The Biggest Possible Black Hole - Sixty Symbols

[@sixtysymbols]

A Brief History of Black Holes by Becky Smethurst... (Amazon links)... US: amzn.to/3u0b4BN and UK: amzn.to/3VxlNPV

[@a.randomjack6661]

You should pin your comment📌so it stays at the top.

[@Globovoyeur]

My copy is on order...

[@mussalo]

Can one get it from anywhere else than Amazon? From EU preferably.

[@juliocardenas4485]

Purchased 👍🏾

[@bentoth9555]

Don't have the free funds to purchase it myself, but I definitely suggested my local library do so.

[@N.I.R.A.T.I.A.S.]

I feel like Dr Becky's ability to freehand draw a black hole and accretion disk is more impressive than I realise.

[@sixtysymbols]

I too was impressed.

[@QirnsChannel]

@@sixtysymbols I appreciate that you ask folks to draw things so often. Math and Science need more drawings! Even when it's just a drawing of a mouse.

[@lukaskern9163]

@@QirnsChannel WORST - MOUSE - EVER!! x'D

[@EPMTUNES]

Anything for the merch

[@88CBAUGH]

10:58 for your viewing pleasure.

[@Booster45]

Dr Becky is back on sixty symbols!

[@Felipehez]

Thanks Brady for keeping this channel alive for so many years! I love your videos and dr Becky!

[@WouterWeggelaar]

I am in love with Becky's enthusiasm and I will absolutely be getting the book!

[@sixtysymbols]

Nice work - hope you enjoy it!

[@writingfriction]

Forget the book- I'm in love with Dr Becky.

[@vzr314]

@@writingfriction welcome to the club mate

[@cynomyS]

@@writingfriction get in line

[@samcooke343]

@@writingfriction You're all too late, sorry 😏

[@TON-ei7ht]

I’ve worked so hard to be featured on this channel. It’s about time!

[@gqqggq7127]

Nothing escapes you!

[@julyanjohns1237]

this vid makes me happy on so many levels A black hole expert discussing the subject of their latest book with a renowned science documentary maker, or from a regular's perspective - Becky and Brody having a wholesome catch up :) inspiring to see how a simple idea over ten years ago of doing vids of professors talking about symbols has had so many positive knock on effects for the people involved with it.

[@stevenhanaway920]

Glad to finally see a video about TON 618! I imaged this with my astrophotography rig/observatory a few years ago, as there aren't many full, true color images of this quasar, especially taken by amateurs/citizen scientists like myself. I wish I had a spectrometer to measure the red/blue shift of objects like this, perhaps one day I will be able to buy or build one. Clear Skies!

[@ogexo]

Phoenix a is bigger

[@ScienceAsylum]

Thanks for the self-gravitational radius info! Looks like I'll be running some new black hole simulations soon.

[@realspacemodels]

Dr. Becky's book is amazing. I got the audiobook, so hours of hearing her talk to you. It's great!

[@kidmohair8151]

I'll add to Dr Becky's thank-you by also thanking you for bringing us *all* the other wonderful scientists from U Nott to youtube! You, sir *are* a gentleman *and* a scholar!

[@bluzedogg]

This is easily one of the best science videos I've ever seen on KZbin. Dr. Smethurst you are awesome.

[@michaelpettersson4919]

I see Dr. Becky, I click. Only after starting the video did I realise that this isn't her channel.

[@bierrollerful]

"Thanks for giving me my start on youtube." That's so sweet. And true. Thanks Sixty Symbols for introducing us to such bright minds.

[@rarelycomments]

Genuinely disappointed that it wasn't called the Disc (of) Innermost Stable Circular Orbits. Disco.

[@AsmodeusMictian]

Always awesome to hear about black holes. Thanks for the amazing video!

[@TheDirge69]

Thank you Brady for giving Dr Becky her start on KZbin, from all of us..

[@artdonovandesign]

Great interview! Thank you, Dr. Becky.

[@thisistopsy]

Heyyyy. This is a very fascinating topic. Thank you for covering this! By the way, we actually found a much bigger black hole. It is the black hole of Phoenix A, the central galaxy of the Phoenix Cluster. It is presumed to have 100 billion solar masses, vs. TON 618's 66 billion. It was inferred based on the properties of the galaxy Phoenix A (its Sérsic profile, a very complicated topic). But what excites me the most is that the James Webb Space Telescope, our favorite space telescope, is scheduled to observe the Phoenix Cluster and the galaxy Phoenix A specifically by July 29-31, 2023. They will not go for the black hole specifically, but they will try to uncover the mystery of the Phoenix Cluster's cooling flow. This is actually a very mysterious topic that we only knew of recently, and the Phoenix Cluster is the quintessential case. Its cooling flow is the strongest we ever observed. A brief summary: cooling flow is when the gases in the very center of the galaxy cluster cools very rapidly, and since cold gas collapses and has no radiation, the outlying gas surrounding the cluster, which is hotter, will come crashing down and "flow" towards the cooler gas at the center. We actually knew very little of why this happens, but it is presumed that the central black hole has got something to do with it. Black holes produce a lot of radiation through their accretion disks, thereby heating the gas around them. So I presume it would be obligatory for JWST to take a closer look at Phoenix A's monster black hole. And more importantly, it may help us understand galaxy clusters and how they work, since cooling flow is considered a feature of a short but very significant phase of a galaxy cluster's evolutionary stage.

[@mikmop]

I love all Brady's video channels and I use to love watching Becky on Sixty Symbols before she started her own channel. I was hoping she would do that because I would go out of my way to watch her appearances. Anyway, glad to see her back doing a cameo on this channel again and that dedication in her book to Brady I thought was just beautiful.

[@pr0hobo]

I wish they explained why the self gravitational radius doesn’t grow or doesn’t grow as fast as the isco.

[@garethdean6382]

The SGO depends in part on the 'gravity gradient' across an object, the tidal forces. Just as Jupiter prevented a planet forming between it and Mars, a black hole can stop 'clumping' of its disk. While the ISCO grows directly with the hole's mass (Twice as heavy, twice as large, relating directly to the strength of gravity at a distance from the hole) the SGO for an object of a certain size rises with the mass of the hole to the 1/3 power. (Relying on the DIFFERENCE between the strength of gravity at either side of the object.) One is just more directly related to the hole's mass and gravity.

[@edwardp7725]

How can you not love Dr. Becky?

[@Triantalex]

??

[@S1nwar]

what people often dont realize is that you couldnt even look at a black hole if you're anywhere near it because the accretion disc is brighter than any star could ever be since the heat production from THAT gravitational pull outscales the energy output of any kind of fusion process

[@WylliamJudd]

WOW!

[@nocare]

Well ton 618 in particular. It outshines every star in the milky way combined many times over. Its 160 trillion times brighter than the sun.

[@bierrollerful]

Sounds like the ultimate boss fight for redheads.

[@nocare]

@Josh Smith that is not true. Black holes have been demonstrated in multiple ways. Includeing 2 direct imagines. The part that is almost certainly not real is a singularity since those are infinitely dense and a quirk of the math. Many if not most physicists believe that singularities will disappear once we have a theory of quantum gravity. Also you used theory wrong. In a scientific context theories are proven and well substantiated. Hypothesis is what you wanted.

[@AureliusEnterprises]

@Josh Smith That's not true at all, there is overwhelming scientific evidence for black holes. They recently made a picture of two of them and prior to that they had stars orbiting what seemed to be 'nothing'. They have data of the gravitational waves of two black holes merging.

[@adamwulf]

I’m curious if hawking radiation would eventually cause these max-sized black holes to shrink small enough to begin accreting again. If so, does that mean the black holes would all hover around that max size, growing to it but no further, and not shrinking much smaller because they’d grow up again

[@danilooliveira6580]

hawking radiation is very, VERY week, it would take a unimaginable amount of time for a blackhole to noticeably shrink through this process. it would probably grow more through eating rogue material flying at it than it would lose mass through hawking radiation. I would hazard to argue that light, neutrinos and other high energy particle hitting the blackhole from all directions would give it more mass than it would lose, but that is just speculation from my part.

[@jackhand4073]

I could be wrong but by the time hawking radiation is a problem, matter and inturn accretion won't be. The time scales are ridiculous. Can someone let me know if my thinking is wrong?

[@prdoyle]

@@jackhand4073 Hawking radiation takes on the order of a googol years to evaporate a big black hole. It could be the slowest process in the universe.

[@adamwulf]

@YeYaTeTeTe Very interesting! Thanks for the calculations - mind boggling time scales indeed!

[@TechSY730]

The rate that Hawking radiation loses energy ("temperature" so to speak) is _inversely_ proportional to mass* Meaning more massive black holes will lose mass _slower_ . In addition to having more mass to lose. In fact, cubically so (how long it takes to fully evaporate is proportional to the mass cubed) * for black holes at least, but this effect is a property of event horizons in general. See Unruh effect for another event horizon caused by acceleration of a reference frame.

[@TheInselaffen]

Dr Becky and Dr Brady, a collab of such joy.

[@artemkras]

Sixty Symbols is where I first saw Dr. Becky a long time ago.

[@jacobopstad5483]

I asked this very question on a Dr. Becky video a while back. I'm so glad to get an answer!

[@mighty8357]

She is just so cheerfull and passionate about her field :)

[@BleuSquid]

I was so confused to hear Brady's voice at the start. I though this was a Dr. Becky video when I clicked on it! Love you both!

[@DouwedeJong]

Probably the best video I have seen from Dr. Becky.

[@dpie4859]

We all love Becky! ❤

[@dreadnought1109]

There are two statements in this video that didn't feel right and when I looked them up seem to be way off. Anyone know if I am just not seeing the data right or if it was just misspoken? "Bigger than the mass over everything in the entire milky way..." Ton: 66b solar mass; Milky Way: ~1.2t solar mass. Wiki says bigger than the mass of the *stars* of the milky way so I can see that difference and where the confusion may be. "crushed down into a space smaller than the solar system" Again Ton 618: 390b km; Solar System: 26b km (Heliopause) So it looks like Ton 618 is bigger than the solar system even at the most generous size. I couldn't find a definition that makes this work.

[@GodwynDi]

90% of that mass is dark matter. Which may or may not exist

[@garethdean6382]

Yes. The statement is one of those factoids that gets repeated a lot because it sounds impressive and simple. In truth TON 618 is about as massive as all the stars of the milky way, compressed into an object with a volume less than the Kuiper Belt. It's roughly true but falls apart on analysis.

[@travelservices1200]

It's an excellent book, I certainly recommend it.

[@christiananderson6761]

Love Dr. Becky and her enthusiasm

[@GGoAwayy]

0:10 Woah! What are these totally obscure pop culture references?

[@Exoil]

Awesome, I just looked at saw that my audio book provider have Beckys book. I've been looking for something to listen to for a while now!

[@alsmith20000]

I didn't understand why the Innermost Stable Circular Orbit being the same size or larger than the Self Gravitational Radius would stop accretion. I assume the latter is basically an interpretation of the Roche limit and the typical sizes of stars? It sounded like a star would disintegrate when approaching a black hole, but its material could still orbit the black hole in a stable way, somewhat further in. If the ISCO was larger than the SGR, wouldn't that just mean that stars are doomed to fall in before they are torn apart?

[@Macieks300]

From what I understood if the ISCO is larger than the SGR then the only thing you can have orbiting the black hole is "clumps" which are probably mostly stars. That means that you can't have the accretion disc because all the stuff orbiting would always start clumping together.

[@caconym358]

I had the same question. IIUC, in a "normal" black hole friction within the accretion disk is responsible for sapping the orbital energy of accreting particles until they hit the ISCO and spiral in. If the theoretical outer boundary of the accretion disk is inside the ISCO, the black hole has no mechanism for reducing the orbits of objects that might otherwise join its accretion disk, and highly elliptical/hyperbolic orbits may even skim within the ISCO without being trapped since they have a lot of excess energy? So you're left with the only ways for an object to enter the black hole being the sort of "bulls-eye" Dr. Becky mentioned, where I guess you'd need a closest approach somewhere between the event horizon and the ISCO depending on the orbital energy of the object, and objects that independently place themselves in circular orbits at or within the ISCO, which don't occur in nature AFAIK. Intuitively it feels like a black hole that massive wouldn't *need* an accretion disk to pull in matter-it could just sweep through space like a giant eraser-but the effect this video's talking about may come down to the fact that a hypermassive black hole doesn't have a proportionally hypermassive accretion disk to pull in matter, so its growth is slowed to what's effectively a stop *relative to its size*. All speculation. :)

[@garethdean6382]

If the ISCO is too large then clumps of matter (Stars, clusters...) will be stable. At that point 'friction' between clumps becomes negligible, in the way that it's very rare for two stars in our galaxy to interact. Compared with an accretion disk where its glow is a direct energy loss, this drastically cuts down the amount of material falling to the center in the same way our sun is not swallowing planets on a regular basis.

[@jip5889]

The thing to keep in mind is that all that mass is concentrated in a point in the center, an infinitely small point. I think we intiuitively mistake the event horizon circle as having the mass evenly spread which is not the case. This is why we get these three other outer circles, EH, ISCO and SGR.

[@B-System]

@@jip5889 That's what I was missing. Thanks.

[@coopergates9680]

Great stuff. Note that black holes too massive for accretion disks are large enough to intercept vast amounts of radiation, whether light or otherwise, so they will keep growing even if they don't swallow bulk matter.

[@RedRocket4000]

Yep they finally large enough to hit a lot of stuff. Smaller black holes fairly tiny targets.

[@HutchCA]

Doesn't Hawking radiation cause black holes evaporate faster as they grow bigger? Edit: My mistake, they evaporate slower as they grow.

[@Droopy95mkDS]

Yaaay Beckyyy ! One of the greatest physics doctor on KZbin (like Dr. Don Lincoln from Fermilab both are amazing imo)

[@cryptic_daemon_]

I really like Dr Becky, she should make her own youtube channel!!

[@fliesbyme]

Once again Becky. Great video. Absolutely fascinating.

[@Geezimac]

Nice to see you back on sixty symbols… for a minute I thought YT dumped an old video in my feed.

[@52flyingbicycles]

Funny thing is the black hole isn’t that dense, if you measure from the event horizon P = M/V M = 60 billion solar masses = 1.2E41 KG S-Radius = 1.7E14 m (assuming no spin) V = 4/3 pi r^3 = 2E43 m^3 P = 1.21E41/2E43 = 0.006 kg/m^3 For comparison, air is about a kilogram per cubic meter, so a ball of consistent plasma 0.2LY in radius would just collapse into a black hole. That’s because the swartzchild radius increases in direct proportion to the mass beneath it, but mass increases as the cube of the radius. IIRC scientists consider us very lucky that the universe only has an average density of 4.9 protons per cubic meter. Too much bigger and the whole thing would collapse into a black hole! Don’t worry though. That may not sound very dense, but remember that is literally the entire galaxy crammed into our solar system. Most of that mass would be the consistent low density plasma of stars!

[@themaverickproject4577]

I liked that video a lot. A nice conversation with Becky. Please think about doing more.

[@RobinWildlife]

Dr. Smethurst is awesome!

[@Worldwave]

yaaaaay Becky on one of Brady's videos! Two of my favorite KZbinrs!

[@Crushnaut]

Couple questions; 1. Wouldn't these ultra massive black holes still be able to eat via things orbiting them giving off energy via gravitational waves and loosing orbital energy? 2. Is the inner most stable orbit an exact circle? If there was structure inside a black hole (big if) could we learn about this structure by studying the shape of the inner most stable orbit? 3. You say things colliding with this black hole would be rare. Yes space is big, but my calculations have the radius of a 50,000,000,000 solar mass black hole as being about 1000 AU (1.5% of a light year). That seems to be getting into the size that stuff would be bull's eyeing it all the time. Perhaps not a solar mass of stuff, but over time I would think this would still appreciably increase its mass. Am I wrong here? 4. Why didn't you draw the black hole top down? LOL Fun Fact; a black hole this big would take about 1.5 x 10^99 years to decay via hawking radiation, however, currently it would not even emit as much heat as it would gain from the cosmic microwave background radiation. Given the expansion of the universe, this black hole will be one of the last objects in the universe.

[@garethdean6382]

1.) Yes, as well as orbital rearrangements. But this is a VERY slow process compared with accretion and would not appreciably add to the hole's mass in the next 100 billion years. 2.) The ISCO is a spherical region where any disruption causes an object to fall into the hole. If the hole is spinning or not itself perfectly spherical, this region grows larger than expected. So measuring it WILL tell us something3.) about the hole. 3.) Not really. The space around these holes is not random, most objects will be orbiting the hole itself, where the physics tends to prevent them hitting it. It is not just a matter of drawing straight lines through a galaxy and seeing how many cross the hole, objects will be actively positioned and moving to avoid collision. It is remarkably hard to hit a central mass.

[@TheGiantHog]

It’s so weird, black holes give me this existential fear like nothing else

[@Astro_Oogo]

I feel the same way! I view it as, we know of our own mortality as humans. But in a much larger scale, black holes are the inevitable ‘death’ of most matter in the universe. Learning about black holes, my atoms are vibrating with anxiety!

[@georgejones3526]

The whole universe gives me the heebee-jeebees.

[@Triantalex]

??

[@uncertainukelele]

This video was awesome, but thanks for the book plug as well, I didn't know about it.

[@tomschmidt381]

That was interesting, I had not thought about black holes having a maximum size.

[@Kevin_Street]

I thought they just grew and grew until they ate everything nearby. It's really surprising to hear they may have a maximum size.

[@trollerjakthetrollinggod-e7761]

@@Kevin_Street it is understandable. The bigger it is, the weaker the surface gravity. At a certain point it's almost nothing

[@nosuchthing8]

I doubt there I'd an actual limit

[@adamplentl5588]

@@nosuchthing8 is that based on something other than your tummy feelings?

[@LMarti13]

When you ask "Is there an upper limit to the mass of a black hole" you go on to answer the question assuming a NATURAL black hole. But what if some hyper-advanced civilization decided to park a sphere of unimaginable mass outside the accretion disk and then launch all of it, all at once, at the speed of light, into the black hole? Surely that would increase the mass higher than the "limit" you describe? I think it's important to distinguish between physical limits and stochastic limits.

[@stephaniejean2426]

Hey friends I'm new here but wow I'm impressed... This channel seems a bit like Numberphile but with physics instead of maths. 💯💜

[@feynstein1004]

I find it interesting that black holes are the only things in the universe that are infinitely scalable. You could take a microscopic black hole, add a planet's worth of mass to it, and it would still be a black hole, all the way up to galactic scales.

[@Ylyrra]

From our perspective outside the event horizon that's self-defining. If we could see inside then maybe we'd have different names for the different behaviours we'd see, and consider them to be different beasts entirely.

[@feynstein1004]

@@Ylyrra I had that thought too but as of yet, we can't peer inside the event horizons, so they're all black holes 😅

[@piratecheese13]

Becky is my favorite place to get deep space picture news

[@pwhite2579]

ordered your hardcover book by Amazon. It is not available in the states at Barnes and Noble (a week ago). Can't wait to read it!

[@djscottdog1]

This is actually a pretty basic idea if you double your size and gravity the diameter of your closest stable orbit doesnt double because of the inverse square law. It doesnt take twice the distance for the gravity to tail off

[@___Kelli___]

Very interesting, thank you for making a video on this subject.

[@OvidiuHretcanu]

another example of the explanation that is waaay more interesting that the answer itself

[@boredgrass]

Finally Sixty Symbols is complete again!

[@ThatFreeWilliam]

WAIT WHAT? Once black holes get too big we won't be able to detect them anymore? That's just awesomely weird.

[@MariusPartenie]

I like that the name of the black hole is TON. It's short for the Tonantzintla Catalogue, but it's kind of funny. Yeah, a black hole does weight a TON.

[@deltalima6703]

Black holes are weightless. If you put one on a scale you will find the scale does not read anything.

[@R_V_]

@@deltalima6703 If you put a black hole on a scale, you will find the scale disappearing into the event horizon.

[@BobbyChipmunk]

@@deltalima6703 oioi you get their point, it has an absolute ton of mass

[@bytefu]

What's even funnier is that an actual black hole with a mass of 1 ton would not be visible even under a microscope, let alone from however many light-years there is to this TON.

[@deltalima6703]

@R V nailed it! Exactly what I was talking about! :D Weight and mass are not the same property, the weight of a black hole is nonsense.

[@wixom01]

Oh, wow, I hadn't heard of this new book. Thumbs up for the video so that I can now go get my Kindle version!

[@Neloish]

Dr. Becky is the best.

[@MasterHigure]

I feel the need to correct the graphics at 3:00: On an image of a black hole, the circular black shadow (which is all we can see of the actual hole) is the limit for which light can come from elsewhere towards the black hole, get close to the black hole, and then get back out to us. The boundary of that sphere is about twice as far out from the center as the actual event horizon. The event horizon is the boundary for where a person can shine a light at us and we can see it. The black shadow is the boundary for where in addition, this person can at the same time shine a light in the exact opposite direction, and that light can escape the black hole. Alternately, the black shadow fills the region of your field of vision where if you shine a light in that direction, the light eventually ends up inside the black hole. It is not difficult to imagine that this lies strictly outside the event horizon, and if I recall correctly, it is a pretty standard calculation (for anyone familiar with the Schwarzschild metric) to find the actual radius. But it has been a decade since I did that math myself, so I don't remember the details.

[@neoanderson7]

Can’t wait to receive my copy. Amazon is taking forever

[@judychurley6623]

Takes me back! I used to sign my photo students' yearbooks with a drawing of a camera!

[@potterma63]

Funny I find this video today. I was just reading the chapter about ultramassive black holes last night!

[@TheSteveMeister]

So you are telling me that I can have becky read me a bedtime story about blackholes? Sounds like a win win.

[@bradwood556]

DR Becky is so awesome!

[@4623620]

Just a thought that came to my mind: if there is a limit to the maximum mass of a black hole, what happens when two black holes, with a combined mass greater than that limit, collide ?

[@mrfurieux9587]

the limit is not a hard limit, it's just a limit for acquiring mass "easily" via an accretion disk. The thing can still grow via other means

[@4623620]

@@mrfurieux9587 Thanks for your reply, but it still leaves the question, does anything special happens when the mass goes beyond this limit ? Also, if it is no "hard" limit, it seems that a title like "The Biggest Possible" is a bit misleading.

[@mrfurieux9587]

@@4623620 apparently nothing special happens, except that the hole goes dark because of the loss of the disk. You're right about the title, it's not a "biggest possible" limit

[@4623620]

@@mrfurieux9587 🖖😎👍 ❗

[@rickseiden1]

Great Video. Bonus Dr. Becky!

[@AppNasty]

3 questions. 1. What makes everything orbit the milkyways's BH? Does its pull reach as far out as the edge or is it that the nearest stars have their own gravity that holds on to the further out stars and those have gravity that pull on further out stars and on and on? 2. Say you find a BH at its max limit. So much that a grain of sand cannot fall into it. What would happen if you took your perfect tech ology and perfect ship to the edge and force shot a missile at the right angle and speed? Would it automatically change its trajectory and orbit? What would happen if it falls in? Would the BH 'trade' it via ejecting something? Would it create a new object? What if you had 2 of them at their max and say...artificially you could push one of them at the right angle and force them to merge? 3. Is there math we could do that would answer what TIME would be like between 2 of these BH in maximum close orbit of one another? Say 2 got as naturally close to each other as possible. And say you in your perfect space ship are protected and in the middle of them. What would time do?

[@paaph8747]

Gotta love how astrophysicists say most matter is dark matter, then completely ignore its existence when talking about things like black hole growth.

[@AnnoyingNewslettersPage6]

Office hours with Dr. Becky!

[@dewaard3301]

Man, just in time for the Christmas gift season too!

[@mikestreet4339]

I love watching someone who's so passionate about the science, excitedly sharing and explaining in layterms what is going on. Questions: 1. I don't get how the ISCO isn't completely subjective for literally every instance of matter in the accretion disc, unless maybe everything within the disk is atomized to be exactly the same uniform individual particle mass relative to each other, depending on its location within a scalar field where individual particle masses are higher and higher the further you orbit from the event horizon? (maybe I answered my own question there, but I'm not positive). -but then similarly, why wouldn't the Self Gravitational Radius just grow infinitely, assuming the black hole was feeding and had a hypothetically infinite source of matter incrementally surrounding it? I understand that's not how matter distributes in the universe, but I just feel like as a thought experiment the SGR would more understandably be subjective for any nearby object according to the mass of said object in relation to the mass of the black hole and distance from event horizon or any matter in the accretion disk. Even if some stars formed outside of the accretion disk, how can the changing mass of the disk or the growing mass of the black hole not eventually influence this group of stars to form/become part of the evolving disk, ad infinitum? 2. Couldn't Hawking Radiation theoretically "whittle down" a black hole that has reached the relative equilibrium of ISCO and SGR, and therefore the decreasing mass of the black hole would eventually pull back the ISCO to the point where any nearby matter could then be more gravitationally attracted to the black hole than to something else, thus restarting "feeding" and reigniting the accretion disk? 3. Dr. Becky can I maybe buy you a coffee some time?

[@Currywurst4444]

A ultra large black hole simply doesnt have an accretion disk. When a smaller black hole comes close to a star it tears it apart and all the friction between particles causes the material to accumulate around the black hole. A ultra large black hole just changes the orbit of any star so it continues to circle around it. All of this is of course what happens on average most of the time, both is still possible with both sizes of black hole. You are farther away from a larger black hole so the gravitational field is less curved. The varying gravitational strength inside a body is what normally rips it apart. You can calculate the gravitational radius with newtons equations to see for yourself. Hawking radiation actually deceases with the large a black hole is. Its connected to the curvature of gravitation too. Also, it is so slow that it only becomes a factor after every single star will be long gone.

[@RFC-3514]

9:50 - You can see the mental effort. _"Don't say 'galaxy clusterfuck', don't say 'galaxy clusterfuck'..."_

[@MyNameIsNotCraig]

Really really interesting video. Thank you!

[@DemoniteBL]

Shouldn't TON 618's event horizon be considerably larger than our solar system?

[@NATESOR]

fascinating stuff. Gotta say, pretty counter intuitive. You'd think the bigger it got, the easier it would be for it to get an ever larger accretion disk. But I'll trust someone with a pHD over my gut intuitions lol.

[@bvbinsane1vanity]

Sounds like you’re reluctantly trusting someone with a pHD over your arrogant gut.

[@ibrahimswiss8714]

It was difficult to understand, that's due to my simple brain. I need to buy the book to understand more, thank you for explaining. 🙏🏼

[@EngineerNick]

That's a massive book `Learning Python` :O Having learned a lot of python from the internet, that makes me feel like I probably still have a lot to learn!

[@simohayha6031]

Isnt the Phoenix Cluster SMBH estimated at one 100 billion solar masses?

[@aurigo_tech]

But with an event horizon as big as TON618, even the bulls eye collisions directly onto the event horizon should not be that rare anymore (at least of small stuff like gas) because it is 1300 AU in diameter - 40x the orbit of Neptune.

[@xaphyrthefirst5334]

When you're right on the inner edge of a black hole's accretion disc, call that Panic! At the ISCO.

[@richard8176]

Is there a theoretical maximum size for a star? If there is what is it, and what would be its radius?

[@PrincessTidge]

Do we know of any black holes with absolutely zero spin? 🤔 I always assumed (perhaps incorrectly) that they all have some spin.

[@IanGrams]

I believe your assumption is correct since real black holes are formed from stars which already have angular momentum and that's a conserved quantity. I think the reason non-rotating black holes are used in calculations is because it makes the math easier but the predictions are still close enough to be useful.

[@oskarskalski2982]

You can do calculation for rotating black holes it is naked Kerr metric but I've heard that those calculations are very hard that's why non rotating black holes are mostly used.

[@HermanVonPetri]

@@IanGrams They are the spherical cows of cosmology.

[@LA-MJ]

It's as likely as hitting the center forever

[@arturocevallossoto5203]

According also to me they should always have some sort of spin to them. Though for some of them it could be so small that zero spin works nicely.

[@principal4816]

How do we measure the mass of a black hole in the first place ?

[@garethdean6382]

The best way is via orbital dynamics, that is, to measure how fast things are orbiting around them. We can get this from the Doppler shift of light at different distances from the hole, or directly if a bright star is orbiting. In our own galaxy we see stars in the center orbiting 'nothing' as speeds that can reach 5% that of light.

[@Algo-sk6ot]

@@garethdean6382 Thanks a lot for the answer, it makes sense. I guess emission by the accretion disc of some wavelengths (X-rays, maybe even gamma rays ?) can also be a signature of very massive black holes, when the latter are active. In the method you describe based on orbital dynamics, how can we know than this is due to a massive black hole rather than a smaller black hole + some dark matter ?

[@garethdean6382]

@@Algo-sk6ot Generally by looking at a range of objects at different distances. For example, whatever's in the center of our milky way doesn't have a diffuse mass, objects twice as far away orbit at 1/4 the speed, as would be expected from a point mass. The 'rotation curve' of our galaxy by contrast shows clear evidence of dark matter throughout it. Stars twice as far out can be orbiting at the SAME speed. If closely orbiting objects show 'messy' orbits, this is evidence of something more complex at the center. A single black hole provides the simplest scenario, an almost platonic ideal.

[@GeoffryGifari]

another thing about black hole size, is there a size distribution? where most supermassive black holes should have radius R, some larger but many smaller, things like that?

[@SearinoxNavras]

I have a different take on the biggest black hole question: our understanding right now is that space is expanding in all directions, and that this is a feature of space itself everywhere. The result of this is that if anything is far enough away from a given point, there is a radius past which the total speed of expansion of that space reaches and then exceeds the speed of light, making it impossible to observe the universe beyond it. Now suppose there was a black hole that was so massive that its event horizon would span billions of light years. Wouldn't there be a point at which the expansion rate of the space within the event horizon can offset and even balance out the infalling caused by the black hole's gravity? Would such a black hole stop growing?

[@c4t4l4n4]

..."Now suppose there was a black hole that was so massive that its event horizon would span billions of light years"... unlikely for any BH to have such a large event horizon. A BH the size of our entire solar system seems possible, but consider the volume of the solar system and squeeze 60 billion solar masses at these densities in there. I think that there would be plenty of room for more.

[@wintersummers3085]

would

[@mrsyettigoosecreature194]

If our universe is inside a black hole I kind of imagine it like a sand timer that fills up one side then turns and fills the other

[@tugbacnarl6060]

This is like a avengers movie❤❤❤ I love and learn a lot from Dr Becky’s content😎😎

[@Jchmcom]

Phoenix A

[@johndododoe1411]

If the SGR means that anything outside the SGR will not be torn apart by the BH, and the ISCO means that anything inside the ISCO is already trapped. Wouldn't ISCO > SGR mean that the accretion disc will no longer be observable from afar, but entire stars etc. can still fall in without any final clue visible to our telescopes, only evidence would be stars disappearing between observations made enough years apart, however such oversized holes could very well exist unseen with no actual size limit.

[@CreepsCompilation]

This conversation and topic is like people who BELIEVE in a FAITH.. Pure speculation, hypothetical ideas, guesswork, and assumptions.. SOLUTION first, all roads lead to black holes..

[@atlantic_love]

She's burning up astronomy. ❤‍🔥❤‍🔥❤‍🔥❤‍🔥❤‍🔥

[@rem45acp]

The lazy part of me just really wants to believe that black holes are just massive magnetars. Magnetars apparently bend light even more than regular neutron stars. This doesn’t hold up well, but it’s easier to think that it’s just a magnetar bending light enough to cover itself up

[@Metalkatt]

The black hole was labeled as a quasar. I thought quasars couldn't form anymore, so it would only be these really old first-gen galaxies that could have possibly made them so big, right?

[@jennifersaar1611]

We're past the era of the quasar, but that doesn't mean they can't still happen under the right circumstances. When the Milky Way and Andromeda merge, there will probably be a short-lived quasar.

[@arpyzero]

According to Wikipedia, TON 618 is extremely distant, so it's an old, old formation. As for how old, that's unknown, but it's definitely some kind of early universe formation.

[@Flesh_Wizard]

The closest quasar is roughly 500 - 600 million light years away