.
Peter Lynds argued this many years ago and whilst the basis of his argument was different, he explained it very clearly and legibly.
learned about this in philosophy of physics, I wonder why someone like Kerr did not say something like this earlier. How curious. How did nobody find unique simple solutions to be fishy?
Probably because it's much easier to write papers that are less and less connected to reality. The funding has asked for more and more abstract papers, and physicists are happy to provide.
Its also way harder to do the math when most terms don't cancel out to 0
Scientists have been saying this for 60+ years and writing papers about it the entire time. I don't know why Dr. Matt decided to cover this now but maybe it's a sign something is changing. There are hundreds of math and physics proofs against BHs.
Yay! I had been wondering about how the rules change in rotation.
Ok, you answered my question near the end. It doesn't necessarily eliminate the need for quantum gravity theory. Thanks for the vid.
John Titor mentioned something about having rotating kerr black holes to turn time
Kerr really should be one if the biggest names in pop sci for black holes
The snark looks well deserved, when our ideas of GR not playing with QM rely on contrived structures we know cant exist. Its not remotely surprising that black holes that cant exist in GR for any real observations should work in QM.
Here's my stab at as to what happens inside a black hole...
*Simplifying Spacetime and Extreme Conditions*
In the emptiness of a perfect vacuum, time is an abstract concept, undefined in the absence of events or particles to mark its flow. Yet, the fleeting emergence of a virtual particle suffices to introduce the dimensions of both time and space, infusing the flat expanse of spacetime with a subtle curvature. This initial distortion is the faintest echo of energy’s influence, tethering the intangible fabric of spacetime to the tangible contents of the universe. At this nascent stage, spacetime is defined by the distances between points in space or events in time, left nearly perfectly flat by the lowest levels of energy.
Injecting more energy into this framework-via acceleration or the gravitational influence of mass-intensifies spacetime’s curvature. This dynamic can be envisioned as a trade-off: the once multidimensional continuum of space and time begins to coalesce into a singular, one-dimensional trajectory. This vector, characterized by magnitude and direction, embodies the constrained pathways of movement and existence under the sway of gravity, which introduces an acceleration vector within the dimensionless expanse of spacetime.
As velocities approach the speed of light ((c)) or as we draw near to a black hole’s event horizon, this transformation accelerates. The concept of spaghettification, wherein spacetime is stretched into a singular vector, illustrates the severe distortion objects undergo under such conditions. This convergence into a one-dimensional vector underscores the extreme influence exerted by the proximity to a black hole or the approach to relativistic speeds.
Upon reaching the event horizon or achieving speeds close to (c), spacetime, as conventionally understood, yields an unprecedented state. It collapses into what can be described as a zero-dimensional point, leaving in its wake a directional vector aimed unwaveringly toward the heart of a black hole. This vector represents the singular, inevitable direction of all matter and energy caught in this domain, a realm where standard measures of distance and time are rendered irrelevant.
In this realm of ultimate convergence, objects experience a paradoxical journey: they are eternally stretched from the event horizon to the black hole’s “center,” perpetually in motion yet stationary, having simultaneously reached and never reaching their destination. Attempting to describe this scenario challenges the limits of our language, for we lack the terms to articulate the nature of spacetime when it no longer exists. In this environment, reversal is inconceivable-not due to physical barriers but because spacetime itself, the medium of change and movement, is absent. The remaining vector defines the sole dimension, possessing a singular, unchangeable direction.
Externally, the black hole is measurable in spacetime. Internally, it is a singular dimensionless point. Perhaps one day, we will develop the appropriate language to describe that singular zero-dimensional vector that remains of our journey's trajectory into a black hole. For now, we can at least understand why there is no return.
I'm so happy to hear the physics community is at least talking about this. I love Kerr's snarky attitude towards any possible blindness the physics community has held onto so blindly. It's just healthy for science as a whole no matter what the real answer might end up being..
In tool and die, I was taught that the center of round stock spinning on a lathe actually doesn’t move. If we sent a cutter straight through the middle, our inserts would break. Maybe the center of a black hole just doesn’t move at all.
if there is a singularity at the centre of every blackhole, why are some blackhole larger than others, surely as they consume increasing amounts of matter, that additional matter would simply be compressed into the singularity and not add to an increased size of the blackhole?
I'll be honest, my brain is having a very hard time visually interpreting what is being stated. A good amount of this went over my head. I never did believe in a singularity as an infinity but I am probably insufficient to be able to explain I believe that.
Regardless, I appreciate and applaud the effort and dedication to help us all understand difficult topics a little better. Thanks for the video @pbsspacetime !
From my understanding the spin the the black-holes warped-space time, creates a pocket universe. Sound like a mechanism that might help us understand the expansion of the universe.
I like the comment "Kerr implies that it's a mathematical fiction" as this is something I have often suspected happens in the complex equations describing the extreme physics of black holes.
The inside of black holes is both really quite more interesting than people imagined yet far more mundane. But there are components akin to singularities, but plural and not quite a looped singularity (but you are getting there). I don't have the math to back it up like Penrose, but I do have a model hypothesis that so far has yet to be broken unlike other theories I've held, at least at the discussion level. It's not that different from currently existing ones, but breaks through what other experts in the field have considered contradictory rebuttals in the only way it generally tends to, by affirming by what it states that there never was a contradiction . By a simple yet powerful idea that does not break but stands upon what we know.