How to Make Black Holes (Both Regular and Supermassive)

[@ArfatXeon]

This is probably the most underrated channels on KZbin. I have only recently started watching your videos and I can already say that you deserve at least a million subs.

[@ProfessorDaveExplains]

tell your friends and help me get there! :)

[@TsarDragon]

Yeah you're right man. I've only watched 2 videos so far but the quality of this content is outstanding. Easy to understand and interesting.

[@SangheiliSpecOp]

1 million soon!

[@Anonymous-wz6or]

@ierdnA adrecaL yeah that's absolutely very true(Sadly people don't like learning that much)..................(Once I met a girl that told me she hates learning!!! )ohh that's really bizarre, atleast for me cuz i am not that kind of girl.........but ya its sure that we all watching this are not that type and it includes u as well😃😃😄😄😊😁👍

[@natureasap4268]

​@@ProfessorDaveExplains and you are there now! :) we celebrate your awesome works

[@dweezilbop6274]

I’ve been binge watching your cosmology series and my 5 year old daughter has shown an interest. She particularly likes the music.

[@WinterNox]

I hope she continues

[@TheActualPES]

Dave, learning about Hawking Radiation and the death of black holes is the first time that I’ve joyously exclaimed “that is f**king amazing!” out loud to myself on my own in a loooong time. I learn a lot from you by watching all of your videos, but THIS little titbit of science is absolutely fascinating, and I’m off to go learn more. Thank you for the years of brilliant science communication. One of my favourite channels on KZbin.

[@ClemensAlive]

Ant Man was close to becoming a black hole!

[@mirandalyneetestewart3083]

ClemensAlive That’s scary.

[@eyoelgashaw5089]

no he entered the quantum realm. meaning that he became subatomic up to the point where space and time don't make sense anymore.

[@AliceSpeltRight]

He definitely became small enough. but I guess it wouldn’t be made for an interesting movie if he did turn into a black hole

[@kumaflamewar6524]

@@AliceSpeltRight but ant man doesn't retain his mass when he changes size, if he did he would simply float away when he gets gigantic because he would displace enough air to float.

[@leslierhorer1412]

@@eyoelgashaw5089 Uh-uh. That does not matter. The existence of a black hole and the Schwarzschild radius depend only upon the mass of the object and its spacial extent, not upon its internal structure, sub-quantum or not. To the universe at large, it makes no difference (except to the hole's angular momentum) whether the contents of the hole are evenly distributed throughout the Schwarzschild sphere or concentrated into a space a fraction of the size of a proton.

[@wsjoiram]

Your explanations about ALL the subjects you cover are amazing. Nobody else is covering key subjects and cross-refering them as methodically and systematically as you. Please, keep it up and thanks. :)

[@bens.5127]

Dave, you know what makes these videos so good and entertaining? You! You sound so excited to be teaching! 😃

[@459luker]

7:56 Why does it have to be the negative of the pair that falls in? isn't there an equal chance that the positive one falls in, thus increasing the mass?

[@VaiskHD]

The mass isn't actually decreased *because* it is the negative one that falls in, as Dave said it, it's only for conservation of energy purpose. The reason why it loses mass is that *both* of the particles are created *from* the energy of the black hole and thus losing one of the two particles that was created from the black hole's mass will result in a decrease in it (remember mass = energy, so to create those 2 particles the black hole lost mass, but as those virtual particles usually recollapse on each other the black hole keep its mass, but if one of those 2 falls within the event horizon, they lose that other particle which was created from its own gravitational field energy, thus lose mass)

[@somerandom7063]

Due to a German spelling error in this video, this comment section now belongs to the BRD. Thank you for your Compliance.

[@BigMuff75]

Sure, Sir Douche-A-Lot.

[@rigrentals5297]

Amazing video. I learned things I didn't even know could happen with black holes. Space is the place.

[@ItalianOrlando]

I've watched a lot of these videos on black holes. I find them absolutely intriguing. But I learned more about them in this 9 minute video than I ever knew before.

[@AntonioFGagliardiLugo]

By far one of the best videos I've seen in KZbin about Black holes. Thank you so much !!!

[@juliakroeger8414]

Hahah, as a german I loved the Schwarz(s)''child'' radius pronunciation

[@hexcodeff6624]

Well, it's just wrong, isn't it?

[@Blubb5000]

HexCodeFF There are several (small) things wrong in this video.

[@Schneeregen_]

I believe that's how the scientist pronounced his name, so that's the pronunciation used when discussing his work.

[@hexcodeff6624]

@@Schneeregen_ Doesn't make it less wrong

[@adaharrisonn]

@@hexcodeff6624 not that wrong. This dude doesn't speak german, lol.

[@v1_trapz487]

your videos make me smile lol. thanks for what your doing its helping me so much in my classes and it's really nice to watch. keep up the good work

[@umbraxenon5529]

2:38 No, because you cannot divide by zero. The escape velocity would *approach* infinity, but it would not *be* infinity, as the answer of dividing any number by 0 only tends towards infinity. It *is* not infinity.

[@SPIRIT1949]

We can't divide by 0 so how do you know that? It couldn't be 0, so it's infinity.

[@SPIRIT1949]

Also, hes the scientist here. He knows more than you.

[@SPIRIT1949]

PLUS, an object with infinite density and infinite gravity. Yes. It does reach infinity.

[@umbraxenon5529]

@@SPIRIT1949 We can't divide by 0, but if you use something called limits, you find that the answer of anything divided by 0 tends towards infinity. It isn't equal to it. Just because someone's a scientist, doesn't mean they're an expert in everything. It might just be an oversimplification on his part.

[@bettercalldelta]

@@umbraxenon5529 well, near infinity is still higher than 300 000 km/s, so that doesn't really matter

[@Релёкс84]

2:15 you say that every shuttle that has made it to space achieved escape velocity, but that's not true: they achieved orbital velocity which allows them to not fall back down while still being gravitationally bound. Also, no shuttle or manned vehicle has ever reached escape velocity yet (but the appolo missions came very close)

[@DarkPlaysThings]

This is true

[@hefko]

Moreover, escape velocity is given for a free, non-propelled object, and it should be understood as “starting” or “initial” for this object. This means a space shuttle or a rocket don’t have to ascent that fast. Plus, linear speed of rotating earth’s surface works as a booster so rocket’s velocity relative to starting platform may be even lower.

[@michaelpisciarino5348]

0:46 Evidence For Black Holes 1:01 "Why are black holes black?" Escape Velocity 3:05 Schwarzchild Radius 4:39 The Event Horizon 5:22 How do we know Black Holes Exist? 6:30 Supermassive Black Holes at the Center of every Galaxy? 7:15 Orbits Remain unperturbed. Black Holes eventually Die in 10^61 years

[@hexcodeff6624]

It's Schwarzschild Radius,

[@professorlegacy]

"We can't take actual photographs of black holes." 29 yr old female computer scientist: "Hold my beer..."

[@trex5863]

She hasn't taken the accurate image it is just an approximation

[@mskellyn07]

@@trex5863 There is one image only that has ever been taken of a real black hole. Search up real black hole and you will find the black hole with a red and orange glow around it. So learn your facts.

[@trex5863]

@@mskellyn07 excuse me , I think you need to read some articles the image which has been taken is not accurate it is just a representation . There is also a Ted talk on it by the scientist himself . I think you should see that . Thanks

[@mskellyn07]

@@trex5863 excuse me could you explain to me how you lost so many brain cells? Thanks.

[@randomrom747]

@@mskellyn07 Your not even bringing up evidence anymore your just calling him/her stupid. No argument whatsoever was in your "no brain cells" claim only disrespect. Here's a link kzbin.info/www/bejne/eHrZlq15i8imj9U Even the description itself states they only took the event horizon shadow

[@Moving_Forward247]

Thanks!

[@isisnoreija]

I just wanted to thank you for making these wonderful videos! I wish, more people would watch them and maybe then stop thinking about stuff like pseudo-science and start asking the right questions and most importantly look for answers in the right places. I am shocked at the loss of trust in science itself all around the world

[@AugmentedOwl]

This is a really amazing video. I had never thought about a lot of this before- I accepted that they existed- I knew where they came from- but I didn't realise the whole escape velocity thing. This video is great!

[@Raz.C]

Addendum, re 2:07 It's wrong to say "To make it into space, you need to reach [insert escape velocity or any other velocity here]" You don't need to reach escape velocity to make it into space. As long as your velocity is not zero and you have the energy to continue your motion, you can make it to space at ANY velocity. You can make it into space with a high altitude weather balloon and a velocity of 1 Km/ h. Escape velocity is instead, the velocity- unassisted by acceleration- needed to escape the gravity well of a body, such that the gravity of the body can no longer bring you back to its surface. Or to put it another way, escape velocity is when the curve described by your vector becomes flatter than the curvature of space around the planetary body in question. You need to reach escape velocity if you want to no longer be gravitationally bound to the body in question. However, you can both 'make it into space' AND be 'gravitationally bound to a planetary body' at the same time. That's why the moon is still with us in orbit. Anyway, no disrespect to Prof. Dave. I'm certain he's already well aware of this and either made a simple mistake or was trying to explain it in simplistic/ layman's terms. There's quite a bit of technical stuff that goes into this (constant acceleration, or constant velocity and 0 acceleration? Hohmann transfer, or direct [which is currently impossible, due to the energy requirements] vector, etc...), so I can understand if Prof. Dave wanted to simplify things to avoid a lengthy tangent...

[@kbabhimitra]

ok I understand ur point, but didn't understand the later part of ur upper paragraph, correct me if I am wrong, and about things like hot air balloons they don't have a velocity of 11.2 km/s right and yet they go up very high almost out of the atmosphere where people feel no weight, I think with constant velocity which need not be 11.2 Km/s anybody can reach outer space, it is only when one is throwing something into the sky it needs 11.2 km/s to escape the gravity, otherwise if u have a rocket or something it can reach outer space slowly too.

[@irodaikromxonova9556]

I love the way you say 'how to make black holes ' as how to make pancakes. Explained in very understandable way, thank you so much!

[@abhishekgujjar9078]

Your videos are best. Thanks for uploading this

[@debunkosaurus8228]

Great video. One minor error. You said the rockets and shuttles we send up have reached escape velocity. They haven't. If they had, they wouldn't orbit; they would leave.

[@caseynichols3851]

Debunkosaurus all they need is more fuel.. there is a reason they don’t leave.. because they don’t want to leave, they want to orbit

[@debunkosaurus8228]

@@caseynichols3851 There's more to it than just more fuel. More fuel means more weight which needs more fuel etc. Obviously it can be done. It has been done (e.g. Voyager 1 and 2). The point I was making is that the comment about rockets and shuttles reaching escape velocity was incorrect.

[@kbabhimitra]

and about things like hot air balloons they don't have a velocity of 11.2 km/s right and yet they go up very high almost out of the atmosphere where people feel no weight, I think with constant velocity which need not be 11.2 Km/s anybody can reach outer space, it is only when one is throwing something into the sky it needs 11.2 km/s to escape the gravity, otherwise if u have a rock or something it can reach outer space slowly too.

[@karancharlee]

Thanks for this channel Professor Dave

[@zacharybrown7869]

This channel is a one stop shop for everything I'm looking for! Great content.

[@Blubb5000]

*Schwarzschild You’re missing an S throughout the entire video.

[@SangheiliSpecOp]

Mistakes were made

[@danielalbornoz9081]

It hurts me a little every time

[@w0lf667]

Typical nitpicker. He ain't a native german to pronounce such words.

[@Blubb5000]

Kerbal Nerd 123 Well, at least it could have been spelled right.

[@SangheiliSpecOp]

@@Blubb5000 you just proved his comment right tho

[@kristinfrostlazerbeams]

Love the way you explain this. Thank you!

[@kbabhimitra]

finally found somebody with actual knowledge with whom I can talk to about space stuff. thnx for providing me the email address, but I would prefer to comment so that other people can see and make it useful for themselves and maybe to start a conversation and spread knowledge.... cheers...

[@Schizniit]

I'd love to see you and Anton Petrov collaborate and talk about black holes

[@ejmtv3]

Wow! So many answered questions!!!

[@steinadler4193]

Hi Dave, it is called "Schwarzschild" not "Schwarzchild" and you pronounce the second part similar to "shield". Literally "Schwarzschild" means black shield, a typically German Jewish name.

[@ProfessorDaveExplains]

Thanks for catching that!

[@kbabhimitra]

wow hey, we got a German here.. cool.. hey man! I learned greetings in German, interesting Language, it's similar to English unlike Spanish.

[@jntyftrftyfjhtyhvyhhgytrdr3949]

you have the greatest intro

[@mikenukem]

Professor Dave, I have a doubt. I can't find any consistent article on this. We just discovered the HR 6819 and, as you probably know, it was spotted by the two stars orbiting a heavier object. It was also reported that "there was an extra wobble in the periodic light shifts of one of the stars that indicated something else was asserting its presence." Question: Why stars don't get their light strongly "dimmer" when they are at their "perihelion" to the massive object? I don't get that impression when I read "wobbling light observation" in the reports and articles. Thanks in advance.

[@BLAngel1]

Hey Dave, great video. Could you explain why the virtual particle that falls into the Black Hole doesn't increase it's mass. Seems like the Black hole should be get bigger and bigger over time.

[@emilyviktorija9012]

Ben Angel I’m no professor but I believe that it’s just because the density of the black hole is already infinite, so no amount of mass added can affect it. I honestly just accept the possibility of infinity’s existence as my answer.

[@emilyviktorija9012]

Ben Angel Actually as I continued watching the video I realized that he said that the black holes actually do get bigger over time, either by swallowing more and more mass or by merging with another black hole

[@mr.curious1714]

Sir when regular black holes do one of the two things, they become supermassive ones: i. When they swallow/eat enough material from their surrounding in their lifetime to form supermassive ones. ii. When they merge with another So I have a doubt regarding the point i: does this not violate hawking radiation, hawking radiation suggests that more a black hole eats more it evaporates even faster. And so every black hole should evaporate and there should be only one way to form supermassive ones, as defined by us humans. Or am I getting/understanding the i or Hawking Radiation wrong? Professor Dave Please Explain!! And Professor Dave, one humble request: Please make a video on Hawking Radiation, because I'm pretty confused when I asked that question to (myself about i)

[@tubesman7]

Are you saying escape velocity is the same as orbital velocity? I always figured escape velocity to be the speed needed to escape the Earths gravity well and for example, orbit the Sun, or head to an outer planet.

[@joegagliardi1938]

I always have trouble picturing what a black hole looks like: I see it represented as a literal "hole" in space, but it is actually an infinitesimal sphere that deforms spacetime so much that light can't escape. The picture he showed of the progressively smaller spheres which created what looked like spacetime wells helped me visualize it better. So is a black hole a point or a sphere with a ridiculously small radius, or are these essentially the same? Stars die and leave behind much smaller spheres, like a white dwarf; is a black hole kind of like a black dwarf/sphere (a physical "object") or is it nothingness, for the lack of a better word? Anyone?

[@lawenda2099]

What they actually *are* is unknown, even if we could actually see them we don't know if we'd understand what we're looking at. As for your point/sphere question, all we know is that they're something, they exist and appear to be spherical in shape, if you could call it a shape. Anything beyond the event horizon is basically a huge "we don't know, sorry". All we know for sure is that they're not only a point in space, but a point in time, some have argued that they're more of a fact than an object as its gravitational effect has a stronger influence on you, if that makes sense.

[@FlatEarthKiller]

Picture this. Black holes are like a door in a mountain far away from your home, that takes you to your room in your house *magically* when you open it. The difference? There is no door, only a portal-ish thing, and you cannot go out, and light cannot too. So this is what makes black holes black. They can pull in light faster than it escapes. It may sound like fantasy(the mountain thing) but we do not know what’s inside.

[@KrisAmos]

If we were to compress a person into a black hole and compare it to the black hole of a star, what would be the difference between the depth of each of their space-time warp? If the person only contains a little mass, and we were compressed into a singularity, I would imagine if we were to hypothetically travel through that black hole, our space-time warp wouldn't be as much as the singularity of a large star. So does this explain the big bang at all? Perhaps the largest star had so much mass that it collapsed into a singularity and its particles would fall through the space-time warp to "puncture" or "penetrate" out of space and create a big bang? Didn't the big bang come from a singularity as well?

[@salaa23]

"....particles appear from quantum foam" Me: w-wait, what?

[@PanSaltzCaballeratos]

7:44 coloring the name "Heisenberg" blue is very appropriate. I approve.

[@TheChrisLeone]

I came here looking to make one, like a 5 minute craft for a black hole. What a scam! Lol, I love you Dave! Keep it up.

[@krasiagg3017]

well if you manage to apply enough pressure to an object for it to become a black hole within 5 minutes u pretty much got what u came for :-D

[@kirkleadbetter1093]

Great stuff as usual Dave. Thank you.

[@TheJimtanker]

Are you going to update this video with the recent imagery from M87? Just found your channel and LOVE it!

[@ProfessorDaveExplains]

Well there is no way to update videos, but I hope to make more astronomy tutorials soon so hopefully I can cover more recent discoveries!

[@markmanning-o4w]

Amazing. Absolutely amazing!

[@tsvetanlozanov3984]

7:55 but why wouldn't the particle be affected by the gravity?

[@Paraselene_Tao]

Around 4:30, I'm not trying to contradict the Big Bang Theory but I have an idea I want clarified. Near the beginning of the big bang everything was very dense. How did the entire universe (at the time) overcome gravity? Wouldn't it be near the density of blackholes? Am I wrong to suggest it might have been that dense? How does science answer this? Thanks for reading and possibly replying. I'll search this up too.

[@Paraselene_Tao]

There's a funny, maybe ironic situation I did not remember until a minute ago: this universe might be a blackhole inside another, larger universe.

[@Paraselene_Tao]

I know there's an inflationary period, but I unfortunately do not understand the math or physics to this epoch. I have a lot to learn.

[@Paraselene_Tao]

Hypothesizing that "our visible universe could be inside a large blackhole inside a larger universe" lacks evidence. I'm just throwing it out there for fun

[@MarcusHaag]

SchwarzSchild radius

[@aliensentinelaextraterrest778]

great video, buen video

[@schifoso]

Great explanation, and very good graphics.

[@danielblanchette3270]

Wow 😮...that's what how I can learn more about it! Thanks so much! #1 Chanel for this subject I'm much more fascinated to get another one of those explanation! I love it! 👌 Very impressive and great work 👍 to this man! Seriously, you can also, put another's one channels followers face member...but my question is, are you doing professor or some other things like teachings ? Sure..got talent to 👍👌You makes better me result

[@megangibbs4158]

🎵*Darn, that huge gravity, Call Messier 70, Say that it's gotta see This dying electron sea. Didn't think it'd happen to me, But pride got the best of me. Now I'm collapsing into A singularity.*🎵 I'm sorry, but this time the void couldn't be controlled.

[@bgeniij]

I have a question about the event horizon that has been bugging me for years. Back in college (actually very close to when this video came out), my physics TA was teaching escape velocities using a photon orbiting black hole as one of the examples. During the example, the TA drew several possible orbits the photon might take. One path had the photon traveling in an elliptic orbit with the periapsis falling within the event horizon, while most of the orbit was still outside the event horizon (I hope that description makes sense). The reason this has bugged me is that I've always heard that nothing can escape the event horizon, not even light. But this orbit still made sense to me; the TA explained that an escape velocity greater than c technically just means that nothing can escape the black hole's orbit, but it could still go outside Schwarzschild radius without reaching escape velocity. Therefore, while the photon could never escape, it was possible that it could still pass in and out of the event horizon while it orbits. I thought this explanation made perfect sense; however, I've never once heard someone use an example of a similar orbit that only partially travels within the event horizon. Instead, I still always hear the event horizon described in the usual "point of no return" fashion, where nothing can ever leave. So, is it literally impossible for light to exit outside the event horizon in any capacity, or is this just said as a simplification of light being unable to escape orbit? Do we actually know? They both would probably look pretty much the same to us since we could still never actually see anything (from Earth that is) that traveled inside the event horizon since the light couldn't escape orbit to reach us either way, so do we even have any way of finding out?

[@maxwellmulford5898]

Small note- Space shuttles don't reach escape velocity because you don't need to to reach orbit. The Saturn V rockets reached escape velocity though.

[@williamchamberlain2263]

(missing ''it' - "you don't need _it_ to reach "?)

[@maxwellmulford5898]

William Chamberlain I think either “it to” or “to to” works. I chose “to to”.

[@drtidrow]

2:10 Errr, the Shuttle reached _orbital_ velocity, not escape velocity... even the Saturn V didn't do that, they merely put the Apollo spacecraft into a very elliptical orbit that brought it close to the Moon.

[@jaromchristensen5598]

I don't understand, how have we sent things beyond earth's orbit without them reaching escape velocity?? like the probes we've sent to take pictures of other planets...those aren't orbiting the earth

[@alphasatari]

Jarom Christensen Rockets don’t directly go straight up in the space, they try to go first in the orbit of Earth which reduces the consumption of fuel and after that they use earth’s orbit to direct themselves in the tangential direction to other planets. To escape from earth’s orbit in the tangential direction they use fuel. You can study more on this using a term called “slingshot”.

[@pandiarajanrajendran4505]

Thanks for the wonderful video! Why don't the north pole of any heavier object have space time curvature? Is space time curvature applicable only on south pole?

[@sorryifoldcomment8596]

Very funny

[@TheRolemodel1337]

2:08 most of them do not escape the earths gravity

[@anuragtiwari2270]

At 2:07 u said that any craft must exceed the escape velocity.. But this is not true, rocket can go beyond earth's gravity at a velocity below escape because they constantly gets energy by burning fuel. If we through a stone then its velocity should be grater to escape becuse it gets energy only once.

[@satyendrapratapsingh7043]

True

[@davidabdollahi7906]

Hello, what do you mean by "black holes eventually die just like everything else in the universe"? What makes you think everything is dying? Aren't there some materials in stable forms which will remain unchanged til the end of time?

[@ProfessorDaveExplains]

I don't think so, even protons and neutrons have finite half-lives, no matter how long.

[@SPIRIT1949]

Is the visual diagram shown in the video accurate? The one with the regular star, neutron star, and black hole.

[@ProfessorDaveExplains]

I mean it's conceptually accurate.

[@madspetersen1708]

Just a little correction: Karl Schwarzschild was german so his name should be pronounced “svartzshield” W is a v in german , i is ee and ch is sj and lastly v is an f So Volkswagen is folks vagen wich means “Peoples wagon”0

[@viktorderksen1265]

actually the first consonant should also be a SH aswell. otherwise it would be "Swarzschild" in german ;-) so in letters of the international phonetic alphabet ist "​​ʃvaɐ̯tsʃɪlt"

[@fazergazer]

I lived in the planet Martok for several years. One service they offered, was to compress your favorite asteroid into a black hole. If memory serves, on earth you had “pet rocks”. Think of these as our equivalent. The first thing I did when I arrived on earth was to buy a Pet Rock off EBay. Of course it is only a facsimile, but call me nostalgic!❤

[@xyz101ytrr]

7:26 if sun were to become a black hole, doesn’t it’s gravity become huge? Will it not change the orbital radius or earth?

[@ProfessorDaveExplains]

Nope. The mass would not change and the orbits would not change.

[@xyz101ytrr]

@dave I’m sorry it’s a little hard for me to grasp this. like we’re assuming if the same mass and same volume of Sun is is turning into a black hole, this will not affect its gravity?

[@ProfessorDaveExplains]

Why would it? We treat bodies like point masses when calculating gravitational force.

[@xyz101ytrr]

Alright. Now it’s understandable.

[@darthjarjarbinkstherealsit6832]

Dave: Light travel at speed of light. Me: Don't you say.

[@mirandalyneetestewart3083]

Nick Cage Meme.

[@penguinuprighter6231]

That's a great explainer.

[@81brassglass79]

You rock Dave!

[@anthonydefex]

Hi Professor Dave. I'm still pondering for some time the nature of black holes from all the knowledge that I've been gaining from viewing these astronomy KZbin videos on black holes and from applying principles of logic. I've been thinking that this statement "Nothing can escape a black hole, matter or light, because it needs to travel faster than light speed, and nothing travels faster than light speed" is not true for the following reason. When a black hole is in quasar mode it shoots a beam of electromagnetic radiation, which IS something that leaves the black hole, so it must be traveling faster than light speed. What do you think?

[@ProfessorDaveExplains]

But that material does not leave the black hole, it never goes past the event horizon. It is part of the accretion disk surrounding the black hole.

[@anthonydefex]

@@ProfessorDaveExplainsThanks for the clarification Professor Dave.

[@MrJeanMaker]

Visualising the warp of spacetime of a black in a 2D plane is easy, but I'm having trouble imagining it in a 3D grid. Where would the event horizon be in a warped 3D grid?

[@ProfessorDaveExplains]

It's definitely tough to imagine! And impossible to depict visually. But if we were showing it in three dimensions, the event horizon would be a sphere.

[@zitt4147]

I rotate the 2d plane by 90 degrees to imagine something close to 3d

[@zitt4147]

I mean, I imagine two 2d plots crossing

[@mikehart5619]

I enjoyed this video as I do all your videos. I do have one question/comment. You said in the escape velocity equation that since the radius of a black home is zero that it would have an infinite escape velocity because the other terms would be divided by zero. But a number divided by zero isn't equal to infinity. It isn't equal to anything since division by zero is undefined. Perhaps a black hole's radius is something greater than zero or perhaps just as our physics breaks down in a black hole so does our math.

[@hg6996]

The radius cannot become zero. Every star has a rotation momentum which is preserved. Reducing the size of the object accelerates it's rotation. When you try to reduce any rotating object into a point you increase the rotation towards infinity. Both values cannot reach infinity. Rotation limits the smallest possible size which in turn limits rotation speed.

[@wesleyteh1901]

But in 2:37, he said that black holes have 0 radius... I thought that you couldn’t divide by zero? *Illuminati confirmed*

[@hexcodeff6624]

That's why it is a singularity, I'd guess

[@SPIRIT1949]

Yup. 0 radius.

[@thebrotha318]

Finally someone who knows what they are talking about. I get so tired of being told you can escape from a black hole if you go faster than the speed of light. Once inside the event horizon there is no out every direction points to the Singularity because space is infinitely warped .

[@thunderspark1536]

I mean you can't go faster than light without breaking the laws of physics

[@ICantThinkOfANameeeee]

"How to make a black hole" *Hey Ferb, I know what we are going to do today*

[@Particleman50]

How could two things infinitesimally small (quantum singularities) ever collide? ....or in other words, how could 2 things that have 0 volume manage to be in the same place at the same time? I guess we know black holes collide, but Im struggling to visualize this. In my mind I can see that they are attracted to each other, moving towards each other but never quite reaching the same place in space given that their both infinitesimally small. Ive been a science enthusiasts my whole life and was happy to randomly find your channel. Keep up the good work. John

[@ProfessorDaveExplains]

Well we don't know what's going on in the singularity itself, but a black hole has an event horizon, so when we say they collide, we are talking about the regions enclosed by their respective event horizons. If that occurs, they merge and become one black hole with greater mass.

[@Particleman50]

@@ProfessorDaveExplains Thanks for the reply. So we can't say for certain if the singularities ever meet in the same place in space....?

[@ProfessorDaveExplains]

Well, I think we assume that they do, because that's where all the mass is, and that's what attracts them to one another, but we don't fully understand black holes, nor am I an expert, so an astrophysicist may be better at answering that question.

[@brandonbartz3718]

Why are there 34 thumbs down? Who is going around KZbin that is so petty that they would leave a dislike on a video like this? I can't imagine being so miserable that I would ever do that. It's strange

[@jakejohnson6954]

It was me

[@brandonbartz3718]

@@jakejohnson6954 lol

[@krasiagg3017]

Probably flatearthers who don't believe in real science. :-D

[@TheWAP5]

Professor Dave, I have a stupid question. Hypothetically speaking, if the escape velocity of an object is >c, can it escape the blackhole?

[@ProfessorDaveExplains]

I suppose, but that's physically impossible.

[@rossjones4252]

How does hawking radiation escape from the schwarzchild radius? Can you please explain in a video thanks

[@anestistziamtzis9628]

If you have a star with initial mass at 50 Solar masses for example, it will lose a great amount of its mass in the form of stellar winds during its evolution. After core collapse and during the explosion most of the remaining mass will form the supernova remnant. Thus, the mass that is left as a black hole is just a fraction of the initial mass. Finally, there is a specific class of stars with initial mass 140-250 Solar mass, that will explode without living a compact remnant behind them.

[@thedaemonator3244]

repeat after me: "ssh-varts-shield" - Schwartzchild

[@mevansmrichard]

Question: When a star goes nova, does it always produce a black hole? Second, when a black hole is formed, how come the energy released is not pulled back into the black hole thereby negating the outward push of energy? I hope that question made sense. I'm fascinated with this stuff but not completely in tune with the science behind it. Thank you in advance.

[@ProfessorDaveExplains]

No the core has to be above a certain mass! It's all outlined in this clip, and also in more detail in the previous one in this series, on stellar evolution.

[@mevansmrichard]

Professor Dave Explains Very cool I will view it this evening. Thanks for the quick reply.

[@naco5571]

i'll keep it in mind

[@kbabhimitra]

and about things like hot air balloons they don't have a velocity of 11.2 km/s right and yet they go up very high almost out of the atmosphere where people feel no weight, I think with constant velocity which need not be 11.2 Km/s anybody can reach outer space, it is only when one is throwing something into the sky it needs 11.2 km/s to escape the gravity, otherwise if u have a rocket or something it can reach outer space slowly too.

[@VanOutloud]

Thanks Professor Dave! This video breaks it down so even a plumber can understand it. Your area in science may not encompass the search for Earth-like planets but I pose a question to you, theoretically. If we are looking for Earth-like planets, shouldn't we concentrate on Milky Way type Galaxies in order for the physics to be equivalent?

[@gamingdoggy3597]

You need more subscribers!

[@ProfessorDaveExplains]

tell your friends!

[@g_rammstein]

you said that black holes eventualy die. but what happens when a bh die? it simply vanquishes or explodes? and if it explodes what becomes of all matter it swallowed?

[@ProfessorDaveExplains]

So like the video says they just slowly evaporate due to Hawking radiation. It takes an insanely long time.

[@milosit]

I just learned more about black holes in 9 minutes than in my 59 years of existence.

[@rb1427]

With regard to Hawking radiation, how does the positive partical escape the "pull" of the black hole?

[@0bzen22]

I like the theory of the massive primordial black holes. It's a right mess of mini black holes, dark matter, giant clouds of hydrogen and chaotic gravitational waves. Have fun modelling that.

[@pyros6139]

I feel compelled to point out that it's spelled "Schwarzschild" Fun fact, it means "black shield" in German.

[@love2o9]

What is the observable universe's swarszchild radius?

[@Blubb5000]

Correction: NONE of the Space Shuttles was going faster than 11.2 km/sec. Their fastest speed was around 8 km/sec., which is the speed needed to stay in orbit around Earth. The Space Shuttle was not designed to leave Earth’s gravitational field.

[@smartdoctorphysicist3095]

Hi I thank you for your information, but you did say if the if the Earth is orbiting a black hold will the people on Earth be dead or will they still be living? You did not say!!

[@ProfessorDaveExplains]

Well if the sun is gone, then we will die real fast.

[@PunmasterSTP]

Killing stars, And making holes. Is there anything Dave, Does not now How to do? I don’t think so, Cause you and I, Can hear his knowledge, Shared on high. It’s no lie. 🌎

[@Jehannum2000]

Prof. A powered missile doesn't need to reach escape velocity to escape Earth's gravitational pull. Imagine something moving up at 1 metre per second (or 1 mph if you're American). Eventually it will leave Earth's influence. Escape velocity is only required for objects without their own thrust, i.e. projectiles.

[@daanbos5918]

2:56 so everything that's black is in theory invincible because black is the absence of light

[@krasiagg3017]

Wouldnt say so. If you look at an object with a black color, that just means that the material or the pigments of the object absorb a large amount of the visible spectrum of light, wich lets the object appear dark and colorless. Thats why there are many different types of "black". But light itself is still reflected to your eye. Even the substance "Vantablack" reflects around 0.04% of the incoming light. Wich of course makes a surface nearly "invisible" for the human eye. But still just nearly invisible. I think a black hole is currently the only thing that is capable of "absorbing" 100% of the light. And the fact that this is probably only due to gravitation is just insane. :-D PS: English isn't my native language. I tried to explain my thought as good as possible. :-D

[@daanbos5918]

Krasia Gaming Reloaded That’s basically what I said but extremely simplified

[@ticktock2000x]

I don't know if my question even CAN be answered, but would it be theoretically possible to build a device that forces particle-antiparticle pairs to form? If so, surely we could find a way to send the antiparticles toward a black hole at rate much faster than occurs naturally.

[@ProfessorDaveExplains]

Hmm, well I can't think of a reason why we specifically couldn't do that, so maybe! A particle physicist would have a better answer.

[@skippypeanutbutter9930]

i love your intro

[@bananajoe8677]

I never understood : why does that compressed mass not extend back again?, some sort of a barriere?

[@araitol3935]

Because it's not an elastic?

[@araitol3935]

My question is how it can be so dense in the first place?

[@TheOne-eu2zw]

i just understood interstellar with crystal clarity thanks to this vid. fuck it man u really are amazing

[@heartofblackonyx]

Love your vids, drives me crazy that you mispronounced schwarzschild radius.

[@tickytickytango5634]

Oh thank god. I've been trying to make a black hole to devour the planet for so long but I just can't figure it out!