Ok everyone, this is officially my final comment on this RUclips channel (8:53 PM, Eastern Daylight Time [GMT -4:00], Tuesday 8 September 2015). After this, any posts/comments will come from the new host, Matt O'Dowd. Thanks for being such a great audience. I've enjoyed interacting with all of you on here. If you want to keep up with me or hear about anything else I might be doing in the future, you can follow me on Twitter. I'm @fizziksgabe.
+PBS Space Time It has been a wonderful time with you Gabe. We all learned a lot. I really like the way you explain everything. Your sincere dedication shows up in your work. Hope you do well in future wherever you might go, whatever you do. :) And Matt, loads of expectations bro!
This episode was your last episode produced for PBS Digital Studios. It is still on the internet, even though you have moved on. Ergo, jobs are event horizons. Thanks for your contributions. This, in particular, was an outstanding presentation.
No, math is antrophology approach to describe underlying structure of the Universe.. if out there are alien civilization, they will too be able to find same the underlying structure but using different symbol and maybe different approach..
Hi there. I'm a computer programmer. I believe that I've just solved the problem of dark matter clusters, gravity, and spinning bodies in space time. I'm not a maths buff. I solved it with thought experiments. Like Einstein. For years his theories bothered me. Why would large bodies bend space and time etc. And I woke up at 4:30 with the answer. Anyone wanna help me get it into a scientific paper. I can't approach a university, I don't even have a degree. Besides I'd like it to break here. On YT. Interested?
You really do have a gift for explaining things in a very clear way and what I find even more valuable are those things about which I have not previously learned. This video is an excellent example of the fact that I have heard time and time again that the reason black holes are dark was because light could not escape. I have heard that spoken by well known physicists. I know black hole physics is still fairly speculative and many questions may never be answered, but it is nice to get at least a bit of information about this subject. Most people are not going to spend their lives studying black holes, but that does not mean that many of us are not extremely interested in this subject. If the next person does even half as good of a job explaining things as you did then I will continue watching this show for a long time.
I started watching this channel with the new host and only watched Gabe's shows later. At first I didn't care for his voice and way of speaking, but after watching all his shows I came to appreciate him much more. I hope things are going well for him.
@@JohnDRambo He got a job at an Institute for Science for a year and later took over at PBS Infinite Series with another woman but the series were cancelled a few months ago, which sucked.
@@MrKudmar right? or got too close to a black hole... He may be writing papers here and there, maybe worth a check if any are interested in Gabe's work? I do not know where he is working from though. If I hear of or see anything interesting concerning Gabe's work I will try to get back here and post.
I don't think he knows what he's talking about, the escape velocity or curvature at the horizon for a photon is too high and it cannot escape. The infinite term he used about an object close to it is wrong, the curvature is large enough to keep photon in but not infinite, it get even larger the other side of the horizon. Even at the center there is no infinite or singularity, that is once again venturing into pure theory, nice to simplify things and works well enough for predictions, but is not real without lab experiment of the infinite (not near) which obviously have never or will ever be done. It's like splitting the difference between you and your next step into infinite pieces, using that it either take 0 time or infinite time to take that step, limits are reach and it becomes finite. Matter may be basic particles on the other side but they are generally doing what they do inside a sun, as far as anyone knows the photon may have gone back to the state they were in before the big bang, where a black hole is the anti-Big Bang for a photon. There is no research of particles at those densities ( we cannot create black holes in a lab) so you could say just about anything you want, put a lot of math around it, and claim you are right. Someone could grab some string theory math, create his model of 'God' from that math, then say I have proven the existence of God because I say so and have the math.
@A Frustrated Gamer From what I understand, information doesn't get deleted from objects falling into black holes, rather it gets frozen in the Event Horizon like a hologram and it's reversible IF you could turn off the black hole. Spooky stuff for sure.
What makes PBS Space Time different from science shows on TV: - they don't spoon feed the audience - they are not like "here is some CGI, you're too dumb for the real science anyways" - they present the historic scientific discourse - they give you the feeling it's not just stuff weird masterminds came up with and you are never able to compete This is really an achievement! *Thank you guys!*
Space Timers -- the channel is not closing down! Yes, *I* am leaving, but the show will continue with a new (astrophysicist) host! No one panic. As they say, the show will go on. We announced all this weeks ago in this video: ruclips.net/video/U8Hx-AkFDCY/видео.html
PBS Space Time Thank you so much for what you've done here to date. I consider myself pretty well versed in science concepts in general, but I still get a lot of things wrong, and this channel has helped me to greatly get my facts straight. Thank you so much!
PBS Space Time I just subscribed about two weeks ago, and I am sincerely sad to see you go, Gabe. You really fueled my interest in spatial concepts and the like, and I wish you luck on your endeavors.
If you change direction from N to W it is not 90 degrees. Go due south from N pole, then turn west go west, then turn north go north you end up where you came from.
Same shit happened to me! I was watching this vid and then got "distracted" for 2 entire weeks (I kid you not). I had even forgotten this original place where I started watching all this physics stuff lol
Gabe, thank you so much for all of this. It's really hard to access good hardcore physics in vanilla form for us non-mathematical-background people. Thanks again, I wish the best for you and your career! Ugo
I've often wondered about this when they talk about 'merging' black holes. How can we observe the merger if they become 'frozen' when close to each others event horizon?
We don't observe a spatial or time merger, only a gravitational one via gravitational waves. The converging gravitational geodesics interfere, if the black holes are small enough they interfere severely and at a short enough wavelength to be observed with earth-bound interferometers (e.g., LIGO). This just means since we know via G.R .that gravity is a function of spacetime (not a force) that is proportional to spacetime, if we observe a distortion in spacetime we can infer a corresponding spacial-time effect. TLDR; We don't 'see' blackhole mergers (via traditional EM methods). Two blackholes closely orbit, cause gravitational waves, those waves are detected by a distortion to a laser beam, those distortions can be reverse engineered to determine the origin (two black holes orbiting).
hmm. maybe our universe is a black hole with it's own unique physics that we are experiencing. anyone outside our black hole(universe), won't know we are there.
It's actually going to be a more practical question than you may realize. Remember, black holes aren't necessarily collapsed stars. Any sufficiently large nebulous mass can "shroud" itself in a black hole, since sufficiently distant objects would accelerate to c before they ever hit it. And as we're finding supermassive black holes at the center of galaxies, that may be exactly what we're looking at.
Daniel I've looked around, I've heard there is a school that believes you would never actually catch up with an event horizon. But the more I look around, the more I realize how very little even the professionals understand black holes. If it is true that you can cross an event horizon, it sounds like you hit a "warp boom" much like planes breaking the sonic barrier make a sonic boom.
+1ranjeeves21 Comet Tail is right; I would add that you have to do easy before you can do hard. I would recommend watching Crash Course Astronomy over on the Crash Course channel first. It starts of really easy (to the point that some people complained the early episodes were too simple), and seamless takes you to greater heights. After that you can come back to Space Time, starting with the oldest videos first as there's a lot of continuity.
You have helped me learn so much. I have been learning physics independently, because I am way far ahead than the people in my school, but my school won't let be take higher classes. This year will be my first year "taking" physics, and it will be a walk on the park. I've had these misconceptions for years. I hope there's more videos like this when your gone. P.S I want to be an astrophysicist.
+Feynstein100 I'm assuring you, you're not alone... My physics teacher doesn't know what a black hole is, and doesn't know what particle physics even is.
+SciAm14 Lucky me I had a teacher who spent months on particle physics, forces&fields, relativity and the basics of quantum theory. Back in the 1970ies. Then again, Austria used to be a leading country in physics (Schroedinger, Pauli, Boltzmann, currently Zeilinger et al.).
I miss you, Gabe. Your style of presenting---fast-paced, challenging, but rewarding to those who took the time to pause/rewatch the video and think through the concepts you're bringing in---really resonated with me in a way that the newer videos don't quite.
This is exactly the moment when i know when/whom to suscribe and hit the bell icon without the video telling me to. Many thanks for making this video for me and other laymen like me. U r aweesomee. Cannot describe it cos its infinite like someone falling inside a black hole :) You are really doing a wonderful job universally.
I've been thinking about what you said about the monkey never crossing the event horizon from the perspective of everyone else... isn't that just a math issue with the Schwarzchild coordinates? If you switch to Eddington-Finkelstein coordinates, the monkey's spacetime path definitely crosses the event horizon. Doesn't that mean we shouldn't be using Schwarzchild coordinates at an event where it fails?
PBS Space Time Also, I'm sorry to see you go. It's been really nice having someone around that gets relativity... but I know you can't be here forever and I wish the best :-) P.S. Thanks for the in-video comment response.
***** Right. But the 't' in Schwarzschild coordinates has a physical meaning -- it's the ticking of the clock of observers at infinity. We use different coordinates to figure out what's *really* going on, i.e. that the monkey crosses just fine, to figure out the Penrose diagram of the spacetime, etc etc. But it doesn't change the fact that our clocks out here *are* the Schwarzschild t-coordinate, so that the monkey's life past his point of entry into the BH will not be found on *any* constant-Schwarzschild-t spatial hyperslice. On the t-clock, those events aren't simultaneous with any other event that occurs that r > R_s. And all moments in the monkey's life prior to that "crossing event" get "spread out" over an infinite number of "cells" in the movie of the universe that the observer at infinity is recording. Turns out all of the above remains true if you use coordinates whose spatial coordinates are standard Schwarzschild coords and whose time coordinate is the proper time of an observer at any fixed r > R_s. Everyone experiences infinite time dilation and redshift relative to the horizon. The horizon *is* the infinite time-dilation, infinite redshift surface (at least for Schwarzschild black holes, which is all I was talking about in this vid).
PBS Space Time Ok, thanks for the clarification. I'm always hesitant to make interpretations when results look "hinky" (for lack of a better word)... but then, I guess, everything in relativity is a bit hinky.
***** Also, to clarify, the monkey's world line enters the black hole region. That is a purely geometric coordinate independent statement. However, certain events on that world line are completely inaccessible to external observers in a specific and peculiar way, namely that those events are shifted to temporal coordinates on our clocks that are somehow _after_ t = \infinity, whatever that means.
Hey guys, I'm studying physics. Great video! I hope I can clear up the confusion about mass at 10:04 - 11:05 : You begin to write the equation (called a 'metric') for a black hole by writing down some assumptions about space: the space is spherically symmetric, the space is static, the space is stationary, etc. These assumptions give you a good-looking equation. But there are some terms you just don't know off the top of your head. You know they're there, but you have to solve for them to see them explicitly. That's what you use Einstein's equations to do. Now, Einstein's equations for a black hole end up being first-order non-homogeneous linear differential equations. When you eventually solve them, you get some constant. It could be anything; but all you know is that it's constant in time. We usually label this constant M because (1) when you make it bigger the equations show more curvature, and (2) when you make it smaller they show less curvature, and (3) if it's zero, there's no curvature. So it sort of looks like this free parameter (the constant) is what we have been calling "mass" for hundreds of years! So we label it M. So I hope this clears up the confusion about mass. Summary: basically, you're right, there doesn't have to be any matter in your space-time for you to write down and solve the equations of a black hole (what you're calling in the video an "idealized version" or a "prototypical BH"). But there ends up being this constant in these equations that is some free parameter. You can label it as mass if you want because it turns out that the mass that we measure with telescopes is just is a good way of parameterizing these equations! For these reasons, there's no interpretative issue/mystery in the physics community, and M has no association with the singularity. Keep up the good work! Physics is awesome, -D
I am confused .. i can understand that according to einstein, mass 'generating gravity' is just space time being curved so an object has to follow that path towards that mass. Why cant we assume black holes as having mass when they do exert newtonian effects on objects near them? Also where and what exactly is 'mass' if its exerting effects on space time? Is it a point like potential for curving space time ? I guess i wont get anywhere unless i had studied maths and physics :(
Did I get this right? You get a constant you don't know what to do with. But because you assume that mass bends spacetime, and the constant does, too, you label this constant M for mass? ... And? Does it make mass being responsible for everything we don't understand about the universe?
This is the most advanced and mind-blowing explanation of the nature of black holes that I've ever seen! I love that the often-considered-unfortunate name "black holes" is quite accurate in a very literal way: that it's actually a hole punched in the universe! Also, before seeing this video I've watched many other more recent PBS Space Time videos, where Matt repeatedly refers to black holes as objects with mass, spin, etc, and that kind of terminology now feels so primitive to me; it makes me wonder why this epic revelation was left behind in a 6-year-old video!
I thought I was alone (taking the phenomenon literally, as you described); but maybe the Universe wanted it that way (I just saw the video, and then read some comments after already formed my opinion on the facts of the matter)… Nonetheless, since I said it - and there are many, many fake personalities out there, on the Internet, these days - I must add “some insights” and substantiate my claims, to prove the authenticity of my thinking… First, I just want to be clear: I like the way Matt presents science & facts - in both the substance & the style (it suits my worldview & meets my expectations). Keep up the good work, Matt! Flick, to try to answer some of the questions you raised, I’ll continue… Scientists, lecturers, science communicators, teachers, professors and alike still talk about BHs as objects with properties you mentioned (mass, charge, spin etc.) because, I think, any of the following is true: *a)* They learned it that way from the standard textbooks, and their life philosophy and/or strategy is “shut up, and calculate”; *b)* They may think differently about certain phenomena, but sometimes the math and/or the ontology of those gets so complicated that people rather “go with the flow” and accept status quo; *c)* Then, there’s this “don’t care” | “not my pay grade” | “I’m (more) concerned about The Economy” etc. approach; *d)* The mass (and other stuff) is the part of the story, and is part of the gravitational system, because real-life BHs do gather/arrange mass of surrounding matter into the accretion disks (and there are, also, quasars, blazars, AGNs etc.); and the whole system could be functionally equated with a massive object at the center; and, finally, *e)* Many (predominantly male) members of the faculty adopt the “tough (Platonic) love” approach to students, or, at least, apply the “get them out of their (cognitive) ‘comfort zone’ (so that they begin to think proactively, hopefully)” coaching doctrine, something akin to perpetual scholastic mind-mini-drills… That last one (e) - a.k.a. “serving nebulous-but-authoritative, hard-to-digest conjectures” method - is most appalling to me. Although I have been known to (occasionally) “lecture people” - as opposed to “giving (only solicited) lectures” - especially when I have to correct the mess they’ve caused (out of their super-confident ignorance on a subject or out of their sheer sloppiness), it’s also true that I have given the best and all of myself when tutoring others, because I think that’s exactly what a lecturer should do: explain all that is related & known about the phenomenon at the present time, as simply as it could be done, no “curved balls” allowed, except the “interactive ones” that are also demystified right away or throughout the teaching course. You may tease “them” students, you may quiz them and probe their imagination & logic & retention of the material, but at the end of the day - what incremental knowledge have you passed to them? The dogma “Let them (academically) suffer a bit - as we once may have - as others have done to us - and we turned out so righteous” (as if our spirit and academic stamina were produced by the steel-strengthening process whose name I cannot recall at this moment) - is both dishonest and inadequate teaching technique. Instead, being intellectually caring towards your promising protégés & protégées, I assert, is the proper way and more effective in the long run, because it doesn’t result in rogue dissent from academia, the life itself will, by its course, teach those students (and anyone else, for that matter) the real-world “toughness”, and, finally, and most importantly - it is far better to give them advanced head start, the “elastic epistemic impulse” (epistemic trampoline, if you will, or academic “gravity-assist”) by teaching them all we know, in earnest, which could (and most likely would) result in the most efficient & impressive advancements for the society as a whole, carried out by your very own mentor-loving, (still) affectionate, science-protecting apprentices; isn’t that more satisfying? (Yes, it certainly is.) The true & truly altruistic meaning of the phrase “standing on the shoulders of the giants” (that preceded us). About primitiveness of terminology (and, in extension, some descriptive framework pertinent to the scientific method): Although sometimes we are stuck with one, we should advance those, too… Maybe, after all, gravity is not what it seems to be? My big bet is that physics is going to be re-vamped soon… For example, I think that the idea of “information” (either physical or quantum) is ill-defined. [I like to think of it through the “‘The Flintstones’ paradigm”.] But only time will tell (I certainly couldn’t, because I have no degree in physics). Stay tuned. I almost forgot: Are you, by any chance, related to Sir Roger?
This video explains the black hole like no other one. No other video talks about how a black hole is " events " that don't happen from our frame of view. Really interesting and amazing
Quick update: our brief hiatus is coming to a close. Brand new video next Wednesday, 9/23, during which we'll also address some of your really excellent black hole questions. After next week we're back to the regular weekly schedule.
If matter freezes and never enters the black hole, then a percentage of that matter could not be ejected from the poles of the black hole because it would be frozen in time. However some matter is ejected from the poles of a black hole when it consumes objects, so this theory is wrong.
you don't understand it DOES enter but we can never see it enter because the light being emitted by it past the event horizon isn't able to be detected by our eyes and if your wondering cameras cant either because that light is everywhere so you couldn't see a thing if you could see it
Then what is that stuff about particles entering a black hole having some event on their world lines that becomes the last events in history? What about the talk of occurrences beyond the event horizon not being able to be assigned a "when"?
+mikezeitgeist2 you don't understand the video... if you LISTEN you'll understand it so go back and rewatch the video besides EVERYTHING we know about BH are guesses even this
+agustin venegas certainly an unusual way of dying for a red shirt. But consistent in that he would just collapse without ever having said a single word.
I watched and subscribed because THANK YOU!!! This was amazing and I'm glad I had the opportunity to experience this channel with you on your last presentation with the show. This was dope AF!!
I feel like many of these so-called misconceptions likely boil down to semantic pedantry. A simpler description can communicate the same idea despite using the "wrong" words.
I know this is an old video, but hopefully someone can help me out here. When he was talking about the collapsing star, and said the infalling matter is infinitely time dilated at the surface, I was wondering if the expansion of the event horizon has any impact on this? It is essentially just a region of spacetime, so it shouldn't be limited in it's expansion by the speed of light, so conceivably, if it grew faster than c, we would indeed see the infalling matter "swallowed up" by it and not frozen on the surface, right?
No, it's not a speed issue. You simply can't see anything pass the event horizon from any outside reference frame. Even if it was expanding faster than light, you wouldn't see it
Imagine a black hole as an actual infinitely deep hole that goes at right angles to our three dimensions . Time turns into space, and objects trapped in the event horizon appear frozen to us, but according to their perspective, they are just drifting slowly into a new universe tipped 90 degrees from our own. Since our own universe is enclosed by a event horizon defined by object traveling at the speed of light, we are essentially sitting inside a black hole, and for all we know it is full of stuff that "fell in" from somewhere else. See? It's actually simple.
+Ironjagg This is the worst video on black holes I have ever seen, many points are truly incorrect. Watch Neil deGrasse Tyson videos if you are interested in this kind of thing.
Wait, I took years to barely understand that black holes are objects with a lot of mass concentrated in a single point, distorting the space-time so deeply that even light can't escape, that's why it is black. Now that's actually not right? Surprises aside I like a lot of Gabe's episodes.
It's not that it's "not right" per se, it's that it doesn't account for the fact that "spacetime" has two components-- space _and_ time. The description you mention here really accounts for the former. The temporal (relating to time) effects of a black hole are far less intuitive and difficult to explain in a short amount of time, so science popularists generally just stick with the more digestible spatial-only description. This is usually some variation of "the pull of gravity is so strong that not even light can escape." You might sometimes hear another version along the lines of "a black hole is black because the escape velocity at the event horizon is the speed of light." This actually isn't totally untrue, but not for the reason you might expect. If I watch you fall into a black hole, I never see you cross the event horizon. It's not a "vision" issue. It's not that your final photons are just "treading water" at the event horizon or anything like that. It's because, as you approach the event horizon, time starts running slower and slower for you relative to my own. 2:1 (time is passing two times slower for you), then 10:1 (ten times slower), then 10,000:1, etc. As you asymptotically approach the horizon, your time coordinates dilate to ∞ with respect to mine. Not just mine, but _any_ observer does not occupy a reference frame comparable to yours (IE, crossing the event horizon). You might be wondering _why_ time has dilated so egregiously. It all comes down to the fact that _all_ reference frames must agree on the speed of light being constant. Here's the rub, however: In order to perceive the speed of light at its constant rate in a region of spacetime where the the escape velocity _is_ the speed of light, your clock... must run infinitely slow. In other words, time stops at the event horizon relative to the outside universe. This is the _real_ reason why black holes are black. Putting it simply, things at the event horizon cannot emit light because there will never be enough time for them to emit it. But how does one reconcile this with the fact that, from _your_ reference frame, you cross the event horizon without issue. In fact, nothing even seems to be any different. That's the common narrative, anyway. But it's not really true, is it? There is a _major_ difference between where you just came from (outside the black hole) and where you are now (inside of it): You cannot turn around and go home. The truth is this: What outside observers perceive as time stopping for you, and what _you_ perceive as an inability to turn around and go home, are actually different presentations of the exact same thing. Your experience differs from theirs because, in your own frame of reference, you _must_ continue to experience proper time (one second will always seem like one second). In reality, what you're experiencing is NOT a series of moments inextricably leading toward the future, but rather a series of _spatial translations_ leading inextricably toward the singularity. You can't turn around and go home because turning around and going home takes time. You're frozen in time, you just don't realize it. Without any framework of time, there can be no turning around. If you can't turn around, you can never go home. This is what a black hole _really_ is.
Perhaps we all need reminding that, from the point of view of an outside observer, the core of the star that forms a black hole never collapses into a point of "infinite density". Once it reaches the event horizon of the new black hole, time dilation means that that matter has no future world line. From our reference frame, it just stops as it is slowly redshifted beyond detectability. It's also worth remembering that mass is simply another form of energy. After all, in Einstein's field equations, it's energy that causes spacetime curvature. We use the word mass as a convenient placeholder, because for all other astronomical objects, it is almost entirely their mass that causes the spacetime curvature that we observe as gravity.
An entangled particle cannot transfer any information, so that won't do anything for you. Otherwise, we would already have faster than light communication.
@A Frustrated Gamer Great, just imagine quantum computers trying to store a 0 or 1 ... due to uncertainty it may be a 0 maybe a 1 or maybe in between. Just imagine an app running with that uncertain code, could be a huge mess. lol
Amazing episode challenging the classic bs of black holes being 'dangerous' or 'sucking stuff in from afar' as well as them being big black spheres that cannot be detected apart from their gravitational pull on the matter surrounding them - someone should do a longer episode on black holes with this POV and with more elaborate visualisations (and pretty accretion discs :3 ) - props for ponies though, and as a European: THANK YOU for pronouncing it schwartzSCHILD instead of schwartz-CHILD!
Well, it's not a simple concept you can understand in one or two videos. There's a lot of stuff to be explained and everything is very complex that it's preferable for a keen learner to take one step at a time
There is a singularity at which all PBS spacetime videos converge into one point of infinite knowledge. If you miss it, you, like me, are doomed to wander an intellectual maze of self-reference eternally.
Yal Rathol Probably more like a tear or scratch in reality. But "error" is an interesting way of describing it. I guess nothing, even the universe, is perfect.
gwar scout74 i've taken to using "error" when describing things like that ever since i heard that one description of vantablack as looking "like a graphical error in real life". and honestly, it's not wrong. vantablack looks like the graphics haven't loaded into reality and you're seeing the void beneath.
Yal Rathol tricky stuff for sure. 99.83 whatever percent of light absorbed. didnt know of it till you mentioned it. So thanks. my source described it as being 2D in a 3D world, if that makes sence. Also it mentioned military applications, no surprise.
gwar scout74 not surprising, though you should be careful with it. it doesn't go on easy, and it eats heat like i eat chips. also, vantablack II absorbs even more light, i think it's 99.95% and it doesn't have to be cooked into the object as hard.
***** no, ghosts are bugs and glitches and all the people who can see them are players, everyone else is an NPC. after all, NPC's don't react to the glitches, do they?
It is most sad to hear you are leaving. Please enjoy your new endeavors and I hope you find much success. (Apologies for my poor writing. I am Japanese and still learning English) .
he exposes a deeper and more self-coherent perspective that is much closer to the actual mathematics of the general realtivity and honestly it's refreshing because other sources tend to oversimplify a lot and there are lots of them
"To outside observers, most of the inital stars matter never crosses the horizon". I always asked myself how many and why.. Is it due to the growing horizon and shrinking of the stars like the animation suggests?
im pretty late to say anything and im not quite sure if I understood it very well, but based on my understanding you can never witness anything crossing the horizon because the closer you get to the blackhole, the slower timescale you're on, so for example like he said if youre 10 feet away from it and im 20 feet away from it, you'll look like you're moving in slowmotion because we aren't on the same timescale, but to you it seems like nothings changed since you are living in that timescale currently. Once you get near to cross the event horizon I believe your time is practically broken, and to all others your time progresses so slowly, or not at all, that we never see anything beyond that point, but since that is the timescale you live in, it's as if nothings different
The slower timescale means gravitational redshift of light extending its wavelength, the closer object is to black hole, the more it happens. So light redshifted enough would be outside of visible spectrum and as such we'd never observe object actually crossing event horizon - instead we will see fading into invisibility as reflected light gets more and more shifted out of visible spectrum.
Yeah likewise, I could 'understand' if they meant that you could never 'see' anything reach the singularity as at infinite density time is supposed to stop. However, he says that the significance of the event horizon is that from inside all directions point towards the singulariry but that the blackhole itself isnt infinitely dense. Also if the monkey appeared to stop at the event horizon wouldnt that mean that from the monkeys point of view the entire future of universe would happen before it ever crossed the event horizon? Also if things freeze at the event horizon how do they gain any extra mass? I watch many videos on blackholes and relativity and there is never an answer that resolves the seemingly unresolvable paradoxes. Im not sure how in depth you actually have to study these things before they can appear at all possible, but theres an event horizon of understanding that I just cant see passed.
You are right. I have made a reply for this video that contains actually the answer for that. I just copy it to here for you: One additional misconception about black holes that it takes infinity time for outside observer until a falling object cross the event horizon. The reality is that when material close very much to event horizon, the event horizon will grow and incorporate the falling material. (Mathematics: The mass becomes bigger very near the Schwarzschild radius due to additional material -> now the Schwarzschild radius become larger calculating with the additional mass -> black hole horizon is increasing -> material will be inside the black hole). So, the ponies will not see that monkey freezing close to the event horizon. They will see that as the monkey becoming very close to black hole, the event horizon is growing and the monkey is inside the bigger black hole. So, the event of monkey crossing of event horizon does happen in finite time for all outside observers (not just for the monkey). If it took infinite time, supermassive black holes would not exist.
So finally as you have written: the horizon is growing, the collapsing start material is shrinking and after a finite time (from outside observer) the horizon become bigger than the collapsing star. After that when additional material (e.g. gas from other stars) become very close the black hole due to gravitation of black hole, the even horizon of black hole grows and incorporates some additional gas, material, etc. So black holes just grows and grows and grows. (The Hawking evaporation is so small than it is totally negligible. And it will be negligible for several billions of years from now until CMB becomes colder than the Hawking temperature of black hole which is very-very tiny.)
Isn't it true that the "infinitely redshifted" photos of light emitted beyond the event horizon never reach us? That they always stay within the event horizon? Really splitting hairs to say that the idea that they cannot leave the black hole isn't true, it appears patently true by the above description.
The photons that get redshifted into oblivion are the photons that leave the monkey *right before* or very near the event horizon. The photons which originate from within the horizon stay in the horizon, as there is no such thing as radially outward once inside.
but isn't energy quantized? as in, finite at the most discrete levels possible, an infinitely redshifted photon means an infinitely small quanta of energy
quantum mechanics is too right to be not right even in theoretical circumstances or maybe not, it's either no such thing as "infinitely redshifted" photons happen, or something is missing
How are there any black holes at all, if nothing can ever cross their event horizon from an outside reference frame? Wouldn't we observe the moment of their creation " frozen" at the event horizon?
So this would imply that if Hawking radiation destroys the black hole in a finite amount of time (from the perspective of a distant observer), then the monkey will be released from the black hole before it fell into it (from the perspective of a distant observer, because it takes an infinite amount of time to reach the horizon). So if there is no contradiction, the money will see the black hole evaporate before falling in.
There is an interpretation that Hawking radiation is the stuff that had been falling into the blackhole for all these billions of years, after being chewed by spaghettification, or maybe that firewall idea, or something of the sort. But I'm not sure how well accepted that interpretation is by mainstream science.
Wait so if time stretches to infinity for the inside observer, they would theoretically have to experience the event of the black hole evaporating since blackholes aren't infinite
LOL "the money will see the black hole evaporate before falling in". I suspect in reality "The money" will probably evaporate long before one gets to reach Earth's orbit, never mind the Event Horizon xD)))
Watch a ‘Stargate’ episode where a military base underground is effected by the gravity waves of a black hole and it really does a fairly easy to understand demonstration on time and its relativity while using many of the same terms time dilation, distortion, gravity waves etc... (also happen to be a great and scary episode due to its implications) The world outside the base experience time as normal as in two weeks go buy, but for staff inside the base its only been 10 minutes while vice versa where time running normally for them every second, but outside the base time is just racing ahead.
Bill Belzek nobody said people with high iq have much common sense. They usually don’t. They spend more time reading about reality than living it. Maybe that’s why Trump is so successful at his job.
This video is really mind-blowing! I keep wondering how black holes grew in the past. Common thought tells us that they grew absorbing matter and even other black holes. Gravitational detectors have recently saw proof of this. But, if nothing can't pass through the event horizon because that will take an infinite amount of time, then black holes won't be able to grow in that way at least not during a finite amount of time...Something is missing here. If anyone can help I would appreciate it!
Objects only slow down on the outside of a black hole from the point of view of an external observer, they still cross the event horizon (and so the black hole still gains mass).
Wow, I had thought I was fairly intelligent until Gabe gave this presentation. I am going to have to watch this presentation several times to get a better grasp on the concepts. Best wishes Gabe on whatever you pursue.
Yes, but in a universe where we have two dimensions of time. An interaction is an event, so the interactions that occur inside the black holes are events. With a second dimension of time, everything that has ever happened, is happening, and will have happened. So if a single interaction is occurring inside of the black hole, then an event has happened. And since the black hole clearly is being held together by interactions inside of the black hole due to gravity, then the forces keeping it together come from interactions within the black hole, and not outside of it.
No the gravity come from the curved spacetime cause by the flattened matters around the black hole that to us never actual enter the black hole and that why its mass have relation with its surface not volumes. U should look into black hole entropy and holographic universe.
I was habit to Noah but this is one of the most... clarifying and so new, to me, video on these subjects and their common oversimpification. And yet Noah had habit us to a different point of view about many of these universe's curiosities. I loved it!
8:50 sorry but how did he get the density of water? the black hole in the center of our galaxy is 8.57*10^36 (kg) and has a radius of 1.27*10^10 (m) this means that the density should be a lot bigger then that of water? or maybe my sources were wrong?
+marco polo Oops! You're totally right. Thanks for catching this. It's the black hole in the center of Andromeda (~200 million solar masses) that's about as dense as water. The Milky Way's central black is about 1000 times denser than water. See that, kids? Always double check your arithmetic as an extra layer of fact-checking. Don't repeat my boo-boos!
Since we see objects that cross the event horizon just "freeze", how can we even "see" the blackhole. Wouldn't you just see the star in a frozen state before its outer layer was inside the event horizon?
We dont actually see anything because of the red shifting. But in theory it's there (at least the information). Freezing thing is a way to visualize the physics. Obviously the actual effects are more complex on human scale objects.
We dont actually see anything because of the red shifting. But in theory it's there (at least the information). Freezing thing is a way to visualize the physics. Obviously the actual effects are more complex on human scale objects.
If an object freezes at the event horizon from our frame of reference, but in actuality mass is falling into the black hole and enlarging it, doesn’t the event horizon expand and thus “swallow” the object and make it disappear?
As something asymptotically approaches a black hole, the ticking of its clock slows to the point where it takes an infinite amount of time between the last moment and the next. It stops emitting photons all together because it literally no longer has enough time to emit even a single one more. This happens very quickly, so even if the event horizon grows, you wouldn't be able to visually "see" whatever it was that you were trying to watch because it would've long since disappeared. That said, you could wear some AR goggles that calculate the object's spatial coordinates and interpolate an image of it at that location so you could "see" it, and it would always remain at the edge of the event horizon-- even if the event horizon got larger. Conversely, if the event horizon were to shrink due to hawking radiation, your infalling object would _still_ forever remain at the edge of the event horizon. Right up until the black hole blinks out of existence.
Still a great video, though I have to take issue with one thing this guy says here: The escape velocity at the event horizon is the speed of light NOT by coincidence - it is in fact exactly the same as saying there is no direction out beyond the event horizon. Let me explain: Photons have no mass and so they travel at the speed of causality (as do gravity waves). The speed of causality is the fastest that cause and effect can travel through space. At the event horizon, spacetime is so curved that no cause and effect can travel fast enough to have an effect on anything outside this area. In other words, all possible futures head in the direction of the centre of the black hole. There is no direction out. Just as no cause and effect can propagate faster than light (the speed of causality). Black holes basically swallow the future.
I'm disappointed you didn't discuss the "surface of last influence". I learned of it in _Gravitation_ by Misner, Thorne, and Wheeler. I was very confused by your spiel about that black hole's mass. I thought that was one of the three properties of black holes: mass, angular momentum or spin, and charge.
I'm 34. I think it's the first time I "ask" someone to explain me something and I don't understand him yet I feel like thanking him for leaving me more confused than I was. So yes, I'm guessing I thank you for these series of videos.
Makes you wonder if the whole universe is inside a black hole with a finite radius, but we're experiencing it to be so limitless because we're inside of it.
First video I see from this channel and already my mind is blown to the point where I need a moment(maybe more) to process it. Gonna go listen to music while I do. Music makes things better.
Not true. They actually red shift and slowly disappear. If an infinite amount of time passed they would have eventually disappeared entirely from red shift to non existence. They would NOT appear to still be there for ever to your perspective what so ever.
Yeah, their image would become redder and redder and slowly disappear. If you could detect infinitely long wavelengths, you could infinitely see their image become "redshifted" - but we cant, so their image will just disappear - at least in my understanding.
Excellent video. I sometimes ask the question "Do black holes exist?" Sometimes it's as if I asked if the earth is flat. Like there is a consensus among physicists that they do indeed exist. After all, there is overwhelming evidence and the model is well understood. But to answer "yes" maybe is to dumb down the question to the level the public can understand. Infinitely distorted spacetime is difficult to grasp. To be clear, I don't dispute the evidence or any part of the physical model. My only issue is with the precise use of the word "exist". I'll be more precise: Do black holes exist /now/ ? Where "now" means "simultaneous with my current moment according to my reference frame". There are no events inside the event horizon that are "now". Furthermore, the collapse of the star to within the Schwartzchild radius is not simultaneous with any event in my past light cone, so the formation of the black hole hasn't happened yet. Of course this doesn't help the monkey at all. Anyone flying into a black hole will experience it as such, exactly as any physicist would predict. I'm sure I'll get replies from people who don't get what I'm saying. I'm more interested in knowing if I got it wrong mathematically. Specifically, in the reference frame of an external observer, is it correct to say that the interior of a black hole is in the present? And is it correct to say that the formation of the black hole (collapse to Rs) happened in the past?
Here’s the thing. Infinity practically can’t exist, and when we mention something become “infinite” it means that it’s approaching an impossibility. Meaning it really ends up approaching 0.
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Ok everyone, this is officially my final comment on this RUclips channel (8:53 PM, Eastern Daylight Time [GMT -4:00], Tuesday 8 September 2015). After this, any posts/comments will come from the new host, Matt O'Dowd.
Thanks for being such a great audience. I've enjoyed interacting with all of you on here. If you want to keep up with me or hear about anything else I might be doing in the future, you can follow me on Twitter. I'm @fizziksgabe.
+PBS Space Time
Thanks.
+PBS Space Time
When is the next video coming out? I thought one came out every Wednesday!
Im not even a native english speaker or a physics student, and i understand and love your videos, so perfectly explained.
+PBS Space Time NO! SHUT UP! MOAR PHYSICS NOW. Thank you for the great content.
+PBS Space Time
It has been a wonderful time with you Gabe. We all learned a lot.
I really like the way you explain everything.
Your sincere dedication shows up in your work. Hope you do well in future wherever you might go, whatever you do. :)
And Matt, loads of expectations bro!
This episode was your last episode produced for PBS Digital Studios. It is still on the internet, even though you have moved on. Ergo, jobs are event horizons. Thanks for your contributions. This, in particular, was an outstanding presentation.
I'm happy that Matt carried on this show and made it his own. But this is a quality episode as well.
So if one accounted for time’s behavior as the monkey falls into the black hole. The monkey’s velocity would be constant?
Black Holes are so heavy that they turn mathematics into philosophy.
No, math is antrophology approach to describe underlying structure of the Universe.. if out there are alien civilization, they will too be able to find same the underlying structure but using different symbol and maybe different approach..
Maths is kinda like philosophy
Math is an application of logic. Logic is a branch of philosophy.
Fuck you for your name.
Hi there. I'm a computer programmer. I believe that I've just solved the problem of dark matter clusters, gravity, and spinning bodies in space time. I'm not a maths buff. I solved it with thought experiments. Like Einstein. For years his theories bothered me. Why would large bodies bend space and time etc. And I woke up at 4:30 with the answer. Anyone wanna help me get it into a scientific paper. I can't approach a university, I don't even have a degree. Besides I'd like it to break here. On YT. Interested?
You really do have a gift for explaining things in a very clear way and what I find even more valuable are those things about which I have not previously learned. This video is an excellent example of the fact that I have heard time and time again that the reason black holes are dark was because light could not escape. I have heard that spoken by well known physicists. I know black hole physics is still fairly speculative and many questions may never be answered, but it is nice to get at least a bit of information about this subject. Most people are not going to spend their lives studying black holes, but that does not mean that many of us are not extremely interested in this subject. If the next person does even half as good of a job explaining things as you did then I will continue watching this show for a long time.
I started watching this channel with the new host and only watched Gabe's shows later. At first I didn't care for his voice and way of speaking, but after watching all his shows I came to appreciate him much more. I hope things are going well for him.
This is still my favorite SpaceTime episode by far. You are missed, Gabe.
What happened to him??
@@JohnDRambo He got a job at an Institute for Science for a year and later took over at PBS Infinite Series with another woman but the series were cancelled a few months ago, which sucked.
@@BertaRS made it seem like he died
@@MrKudmar right? or got too close to a black hole... He may be writing papers here and there, maybe worth a check if any are interested in Gabe's work? I do not know where he is working from though. If I hear of or see anything interesting concerning Gabe's work I will try to get back here and post.
He was better than the new guy..oh well
Great, so everything I already didn't understand about black holes is actually not true. Thanks anyway! 😂
It is true because you didn,t understand
Hahahha, this was my exact reaction xD.. Still will keep watching the other videos so I can not understand more :D
We are the monkey, frozen in time.
I don't think he knows what he's talking about, the escape velocity or curvature at the horizon for a photon is too high and it cannot escape. The infinite term he used about an object close to it is wrong, the curvature is large enough to keep photon in but not infinite, it get even larger the other side of the horizon. Even at the center there is no infinite or singularity, that is once again venturing into pure theory, nice to simplify things and works well enough for predictions, but is not real without lab experiment of the infinite (not near) which obviously have never or will ever be done. It's like splitting the difference between you and your next step into infinite pieces, using that it either take 0 time or infinite time to take that step, limits are reach and it becomes finite. Matter may be basic particles on the other side but they are generally doing what they do inside a sun, as far as anyone knows the photon may have gone back to the state they were in before the big bang, where a black hole is the anti-Big Bang for a photon. There is no research of particles at those densities ( we cannot create black holes in a lab) so you could say just about anything you want, put a lot of math around it, and claim you are right. Someone could grab some string theory math, create his model of 'God' from that math, then say I have proven the existence of God because I say so and have the math.
@A Frustrated Gamer From what I understand, information doesn't get deleted from objects falling into black holes, rather it gets frozen in the Event Horizon like a hologram and it's reversible IF you could turn off the black hole. Spooky stuff for sure.
What makes PBS Space Time different from science shows on TV:
- they don't spoon feed the audience
- they are not like "here is some CGI, you're too dumb for the real science anyways"
- they present the historic scientific discourse
- they give you the feeling it's not just stuff weird masterminds came up with and you are never able to compete
This is really an achievement! *Thank you guys!*
Space Timers -- the channel is not closing down! Yes, *I* am leaving, but the show will continue with a new (astrophysicist) host! No one panic. As they say, the show will go on. We announced all this weeks ago in this video: ruclips.net/video/U8Hx-AkFDCY/видео.html
+PBS Space Time Thanks for everything I learn. From Argentina, good luck
PBS Space Time Thank you, Gabe! Good luck at NSF
Thanks a lot, Gabe! I've learned a lot with your videos. I wish you a lot of Success!!
PBS Space Time Thank you so much for what you've done here to date. I consider myself pretty well versed in science concepts in general, but I still get a lot of things wrong, and this channel has helped me to greatly get my facts straight. Thank you so much!
PBS Space Time I just subscribed about two weeks ago, and I am sincerely sad to see you go, Gabe. You really fueled my interest in spatial concepts and the like, and I wish you luck on your endeavors.
4:53
>lets pretend that the sun is a perfect sphere
>displays a bumpy circle
Topologically
Thats not bumpa. I think its the light rays coming out
Haha this was a good one haha
Hands down the best finale to the Spacetime curvature series. The misconceptions refuted helped tremendously. You will be remembered. Cheers
A list of 5 things we know about the inside of black holes:
1. What they look like.
2.
3.
4.
5.
Edit: We got one.
High five 😝😝
Asim Deyaf I don't see a problem with 4. Care to elaborate?
Though 3. looks a bit fishy. Not sure I can believe that.
Asim Deyaf You got a sign wrong
+Asim Deyaf illuminati?
I think I forgot six.
6.
LOL!! Wasn't expecting to see Rainbow Dash and Fluttershy on a PBS Space Time video! But I'm not complaining..
I didn't expect to see you learning about black holes. The universe always has many mysteries for us to solve. Also, nice bumping into you again!
I hear Baasik is doing the soundtrack for their next video.
It was really unexpected XD
+Black Gryph0n Rainbow Dash and Fluttershy caught me off guard
fucking disgusting ponies. that shit ruined the video
This is the worst My Little Pony fanfic I've ever heard.
Then, clearly, you don't spend much time on FIMFiction.
And not even a good fap.
Slappy I may disagree
Twilight disagrees.
Fervidor ...or the best, depending on how you look at it.
Like how on the center of the North Pole every direction is south.
Gee Buttersnaps or on the South Pole only way is north...
If you change direction from N to W it is not 90 degrees. Go due south from N pole, then turn west go west, then turn north go north you end up where you came from.
Bruh I'm high right now and this isn't helping.
@@alexg1778 same
To the equator would be a better analogy
*pause ... checks out Relativity playlist*
Holy shit, you guys mean business.
Same shit happened to me! I was watching this vid and then got "distracted" for 2 entire weeks (I kid you not). I had even forgotten this original place where I started watching all this physics stuff lol
+Ritwik Ghosh It's been three weeks for me and I don't know what's what anymore
Gabe, thank you so much for all of this. It's really hard to access good hardcore physics in vanilla form for us non-mathematical-background people. Thanks again, I wish the best for you and your career!
Ugo
dude...space is crazy
***** k
Space isn't crazy, you're just not a custom to it all
DigitalizedElements what do u mean by that?
I've often wondered about this when they talk about 'merging' black holes.
How can we observe the merger if they become 'frozen' when close to each others event horizon?
Good question!
We don't observe a spatial or time merger, only a gravitational one via gravitational waves. The converging gravitational geodesics interfere, if the black holes are small enough they interfere severely and at a short enough wavelength to be observed with earth-bound interferometers (e.g., LIGO). This just means since we know via G.R .that gravity is a function of spacetime (not a force) that is proportional to spacetime, if we observe a distortion in spacetime we can infer a corresponding spacial-time effect.
TLDR; We don't 'see' blackhole mergers (via traditional EM methods). Two blackholes closely orbit, cause gravitational waves, those waves are detected by a distortion to a laser beam, those distortions can be reverse engineered to determine the origin (two black holes orbiting).
hmm. maybe our universe is a black hole with it's own unique physics that we are experiencing. anyone outside our black hole(universe), won't know we are there.
That is a pretty cool thought
that is exactly what ive thought for years
It's actually going to be a more practical question than you may realize. Remember, black holes aren't necessarily collapsed stars. Any sufficiently large nebulous mass can "shroud" itself in a black hole, since sufficiently distant objects would accelerate to c before they ever hit it. And as we're finding supermassive black holes at the center of galaxies, that may be exactly what we're looking at.
Ronny Biggs are there any renowned physicists that have made or talked about this hypothesis?
Daniel I've looked around, I've heard there is a school that believes you would never actually catch up with an event horizon. But the more I look around, the more I realize how very little even the professionals understand black holes.
If it is true that you can cross an event horizon, it sounds like you hit a "warp boom" much like planes breaking the sonic barrier make a sonic boom.
Oh well I tried... Back to ultimate fails compilation.
hahahajaha
😂😂
It takes some effort, but I think most people are far more capable than they think. they just don't like taking effort...
+1ranjeeves21 Comet Tail is right; I would add that you have to do easy before you can do hard. I would recommend watching Crash Course Astronomy over on the Crash Course channel first. It starts of really easy (to the point that some people complained the early episodes were too simple), and seamless takes you to greater heights. After that you can come back to Space Time, starting with the oldest videos first as there's a lot of continuity.
Haha lol.
You have helped me learn so much. I have been learning physics independently, because I am way far ahead than the people in my school, but my school won't let be take higher classes. This year will be my first year "taking" physics, and it will be a walk on the park.
I've had these misconceptions for years.
I hope there's more videos like this when your gone.
P.S I want to be an astrophysicist.
Just curious but how old are you?
+loose600se 16
Keep it up! Get really good at math!
+Feynstein100 I'm assuring you, you're not alone...
My physics teacher doesn't know what a black hole is, and doesn't know what particle physics even is.
+SciAm14 Lucky me I had a teacher who spent months on particle physics, forces&fields, relativity and the basics of quantum theory. Back in the 1970ies. Then again, Austria used to be a leading country in physics (Schroedinger, Pauli, Boltzmann, currently Zeilinger et al.).
I miss you, Gabe. Your style of presenting---fast-paced, challenging, but rewarding to those who took the time to pause/rewatch the video and think through the concepts you're bringing in---really resonated with me in a way that the newer videos don't quite.
:)
This is exactly the moment when i know when/whom to suscribe and hit the bell icon without the video telling me to.
Many thanks for making this video for me and other laymen like me.
U r aweesomee. Cannot describe it cos its infinite like someone falling inside a black hole :)
You are really doing a wonderful job universally.
Finally, I understood the true meaning of 'event' horizon !! Thank you!
Too bad once you meet the event horizon, there's no going back. ;D
Yeah, but you understand it incorectly.
@@automatonlabs7841 how
@@kx7500 Someone with finite mind explaned infinity? Hahaha
@@automatonlabs7841 damn, thanks for letting me know your input is worthless lol
I've been thinking about what you said about the monkey never crossing the event horizon from the perspective of everyone else... isn't that just a math issue with the Schwarzchild coordinates? If you switch to Eddington-Finkelstein coordinates, the monkey's spacetime path definitely crosses the event horizon. Doesn't that mean we shouldn't be using Schwarzchild coordinates at an event where it fails?
PBS Space Time Also, I'm sorry to see you go. It's been really nice having someone around that gets relativity... but I know you can't be here forever and I wish the best :-)
P.S. Thanks for the in-video comment response.
***** Right. But the 't' in Schwarzschild coordinates has a physical meaning -- it's the ticking of the clock of observers at infinity. We use different coordinates to figure out what's *really* going on, i.e. that the monkey crosses just fine, to figure out the Penrose diagram of the spacetime, etc etc. But it doesn't change the fact that our clocks out here *are* the Schwarzschild t-coordinate, so that the monkey's life past his point of entry into the BH will not be found on *any* constant-Schwarzschild-t spatial hyperslice. On the t-clock, those events aren't simultaneous with any other event that occurs that r > R_s. And all moments in the monkey's life prior to that "crossing event" get "spread out" over an infinite number of "cells" in the movie of the universe that the observer at infinity is recording.
Turns out all of the above remains true if you use coordinates whose spatial coordinates are standard Schwarzschild coords and whose time coordinate is the proper time of an observer at any fixed r > R_s. Everyone experiences infinite time dilation and redshift relative to the horizon. The horizon *is* the infinite time-dilation, infinite redshift surface (at least for Schwarzschild black holes, which is all I was talking about in this vid).
PBS Space Time
Ok, thanks for the clarification. I'm always hesitant to make interpretations when results look "hinky" (for lack of a better word)... but then, I guess, everything in relativity is a bit hinky.
***** A wise approach (that I also try to adopt).
***** Also, to clarify, the monkey's world line enters the black hole region. That is a purely geometric coordinate independent statement. However, certain events on that world line are completely inaccessible to external observers in a specific and peculiar way, namely that those events are shifted to temporal coordinates on our clocks that are somehow _after_ t = \infinity, whatever that means.
"Let's pretend that the sun is a perfect sphere."
* proceeds to display a bumpy, cartoonish image of the sun *
Lolol
This made me realize everything I knew about black holes was flawed. Thank you for this enlightenment.
Hey guys, I'm studying physics. Great video! I hope I can clear up the confusion about mass at 10:04 - 11:05 : You begin to write the equation (called a 'metric') for a black hole by writing down some assumptions about space: the space is spherically symmetric, the space is static, the space is stationary, etc. These assumptions give you a good-looking equation. But there are some terms you just don't know off the top of your head. You know they're there, but you have to solve for them to see them explicitly. That's what you use Einstein's equations to do. Now, Einstein's equations for a black hole end up being first-order non-homogeneous linear differential equations. When you eventually solve them, you get some constant. It could be anything; but all you know is that it's constant in time. We usually label this constant M because (1) when you make it bigger the equations show more curvature, and (2) when you make it smaller they show less curvature, and (3) if it's zero, there's no curvature. So it sort of looks like this free parameter (the constant) is what we have been calling "mass" for hundreds of years! So we label it M. So I hope this clears up the confusion about mass. Summary: basically, you're right, there doesn't have to be any matter in your space-time for you to write down and solve the equations of a black hole (what you're calling in the video an "idealized version" or a "prototypical BH"). But there ends up being this constant in these equations that is some free parameter. You can label it as mass if you want because it turns out that the mass that we measure with telescopes is just is a good way of parameterizing these equations! For these reasons, there's no interpretative issue/mystery in the physics community, and M has no association with the singularity. Keep up the good work! Physics is awesome, -D
+Donald Pierce
I understood every word you said... until I tried to put them all together.
and then nadda. ;-)
too long; don't read
I am confused .. i can understand that according to einstein, mass 'generating gravity' is just space time being curved so an object has to follow that path towards that mass. Why cant we assume black holes as having mass when they do exert newtonian effects on objects near them? Also where and what exactly is 'mass' if its exerting effects on space time? Is it a point like potential for curving space time ? I guess i wont get anywhere unless i had studied maths and physics :(
please! explain the difference of BH singularity & Mass that both cause gravity ?
Did I get this right? You get a constant you don't know what to do with. But because you assume that mass bends spacetime, and the constant does, too, you label this constant M for mass?
... And? Does it make mass being responsible for everything we don't understand about the universe?
This is the most advanced and mind-blowing explanation of the nature of black holes that I've ever seen! I love that the often-considered-unfortunate name "black holes" is quite accurate in a very literal way: that it's actually a hole punched in the universe!
Also, before seeing this video I've watched many other more recent PBS Space Time videos, where Matt repeatedly refers to black holes as objects with mass, spin, etc, and that kind of terminology now feels so primitive to me; it makes me wonder why this epic revelation was left behind in a 6-year-old video!
I thought I was alone (taking the phenomenon literally, as you described); but maybe the Universe wanted it that way (I just saw the video, and then read some comments after already formed my opinion on the facts of the matter)… Nonetheless, since I said it - and there are many, many fake personalities out there, on the Internet, these days - I must add “some insights” and substantiate my claims, to prove the authenticity of my thinking…
First, I just want to be clear: I like the way Matt presents science & facts - in both the substance & the style (it suits my worldview & meets my expectations). Keep up the good work, Matt!
Flick, to try to answer some of the questions you raised, I’ll continue… Scientists, lecturers, science communicators, teachers, professors and alike still talk about BHs as objects with properties you mentioned (mass, charge, spin etc.) because, I think, any of the following is true: *a)* They learned it that way from the standard textbooks, and their life philosophy and/or strategy is “shut up, and calculate”; *b)* They may think differently about certain phenomena, but sometimes the math and/or the ontology of those gets so complicated that people rather “go with the flow” and accept status quo; *c)* Then, there’s this “don’t care” | “not my pay grade” | “I’m (more) concerned about The Economy” etc. approach; *d)* The mass (and other stuff) is the part of the story, and is part of the gravitational system, because real-life BHs do gather/arrange mass of surrounding matter into the accretion disks (and there are, also, quasars, blazars, AGNs etc.); and the whole system could be functionally equated with a massive object at the center; and, finally, *e)* Many (predominantly male) members of the faculty adopt the “tough (Platonic) love” approach to students, or, at least, apply the “get them out of their (cognitive) ‘comfort zone’ (so that they begin to think proactively, hopefully)” coaching doctrine, something akin to perpetual scholastic mind-mini-drills…
That last one (e) - a.k.a. “serving nebulous-but-authoritative, hard-to-digest conjectures” method - is most appalling to me. Although I have been known to (occasionally) “lecture people” - as opposed to “giving (only solicited) lectures” - especially when I have to correct the mess they’ve caused (out of their super-confident ignorance on a subject or out of their sheer sloppiness), it’s also true that I have given the best and all of myself when tutoring others, because I think that’s exactly what a lecturer should do: explain all that is related & known about the phenomenon at the present time, as simply as it could be done, no “curved balls” allowed, except the “interactive ones” that are also demystified right away or throughout the teaching course. You may tease “them” students, you may quiz them and probe their imagination & logic & retention of the material, but at the end of the day - what incremental knowledge have you passed to them? The dogma “Let them (academically) suffer a bit - as we once may have - as others have done to us - and we turned out so righteous” (as if our spirit and academic stamina were produced by the steel-strengthening process whose name I cannot recall at this moment) - is both dishonest and inadequate teaching technique. Instead, being intellectually caring towards your promising protégés & protégées, I assert, is the proper way and more effective in the long run, because it doesn’t result in rogue dissent from academia, the life itself will, by its course, teach those students (and anyone else, for that matter) the real-world “toughness”, and, finally, and most importantly - it is far better to give them advanced head start, the “elastic epistemic impulse” (epistemic trampoline, if you will, or academic “gravity-assist”) by teaching them all we know, in earnest, which could (and most likely would) result in the most efficient & impressive advancements for the society as a whole, carried out by your very own mentor-loving, (still) affectionate, science-protecting apprentices; isn’t that more satisfying? (Yes, it certainly is.) The true & truly altruistic meaning of the phrase “standing on the shoulders of the giants” (that preceded us).
About primitiveness of terminology (and, in extension, some descriptive framework pertinent to the scientific method): Although sometimes we are stuck with one, we should advance those, too…
Maybe, after all, gravity is not what it seems to be? My big bet is that physics is going to be re-vamped soon… For example, I think that the idea of “information” (either physical or quantum) is ill-defined. [I like to think of it through the “‘The Flintstones’ paradigm”.] But only time will tell (I certainly couldn’t, because I have no degree in physics). Stay tuned.
I almost forgot: Are you, by any chance, related to Sir Roger?
This video explains the black hole like no other one. No other video talks about how a black hole is " events " that don't happen from our frame of view. Really interesting and amazing
basically shat on everything I've ever learned about blackholes from watching and reading on the internet
+Crazycow500 That is hilarious and depressing all at the same time.
That's because he's shitting on the reality of black holes.
Quick update: our brief hiatus is coming to a close. Brand new video next Wednesday, 9/23, during which we'll also address some of your really excellent black hole questions. After next week we're back to the regular weekly schedule.
If matter freezes and never enters the black hole, then a percentage of that matter could not be ejected from the poles of the black hole because it would be frozen in time. However some matter is ejected from the poles of a black hole when it consumes objects, so this theory is wrong.
you don't understand it DOES enter but we can never see it enter because the light being emitted by it past the event horizon isn't able to be detected by our eyes and if your wondering cameras cant either because that light is everywhere so you couldn't see a thing if you could see it
if that makes any sense than your welcome :-)
Then what is that stuff about particles entering a black hole having some event on their world lines that becomes the last events in history? What about the talk of occurrences beyond the event horizon not being able to be assigned a "when"?
+mikezeitgeist2 you don't understand the video... if you LISTEN you'll understand it so go back and rewatch the video besides EVERYTHING we know about BH are guesses even this
I would have never been able to get this...without the ponies. :)
Me neither, if he had said "a guy in a red shirt" instead of pony, I'd be totally lost
+agustin venegas certainly an unusual way of dying for a red shirt. But consistent in that he would just collapse without ever having said a single word.
agustin venegas And if he used an apple? I'd know less than i did before.
I'm really glad that ponies are part of scientific discussion now. It makes everything better. :)
One of the best descriptions of black holes I've found yet on RUclips. 👍
Sad you're leaving, really enjoyed the way you explain and interpret these difficult subjects. One of the very top notch educational series on YT.
Best science channel on youtube.
I need Ibuprofen, Aspirin and Tylenol after this video.
And probably a shot.
OTC drugs and alcohol. . You're doing it wrong.
Lou Sensei hey, he didn't specify what kind of shot...
lsd also
I watched and subscribed because THANK YOU!!! This was amazing and I'm glad I had the opportunity to experience this channel with you on your last presentation with the show. This was dope AF!!
This literally changed everything i thought i knew about black holes before thanks so much for a great video!
I'm calling animal services
hee hee!
I like the idea the earth would be a peanut sized black hole 🥜
Yes…comforting lol
Encouraging, even.
I only knew PBS with Matt for some reason, but Gabe was equally awesome!
I feel like many of these so-called misconceptions likely boil down to semantic pedantry. A simpler description can communicate the same idea despite using the "wrong" words.
I know this is an old video, but hopefully someone can help me out here. When he was talking about the collapsing star, and said the infalling matter is infinitely time dilated at the surface, I was wondering if the expansion of the event horizon has any impact on this? It is essentially just a region of spacetime, so it shouldn't be limited in it's expansion by the speed of light, so conceivably, if it grew faster than c, we would indeed see the infalling matter "swallowed up" by it and not frozen on the surface, right?
No, it's not a speed issue. You simply can't see anything pass the event horizon from any outside reference frame. Even if it was expanding faster than light, you wouldn't see it
How about never using a word infinite?
Imagine a black hole as an actual infinitely deep hole that goes at right angles to our three dimensions . Time turns into space, and objects trapped in the event horizon appear frozen to us, but according to their perspective, they are just drifting slowly into a new universe tipped 90 degrees from our own. Since our own universe is enclosed by a event horizon defined by object traveling at the speed of light, we are essentially sitting inside a black hole, and for all we know it is full of stuff that "fell in" from somewhere else. See? It's actually simple.
@@jamesdavison6290 That is incorect for a lot of reasons.
This video just blew my mind. Brilliant. Thank you Gabe and Space Time.
Loved Gabe’s style. He is how I discovered PBS ST, amongst the highest quality YT science channel hands down.
I miss Gabe. Maybe he can do a guest video or guest appearance some time.
(Matt is a fantastic host, too. Porque no los dos?)
*scrolls down comments halfway through the video to see if anyone is as lost as i am*
+Ironjagg Yeah, I'm there with you.
+Ironjagg *scrolls down comments in the middle of the video to see if anyone got really angry that there were a couple of ponies*
+Ironjagg Hahaha
im also lost as a fuckin' blind hamster on the another part of the fuckin' universe
+Ironjagg This is the worst video on black holes I have ever seen, many points are truly incorrect. Watch Neil deGrasse Tyson videos if you are interested in this kind of thing.
Wait, I took years to barely understand that black holes are objects with a lot of mass concentrated in a single point, distorting the space-time so deeply that even light can't escape, that's why it is black.
Now that's actually not right?
Surprises aside I like a lot of Gabe's episodes.
It's not that it's "not right" per se, it's that it doesn't account for the fact that "spacetime" has two components-- space _and_ time. The description you mention here really accounts for the former. The temporal (relating to time) effects of a black hole are far less intuitive and difficult to explain in a short amount of time, so science popularists generally just stick with the more digestible spatial-only description. This is usually some variation of "the pull of gravity is so strong that not even light can escape." You might sometimes hear another version along the lines of "a black hole is black because the escape velocity at the event horizon is the speed of light." This actually isn't totally untrue, but not for the reason you might expect.
If I watch you fall into a black hole, I never see you cross the event horizon. It's not a "vision" issue. It's not that your final photons are just "treading water" at the event horizon or anything like that. It's because, as you approach the event horizon, time starts running slower and slower for you relative to my own. 2:1 (time is passing two times slower for you), then 10:1 (ten times slower), then 10,000:1, etc. As you asymptotically approach the horizon, your time coordinates dilate to ∞ with respect to mine. Not just mine, but _any_ observer does not occupy a reference frame comparable to yours (IE, crossing the event horizon). You might be wondering _why_ time has dilated so egregiously. It all comes down to the fact that _all_ reference frames must agree on the speed of light being constant. Here's the rub, however: In order to perceive the speed of light at its constant rate in a region of spacetime where the the escape velocity _is_ the speed of light, your clock... must run infinitely slow. In other words, time stops at the event horizon relative to the outside universe. This is the _real_ reason why black holes are black. Putting it simply, things at the event horizon cannot emit light because there will never be enough time for them to emit it.
But how does one reconcile this with the fact that, from _your_ reference frame, you cross the event horizon without issue. In fact, nothing even seems to be any different. That's the common narrative, anyway. But it's not really true, is it? There is a _major_ difference between where you just came from (outside the black hole) and where you are now (inside of it): You cannot turn around and go home. The truth is this: What outside observers perceive as time stopping for you, and what _you_ perceive as an inability to turn around and go home, are actually different presentations of the exact same thing. Your experience differs from theirs because, in your own frame of reference, you _must_ continue to experience proper time (one second will always seem like one second). In reality, what you're experiencing is NOT a series of moments inextricably leading toward the future, but rather a series of _spatial translations_ leading inextricably toward the singularity.
You can't turn around and go home because turning around and going home takes time. You're frozen in time, you just don't realize it. Without any framework of time, there can be no turning around. If you can't turn around, you can never go home. This is what a black hole _really_ is.
@@sasca854 Thanks for this comment, I like your writing syle.
Perhaps we all need reminding that, from the point of view of an outside observer, the core of the star that forms a black hole never collapses into a point of "infinite density". Once it reaches the event horizon of the new black hole, time dilation means that that matter has no future world line. From our reference frame, it just stops as it is slowly redshifted beyond detectability.
It's also worth remembering that mass is simply another form of energy. After all, in Einstein's field equations, it's energy that causes spacetime curvature. We use the word mass as a convenient placeholder, because for all other astronomical objects, it is almost entirely their mass that causes the spacetime curvature that we observe as gravity.
Ponies make physics more understandable. Does this mean we'll see Twilight Sparkle demonstrate quantum teleportation?
That would be great to see
Zomg yass!!!
ponies make everything better :3
They should send a probe with an entangled particle into the billion solar mass black hole in the center of the milky way.
. . . pretty certain i did that last week. That's shrooms for ya!
An entangled particle cannot transfer any information, so that won't do anything for you. Otherwise, we would already have faster than light communication.
Alex Black That may be difficult without an Omega 4 relay.
Alex Black by the time it reaches the black hole, the human civilization will most likely be extinct
darn details
General relativity: *exists*
Quantum physics: "am I a joke you?"
This video: * exists *
Quantum Mechanics: Let me in, *LET ME IIIIIIINNNNN!!!!*
This is a really good comment!
@A Frustrated Gamer Great, just imagine quantum computers trying to store a 0 or 1 ... due to uncertainty it may be a 0 maybe a 1 or maybe in between. Just imagine an app running with that uncertain code, could be a huge mess. lol
Amazing episode challenging the classic bs of black holes being 'dangerous' or 'sucking stuff in from afar' as well as them being big black spheres that cannot be detected apart from their gravitational pull on the matter surrounding them - someone should do a longer episode on black holes with this POV and with more elaborate visualisations (and pretty accretion discs :3 ) - props for ponies though, and as a European: THANK YOU for pronouncing it schwartzSCHILD instead of schwartz-CHILD!
0:50 Clicked on 'Curved Spacetime'.
That video: This video is based on 4 other videos.
😒😒😒
Well, it's not a simple concept you can understand in one or two videos. There's a lot of stuff to be explained and everything is very complex that it's preferable for a keen learner to take one step at a time
Welcome to physics xD
Pranav Soni which are based on 300 other videos
There is a singularity at which all PBS spacetime videos converge into one point of infinite knowledge. If you miss it, you, like me, are doomed to wander an intellectual maze of self-reference eternally.
Gonna miss you, Gabe. Good luck in the new spacetimes you venture towards :D
so basically, black holes are an error in reality.
Yal Rathol Probably more like a tear or scratch in reality. But "error" is an interesting way of describing it. I guess nothing, even the universe, is perfect.
gwar scout74 i've taken to using "error" when describing things like that ever since i heard that one description of vantablack as looking "like a graphical error in real life". and honestly, it's not wrong. vantablack looks like the graphics haven't loaded into reality and you're seeing the void beneath.
Yal Rathol tricky stuff for sure. 99.83 whatever percent of light absorbed. didnt know of it till you mentioned it. So thanks. my source described it as being 2D in a 3D world, if that makes sence. Also it mentioned military applications, no surprise.
gwar scout74 not surprising, though you should be careful with it. it doesn't go on easy, and it eats heat like i eat chips.
also, vantablack II absorbs even more light, i think it's 99.95% and it doesn't have to be cooked into the object as hard.
***** no, ghosts are bugs and glitches and all the people who can see them are players, everyone else is an NPC. after all, NPC's don't react to the glitches, do they?
It is most sad to hear you are leaving. Please enjoy your new endeavors and I hope you find much success. (Apologies for my poor writing. I am Japanese and still learning English) .
Enough misconceptions!
Just tell me that everything i was ever told was a lie already!
Etuate Lafferte well lies can help us out in our daily life science so chill out
Pratik Gore I was only joking because he said "Misconception" like 50 times!
he exposes a deeper and more self-coherent perspective that is much closer to the actual mathematics of the general realtivity and honestly it's refreshing because other sources tend to oversimplify a lot and there are lots of them
try lsd
"To outside observers, most of the inital stars matter never crosses the horizon". I always asked myself how many and why.. Is it due to the growing horizon and shrinking of the stars like the animation suggests?
im pretty late to say anything and im not quite sure if I understood it very well, but based on my understanding you can never witness anything crossing the horizon because the closer you get to the blackhole, the slower timescale you're on, so for example like he said if youre 10 feet away from it and im 20 feet away from it, you'll look like you're moving in slowmotion because we aren't on the same timescale, but to you it seems like nothings changed since you are living in that timescale currently. Once you get near to cross the event horizon I believe your time is practically broken, and to all others your time progresses so slowly, or not at all, that we never see anything beyond that point, but since that is the timescale you live in, it's as if nothings different
The slower timescale means gravitational redshift of light extending its wavelength, the closer object is to black hole, the more it happens. So light redshifted enough would be outside of visible spectrum and as such we'd never observe object actually crossing event horizon - instead we will see fading into invisibility as reflected light gets more and more shifted out of visible spectrum.
Yeah likewise, I could 'understand' if they meant that you could never 'see' anything reach the singularity as at infinite density time is supposed to stop. However, he says that the significance of the event horizon is that from inside all directions point towards the singulariry but that the blackhole itself isnt infinitely dense. Also if the monkey appeared to stop at the event horizon wouldnt that mean that from the monkeys point of view the entire future of universe would happen before it ever crossed the event horizon?
Also if things freeze at the event horizon how do they gain any extra mass?
I watch many videos on blackholes and relativity and there is never an answer that resolves the seemingly unresolvable paradoxes. Im not sure how in depth you actually have to study these things before they can appear at all possible, but theres an event horizon of understanding that I just cant see passed.
You are right. I have made a reply for this video that contains actually the answer for that.
I just copy it to here for you:
One additional misconception about black holes that it takes infinity time for outside observer until a falling object cross the event horizon.
The reality is that when material close very much to event horizon, the event horizon will grow and incorporate the falling material. (Mathematics: The mass becomes bigger very near the Schwarzschild radius due to additional material -> now the Schwarzschild radius become larger calculating with the additional mass -> black hole horizon is increasing -> material will be inside the black hole).
So, the ponies will not see that monkey freezing close to the event horizon. They will see that as the monkey becoming very close to black hole, the event horizon is growing and the monkey is inside the bigger black hole.
So, the event of monkey crossing of event horizon does happen in finite time for all outside observers (not just for the monkey).
If it took infinite time, supermassive black holes would not exist.
So finally as you have written: the horizon is growing, the collapsing start material is shrinking and after a finite time (from outside observer) the horizon become bigger than the collapsing star.
After that when additional material (e.g. gas from other stars) become very close the black hole due to gravitation of black hole, the even horizon of black hole grows and incorporates some additional gas, material, etc.
So black holes just grows and grows and grows. (The Hawking evaporation is so small than it is totally negligible. And it will be negligible for several billions of years from now until CMB becomes colder than the Hawking temperature of black hole which is very-very tiny.)
This is the first episode that I've managed to fully understand.
This is the single best episode of spacetime. It was immesurably formative for me.
Isn't it true that the "infinitely redshifted" photos of light emitted beyond the event horizon never reach us? That they always stay within the event horizon? Really splitting hairs to say that the idea that they cannot leave the black hole isn't true, it appears patently true by the above description.
The photons that get redshifted into oblivion are the photons that leave the monkey *right before* or very near the event horizon. The photons which originate from within the horizon stay in the horizon, as there is no such thing as radially outward once inside.
but isn't energy quantized? as in, finite at the most discrete levels possible, an infinitely redshifted photon means an infinitely small quanta of energy
even if such a thing can't reach us, in theory quantum mechanics is predicted to be false
quantum mechanics is too right to be not right even in theoretical circumstances or maybe not, it's either no such thing as "infinitely redshifted" photons happen, or something is missing
@@BlackTakGolD That is true. What he means is this small quanta is so small that nothing will detect it.
How are there any black holes at all, if nothing can ever cross their event horizon from an outside reference frame?
Wouldn't we observe the moment of their creation " frozen" at the event horizon?
That's the magic of physics
So this would imply that if Hawking radiation destroys the black hole in a finite amount of time (from the perspective of a distant observer), then the monkey will be released from the black hole before it fell into it (from the perspective of a distant observer, because it takes an infinite amount of time to reach the horizon). So if there is no contradiction, the money will see the black hole evaporate before falling in.
cherubin7th, we will need to wait trillions of trillions of years for black holes to evaporate to find out...
There is an interpretation that Hawking radiation is the stuff that had been falling into the blackhole for all these billions of years, after being chewed by spaghettification, or maybe that firewall idea, or something of the sort. But I'm not sure how well accepted that interpretation is by mainstream science.
Wait so if time stretches to infinity for the inside observer, they would theoretically have to experience the event of the black hole evaporating since blackholes aren't infinite
LOL "the money will see the black hole evaporate before falling in". I suspect in reality "The money" will probably evaporate long before one gets to reach Earth's orbit, never mind the Event Horizon xD)))
And then boom, time travel
Watch a ‘Stargate’ episode where a military base underground is effected by the gravity waves of a black hole and it really does a fairly easy to understand demonstration on time and its relativity while using many of the same terms time dilation, distortion, gravity waves etc... (also happen to be a great and scary episode due to its implications)
The world outside the base experience time as normal as in two weeks go buy, but for staff inside the base its only been 10 minutes while vice versa where time running normally for them every second, but outside the base time is just racing ahead.
This is fucking amazing.
I know, right?
+IDo Things Well, excuse me for spelling out the whole phrase.
so Black Holes are like the Trash Bin on windows microsoft that absorbs every file on your desktop even if you don't delete it?
Funny you mention that. There's a video floating around regarding the data going into a blackhole being like emptying the trash bin on your computer.
Commie Trump is like a black hole to all the puny IQ points of the Deplorables orbiting around him
@@billbelzek6748 What a fucking random comment. Did CNN lose track of one of their bots?
Bill Belzek nobody said people with high iq have much common sense. They usually don’t. They spend more time reading about reality than living it. Maybe that’s why Trump is so successful at his job.
you ever used the Windows's Trash? How did you do exactly?
Gabe was such an awesome host
Matt is good too.
NPC #102117 who gives a duck if hes gay
NPC #102117 wtf?
@@nacirmohay162 Matt has already made up his mind about a lot of stuff to which we don't know the answer.
wrg
What a way to leave this show. This is the episode that can't get out of my head. Wish you'd be back... you're an amazing host.
This video is really mind-blowing! I keep wondering how black holes grew in the past. Common thought tells us that they grew absorbing matter and even other black holes. Gravitational detectors have recently saw proof of this. But, if nothing can't pass through the event horizon because that will take an infinite amount of time, then black holes won't be able to grow in that way at least not during a finite amount of time...Something is missing here. If anyone can help I would appreciate it!
Objects only slow down on the outside of a black hole from the point of view of an external observer, they still cross the event horizon (and so the black hole still gains mass).
Wow, I had thought I was fairly intelligent until Gabe gave this presentation. I am going to have to watch this presentation several times to get a better grasp on the concepts. Best wishes Gabe on whatever you pursue.
Yes, but in a universe where we have two dimensions of time. An interaction is an event, so the interactions that occur inside the black holes are events. With a second dimension of time, everything that has ever happened, is happening, and will have happened. So if a single interaction is occurring inside of the black hole, then an event has happened.
And since the black hole clearly is being held together by interactions inside of the black hole due to gravity, then the forces keeping it together come from interactions within the black hole, and not outside of it.
No the gravity come from the curved spacetime cause by the flattened matters around the black hole that to us never actual enter the black hole and that why its mass have relation with its surface not volumes.
U should look into black hole entropy and holographic universe.
I was habit to Noah but this is one of the most... clarifying and so new, to me, video on these subjects and their common oversimpification. And yet Noah had habit us to a different point of view about many of these universe's curiosities.
I loved it!
8:50 sorry but how did he get the density of water?
the black hole in the center of our galaxy is 8.57*10^36 (kg) and has a radius of 1.27*10^10 (m)
this means that the density should be a lot bigger then that of water? or maybe my sources were wrong?
+marco polo Oops! You're totally right. Thanks for catching this. It's the black hole in the center of Andromeda (~200 million solar masses) that's about as dense as water. The Milky Way's central black is about 1000 times denser than water. See that, kids? Always double check your arithmetic as an extra layer of fact-checking. Don't repeat my boo-boos!
PBS Space Time Wow you actually replied :p
+marco polo I mean, of course. You caught a really important error!
Since we see objects that cross the event horizon just "freeze", how can we even "see" the blackhole. Wouldn't you just see the star in a frozen state before its outer layer was inside the event horizon?
Rodney Smith Hmmm interesting
We dont actually see anything because of the red shifting. But in theory it's there (at least the information). Freezing thing is a way to visualize the physics. Obviously the actual effects are more complex on human scale objects.
We dont actually see anything because of the red shifting. But in theory it's there (at least the information). Freezing thing is a way to visualize the physics. Obviously the actual effects are more complex on human scale objects.
This guy is amazing! This episode is amazing!
Misconceptions debunking was great. I can imagine more clearly now. Thank you
Damn you Gabe for making us fall in love with you only to have you throw us away!😥
Goodbye gabe! A moment of silence for the wonderful host.
Damn bro Im gonna miss you on PBS spacetime. I love you 3000
this video was published in 2015, but the black hole of youtube didn't let its light escape until hulk snapped it back into existence
If an object freezes at the event horizon from our frame of reference, but in actuality mass is falling into the black hole and enlarging it, doesn’t the event horizon expand and thus “swallow” the object and make it disappear?
As something asymptotically approaches a black hole, the ticking of its clock slows to the point where it takes an infinite amount of time between the last moment and the next. It stops emitting photons all together because it literally no longer has enough time to emit even a single one more. This happens very quickly, so even if the event horizon grows, you wouldn't be able to visually "see" whatever it was that you were trying to watch because it would've long since disappeared. That said, you could wear some AR goggles that calculate the object's spatial coordinates and interpolate an image of it at that location so you could "see" it, and it would always remain at the edge of the event horizon-- even if the event horizon got larger. Conversely, if the event horizon were to shrink due to hawking radiation, your infalling object would _still_ forever remain at the edge of the event horizon. Right up until the black hole blinks out of existence.
best explanation of event horizon.
Still a great video, though I have to take issue with one thing this guy says here: The escape velocity at the event horizon is the speed of light NOT by coincidence - it is in fact exactly the same as saying there is no direction out beyond the event horizon. Let me explain:
Photons have no mass and so they travel at the speed of causality (as do gravity waves).
The speed of causality is the fastest that cause and effect can travel through space.
At the event horizon, spacetime is so curved that no cause and effect can travel fast enough to have an effect on anything outside this area. In other words, all possible futures head in the direction of the centre of the black hole. There is no direction out. Just as no cause and effect can propagate faster than light (the speed of causality). Black holes basically swallow the future.
Best video about black holes I have ever seen!! Well done!!
falco447 really?
I'm disappointed you didn't discuss the "surface of last influence". I learned of it in _Gravitation_ by Misner, Thorne, and Wheeler. I was very confused by your spiel about that black hole's mass. I thought that was one of the three properties of black holes: mass, angular momentum or spin, and charge.
I'm 34. I think it's the first time I "ask" someone to explain me something and I don't understand him yet I feel like thanking him for leaving me more confused than I was. So yes, I'm guessing I thank you for these series of videos.
Makes you wonder if the whole universe is inside a black hole with a finite radius, but we're experiencing it to be so limitless because we're inside of it.
Edge of the Visible universe is an Event Horizon.
Yes.
Using pony and monkey doesn't make it easier for me :V LOL
First video I see from this channel and already my mind is blown to the point where I need a moment(maybe more) to process it. Gonna go listen to music while I do. Music makes things better.
i wish gabe would comeback, i like matt but gabe is so much easier to understand
Man, I feel the exact opposite. Plus Matt's Australian accent and slower speaking style are much more pleasant to listen to.
both great
This is great, it makes me sad that on CNN right now, they refer to black holes as a vacuum. Hope you come back or do interviews for the news
Best video on black holes on youtube. I could have watched for an hour. Cheers
magrathean0 really?
Gabe, You really have a fun way to explain complex stuffs. It must have been sad for the followers to see you leaving. Best of luck
Not true. They actually red shift and slowly disappear. If an infinite amount of time passed they would have eventually disappeared entirely from red shift to non existence. They would NOT appear to still be there for ever to your perspective what so ever.
Yeah, their image would become redder and redder and slowly disappear. If you could detect infinitely long wavelengths, you could infinitely see their image become "redshifted" - but we cant, so their image will just disappear - at least in my understanding.
I got lost when he said "infinite amount of time".
whos watching this in 2019 at 3am
Does 2:48 am count?
Does 2:59 count?
Does 6:16 am count?
No none of those other times count. His question was very precise you butt pirates.
@ are you the british ass police?
Excellent video. I sometimes ask the question "Do black holes exist?" Sometimes it's as if I asked if the earth is flat. Like there is a consensus among physicists that they do indeed exist. After all, there is overwhelming evidence and the model is well understood. But to answer "yes" maybe is to dumb down the question to the level the public can understand. Infinitely distorted spacetime is difficult to grasp. To be clear, I don't dispute the evidence or any part of the physical model. My only issue is with the precise use of the word "exist".
I'll be more precise: Do black holes exist /now/ ? Where "now" means "simultaneous with my current moment according to my reference frame". There are no events inside the event horizon that are "now". Furthermore, the collapse of the star to within the Schwartzchild radius is not simultaneous with any event in my past light cone, so the formation of the black hole hasn't happened yet.
Of course this doesn't help the monkey at all. Anyone flying into a black hole will experience it as such, exactly as any physicist would predict.
I'm sure I'll get replies from people who don't get what I'm saying. I'm more interested in knowing if I got it wrong mathematically. Specifically, in the reference frame of an external observer, is it correct to say that the interior of a black hole is in the present? And is it correct to say that the formation of the black hole (collapse to Rs) happened in the past?
Here’s the thing. Infinity practically can’t exist, and when we mention something become “infinite” it means that it’s approaching an impossibility. Meaning it really ends up approaching 0.