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1,310,892 Views • Feb 22, 2024 • Click to toggle off description
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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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YouTube Comments - 3,449 Comments
Top Comments of this video!! :3
Kerr is still shaking things up at 90 years old. What a beast.
1.3K |
10:45 It can’t be put into words how utterly disappointed I am that this isn’t called a Ringularity.
1.6K |
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.
279 |
Man, he's 90 and still contributing to physics. That's life goals right there.
1.9K |
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.
1K |
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.
78 |
I'm glad PBS is still going after all these years. And still has decent content.
75 |
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.
752 |
"Singularity-free spacetime!" - Sounds like a great slogan for a T-shirt.
603 |
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.
26 |
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!
44 |
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
725 |
kerr is like 90 and still producing new ideas. what a g
279 |
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...
14 |
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.
8 |
Although I barely understand 5% of the mathematics and physics behind it, I enjoy watching this show. Very relaxing! Thank you!
107 |
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 YouTube 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!
206 |
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.
5 |
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.
5 |
@CallOfCutie69
2 months ago
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.
2.2K |