What if Singularities DO NOT Exist?

[@pathutchison7688]

I love how you don’t treat us viewers like we are stupid, and yet at the same time you find simple ways to convey complex ideas. It’s a fine line to walk, and you do it very well.

[@CallOfCutie69]

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.

[@Rio-zh2wb]

True

[@tdk99-i8n]

And Rodger Penrose is 92

[@rachel_rexxx]

Ageism be damned!

[@CallOfCutie69]

@@tdk99-i8n true, but Penrose Singularity Theorem was published in 1965, when he was around 34.

[@markdowning7959]

Sounds like good news for monkeys.

[@caleschley]

Kerr is still shaking things up at 90 years old. What a beast.

[@RedRocket4000]

Sorry to general public that is too old to do anything recently it seams.

[@jonathandawson3091]

That's because the young people are caught up in gender identity than physics. Neil Tyson for instance.

[@rickyspanish4792]

And being snarky about it! That sassy old bastard!

[@rickyspanish4792]

@@jonathandawson3091 stop making yourself look like a clown

[@HunterW.Photography]

@@jonathandawson3091you are not welcome in these spaces

[@troysanders915]

I've been watching PBS for 40 years. From 3-2-1 contact to Spacetime and more. You're a kids and now a mans best friend.

[@joshuamacks6087]

You better donate!

[@Jelly_Beanz02]

@@joshuamacks6087I’m not against donating but telling someone that they better donate is just weird. You don’t know this man’s situation, he may not have the means to donate. A KZbinr doing it is fine because it’s not directed to an individual but to anyone who actually can but a random viewer doing it? Weird, annoying, and insensitive.

[@anarex0929]

Google censors are working hard in this channel.. I only mentioned an incident that happened in the past with PBS space-time and my comments where deleted 2x

[@Impaled_Onion-thatsmine]

If a singular are offset all particular are affected then inverted toward the singular as a metaphysic that nonsense

[@Valdagast]

Man, he's 90 and still contributing to physics. That's life goals right there.

[@emersonmsd]

Thank God for boomers😂

[@philallsopp42]

Exactly!!!!!!!!!! Enough of the “retirement ‘communities’” already.

[@savagesarethebest7251]

@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

[@nuntana2]

@@emersonmsd Penrose is not a boomer. He's one of the few golden gen left in the world. Uncomplaining and tough as old boots 🙂

[@impulse255dj]

@@emersonmsd He was born in 34' so he actually predates boomers by more than a decade.

[@anapananapa]

This definitely feels like a “ all models are wrong (but some are useful)” situation. I think we often forget that the ‘map’ is not the ‘territory’, and should be careful to not define the world by our models, but define our models by the world.

[@HermanVonPetri]

Indeed. Mathematics is not reality; it's merely a (very powerful) language we use to describe reality. Sometimes we also use it to describe concepts that have no basis in reality whatsoever. And just as any language has imperfections, so does mathematics.

[@ryanwinsor4458]

we will never have a singular theory for everything. all new ideas must be tested against all current theories. as we learn, we drop ideas that no longer fit our current understanding, while also inventing new possible theories to explain the new questions our previous answers unlocked.

[@markloveless1001]

Alfred Korzybski for the win. Well played.

[@Zeraevous]

I've resd that Box quote to data science candidates and asked them to give some likely and illustrative examples. Some get it right away, some get it after a bit of context.

[@myboatforacar]

I always liked to think of this as the Camelot Principle: "It's only a model." --Patsy, _Monty Python and the Holy Grail_

[@robinharwood5044]

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 dφs􏰁2 , ∆Σ + Σdθ2 + sin2θ 􏰀(r2 + a2)dφs − adts􏰁2 (13) Σ We stared at this metric for a very short time, gave up and went for coffee. " I did the same.

[@ILKOSTFU]

XDD

[@HichigoShirosaki1]

There's a point where math becomes an alien language with all the variables. 😂

[@Grundrisse]

@@HichigoShirosaki1 Math has already become an alien language considering reality is "overrated" to them.

[@CSTEnjoyer]

@@Grundrissewell, as someone that understands those words even though I can't see the formula because KZbin 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

[@gabedude68]

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.

[@oohwha]

"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...

[@funicon3689]

😅

[@asanboo]

Such a good reference.

[@maddestG1]

THE EYE OF MORDOR

[@ElectricEuphoria]

"middle earth" hits different now

[@philbertgodphry1]

10:45 It can’t be put into words how utterly disappointed I am that this isn’t called a Ringularity.

[@vxvDREWvxv]

Both are technically correct terms

[@mattvjmeasures]

A thingularity

[@RWin-fp5jn]

Nice one! Ringularity it shall be!!!

[@heavenlymonkey]

That has a nice ring to it

[@Mittencarpentry]

I accept your termination.

[@chaosmkmk]

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.

[@mrptr9013]

13:40

[@melgross]

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.

[@michaelhall2709]

@@WilliamTaylor-h4rDon’t bogart that joint, pal.

[@brown2889]

@@melgrossI like that. Having a bit of faith, and yes it is strange.

[@laurenpinschannels]

I'm looking forward to the updated version of Bohemian Gravity when we figure this all out

[@Breakemoff2]

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

[@pbsspacetime]

You got it! We're happy to help you dream of science. . .

[@thedownwardmachine]

Also consider watching How It’s Made for reliable fall-asleep material

[@Breakemoff2]

@@pbsspacetime thank you!!!! 🪐 ✨ 🌌

[@Budgy.Derpy12]

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 💗

[@Breakemoff2]

@@thedownwardmachineI watch a lot from the Astrum channel! He even had a “sleep space” podcast 😅

[@randyhavard6084]

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.

[@yanair2091]

And since it makes sense - it must be true.

[@randyhavard6084]

@@yanair2091 could be true

[@2008M5]

I've always played out a thought experiment in my head. Let's say we start with a Neutron star. Super dense but not yet dense enought to prevent light from escaping. Add 1 gram of a mass at a time. At some point, it will reach Black hole status. So, 1 gram more = Black hole, 1 gram less = Neutron star. Why did we always give black holes this mythical status when really they are just slightly more dense than a neutron star?

[@randyhavard6084]

@@2008M5 I've always thought the object would still be there and basically just as large only so dense that light can't escape

[@elquesohombre9931]

@@2008M5i mean light is meant to be moving at C from all reference points, so if light is entering a black hole and does not ever come out, the light has nowhere to move and is no longer moving at C. This just doesn’t match up with our observations considering movement in space results in time dilation which gets exponentially longer as you approach C, something we have confirmed through the use of atomic clocks. This gets to the point that it becomes impossible with mass to travel at C. Light can BEND sure but if it cannot escape the gravitational pull, it will only be pulled further towards the center as it feels a greater gravitational pull the closer it gets. If it were to somehow maintain its orbit due to inertia, it must not only enter at the right angle but then light could theoretically also slingshot out which would not be an inescapable prison. To argue that the stuff is still there in a mostly identical state would mean that light could just kind of stop in the middle of an object, which should not be possible if the speed of light is so built into the universe that time bends to make sure everything obeys that speed limit. This special pocket being just a pocket with slightly larger gravitational pull than a neutron star makes it that much more significant, because sure time is extremely warped nearby a neutron star but it doesn’t just kind of break, and the speed of light is still C from any reference point near and at the neutron star. Something significant changes. Think of how something with an average density exactly 1 microgram less than water is dropped into it. If you add those 2 micrograms it starts sinking when it was floating just fine before hand. The limit in this case is whether light can get out or not. The second it cannot, a lot more can change as a result than just a sinking object, but that makes sense because of how significant the speed of light is.

[@Zamicol]

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.

[@ChicoRasia_CLabs]

+1

[@astrophyz]

That's EVERY PBS spacetime. Lol

[@PainterVierax]

@@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.

[@udaypsaroj]

14:08 lol, though

[@honestabe411]

Agreed

[@The_Real_Kyrros]

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 KZbin 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!

[@larrymunn5279]

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.

[@calamariaxo]

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.

[@WanderTheNomad]

Communication from academia to lay people is disappointingly scarce.

[@viralplatipuss]

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.

[@coyotewayfarer4380]

@@larrymunn5279 Except many will argue that the universe itself is infinite, that it stretches out infinitely beyond the observable universe.

[@ZoonCrypticon]

Although I barely understand 5% of the mathematics and physics behind it, I enjoy watching this show. Very relaxing! Thank you!

[@SolaceEasy]

Like lying on a bed of nails.

[@hikingwithhollywood]

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!

[@zqxzqxzqx1]

Same on all counts. Very exciting!

[@silvercloud1641]

Like a flat whirlpool/vortex?

[@SentientRaven]

"Singularity-free spacetime!" - Sounds like a great slogan for a T-shirt.

[@cbunn81]

I would have said it sounds like a marketing gimmick, like "splinter-free toilet paper."

[@brown2889]

@@cbunn81 😂

[@oneeleven7897]

Yes please, I’d buy one

[@StardollDJ]

Put me down for one of those

[@The_Real_Kyrros]

@@cbunn81 Maybe so; but with some of the lower quality 'eco friendly' bathroom tissues I've seen out there, splinters are a legitimate concern. 😬

[@biopsiesbeanieboos55]

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.

[@Seafaringslinky]

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

[@zutaca2825]

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

[@paulmoffat9306]

He also brought up, that a 'singularity' could be a Planck star, as it could not get any smaller, in an earlier episode.

[@Flesh_Wizard]

neutron star jail (it was caught evading taxes)

[@bierrollerful]

The event horizon isn't a physical thing - much like the horizon on Earth isn't a physical thing. You shouldn't take it literally when he says "growing the horizon beyond the surface". At some mass, the curvature around the star will be too strong for light to escape - then you have an event horizon. The internal pressure that keeps the neutron star a star cannot resist the inward force of this much mass. Dr. Becky did an excellent video on this two weeks ago, titled: "FOUND in the MASS GAP: The heaviest neutron star OR the lightest black hole?"

[@karolbienioszek9902]

I can't believe that a theorem of 90 years old physicist is challenged by another 90 years old physicist.

[@ennuiincarnate]

Wizards. They're always old and grey. Takes time to get the math and sigils right.

[@KafshakTashtak]

Shows that it takes 70 years to master the topic to be able to challenge it.

[@danielgrizzlus3950]

shows how dead physics has become

[@mgancarzjr]

​@@ennuiincarnatelevel 90 wizards. As terrifying at it is rare.

[@AmeliusDex]

Futurama is predicting the future I say!

[@drakesmith5462]

The deterioration of the word geodesic in this video is hilarious

[@Tenbed]

I'm glad PBS is still going after all these years. And still has decent content.

[@Kraken9911]

PBS FRONTLINE is pretty solid too. No agenda just straight facts and a story built on them.

[@HernanHH95]

Yep. There are tons of science channels which just use filler words and cool images. But say nothing or repeat the same

[@go-away-5555]

PBS was launched in 1970

[@J5460-r8z]

Well?

[@apollomann9540]

@@go-away-5555I remember, it was our 4th channel.

[@Czeckie]

kerr is like 90 and still producing new ideas. what a g

[@ehsnils]

To me a true singularity has to be the plank length or less. But I'd still consider that black holes can exists.

[@tylercrews9025]

​@@ehsnilswhat are you even responding to

[@ClaymorePvP]

we literally have a photo of a real blackhole its not a debate topic anymore, they do exist

[@tanyachou4474]

I agree ❤

[@gillianlovell9578]

@@ehsnils *Planck*. Look it up.

[@BaconJake14]

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.

[@CaptainCanuck68]

I got stuck on physics and math too. I went into comp sci at first then branched into med lab science. I'm technically retired now so I just kind of dabble around the edges because it still fascinates me how far we keep going. I'll try to catch up, but you can only science so hard.

[@sierrarasberry9722]

I have an almost identical life experience and view of this channel too. I feel this deeply!

[@angelgarza9366]

I don't remember why I was thinking I didn't like the idea of the singularity a few days ago, looked up some singular videos, and found this one, PBS spacetime never disappoints !

[@kaczan3]

10:16 "Built on a foundation of sand" Kerr is good at scientist rap fights.

[@levybenathome]

Concrete is mostly sand, so most large buildings are built on foundations of (mostly) sand. It's not bad stuff.

[@markiv2942]

That's not rap, that's Borges.

[@coopergates9680]

I was hoping there'd be a Viva la Vida plug

[@WanderTheNomad]

​@@levybenathomeIs it still considered sand if it's been converted to concrete? 🤔

[@levybenathome]

@@WanderTheNomad Not *considered* sand, but then, we aren't considered stardust. It can return to sand if the cements leach out.

[@Sparta22033]

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.

[@RadeticDaniel]

Yeap, school is a horrible place for those who really like learning in depth or have fast pace for the topics approached in class

[@ddo8521]

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.

[@morlath4767]

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.

[@bocephusbirchcull4044]

I wasn’t taught anything of that sort in school. Schools don’t teach things like that.

[@bocephusbirchcull4044]

@@morlath4767So basically your teacher kept up on developments and you’re chastising them for doing their job… Great story…

[@乂]

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!

[@LuisSierra42]

Physicists have rizz

[@TheNewPhysics]

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.

[@nuntana2]

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.

[@cerostymc]

Why does this comment sound like it was written by ChatGPT...

[@Grundrisse]

@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, and 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.

[@gregkarney1441]

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.

[@paulthomas963]

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.

[@SpaceBearEngineer]

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.

[@JudoGeoff]

Your opening line reminded me of the expression: All models are wrong. Some of them are useful.

[@Billy4321able]

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.

[@chriss3404]

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. 😅

[@lomiification]

He's still using the same model, GR, just not throwing out as much of it

[@JSLEnterprises]

​@@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.

[@dembro27]

For the sake of my sanity, I appreciate the work of any physicist who sees infinity as a red flag and tries to ignore, disprove, or bound it in some way.

[@456death654]

Every physicist sees infinity as a red flag in the maths

[@DrWhom]

no, what happens at the singularity has always been acknowledged as the point where our understanding must break down e.g. read up on it in the standard tome on this, Gravitation the theorem only says - well, Matt explains it quite well in the vid however, science popularisers have often been sloppy about this, and a lot of crackpot lay people seem to think we really do believe in "physical infinity" - the truth is that we are necessarily agnostic about this, since what could it mean?

[@isilver78]

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!

[@yitz7805]

do you remember what that model was?

[@snorkfire]

Hey, I’d love to hear the rationale for the formation of a singularity within a region (within the event horizon) where time dilation has brought time to a halt for the rest of our universe. I just cannot see how this massive singularity formation event ever happens. Is there a relativistic rationalization that allows events to occur within a black hole?

[@PaigeTArt]

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.

[@arminthaller7284]

May I add another question: If the event horizon is the border where the escape speed equals the speed of light something falling towards the event horizon should reach the speed of light when coming there, or a wavelength of 0 if it's light. Where goes the excess energy if it is falling further inside the event horizon and higher speed / frequency is not possible? Shouldn't the inertia rise so much that not even the gravity of a black hole is enough to pull it beyond the event horizon? I imagine time 'freezing' close to the event horizon, so that the object won't reach the event horizon in any finite time interval of our observer's time.

[@WhydoIsuddenlyhaveahandle]

Black-holium 😂 I like it. Interesting point. If we can invent nutronium for neutron stars, why not a new matter for black hole?

[@rubenrosales725]

My hypothesis which i call #Triangularhypothesis say's their not physical as you described. It's actually the opposite. #Blackholes according to my hypothesis are better described as #hypervacuums in laymen terms it's a region of the universe where's Space, Gravity and even Time does not exist. Like I said Hyper vacuum. My hypothesis also works great with #generalrelativity #quantumphysics beats string (( theory )) 🤷 just saying.

[@literallynothinghere9089]

So you are saying that at the very end, deep inside the core lies some sort of black holium particle at the very center? That would make the black hole a glorified star with a core made out of the most special particle in the universe but I also think its interesting

[@Arnaz87]

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!!

[@JoelBarnes0]

I was giddy when I saw the new Kerr paper. Thanks so much for devoting an episode to this discussion.

[@PetouKan]

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.

[@JackDespero]

When hearing the name Kerr, I was surprised "Isn't that the guy from spinning black holes which I learnt during my physics degree?" Sometimes one forgets that these people are actual human beings, not creatures of legend, and some are actually still alive and working!

[@sci1905]

The closest thing to witnessing a singularity in my life is when I reached the bottom of an ice cream cone of a drumstick.

[@gregorygant4242]

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 ?

[@dragoscoco2173]

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.

[@damfadd]

And all there is at the bottom is a cone of chocolate

[@SeC-q9m]

Did you begin orbiting or found you devoured it?

[@ascohn]

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.

[@Chris-ib8oi]

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?

[@tyharris9994]

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?

[@dirtbird7415]

They probably don't exist. A Singularity is just a mathematical description. In this particular case , that is a "Singularity". It's just our lack of a description because our current mathematics and understanding is incomplete. So that is the term we give. Think about it , we have all sorts of descriptive words. Singularity = we don't know Dark matter = we don't know Dark energy = we don't know

[@stevedekorte]

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.

[@lomiification]

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

[@iamthe80s49]

"Kerr was also a Black, disabled, trans-woman." Thanks Gemini!

[@dercooney]

i figured singularities were just the asymptote, and the progressively steeper time dilation that comes with increased density meant that you never actually get there

[@TurboElectricUK]

Yup it's amazing how that's obvious to you and me, but a career scientist doesn't see this.

[@dercooney]

@@TurboElectricUK i can point out the conceptual parts, but getting the math right is a whole other thing

[@jmunt]

@@TurboElectricUK This has actually been discussed on many videos I've seen. In relativity, time dilation only happens from an outside observer's perspective. If you had a rocket with infinite fuel and you asymptotically approach the speed of light, to an outside observer your time would freeze and you would never age but from your perspective you continue aging as normal. Same thing happens as you approach the event horizon of a black hole, from an outside observer's reference frame your time would stop, but the one traveling into the black hole has their own reference frame where time continues moving forward like normal. Even outside the black hole, there is relativity of simultaneity where events can happen in different orders in different near-light-speed reference frames. This is the same concept except the one approaching the event horizon has their events further and further into the other reference frame's future until it is infinitely far in their future and beyond. This doesn't make the in-falling person's reference frame any less valid. So you see, it's not that theoretical physicists are all dumber than you, it's that this is a very very old concept. One of the big contributions of Roger Penrose was creating the Penrose diagram which helps physicists visualize exactly what I just described. They're several steps ahead of you mate. Not saying everything is figured out, its still a mystery, but its a mystery precisely because all of the obvious solutions like this one have already been considered.

[@CheCheDaWaff]

An observer doesn’t experience time dilation in their own reference frame. (This is “the principle of relativity”!) Therefore from the observer’s perspective you’re describing a situation in which they reach a singularity in finite time.

[@slightlyamusedblackkidfrom9153]

But how can nothing reach the singularity if the black hole grows in mass from everything it eats? Makes no sense

[@patrick247two]

Kerr's Contract Bridge contribution is also mind bending.

[@leonreynolds77]

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.

[@FabioCiardullo]

6:09 I was half expecting the video to abruptly end when he said spacetime

[@mvmlego1212]

"Matt's non-null geodesic has reached the singularity. He will not return for comments."

[@72marshflower15]

We got an ad instead.. about the same thing.

[@joseo2782]

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!!

[@Aethelhald]

I've always found the idea of a singularity implausible too. I think it's far more likely that black holes just aren't what we think they are, or they don't do what we think they do. Either that, or the conditions at the center are so extreme that matter entering it is converted into some kind of unfathomable exotic state.

[@SKy_the_Thunder]

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...

[@CD4017BE]

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?

[@SKy_the_Thunder]

@@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.

[@lomiification]

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

[@SKy_the_Thunder]

@@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.

[@Christopher_R_Gugliuzza]

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.

[@ulrichkristensen4087]

Well a photon travels a to b instantly, for an outsider looking at the beam, the photon takes time to travel from a to b, massless objects do not experience time

[@MelGibsonFan]

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...

[@arab6745]

The idea of a singularity never made sense to me. How can mass be crushed into an infinitesimal point? but more importantly since black holes have different masses and event horizon sizes, how can they all have the same real size of a point??

[@shawns0762]

@@arab6745 Most people don't know that Einstein said that singularities are not possible. In the 1939 journal "Annals of Mathematics" he wrote - "The essential result of this investigation is a clear understanding as to why the Schwarzchild singularities (Schwarzchild was the first to raise the issue of G.R. predicting singularities) do not exist in physical reality. Although the theory given here treats only clusters (star clusters) whose particles move along circular paths it does seem subject to reasonable doubt that more general cases will have analogous results. The Schwarzchild singularities do not appear for the reason that matter cannot be concentrated arbitrarily. And this is due to the fact that otherwise the constituting particles would reach the velocity of light." He was referring to the phenomenon of dilation (sometimes called gamma or y) mass that is dilated is smeared through spacetime relative to an outside observer. It's the phenomenon behind the phrase "mass becomes infinite at the speed of light". A 2-axis graph illustrates the squared nature of the phenomenon, dilation increases at an exponential rate the closer you get to the speed of light. A "time dilation" graph illustrates the same phenomenon, it's not just time that gets dilated. Dilation will occur wherever there is an astronomical quantity of mass. This includes the centers of very high mass stars and the overwhelming majority of galaxy centers. It can be inferred mathematically that the mass at the center of our own galaxy is dilated. This means that there is no valid XYZ coordinate we can attribute to it, you can't point your finger at something that is smeared through spacetime. More precisely, everywhere you point is equally valid. In other words that mass is all around us. This is the explanation for galaxy rotation curves/dark matter, the "missing mass" is dilated mass. Dilation does not occur in galaxies with low mass centers because they do not have enough mass to achieve relativistic velocities. It has recently been confirmed in 6 very low mass galaxies including NGC 1052-DF2 and DF4 to have no dark matter. In other words, they have normal rotation rates.

[@l21n18]

What does “woo” even mean? That’s just a term of abuse to avoid serious engagement? If it’s Anything that contradicts one’s day to day experience that’s a pretty bad metric to use to evaluate an idea. Lots of stuff he accepts as scientific contradict that

[@go-away-5555]

@@l21n18woo is an untestable hypothesis

[@redx11x]

​@@l21n18woo is conjecture upon conjecture.

[@nathanielgrant6593]

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...

[@brandoloudly9457]

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

[@Pao234_]

​@@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

[@donmead6751]

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.

[@brandoloudly9457]

that's what i said bro @@donmead6751

[@oneknight]

Looking forward to upcoming papers that will disprove this theories :)

[@meneeRubieko]

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

[@clearnightsky]

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.

[@d.dementedengineerc99isurf26]

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!

[@adamk897]

Heaviest objects in the universe: - A black hole - The knee-on-belly of a good grappler - My regret over not becoming an astrophysicist

[@DatDaDu]

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)

[@codebrick]

node_modules

[@pacotaco1246]

theres still time, spacetime

[@nickcarroll8565]

Also your mom

[@scar6073]

Nothing to regret. You lost nothing of value.

[@theziggy1342]

9:30 crude but super effective for anyone with a bit of calculus background. Affine parameters are mathematically useful, but don't track anything _real_. Real is all "limits as you approach..." I think I'm more intrigued by the implications that has for the singularity in the Big Bang story.

[@aapddd]

My beer belly is not far from being a singularity, so we know soon enough.

[@googoogjoobgoogoogjoob]

The singularity, like infinity, was always an admission of defeat.

[@ItsEverythingElse]

Infinities are real.

[@Mentaculus42]

The “Old One” doesn’t divide by zero!

[@Timbo6669]

@@ItsEverythingElse”real” on paper only.

[@yalexander9432]

​@ItsEverythingElse Probably only in terms of the size of reality itself. I personally doubt infinite values actually exist within reality

[@ARVash]

​@@ItsEverythingElse maybe

[@alainpean1119]

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."

[@sharif1306]

Okay. So this is how Cooper ended up in the tesseract inside Gargantua. 🤯

[@astrophyz]

Acthually, yea.

[@omgIoIwtf]

No, plot armour got him there

[@kronos444]

No, love got him there

[@astrophyz]

@@kronos444 bwahahaha

[@snaffu1]

​@@omgIoIwtfkept him from becoming Cooper flavored atomic spaghetti 😂

[@rolandlee6898]

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.

[@WakenerOne]

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.

[@GonzoTehGreat]

_"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...

[@paulthomas963]

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.

[@WhydoIsuddenlyhaveahandle]

Me too! This channel even has multiple episodes about rings inside of black holes. It I like I have my own Mandela effect going on

[@allieindigo]

Dear SpaceTime, PLEEASE keep us updated on this it's so fascinating and incredible that we may actually be able to uncover new advancements in GR and the physics of black wholes after so much time of little change in the field. The true nature of the interiors of black wholes is one of the most interesting things in all of physics, alongside the group theory related mathematical foundations of our... spacetime! :D

[@evangonzalez2245]

It's the black halves that get really interesting 😋

[@AJarOfYams]

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

[@NondescriptMammal]

Cosmology is 99% speculation built on assumptions, any conclusions are imaginary

[@nickolasrealmjumper5172]

I'm at 12:17 and what my brain is hearing is that instead of a black hole just being an inescapable force. It's instead something similar to a star collapsing into a 4th dimensional object in a super compressed shell and has a hollow interior will mostly stable 3rd dimensional space.

[@nickolasrealmjumper5172]

*With a misty stable 3rd dimensional space.

[@nickolasrealmjumper5172]

*Mostly stable. Damn auto correct and the fact that I can't edit comments on mobile for some reason

[@xpusostomos]

That's great and all, but I'm still not jumping into a black hole.

[@Hugh.G.Rectionx]

you scared bro?

[@RealisticExpectations]

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.

[@dexter8705]

Singularity; definition= a place or region where the rate of gravity is faster than the speed of light, ex: earth's 10ms, sun 274ms. Black hole 500,000ms...

[@donaldcharlong9586]

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?

[@TheOJDrinker]

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.

[@ivolol]

Note to video editor: moving the host left and right, from side to centre of screen, in between showing and hiding other media, is a bit disorientating if there's not much time between two pieces of media appearing. Ala 2:44 for these short transistions, just leave them on the side of the video.

[@damunzy]

Very much agreed. Should have just left the host on the right side of the screen.

[@chriscaventer596]

"Faith, not science! Sixty years without a proof, but they believe!" This is throwing such shade, and i love it. thank you

[@nathanclaspell6003]

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.

[@peachypet808]

​@@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

[@someoneelse3456]

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?

[@bocephusbirchcull4044]

@@someoneelse3456They don’t do that. That’s religion.

[@bocephusbirchcull4044]

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’…

[@robertwalkley4665]

If a rotating black hole avoids a true, but hypothetical singularity, is it possible that the instability at the center of a non-rotating black hole actually triggers rotation to occur, so that all black holes end up finding equilibrium via rotation?

[@lucas60336]

I'm not a theoretical physicist, but to me I would imagine that time dilation would prevent a singularity point in a black hole from ever really occurring. Essentially once the body starts collapsing at very near light speed its relative time would exponentially slow down as it nudged towards forming a singularity, meaning it would take an unimaginable amount of time for it to form, and probably longer than the lifetime of the black hole itself, due to hawking radiation. Just my armchair theory tho.

[@alexandr.g211]

Good point. But somehow physicists keep telling us that even though time slows down to a halt at event horizon the object still keeps moving and goes right through (in his own frame that is). So it looks like in GR you can move through space without moving through time. Probably because the 4 dimensions are treated as equals. Which to me seems a bit overstretched. If you assume that an object stops moving when time comes to a halt then all matter should accumulate at black hole event horizon, the layer would provably be a plank length thick and the expansion of the black hole would be constantly pushing this layer outwards. This is because once matter stuck at event horizon sees itself get left inside event horizon due to expansion of black hole - time for that matter should go backwards and its velocity would be negative and so it would get right back to the event horizon.

[@eugene_stets]

That's my point as well. Singularities have never had a place in my head, even Einstein himself hated them. I believe, the matter movement in BH is essentially halted after it reached the light speed which is by itself requires the infinite energy that no BH of any mass could possibly posses. The scary spinning of the neutron stars are giving the bold hints about how the nature can vent up just any excess of energy - it just spins the matter even more, up to the light speed. Meantime, the "heat death" of the universe will eventually tear up the black holes and even break apart all the atoms. Quantum fields will explode everywhere once again beginning another BIG BANG cycle. BB from the singularity is just another myth. Universe "Heat Death" and the Big Bang are actually the very same event, it happened before and it will happen again, defining the very same physics properties for each cycle. Fortunately for all intelligent life this cycles takes a decent time, unfortunately is that no civilization will slip through. The real mystery to me is the properties of the quantum fields which are making this tuned expansion-explosion clockwork possible. It makes me wonder how exactly and why the quantum fields crushed into our almost empty cold realm (with the achieved properties of the true vacuum thanks to exponential expansion) causing a tremendous matter injection event (the so called Big Bang) which is also helps to significantly slow down the expansion for a time. Also, it caused our fully re-energised reality plane to bump off from some other quantum reality plane making it possible for the matter to form from a free quantum charges until our reality plane sunk into low energy state by Universe expansion again.

[@alexandr.g211]

@@eugene_stets I don't think that matter needs to reach light speed in order to reach event horizon. Its acceleration is equal to light speed at event horizon but that is not necessarily the case with it's velocity, therefore mass doesn't have to fly off to infinity in order for a particle to actually reach the event horizon, so no paradox there. Regarding your further points - seems similar to the approach of Roger Penrose, which very much appeals to me. Its formulated via GR though, as I understood it, and states that at the point in the evolution of the universe when the last "piece" of stable matter disintegrates there is nothing to reference space and time against. The energy that was present in the system all along is still there since there is no way for the universe to get rid of it. It must be there in one form or another. Hence at this point one can not define the energy density of the universe specifically because its space parameters can not be defined. So Sir Penrose suggests that an infinitely large universe and and infinitely small universe are equivalents at this moment. There you have your singularity at the new big bang. And in order to avoid the infinities one can simply state that the new big bang occurs exactly at the Plank time of the disintegration of the last stable particle of matter. *by "stable" I mean anything BUT the vacuum energy particles which as I understand always net to zero mass within an immensely short time. P.S. I have a feeling that we are from the same country)

[@kk346592]

Singularities don't exist because nothing has ever reached the singularities, from the perspective of everything outside an event horizon.

[@nickhowatson4745]

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?

[@BlinksTwiceProfusely]

Thats such a good point

[@joelichtenthal6098]

Hi, you've missed a very crucial point. Kerr and Penrose (and Hawking) use a different definition of a singularity. Kerr speaks of a "real" singularity, if a curvature scalar (ex.: Kretschmann-scalar) diverges. Penrose speaks of a singular spacetime, where he uses causal geodesics which are incomplete AND INEXTENDEBLE (thats the part missing). The whole argument of the affine length is, that Kerr tries to find incomplete Geodesics of finite affine length, which end at a point where the curvature don't diverges. He does that by "flying through the ring singularity" and by claiming that the part of spacetime, "after" you flew trough the ring, is unphysical. But in the maximal extension of Kerr-spacetime, that part has to be implemented, for the spacetime to be "inextendeble"/"maximal". Therefore, when Kerr "shows" that there would be no "real" singularity, it wouldn't be either by the definition penrose uses. All Kerr does is question if the condition of inextendibility is justified. There are some good arguments why not: a maximal schwarzschild-spacetime would include white holes. And there are some good arguments for having the condition: for example you could remove the origin of minkowski-spacetime, then it would be geodesically incomplete. You may ask: Why even use geodesics? In electrodynamics you can easily describe singularities with diverging Tensors, because it all takes place "in" spacetime. In GR you try to describe a part "outside" your understanding. You having trouble tosay, curvature diverges at that point, if the point is not part of spacetime. We must therefore ask of your definition: “scalar invariant approaches infinity as the manifold point approaches what ?”

[@tyrrian2520]

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 KZbin videos, but I think Einstein was wrong” or some other conclusion to that end.

[@paulthomas963]

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.

[@pappoochacha]

So interstellar was right 😂

[@n1ira]

I've never really bought the idea that black holes have a singularity that is infinite mass because in the end it's just mass that's very dense. Glad people like Kerr exist to point out the false presumptions people have just taken blindly as truth

[@angelodecock6280]

Thank you for highlighting Kerr's paper, this was an incredible video! Ever since hearing the explanation of a singularity, I've felt unsatisfied by it. In high school physics I was taught how to calculate the escape velocity of stellar objects, and the relation between mass, volume and escape velocity. In my mind that meant that a certain mass would attract everything, including light at a certain density. To me, it makes a lot of sense for the matter that formerly comprised the star to be squished together in a more compact form than neutron stars inside the black hole, however not at an infinite density. Your explanation of Kerr's thoughts about rotating black holes and the ring singularity inside them not existing was amazing and it reminded me of those thoughts again. If Kerr is proven right, perhaps a whole new model for black holes can be made by physicists to explain what happens inside. Simply incredible to think about...

[@roppa789]

13:31 “Not too many physicists actually believe black hole singularities exist “….. yeah, exactly. We don’t ‘know’, as always, is the correct answer. A hypothesis may need tweaking. Wow! Who would have guessed?

[@Deltakitty32780]

Ditto😊

[@ewutermohlen]

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.

[@NoName-zi9qs]

Singularities in Einstein's General Relativity (GR) emerge not as physical entities but as indicators of a breakdown in the mathematical framework itself. Here's the reasoning: GR operates on a differentiable, piecewise smooth Riemannian manifold, which provides the stage for describing spacetime. When energy and matter are introduced, they induce curvature in this manifold. However, as the energy density increases, we eventually encounter a singularity, typically revealed through the computation of the Kretschmann scalar-a full contraction of the Riemann curvature tensor. This scalar, which characterizes the intensity of curvature, diverges at the singularity. Yet, by construction, our Riemannian manifold is smooth and differentiable everywhere. The appearance of a singularity suggests a paradox, as the manifold should not hold such non-smooth points. This inconsistency signals that the underlying mathematical description is incomplete or flawed. Thus, the singularities do not represent physical phenomena but rather the limits of our current theoretical model. The mathematics, in this case, tells an incomplete or internally inconsistent story.

[@michaelaj9019]

I love to watch this channel until I'm utterly confused... I get about halfway through most on a good day.👍🏽

[@felivent]

I didn't understand 99.99% but I followed along 'cause I just wanted to know if it's possible to get in and out of a black hole and live to tell the story

[@watgaz518]

What came first, eternal space or singularities? I’d say the former. Eventually, the space was peppered with singularities, each having their own compositions. Then via, either a BB or several BBs from that singularity, a universe was created, and the CMB was/is what defined us from other universes in a multiverse?

[@samiam8114]

Maybe a black hole is just an extremely dense neutron star. Never fully collapsing into a singularity.

[@paulthomas963]

The only kind of "black hole" that can really exist in physical reality is a neutron star.

[@nerobaal6655]

I’m glad you people at PBS covered this.

[@connecteddthoughts]

Maybe singularities really do "break" physics. And what is a region of alternate physics? A universe.

[@quantummaniac5]

I had no idea Kerr was still alive. I love that guy's work. I'm looking forward to reading this paper for myself!

[@arinalikes5911]

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?

[@lomiification]

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

[@paulthomas963]

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.

[@rome-s4c]

I’ve recently been studying Einsteins theory of general relativity and I’ve realized that because it was explained from a genius a lot of us are overlooking just how powerful this theory is. Einstein's theory of general relativity is a cornerstone of modern physics, yet its full potential is often overlooked. The theory fundamentally alters our understanding of time and space, demonstrating that mass influences the fabric of spacetime. This principle is central to discussions on time travel and interstellar journeys. Traditionally, the pursuit of interstellar travel has focused on achieving light speed. However, considering mass as the key to controlling time suggests a different approach. Time is not simply a linear dimension; its manipulation is tied to mass at a quantum level. Light, despite being the fastest entity in our 3-dimensional world due to its masslessness, is still bound by the constraints of the third dimension and cannot surpass the universe's expansion. Gravitational lensing, a phenomenon where light bends around massive objects, supports the idea that controlling mass can alter spacetime. If we could manipulate mass around an object or vehicle, we could theoretically warp space, drawing distant points closer and bypassing the need for conventional travel methods. Envisioning a machine that can shrink an object while maintaining or increasing its mass could offer a pathway to time travel. This concept builds on Einstein's insights but looks through a different lens. By bending spacetime itself, rather than moving through it at immense speeds, we might achieve unprecedented control over our journeys through the cosmos. While this theory requires further exploration and experimental validation, it is rooted in the profound implications of general relativity. Pursuing this line of thought could revolutionize our approach to time and space travel, offering new horizons for scientific discovery.

[@brazenclips]

Singularities never made sense in anything resembling practical application of physics. Next on the chopping block: string theory

[@paulthomas963]

That should've been chopped first. We're coming for the Big Bang too.

[@Andy009Duncan]

Do you have an episode covering Planck stars? I haven't been able to find one, if you have. If you don't have an episode on Planck stars, would you like to do one?

[@ContentByRyan]

I believe that black holes are time machines. You fly into one, you hit an unreal singularity, mass becomes unreal. Boom, you're a tachyon.

[@Southernbredbread]

7:50 he begins to answer the question without the background information if anyone is interested.

[@azjaguar]

The “hypothetical point” is actually a conduit gap that jumps the connection toward an inverted stereo-enantiomer. There are Two (2) sheets of spacetime. One the zone we inhabit. And, the other … the “anti-matter” sheet, or the other side of the gap between “The Interstitial Void”, a sort of super-highway for transit between two super massive black holes. For example, Sag A to the Andromeda galaxy’s galactic center. 😊 1:29

[@RobertMertensPhD]

Some years ago I had to deal with a mathematical problem with a singularity in the result, of a practical problem in the real world, one in which I KNEW that the singularity was wrong. I suppose I wrestled with the problem long enough to figure out a numerical path to a correct solution, even if only approximate, but good enough for a practical application. As it turns out, the solution was in rings. Now that I think of that problem, I may be able to plot a solution to the black hole singularity issue. I've been noddleing at this problem for a number of years, but never really began researching it until recently. I first suggested this to an astrophysicist who was visiting our university physics department in 1995 as a guest lecturer. I don't remember his name. The ring notion sounds like part of a solution that perhaps might tbe better characterized with a more spherical solution. A sphere-singularity? Or perhaps even more of a gas-like cloud. I considered once, naming a paper I planned to write, "Every Black Hole has Two Event Horizons." Of course, one inside and one outside. If there is indeed a ring "singularity" near the core, then what we will have is a "galaxy generator" or a "light machine", one that effectively powers, ignites or lights-up a galaxy, and an answer to the question about dark matter. There are quite a few papers suggesting that black holes in the shape or torroids could be a viable object, but what is suggested here is that, only torroidal black holes exist. If that is the case, there might be not just one, but two ways for matter to escape black holes. The first in a paper by S. Hawking, through spontaneous generation of matter (I believe it's referred to as Hawking Radiation), and the second through quantum tunnelling near the "core" of the black hole, and then, given the immense electromagnetic fields generated near the core, escaping matter being ejected at near light speed. Depending on the charge of the tunneling matter, it would be ejected either north or south. This would also suggest that there is a tiny little hole that goes all the way through the torroidal black hole. On the other hand, this isn't the first wackadoodle idea I've ever come up with. I'm just happy to see that I'm not the only one considering it. This singularity notion really stuck in my craw. I was looking for a starting place for my next paper. Maybe I've found it. And if Kerr did it 90, maybe I can do it at 70.

[@helloidharbl6753]

I know 60 year olds who can't remember what day it is. Here's this 90 year old still shakin' up theoretical physics.

[@KillerQ13]

A nonrotating black hole does seem quite silly. It implies that it has no momentum and if that were the case, its position would be everywhere. Even creating one theoretically would be absurd: Absolute zero, no vacuum fluctuations, and no entropy interacting with this ideal. The matter in this area wouldn't even be able to move to gravitational collapse and no matter how you "nudge" it, it's a direction towards rotation. No vacuum fluctuations also means no Hawking radiation so even if created, you would have no way of knowing it was "there". The whole thing falls apart. Near zero rotation does make for some interesting things though. Like fudging quantum physics in one direction or the other.

[@KillerQ13]

The preference for matter over antimatter may even be a related to a preference of rotation of all the black holes combined. Time has a prevalent direction if antimatter is understood as running counter.

[@dexter8705]

I love the accurate animations in this video