Spinning a black hole as fast as possible

Go to brilliant.org/drbecky to get a 30-day free trial and the first 200 people will get 20% off their annual subscription! This summer, I published two research papers with my collaborators about the growth of supermassive black holes. One of those research papers was about what processes cause SMBHs to spin at their maximum rates, and the subsequent effect on their galaxy’s. So in this video we’re going to dive into that research paper and I’ll explain what we found…
Beckmann, Smethurst et al. (2023; the spins of SMBHs) - arxiv.org/pdf/2211.13614.pdf
Smethurst, Beckmann et al. (2023; coevolution of SMBHs and their galaxy’s) - arxiv.org/pdf/2211.13677.pdf
My other research papers - ui.adsabs.harvard.edu/search/...
Reynolds (2021; observationally measuring spin review) - arxiv.org/pdf/2011.08948.pdf
Fabian (2002; FeK⍺ line to measure spin) - arxiv.org/pdf/astro-ph/020609...
Martin et al. (2018; simulations show less than 35% of all mass in SMBHs due to mergers) - arxiv.org/pdf/1801.09699.pdf
McAlpine et al. (2020; simulations show less than 15% of mass in SMBHs due to mergers) - arxiv.org/pdf/2002.00959.pdf
Tadhunter et al. (2018; using HST to image the outflow from a SMBH) - arxiv.org/pdf/1805.00514.pdf
00:00 - Introduction
01:17 - What do we mean by black hole “spin”?
04:19 - How fast can black holes spin?
06:47 - How you actually measure black hole spin
09:52 - Why the spin of a SMBH affects the whole galaxy
15:34 - My new research: galaxy merger-free growth of SMBHs leads to the highest spins in simulations
18:55 - Can we test these results with observations?
20:41 - Brilliant
21:47 - Bloopers
Video filmed on a Sony ⍺7 IV
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👩🏽‍💻 I'm Dr. Becky Smethurst, an astrophysicist at the University of Oxford (Christ Church). I love making videos about science with an unnatural level of enthusiasm. I like to focus on how we know things, not just what we know. And especially, the things we still don't know. If you've ever wondered about something in space and couldn't find an answer online - you can ask me! My day job is to do research into how supermassive black holes can affect the galaxies that they live in. In particular, I look at whether the energy output from the disk of material orbiting around a growing supermassive black hole can stop a galaxy from forming stars.
drbecky.uk.com
rebeccasmethurst.co.uk

[@Zouzou123gen]

It's one thing to explain research done by others; it's a hugely different feat (IMO) to talk about your own research! I'm sure you have so many things you want to tell us, but you manage to summarize it, explain the rationale, and remain objective about it. Thanks please keep doing this!

[@danleeselman4827]

It has become so institutionalized doing science for money. Science for scientific sake doesn't give you your paycheck.

[@davidelliott5843]

How does black hole research make money?

[@djoswald9128]

@@danleeselman4827 “Yes it does. Centripetal force. I still find it hard to believe. Show me galaxies without black 🕳️’s.?.😉.?

[@LeslieShaff-ud1ty]

Zouzou, you have been there, Congrats!

[@jasonbrown9142]

What happens to the ejection matter of the quasars over time where the ejection is perpendicular to the galactic disc? Does this give rise to globular clusters ultimately or are those more a function of galactic collisions? Does the gravity of the galaxy hold onto it or is it ultimately ejected from the galaxy into the void? What are the implications of retro movement versus standard rotation, if any? So many questions…

[@meslud]

Did you know that Schwarzschild (which is just a German name) literally translated into English means "black shield", so imagine my confusion when I first tried to find out anything about what kind of "shield" a black hole has ^^

[@ENDESGA]

This is honestly such an amazing job, Becky and Ricarda! I absolutely love how it's "this is a paper, by me!", because you don't see this too often! Huge congratulations~!

[@FLPhotoCatcher]

Indeed. 👍 But who put Pluto in the list of planets? 🤨

[@rjblaskiewicz]

There was a moment where you were describing the orientation of the axis of spin and material falling in from the rest of the galaxy where it was entirely plain on your face that you absolutely love your job.

[@manifold1476]

timestamp? svp

[@reasonerenlightened2456]

it is a preposterous claim in this video that we know the laws of physics inside a black hole therefore we know it is "spinning"

[@AJMansfield1]

2:00 ngl I do genuinely appreciate the clarification that for black holes, spin really does mean a concept related to angular momentum. We're often told that black holes act like "fundamental particles" that only have mass, charge, and spin, but usually the only type of "spin" that a fundamental particle has is this quantum number that has more to do with group theory than macroscopic angular rotations.

[@gurupkaargill2049]

Mam I'm a layman in the field of astrophysics, but i find your lectures on space so fascinating that i couldn't restrain my self from ordering your both books on Amazon, i received those recently, I'm from India, presently I'm reading your book ten things you should know, i hv completed the reading of book on Black Holes, God bless you in all aspects of your life and help you countinue researching and writing about space 🎉🎉

[@melanocrisis]

I can't imagine what it feels like to put out literal art and knowledge for the world to see - in a form of research papers. Huge congratulations - you are the real pioneers of humankind.

[@danleeselman4827]

why waste time arguing about the scientific reality between a movie made for entertainment and reality.

[@borisborcic]

Bravo! I opened the comments after watching the video and salient among the intentions of communication collected, was the idea to name this work of Dr Becky's _a powerful model of, or illustration for the name of_ ART. (Now if that's "frame dragging" (of model making) there's an implied conceptual BH to question;)) Would it not make sense btw to split the scope of the name of art and to look for a qualifier to name _the sector of art_ that would here be illustrated? What about "cognitive art" -- it's friends enough to your "...and knowledge"? That's a tame choice. But it precedes the candid question, _can you locate art that would in your opinion be self-evident to call_ "non-cognitive"?_ For a crazy wild alternate choice, "Spin Art"... to promote effort to think of SMBH Spin and of Quantum-Mechanical Spin as forming a wild pair, like say the North and South poles of the Earth -- deeply related but in many regards related by being _particularly_ contrasting. "Spin Art" is also crazy because it's not aligned with the spin _of the name of spin_ where seduction is involved, as it is in art (in principle)... _That_ spin is distinct from the "angular momentum" spin of the name of spin in physics that's here wanted... except perhaps for spin _as evidenced by exotic trajectories of bouncing or flying balls_ -- likely at the linguistic origin. ...this returns me to "frame dragging". Admittedly unique to BH spin (in contrast to QM spin), "frame dragging" is both pure advanced physics and _arguably aligned with the spin of the name of spin where seduction is involved, like in art._

[@reasonerenlightened2456]

it is a preposterous claim in this video that we know the laws of physics inside a black hole therefore we know it is "spinning"

[@FLPhotoCatcher]

Dr Becky and all scientists might have to change their minds about what she says at 10:48. A new study has found evidence of black holes ‘burping’ out matter years after consuming a star... I sense a new video about black holes coming.

[@borisborcic]

@reasonerenlightened2456 no more preposterous than claiming we know there's mass inside the hole and that it therefore has (linear) inertia, and gravity. While rotational inertia (spin) is familiar from usual bodies, rotational gravity (frame dragging) is rather special to bh (although I wouldn't be surprised to learn it can be significant around neutron stars as well).

[@MultiNacnud]

Congratulations on your paper Dr Becky et al. Until now I thought Peter Mandelson was the UK's foremost spin doctor.

[@azdgariarada]

Hearing about your own research is very exciting. I did a little "hey, I know that author!" as soon as you mentioned your papers.

[@martinkellermayr8766]

Great video as always, just one detail I noticed at 5:20, shouldn't the radius of the event horizon get bigger with a more massive black hole?

[@oystercatcher943]

Totally. I think. The equation seems to contradict what Becky said. But great video. I’ll let that go

[@noneofyourbusiness5326]

Just to be nitpicky, wouldn't the angular momentum of the Black Hole be slightly smaller than the original star, given that part of the original star has been scattered into the nebula created in the super nova?

[@ivoivanov7407]

Yes, you are completely right, the angular momentum of the black hole is smaller than angular moment of the original star. Rest of the momentum is "carried away" by the matter of the nebulae created by star's collapse.

[@DrakeLarson-js9px]

Dr. Becky cover that in her ice skater example

[@MauricioA666]

Finally, I got your book thanks to my wife on my birthday. It wasn't easy to get (we live in Colombia), but it is here, and I will read it as soon as possible. Thanks Dr Becky for your great work, and share all your knowledge. Greetings from Rionegro (Antioquia).

[@JarredHarvey-ix4qb]

You have such an impressive flow Detailed, yet succinct. Mature and playful, you'd be such an awesome lecturer

[@azdgariarada]

I'd love to see a video with more in depth information about how you run your simulations of (one presumes, millions of?) galaxies, SMBHs, etc.

[@sophiophile]

Paper titles are in the vid.

[@azdgariarada]

@@sophiophile Did I say I wanted to read a paper? I'm lazy and stupid. I'm not going to try and understand a scientific paper. I want pretty smart science lady to dumb it down for me and spoon feed it to me in easy to digest TV format. Duh! ;-P

[@sophiophile]

@@azdgariarada Fair enough. She has expressed in the past that the simulations+code side of things is not something she is deeply involved with. Maybe an interview with a co-author would be better.

[@BenWard29]

So is a galaxy just a giant supermassive black hole accretion disk?

[@pikmin4743]

awesome! congrats on publishing and thank you for sharing and informing us

[@BHNative]

Happy to have stumbled through, you’re great!

[@ondrej_hrdina]

The universe is amazing -⁠ thank you so much for trying to find out how it all works. It's a joy to hear about such a fascinating subject from a scientist doing the actual work on it. Not only that, you always explain the essentials really well. Congrats on the papers to everyone who contributed!

[@CydoniaPhysGeekGirl]

I am currently working on something that I hope will explain not just the how but also the why. Very exciting work! Sadly I have several physical health problems standing in my way, delaying my work.

[@CydoniaPhysGeekGirl]

Exploring a new paradigm for dark energy.

[@TheAslakVind]

I am so thankful for the with and depth of your videoes, you are truely able to explain without dumbing down. I have a dumb job, and watch your videoes to keep my brain working at full speed.

[@MrDlenrek]

Brilliant episode! Love it when you go deep into some of your own research

[@MCsCreations]

Fascinating stuff indeed! Thanks a bunch, dr. Becky! 😃 You guys did a fantastic job, congrats! Stay safe there with your family! 🖖😊

[@alexz1104]

So cool to actually see some of your own research featured on the channel. Great job Dr Becky!

[@neoanderson7]

Always a delight to hear from Dr. Becky. Hopefully get some HST time as well as JWST. 🤞

[@davidmarksberry5970]

Great job!! Thank you Dr. Becky!! Using all the big fancy words but string them together in a way that I walk away understanding the basis of the video..🎉🎉🎉

[@raydenn6027]

Interesting, very interesting Dr Becky is so good at explaining her passion. I love the bloopers too.

[@johnmccausland8466]

I always look forward to watching your videos Dr Smethurst. Amazing content.

[@21palica]

I remember a wonderful example of how the black hole's spin increases as it swallows up material, using a spinning bicycle wheel (representing the black hole) and a hand (representing the spinning material falling inside it). Every time the spinning material hits the surface of the black hole, if it's spinning in the same direction, it will increase the black hole's spin, and vice versa. I am sorry, but I forgot the physicist that was making that wonderfully simple example in the documentary. Congratulation on the paper Dr. Becky! I will be buying your book when it comes out, and can't wait to read it!

[@v4vd]

tysm dr.becky for this lovely insight!

[@pablotroncosounwin2917]

Congrats, Dr. becky. You've made another masterpiece 👏👏👏 Isn't the assumption that the mass of the original star remains the same when exploding in a supernova? I understand that vast amounts of mass AND energy are spitted out during the collapse.

[@BrookeSimmons]

You're right, the masses aren't exactly the same -- but nevertheless the change in size is so dramatic between star and black hole that even if you only consider the portion of the star that will become a black hole, the collapse still requires a huge spin-up.

[@AKjohndoe]

It is amazing having the person who wrote it, explaining it. Thank you Dr. Becky!

[@jimmagwojo2718]

Thanks for sharing your research Dr Becky a lot of scientists make their work for their peers by explaining this to us like this we feel like we have become your peers too

[@Joshua-by4qv]

Young brilliant women. And they are here to do the hard work for us. Nothing fascinates me more than cosmology. Keep up the great research.

[@vanikaghajanyan7760]

5:28 The Kerr metric is only a particular solution corresponding to a certain distribution of masses in a rotating body. Moreover, this metric contains a trick: when we change only the sign of time or only the sign of the azimuthal angle, the invariance of the metric is violated. This is as it should be, since such transformations are equivalent to changing the direction of rotation, and the nature of the gravitational field depends on the sign of the angular velocity. Obviously, if ar(G), then there is a singularity on the ring with r=0. P.S. About the accretion of matter: the energy of the particle is equal to the derivative of the action in time x(0)/c: and defined in world and proper time: E(0)=с∂S/∂x(0), E=∂S/∂t [momentum p(k)=∂S/∂x(k)]. Then E(0)=E√g(00)=const and E(0) is preserved, and E is not preserved. E=mc^2/√1-v^2/c^2, where in the static case v=dl/dt=-dl/dt√g(00).Thus, when a particle moves in a gravitational field, the energy E(0)=mc^2(√g(00)/√1-v^2/c^2 is preserved. This formula remains valid in the case of a stationary field if, when determining the velocity v, one uses the proper time measured by the clock synchronized along the trajectory of the particle.

[@DenizenoftheAges]

Amazing. Thanks!

[@ross077]

Thanks for this great explainer on the geometry of super massive black holes and how they affect their host galaxies Becky. It makes sense in my head and I hope your ongoing research on this subject yields plenty of useful scientific results 👍

[@davidpearson3304]

Admittedly most of the stuff on here goes right over my head and I can’t even begin to wrap my arms around it……But….today I actually sort of understood it. 😳🤷🏼‍♂️. Maybe watching Dr B’s videos is starting to sink in.

[@OhAncientOne]

Formulas with the descriptions are 🏆 Thanks!

[@CloudhoundCoUk]

Fantastic thank you, Dr Becky.

[@EdmundWChan]

very informative. thank you doc!

[@DouwedeJong]

thanks for explaining. that was super interesting.

[@grayjphys]

great video, love the nail color too!

[@artlovepeace42]

Amazing stuff as always and congratulations on writing such great research! Question 🙋‍♂️: Can a black-hole’s spin get “redirected” so much, from a galactic merger, to reverse the black-holes spin? Would it’s spin be able to become the exact opposite of its original spin (a 1 to a -1)?

[@paulgar8]

Great Video, Thank You!

[@Erik_001]

Love your work. Thanks.

[@jessicamorgan3073]

Thanks Drs Becky and Ricarda (and Dr Chris too!). 😊

[@noneofyourbusiness5326]

I love the explanation of how you measure that spin. You do a wonderful job of talking to us average people.

[@rickrivethead]

Love your Stuff btw!!!

[@philurbaniak1811]

👍👍 sounds awesome, really interesting ideas!

[@kevindoom]

Best one yet Becky

[@EarlWallaceNYC]

Fantastic explanation. I had to read Wald twice to get the understanding you gave in 10minutes. Nice ! Kudos.

[@Fearls1]

Amazing, thank you Professor!

[@RevP369]

Brilliant! As usual, further explanation the unusual.🙏

[@shaunehuolohan5736]

Thankyou Dr Smethurst Amazing I can comprehend this, due to your explanation.

[@Benmarkk2009]

Lol I like that Dr. Becky says that maths is plural but is saying “The maths isn’t adding up” or “the maths doesn’t make sense.” Like its singular 😂

[@10kanutt]

That's the norm in British English. Maths is short for Mathematics. Mathematics is singular with the s, and therefore maths is as well.

[@dtutssel]

Mathematics isn't a plural.

[@Benmarkk2009]

@@dtutssel omg nvm 🤦🏻‍♂️🙄

[@nemoniemand9264]

Impressive work!

[@mattslaboratory5996]

Excellent explanation, as always. I also had fun, for a while, trying to decide if you were saying "ion" or "iron," but my clumsy American ears eventually figured it out, I think.

[@FLPhotoCatcher]

When she says "maths" it sounds very much like she is saying "mass". And "mass" is something an astrophysicist often talks about. It is clearer to say "math"... No, an *abbreviation* does not need to be plural.

[@timpointing]

@@FLPhotoCatcher Another clear, unambiguous way to say the word is "mathematics". While it is much longer and may not be one's natural go-to word, there will never be a chance that somebody thought you said "massematics" 😛

[@Yves_Breeze]

@@FLPhotoCatcherAll words are made up, but to the degree that one can speak “correctly”: math is correct in the American dialect and saying maths is correct in the British dialect

[@douglaswilkinson5700]

The British do not pronounce the letter *r* unless it is in word-initial position: they say *kaht* for card (they also devoice the *d* to a *t* in word-final position), *staht* for start, etc.

[@jmiddlefinger]

I could listen to Dr. Becky all day. Not only do I learn amazing new things about the universe around us, but she makes me so nostalgic for the years I spent in Yorkshire as a U.S. serviceman.

[@drwaynebuck]

Thank you for the equations. More please!

[@chrischen82]

hey Becky, thaks for your wonderful talk about the spin (and all your other videos). I had a bit trouble undersanding your graphs shown. it would be great to get an explanation for the axis before talking about the gaphs. Have a great time. 🙂 Greatings from Dresden, Germany

[@martynnewby6298]

Dr Becky. This lecture is finely pitched. It appears undergraduate light. Good. I can watch this with my breakfast and rise from table full and content in body and mind.

[@ryvyr]

Such a *massive* undertaking ^^ Much the grazie :>

[@MYBLOODYUSERNAMEFFS]

🤯 that was awesome 😊

[@NathanAkers]

Dr Becky, I learn tons from you. This stuff is fascinating. A couple questions came to mind here that I’ve never thought about, and some feel kinda basic, but here we go: (1) Are there any bodies in space that don’t have a spin? What would happen if they didn’t? Is spin required for gravity? (2) Since matter is being drawn into black holes, and jets of feedback are being expelled, I think that means that space has a lot of matter that’s disconnected from bodies (stars, planets, etc), no? If so, how do we imagine this loose material? Why would it not fill the void of space evenly like gas in a container would? Thanks!!

[@PhilMason1972]

I’m going to need to watch this again… got the book now though!!

[@michaelvalencia3537]

Loved your book!

[@martynspooner5822]

And here is me pretending I understand all this and I am busy checking the maths now. ( not really truly) I I do grasp wee bits and I am happy enough with that although admittedly sometimes I feel like I've sneaked into somewhere where I have no right of being but that is what makes it so fun. Thanks for sharing your brilliant work so layman like myself can have a peek.

[@jondor654]

Same here. A word of caution. Not too close to that horizon.

[@martynspooner5822]

@@jondor654 Will keep that in mind. Ps how will I know if I am too close.

[@isaacgrosof212]

5:15 I'm confused by this part - why does having more mass due to spin make the effect horizon shrink? Normally having more mass makes the effect horizon bigger, right?

[@douglaswilkinson5700]

Matter in the accretion disk rotates around the BH. Since angular momentum is conserved this energy spins-up the singularity at the center of the BH. The event horizon spins faster and faster. As it approaches the speed of light the event horizon must *shrink* to prevent it from reaching the speed of light. If the event horizon were to actually reach this speed then the *singularity* would be exposed or *naked.* As I recall the *Cosmic Censorship Hypothesis* states that singularities can never be *naked.*

[@isaacgrosof212]

This still doesn't make sense - as shown in the figure-skater example, having a smaller radius means faster angular speed for a given angular momentum. Shrinking wouldn't slow things down, expanding would.

[@martixy2]

200 comments I scrolled through for an explanation and you're the only person to bring up this point. Shows you how much of the audience pays attention.

[@dsdy1205]

@@isaacgrosof212 You're treating the black hole as a solid newtonian ball, which does not hold under GR. A 'spinning' black hole drags spacetime along its equator. The result of this is that there is an ellipsoidal volume of spacetime around the black hole called the ergosphere that rotates with it, and this volume of spacetime contains a good part of the black hole's angular momentum. The ergosphere does in fact grow bigger as the black hole's spin parameter grows, which makes intuitive sense.

[@adriancopping1253]

Thank you Becky 👍

[@davydatwood3158]

The first time I encountered the phrase "hard science fiction" was in the afterword of an anthology explaining the science used in the stories. One of the features of this setting was the use of miniature black holes as a form of energy storage - put energy in, black hole spins faster and stores energy; slow black hole down, energy comes out. I don't remember most of the details (and I can't remember either the auth-- wait, in the middle of this sentence the title came back to me). The book is the McAndrews Chronicles by Charles Sheffield. Anyway, I don't remember the details but this video does quite resonate with that memory, so it was very, very engaging. Also: Canadian English is a mix of American and British English and so one could argue that Canadian English is the "best" English because it's subjected the language to a Darwinian contest of survival. From that admittedly nebulous premise, I conclude that although "zed" is correct and "zee" is not, "math" and not "maths" is the best way to truncate "mathematics." (Mostly because "ths" is really hard to say, your tongue is rushing to change position. I suggest that "maths" only persists in the UK because most British accents would actually say "maffs," which is much easier to say than "maths" and also flows better than either "math" or "maff.")

[@burnte]

Fantastic book, I bought it in hardback last year and the audio book.

[@malectric]

I'd be interested to know whether there are any deviations from what is expected (considering known/"visible" mass) that could be a result of dark matter being present? I have heard it being hypothesized that supermassive black holes (and galaxies) might not have been able to form without the presence of dark matter. Just love your channel. I think your taking time out to inform people outside academia of your interests and findings is terrific.

[@Darkrealm7]

"Space is hard, words are harder" is my new favorite quote of all time

[@gustavderkits8433]

Kudos for getting, not just any skater spinning, but the world record. Well done. Angular momentum is hard for most people to grasp.

[@AndrewDRSWilliamson]

We just love the black holes 🕳 😂. Good luck with your paper!.

[@JoieVientLeMatin]

I also love your presentation style. It is resulting in me having a growing fascination for astrophysics. So, a quick question from a neophyte in this science - that you probably already covered when I wasn't looking: The time scale over which many of the phenomena being discussed is huge - completely outside anything meaningful to us mere humans. For instance, the period over which black holes have merged. So how do you determine if a black hole has experienced no mergers or many mergers?

[@Adam-zt4cn]

In the equation at 4:57, the Schwarzschild radius and the mass are in a linear relationship; One gets bigger, the other gets bigger. But at 5:20 you say the exact opposite: "If a black hole has more mass, the event horizon shrinks" Aren't these two statements at complete contradiction??

[@Adam-zt4cn]

And I do realize the first equation is for non-spinning black holes, but I don't see the intuitive connection between "more mass -> smaller radius", because all previous intuition would suggest the opposite. It would seem like the rest-mass and the energy-equivalence mass behave differently, one increasing the radius and one reducing the radius. I can't wrap my head around this.

[@hyfy-tr2jy]

Dr Becky....would you ever consider doing your own documentary series of celestial objects, planets and the like? I think you would do a smashing job of it?

[@AndrewBlacker-wr2ve]

Dr. Becky is a great source for information concerning black holes. And while she knows quite a bit about other "things" in the universe, she might not be the best authoritative source on say, the Oort cloud. Or planetary ring structures. However, Dr B could host those specialists in a Socratic dialouge and make a great series.

[@dtutssel]

Hasn't stopped Brian Cox doing loads of tedious TV things. I'd rather watch Dr becky

[@rcarter-ip8xd]

Really enjoy your videos cause the kind of questions you ask yourself are the same questions I ask myself. Only you can answer your questions and I, as an arm chair enthusiast, am just SOL. So, on this video I remembered another video of yours where you talked about a ring galaxy, Hoag's Object, and it made me wonder, could a spinning black hole whose axis was 90 degrees to the plane of the galaxy disk, explain why the ring is seen in Hoag's Object?

[@user-gw4mb9nh7i]

love how you see through our contractions (butchering) of the English language like black holes compressing(accreting) of close star matter, and then promulgate (burp out) our processed info into the AdS in an effort to define all. Perhaps our attempts at contracting words are similar to the circle of the universe's information from the MULTIPLE SINGULARITIES TO THE SINGULAR PLURALITY. If you see the curve...

[@louisgiokas2206]

In the bloopers section you talk about the term "maths" (the spell checker in my browser in right now flagging it as incorrect) and how the Americans changed the language. Actually, at the time of American Revolution there was a conscious decision to do so. Something to do with breaking away from the colonizing oppressor. Actually, I lived in the UK for a while and sometimes find myself using terms like maths. Also, my first three cars were small British sportscars. The shop manual for my MGB actually had a glossary of British to American terms. By the way, thanks for sharing your research. It is interesting to see what various KZbinrs, especially on science channels, are doing.

[@jbvmpsmtr5488]

I like the way you explain things. 👍😎

[@The_Green_Man_OAP]

What is "a" though? 😵

[@judelekpa2778]

Funny, whenever Dr Becky says something is difficult to... the next statement she makes is there is a way and she then goes on to explain how... Great Job Dr Becky... From Nigeria.

[@johnallison7608]

Wow! Tour de Force Dr B!!

[@mb1287t]

Good job

[@IaIaCthulhuFtagn]

Wouldn't a star lose some of that mass when it goes supernova and explodes expelling both mass and energy out, or does it usually manage to gobble it all back up when it collapses?

[@mrnitro30103]

Love to have more maths and tech details for sure.

[@michaelare]

Fascinating!

[@mike2884]

My fav channel on Black hole info! ❤ Wondering if dark matter "stuff " ,can spin as fast as Black hole ?

[@desdoyle7839]

Fascinating

[@iborgiwc7899]

@Dr. Becky Please do cover the "theoretical" situation where the spin does exceed C, and what happens to the horizons at the convergence point and beyond, particularly in relation to white holes. Please also cover Kip throrns works in this regard. thanks in advance.

[@unamngxale8286]

I love your videos

[@tony52398]

Dr. Becky Is there any theoretical way to map the mass distribution inside a black hole? In my head I’m picturing two black holes merging, the singularities should still be a distance apart even if they are inside the event horizons of the other black hole. By gravitational lensing or some other effect could you understand the mass distributions inside the event horizons?

[@leonais1]

I think Dr Becky made a video about black hole mergers recently? I seem to remember there was no observed data and it was not even certain the black holes merged instead of falling into a binary orbit.

[@lukekowa]

thats a crazily amaZing question can't wait for the answer

[@thomasgade226]

Some hope to measure gravitational waves to use as a "telescope" to view critical data about the merger, particularly at the very end during the so-called "ringdown" right between vibration and silence. That's for two ultradense objects circling rapidly around eachother, many times per second. Then they coalesce into one, while the last wobble fizzles away, hence ringdown.

[@WestOfEarth]

Very clear and concise explanation. I can see the difficulty in correlating accretion spin with bh spin. Sort of like trying to infer the rotation of Venus by measuring the speed of its clouds. I'm curious if bh whose spin axis is perpendicular to the galactic spin axis are the cause of barred galaxy structure?

[@andrewsallee6044]

This triggered some new questions for me that I have, so far, not been able to answer: 1. Is the universe spinning? 2. Would that mean that a universal frame of reference is non-inertial? 3. How would an anisotropic universe affect our theories of gravitation? 4. Would a spinning universe replace inflation?

[@jasimmathsandphysics]

I saw you on sky at night again I wish you had more time on it because you explain it well 😂

[@arpharsed]

Thank you.

[@SurajKumar-ln8ij]

There also ton of wacky things that makes BH even more mysterious like frame dragging ,pro grade and retrograde spin, charge, density and its play with optics and light.n

[@malectric]

Thanks

[@Kane-ib5sn]

the outer-surface of a black-hole/darkened-star, has to spin above the speed of light (locally), in order to expatriate energy - some of it in the form of electromagnetic waves, stretching/dispersing out into gravity waves, as photons collide with other photons moving in opposite direction &spin, same amplitude (destructive interference - which does not actually destroy energy - it causes zero relative motion to the origin of expatriation. since the accumulating wavefront is defined by hooke's law...the wavefront weakens at the square of the distance - becoming a gravity wave). such is the case of a nebula formation, a Black hole / Darkened star may explode, if its core tangential-speed exceeds 'c' (locally). in the greater/grand-scheme, this described phenomenon gave us the Big Bang/Big Spin. that is my interpretation.

[@michaelripley4528]

Your mind is Way faster than your tounge😁 AGU!! Another Great Upload‼️