Inside a Black Hole: From the Event Horizon to the Singularity
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- Опубліковано 30 тра 2024
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REFERENCES
Time travel via BH: • How Time Travel is Pos...
Inside a BH: • What would we see if w...
BBC Article: tinyurl.com/22mjo8h2
Space.com article: tinyurl.com/rl6mau2
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CHAPTERS
0:00 What is a Black Hole?
2:10 Best way learn a Foreign Language
3:33 Are Black Holes dense and black inside?
5:48 Light cone explanation
9:52 Spaghettification and time dilation problem
13:41 View from inside the black hole
16:56 What happens at the singularity?
17:39 Could you go back in time in a black hole?
SUMMARY
Most black holes are formed when a massive star at least 30 times the mass of our sun runs out of fuel. It then collapses uncontrolled against all other forces of nature into a theoretically infinitesimally small volume. This region of infinitesimal spacetime is called a singularity. The spherical volume of space around this singularity is what we call a Black Hole. The radius of this region was first described by German physicist Karl Schwarzschild.
The edge of this radius is called the event horizon. It is the point beyond which nothing can escape, not even light. Unlike the singularity at its center, General relativity does describe what happens inside this region beyond the event horizon.
Presuming the mass is concentrated in a tiny volume inside, what we would have between this singularity and the edge of the black hole, is mostly empty space. It may contain things that have fallen through, but if the black hole is not very active, that is, if things are not falling into it, then there would be just empty space inside.
But this empty space would not be anything like the empty space that astronauts see far away from earth. First you wouldn’t see all black on the inside. It would be lit up from all the light that’s falling into it. And everything would be falling towards the singularity. And this singularity would appear to be located in all directions. No matter which way you moved, you would be moving towards it. There would be no other path.
Let’s now follow this astronaut all the way from his spaceship far away from the black hole to the black hole and then to the inside of the black hole, and on to the singularity. Even though time would appear to stop at the event horizon from a perspective far away from the black hole, from the Astronaut’s perspective, time would tick normally and He would simply just go right on through to the inside.
If he were to look back towards you, he wouldn’t see any visible light because most of the light near the event horizon would be so highly blue shifted that it would be in the x-ray part of the light spectrum. Infrared light and the cosmic microwave background light however would now be in the visible spectrum, so the astronaut might see these.
Also the light from all around the black hole may be visible to him, since the severe gravitational well would bend light from all around the black hole. But it would be distorted. What about spaghettification? Ironically, the more massive a black hole is, the less dangerous it is from the perspective of its gravity ripping your body apart.
This is because while gravity grows linearly with mass, it decreases with the square of the distance. Since making a black hole bigger means making its event horizon further away from the singularity where all the mass of the black hole is contained, the net effect is that the gravitational field at the surface goes down. As a consequence, for a sufficiently massive black hole, its surface gravity at the event horizon can be as small as it is on earth.
Now, the astronaut has made it inside the event horizon, what does he see now?
#blackhole
#singularity
The singularity, if it exists, would be felt in every direction. No matter which way the astronaut would try to move, he would still be moving towards the singularity. The true nature of the singularity is still a mystery. It is not clear that it would be a physical place inside.
But what would the astronaut actually see after he went inside? Assuming he is not moving at the speed of light,
he would be able to see the light that entered the black hole behind him. He would still see the outside world from inside the black hole. But this light would be a beam of light that would get smaller and smaller as he continued his journey. It would be a beam because only the light directly behind him could reach him. The light from the sides would be headed towards the singularity, so it would not travel sideways for him to be able to view it.
In front he would see total darkness because no light would be able to move backward toward him. So as he approached the singularity, his world would steadily darken until he gets the last glimpse of light from behind, and he smashes into the unknown physics of the singularity. - Наука та технологія
Ten thousand videos online about "what would happen if somebody fell inside a black hole" all say the exact same thing,
but YOU PRESENT ENTIRELY NEW MATERIAL THAT ABSOLUTELY NONE OF THOSE OTHER VIDEOS DO! Thank you!
Brilliance is the ability to fully explain the seemingly unexplainable; Arvin does this in spectacular fashion. Nice trip!
Inexplicable.
My thoery--Black holes aren't holes at all. They are black spheres made of pure dark matter.
Yes, he is the best
I think we call this "imaginative".
As in, having an active "imagination" 😏
Amen!
Oh yes! This is the episode I had been waiting for, I have heard talks about what happens inside a black hole from Neil De Grasse Tyson, Sean Carroll, Brian Greene and Janna Levin but I know for sure Arvin Ash would answer all of my questions on this topic.
Yeah, he is the best. So many concepts are explained so well and easily.
Niel Degrasse Tyson is a hack who's full of more hot air than a balloon.
Also check out Dialect and PBS.
@@creativesource3514i forgot about dialect! Thank you!
@@tomorowsnobodys Dialect is really interesting because he goes out of his way to challenge the UA-cam physics community quite bluntly!😂 But his stuff is really good too. I always wonder who he is as he does not say.
I've been watching your channel for years and this is the first time I think I fully understood such a complicated topic all the way through the video. Very well done.
Great to hear!
@@ArvinAsh- Hi there! Re. only seeing a narrow beam of light from the direction you fell from when you're inside the event horizon... wouldn't you also see light from a vast region around your direction of origin that hit the blackholes at an angle and got bent into your trajectory? This might represent light that was emitted further back in time than your origin light for similar distances maybe, so you might see a weird hyperbolic panoramic view in all directions that includes a time gradient as you look away from the direction of origin
What a wonderful video, Professor.
Your research, script, presentation and animated graphics were fantastic! (As always)
Thank you so much 😊
This has got to be your best video yet!!! Absolutely well done and easy to understand and follow along! I've always wondered what it would look like falling into the singularity, now I know! Fantastic job to you and the rest of the staff
It's bizzare to imagine the scenario where everywhere (left, right, up, down) you look there is the singularity even though technically it is a core of a "sphere" and only along one direction
But that's how we are now with time. Every second that passes, is one second in the "forward direction". There is no going back in time, or sideways, etc. (yes, I am aware of time dilation, but that is still going only forward, just at different rates relative to other observers, still no going backwards or sideways).
@@destructionman1 true, but that's a temporal direction... The commenter is saying that the spatial directions will all look the same. No matter how much GR says that space and time are equivalent, they aren't experienced that way by humans... We absolutely experience time and space differently. So it is wild that you'd always be seeing the center
Just wanted to thank you, Arvin, for content that always intriguing and fascinating. Well done.
Kudos to Arvin for pointing that the unphysical nature of the swapping of the time and space (radial coordinate only) in Schwarzschild coordinates. Nicely done.
Timestamp? What’s unphysical about it?
@@DrDeuteron It's unphysical because it doesn't exist. There is nothing that happens upon crossing the horizon and all world-lines are necessarily future-directed. The space/time switching nonsense comes about from Schwarzschild-Droste coordinates which is an exterior solution. In any other coordinate system there isn't any switch. Curious, what do you even think gets switched in Schwarzschild-Droste?
@@kylelochlann5053 the signs of g_tt and g_rr, which means future light ones point to smaller radii. My understanding is that shwarzschild is exterior to spherically symmetric mass, exactly by Beckensteins theorem, so the horizon isn’t a problem. If it were, why go to other coordinates to removed the coordinate singularity?
I always learn something from your videos, and I've been interested in physics for decades. It makes sense that the gravitational pull is weaker the larger the Schwarzchild radius.. I had never even considered this. All the pop-science videos would have you believe spaghettification were inevitable instantly at the event horizon.
Actually, with solar mass bh’s, it’s extremely likely that spaghettification would occur well before the eh as the gradient in the strength of gravity approaching the bh is SO extreme with smaller bh’s.
@@aaronperelmuter8433 the gradient at the horizon for a solar mass is like getting strapped to a gurney and spinning a million RPMs. Your head an feet are coming apart.
There is an online black hole calculator by Viktor Toth that lets you put in any quantity, such as mass, and it tells your the radius, acceleration of gravity, tidal force, Hawking temperature, how long you have to live after falling through the horizon, and how long the black hole has left before it goes poof! due to Hawking radiation. It's great fun to play with. Try putting in one kilogram, or a radius of one meter, or set the tidal at the surface to be one G per meter.
ur channel brought me through my covid infection, i had fever dreams while sleeping listeing to ur videos. almost transendential. love u man. and as always. and never ending. its coming up. RIGHT NOW.
Exceptionally accurate and clear, clearing up some of those maybe fun but incorrect sci-fi myths. Perfect! 👏👏👏
Great show. The tilted light cone was a really cool way of looking at it. I have a simple question with (to me) far out implications. If we were to observe the astronaut approaching a black hole, I'd assume that as the red shift increased it would to continue to the infra red, and on out into long radio waves. But would it ever stop wiggling entirely? If not, it seems to me to imply that the astronaut (in our reference frame) never quite reaches the event horizon, from which it would follow that in our frame of reference, nothing not there before its formation has ever pierced the event horizon of a black hole.
funny thing is that the black hole itself is that. It is the collapsed star falling towards the singularity, hence, a frozen star
You are correct. The interior of a bh is in our infinite future. I studies these thing under Kip Thorne, and my conclusion is that curved space is hard to grasp, but doable, and curved time is a major mind fuxk. But your comment is spot on.
If I understand your question correctly, yes you are generally right -- every object a black hole has ever absorbed, would to our perspective still be absorbing it and we would still see photons being emitted from the object, albeit rarely. So e.g. say a black hole absorbed an object that emits 1 photon per second (relative to the object itself), we may still see that object, but it (relative to us) is emitting 1 photon every 10 seconds, and that photon is red-shifted (lower energy to us than the energy it had as seen from the object itself). Something like that.
It is hypothesized that we can in principle see a few photons from very very long ago this way. So say a black hole forms 1 second after the big bang and absorbs something then - we can, in principle, see this object (albeit dimmer and red-shifted, as described). Imagine seeing an image of a dinosaur on the rim of a black hole in the milky way? Obviously not gonna happen, but physics does allow it. Mind boggling stuff.
And although we don't actually see the objects that a black hole absorb get absorbed, we can observe the black hole increase in mass (and electrical charge, and change its angular momentum, etc.) and therefore increase in radius.
Needless to say, this universe is fascinating :)
@@DrDeuteron Thanks Dr. Deuteron! So we hear from time to time of black holes merging. But in our reference frame (RF) they will never pierce one another's event horizon, since nothing would ever enter a black hole in our RF. So black holes cannot merge from the point of view of anyone outside. They just circle, I'd assume faster and faster until the relativistic effects take over, then slower and slower. In the end I suppose that by gravitational lensing you'd conclude that in our RF the two black holes were next to each other forever. Is that what we "see"?
@@DrDeuteron Also. I just thought about another cool implication that would seem to be a logical consequence: Take any black hole. In a very long time, we are told, it will disburse its mass through Hawking Radiation until it reappears, I suppose as a Neutron Star. But then for anyone falling in to a black hole, as soon as they reach the event horizon, an infinite amount of time will have passed in our RF, so the Hawking radiation and reappearance of a star will occur before they fall into the black hole. Hence no one, even in their own RF could ever get beyond the event horizon. I know it doesn't sound right, but it seems to me a consequence. I wonder where my error is. Maybe along the lines of the relativity of simultaneity though I'm not sure how.
What about the edge case of a neutron star just shy of being a black hole? What if I add just one gram of matter to it? Would the inside morph into a singularity instantly?
This is a great question that I have also pondered. I imagine there will be "nucleation sites" where microscopic black holes (probably the size of the Planck distance) form and then grow and merge with others. How fast this happens will depend on how quickly all the particles falling into these black holes can shed their momentum, remember they have to somehow go from their current momentum to zero at the singularity. Conservation of momentum says that this energy cannot just disappear, so it has to be radiated as light, gravitational waves etc. and transfer to other particles that will escape the overall gravity well at very high speed probably. This is what I can never understand about these animations: What happens to the momentum of the infalling astronaut?
@@ebenolivier2762 >Conservation of momentum says that this energy cannot just disappear
Nigga please, redshifted photons lose their energy to nothingness
@@ebenolivier2762 It is simpler than that, the momentum is just energy so once it is inside the growing event horizon (imagine some matter falling towards the centre of the neutron star, 'nucleating' a single black hole near the centre and then pulling the rest of the neutron star towards that central black hole) it will just become part of the black hole mass. Probably all of that will happen in a microsecond.
Penrose drew a diagram of core collapse in his famous paper. The horizon forms at a mid radius, before the singularity, and as matter crosses it, it grows to the final radius.
Regarding the mass limits, the neutron star runs out of degeneracy pressure before it’s a blackhole, so it starts to collapse before there is a horizon. The radius at the limit is around 12 km, and the final horizon is around 7.5 km…so there is a no man’s land.
Not sure how fast the collapse is, tho. All I heard was less than second
Lots of uncertainty in the equation of state of nuclear matter….unlike white dwarfs, where we pretty much know how electrons behave.
@@tonywells6990Yes, but if the energy becomes part of the BH mass it is forever cut off from the rest of the universe since nothing can escape a BH. This will violate conservation of energy/mass won't it?
Arvin. I have so enjoyed this video chapter. I leaned something here. Thank you Mr Incredible. You're keeping us informed.
Always awesomely explained 🙂
Thanks Arvin! Titling the light cone was a very effective graphic. And I like the casual dropping of a “BS” in there. I like when education channels (Dr Becky does it too) are reflective of their audience and common parlance used today. Makes things more casual and relatable. Society is changing
Yeah that caught me off guard in the most pleasant way.
Hi. This was amazing!! Never ever found out anything clearer and better explained ❤❤❤❤ thank you so much ❤❤❤❤
Thank you! The widespread saying of space and time switching inside a black hole never made sense to me. It always feels more like space gains some time-like property as in it becomes directional towards the singularity. Good to have this verified by your video!
Just awesome Arvin loved it … please bring up more !!
What a wonderful movie! Thanks a lot ❤Arvin Ash 1:17 ... and time from our perspective far away from the black hole appears to come to a complete stop here at the event horizon. But this region within the black hole unlike the singularity at its center is not completely mysterious. General relativity does describe what happens inside it. And what happens inside is some of the weirdest stuff that you might not even be able to imagine. It's a region where space and time behave in bizarre ways and our intuitions about reality are challenged. We are going to take a journey that we could never take in real life, and survive to tell it. We are going to go inside a black hole and describe both graphically and visually what would happen and what we would see. 1:54 ... 4:46 But presuming the mass is concentrated in a tiny volume inside what we would have between this singularity and the edge of the black hole, also called its event horizon, is mostly empty space. It may contain things that have fallen through, but if the black hole is not very active, that is, if thing are not falling into it, then there would be just empty space inside. But this empty space would not be anything like the empty space that astronauts see far away from from earth. 5:14 it would have some bizarre properties. First while black holes are black when we look at them from the outsie, you wouldn't see all balck on the inside. It would be lit up from all the light that's falling into it. And everything would be falling towards the singularity. And this singularity would appear to be locate in all directions. No matter which way you moved, you would be moving towards it. There would be no other path. 5:38 ... This might not seem intuitive, but it starts to make sense when you dive into the physics of it. And the pphysics says that space and time would get twistd. What does this mean? To better understand what happens to space and time inside a black hole, let's start by briefly reviewing hw we describe movement in spacetime graphically. 5:55 ... 8:38 ... This tilting becomes more pronounced as the gravity of the object increases. And in the presence of a black hole, the gravity is so pronounced that the light cone continues to tilt until at the edge of the event horizon, it tilts a complete 45% towards it. This means that no object including photons have anyworld lines away from the black hole. Everything falls insider once it 9:18 ... enters the event horizon. There is no turning back at this point. It's a point of no return. ... 9:55 at this point you might say wait a minute this is all bullshit becaue the astronaut could never be inside a black hole it would either take forever, because time stops at the event horizon, or he would be pulled apart, that is , spaghettified on his way due to the high gravitational pull. Thiese are legitimate objects. But let me address how the issues of time dilation and spaghettification can be overcome. 10:16 Regarding time dilation, you may have heard that time slows down in a gravitational field. This is correct. And you may have heard that time comes to complete stop at the event horizon. 🕕This is not quite correct. 🕕If you are observing the astronaut falling in the black hole from somewhere far away, it would appear to you that he never enters the black hole, even if you watched him for eternity. This is because his photons can never reach you from the edge of the event horizon because all photons at the edge can only go inside. The gravitational well is so strong there that any photons there cannot escape to the outside. So the last photons you will see are highly redshited photons from just above the event horizon. You will never actually see him go insde. But from the Astronaut's perspective, 🕧time would tick normally as he fell into the black hole 🕜and he would simply just go right on through to the inside. This is just something that you can never observe from far away. If he were to look back towards you, well he wouldn't actaully see any visible light because most of the light near the event horizon would be so highly blue shifted that it would be in the x-ray part of the light spectrum, so he could not really see this light with his eyes. Infrared light and teh cosmic microwave background light now would be in the visible spectrum so the astronaut might see these. 11:37 ... 13:38 ... now the astronaut has made it inside the event horizon, what does he see now? First let's look at what happens to our light cone inside. We know that it was 45 degree 【 C = light speed, the first universal speed limit. 】 at the edge of the event horizon 【No 3d object exists there: 3d(3τ)||(t3)δ3 ---> 2d(2τ)1δ(1t)||(τ1)d1(τ2)δ2 , e.g. an electron (up-spin) plunges into Dirac sea, merging with its quantum field in the form of the equivalent energy. 】. As you might imagine it continues to tilt more and more al the way to the singularity. It goes from 45 degrees at the event horizon, all the way to 90 degrees at the singularity. Some characterize this 90 degree 【 D = dark speed, the second universal speed limit i.e. the maximum rate of spacetime expansion in the second inflationary epoch. 】 shift as a "switching" of place between time and space 【Supposedly the light cone is 90 degree at the singularity of an edge of another event horizon on which Dirac sea sits, in terms of the cosmological model of Bible, the singularity is a geometric point of the cosmological buffer zone from 54 C-QUANTA-R5, the stage of Dirac sea, which plays an important role in generating an electron (down-spin) as long as Dirac sea gets an input of an equivalent energy elsewhere back to Planck world.】This is not an accurate characterization. One of the hallmarks of general relativity is that the choice of coordinate system really makes no difference in the characteristics of spacetime. One could choose a coordinate system where no such switch occurs. But it would describe the same spacetime inside the black hole. The singularity, if it exists, is really every where in the sense that its gravitational well will be felt in everydirection, whether he goes sideays or backwards, NO matter which way eh astronaut would try to move, he would will still be moving towards the singularity. Since time can only flow one way, it means that all future events lie at the singularity. The singularity now becomes an inevitable moment in time. 14:46
I could not find l mathematical symbol tile on my keyboard 🎹 on my smartphone TCL
the astronaut falling into the blackhole looks really high. It must make his experience extra special.
Came to the comment section for this lmao
I can only conclude observing this astronaut that the solution to unifying quantum mechanics and general relativity is DMT
Awesome Arvin
Super fascinating! Love it!
What blows my mind thinking about this is, gravity becomes so strong that your light cone only points to the singularity. Anything beyond the event horizon is your past. All your possible futures only lead to the singularity.
And on top of that - the singularity is not a point in space, but point in time…. Space becomes time and time becomes space… awesome)))
If time appears to come to a complete stop at the event horizon, then does that imply that the event horizon is infinitely far away?
Yes. The reason you cannot leave a bh is that outside is the past, and you can’t go to the past. Curved time is just really weird.
@@DrDeuteronActually, the reason a bh can’t be escaped is due to the gravity preventing anything from doing so. The past is always the past. I can go into my home, when the outside could be considered the past, as it’s where I came from. But I can exit said house because no FORCE is preventing me from doing so. Nothing to do with time. The notion that the past is always outside and the future always inside the eh is merely consequential, but it isn’t what is physically preventing anything from exiting. The spacetime curvature is too high, that’s what prevents escape, but frame dragging also adds to the difficulty of departure.
@@aaronperelmuter8433 I’ll go with Kip Thorne’s explanation over yours.
Beautiful explanation. Thank you.
Excellent as uaual. Thanks Arvin
Very well made video, but I think there is a mistake at the end : after crossing the horizon, the light behind you wouldn't become highly blueshifted, it would instead be redshifted, and it wouldn't be concentrated into a beam but still occupy a whole hemisphere behind you. This can be seen in the simulation by Andrew J S Hamilton which was briefly shown in the video.
Why would it be a hemisphere? Shouldn't it be a funnel (cone like structure) as all lights rays tends to convergence towards the singularity?
@@ActionReplay91 No, ingoing null geodesics look kind of like logarithmic spirals below the Schwarzschild horizon (globally), they are not all falling radially inwards in general. Therfore, they can 'hit you from the sides' as well. In simpler terms, it looks like this bc. of gravitational lensing (as it was successfully quoted from Andrew Hamilton at 12:00 in this video, yet messed up somehow at the end). The relativistic beaming/aberration only happens when you try to maintain a constant Schwarzschild r coordinate (as pointed out by ScienceClic).
@@user-hq3dq3vx5x just a question - let's hypothetically supposed a that an observer is under acceleration due to gravity (before hitting the singularity), and will that observer be able to distinguish the two light rays? The ones radially falling directly inwards Vs. The ones spiralling towards the centre?
@@ActionReplay91 Please do not use the word 'acceleration' in this context. The astronaut is a free faller. Free faller means timelike geodesic motion. On these wordlines, proper 4-acceleration is 0 by def. I am not entirely sure that I understand your question properly, but yes, oc. he can estimate/tell the difference, if he knows how the background stars would look like without the lensing effect of the black hole. (It helps very much of course if he is familiar with GR and raytracing.)
Error: 11.29. Light falling into the black hole is RED-shifted, not blue-shifted to the in-falling observer. Upon crossing the horizon the in-falling light is stretched to twice its emitted wavelength.
In fact, you're right no matter how fast it's going your reference point is slower than you and you're running away from it or it's going away from you, so it goes red like what we perceive with telescopes and call Hubble constant!
this video is full of misconceptions, errors and popular myths, it's wrong
@@trucker-lolwhere's your video with the correct interpretation and math
nothing stops at the point of no return
@@tylermcnally8232lol he don't have one
I like how you explain things and break things down
Great stuff, another home run, hooray Arvin!
This is my favorite Arvin video, to date !!!!!
Excellent episode!
Arvin you're the best my friend
Fantastic video❤
Fascinating video.
Astounding explanations !
Thanks Arvin
I really enjoyed this one. Entertaining and informative, thank you 🙏🏻
Nicely done
This was so good! Thank you so much!
Love your work 😊😊😊
what an awesome video, great job.
Excellent! I enjoyed this one. Thank you.
The exploration of such fascinating ideas pushes the boundaries of our understanding and drives scientific progress. Keep the curiosity alive - the future might hold some incredible revelations that could change our understanding of space, time, and the potential for traversing the continuum in ways we can’t yet imagine!
Wow, that's exactly how I was imagining it. Some internet physicist was arguing with me that you can see in front of you while looking at the singularity behind the event horizon.
First time I understand your video fully
Aww sweet nighttime upload! Great vid too. Light moving equally in time and space is astounding
It's a convention, a choice of units where "speed of light" = 1. Astounding is that it is the same for all observers.
Love this channel
Very well explained
13:05 This is such an interesting property of massive black holes, and produces some truly mind boggling sci-fi options, like the Birch World, a Dyson-Sphere-esque construction built around supermassive black holes that provides virtually limitless living space.
This is the best video, I want to hear more about that last bit of inner and outer event horizons
Thanks Dear Arvin Sir for your detailed explanation videos related to science and universe.
Would you please make a detailed video regarding quantum fluctuations and how these fluctuations give rise to space time matter and energy. Anyways I had enjoyed all your videos and they were great.
Lots of love ❤ and wishing you a longer prosperous life ahead. Love from INDIA 🇮🇳.
Thanks!
Wow amazing content this guy is the best
These are among the best science videos on UA-cam.
This should be amazing! 😊
Thank you. I understood everything.
This is a really nice video about cosmology, thanks Arvin, great!
A lot of people try to explain the functionality of black holes with a vacuum cleaner, and that's a bit superficial in my opinion.
There are different categories of black holes (primordial, normal, massive, supermassive and the powerful variant, the quasar) from galaxy rotor to matter converter and galactic power house, it really has it all.
But one thing is certain: without them our universe could hardly function!
There’s only one single type of bh, what you describe as different “types of bh’s” are actually all the exact same thing, just that some are heavier/more massive than others. But that certainly has no effect whatsoever on the type of bh. You might sub-categorise bh’s with electric charge and those with angular momentum, but even those are STILL the exact same type of physical phenomena as all other bh’s. That’s the very definition and meaning of the famous quote, “bh’s have no hair”.
@@aaronperelmuter8433 "category" was the world, sorry I am not English or Northamerican, the perfect translation sometimes fail...
@@thekingofmojacar5333 my apologies, your English is excellent, by the way. Better than many people who only speak English.
Very interesting stuff
No bullshit here! Love your channel Arvin!
That was an awesome show by the way.
It always amazes me how stable black holes appear to be (high entropy, Hawking radiation), it’s already collapsed, but yet it feels like iblack holes are like dark stars in principle.
Black holes if they are not piddlingly pico, femto or atto scale, i.e. smaller than an electron and comprised of several thousands to a few hundred thousands of tons of mass, effectively act like memory devices, near-perfect spacetime capacitors, that only leak "spacetime charge" slowly, like a near perfect capacitor, via Hawking radiation until they are piddling, then they flame out brilliantly like a big bang singularity?!
Look at black holes, the matter disappears into curved spacetime past the event horizons of the near perfect spheres, but the universal acceleration or gravity of the disappeared fermions etc. is remembered and projected outward at the constant speed of light; we'd still orbit our black hole sun if it collapsed to a singularity right now, but darn it we'd get pretty cold after 8 minutes or so? We'd orbit that sun for a very long time, until it got sucked into a larger memory sphere far into the future?
Not to worry, thank Schwarzchild, Chandresekar, Albert and Oppenheimer for the future memories?! Like Dali showed, it's persistent?! As Frank & Furter sang, let's do the time warp again?!
This, and other videos like it who base their presentations on the latest theoretical work, are profoundly important to the accurate, popular understanding of science.
Since black holes are so ridiculously far away we will _never_ be able to send a probe or a human to examine them. Thus, this theoretical work is what we will base _all_ of our science on.
Kudos to Prof. Ash! 😊
We do observe them
I like this Arvin Arsh channel.
❤ Very good 👍🏼
If you were in a non inertial reference frame looking out light would be blueshifted but if you were in an inertial reference frame that same light is red shifted.
Black holes illustrate the need for a unified theory incorporating quantum gravity, as they are where extreme gravity appears to 'crush' matter down to infinitesimal scales. However, I believe we can make progress if we look at it in the following terms: 1The singularity should be góregarded not as a location in space at all, but as a future point in time, thus its omnipresence regardless of which way an infalling observer looks. 2. In Relativity, mass is not a measure of 'stuff', of 'matter', which can be 'converted' into energy; it IS confined energy. 3. The singularity therefore represents energy at an incredible degree of confinement at a point in the future, a point towards which spacetime is flowing faster than the speed of causality/light.
Once you enter the Event Horizon, space and time switch place.
The singularity is not at the 'center'. It's in the future.
Any movement in time, will bring you close to the center/singularity.
Exiting the black hole is just as impossible as going back in time.
masterfull once again my friend!
though, neill de grasse tyson would probably disagree, he recently spoke out that he figures the possibilty for a black hole to actually create an entire new universe inside it with its own tick of time.
much like i hypothesised a couple years ago but my intuition tells me i'm wrong, or at least a whole new set of rules in physics would apply
That was nice and I like the notion that time travel may be (maybe) possible with the help of rotating black holes :)
I don't think traveling back in time is possible but I don't feel the need to disprove a theory that hasn't been proven to begin with. The burden is on the time-travel enthusiasts.
Arvin did do a good job of showing the difference between apparent time stoppage and actual time stoppage. Actual time stoppage at the event horizon is impossible. In GR (whether a weak field or extremely strong) clock comparisons run in opposites. If my near event horizon clock is running much slower from your distant perspective, then I will see your clock running much faster (as long as the signals are infrared, as Arvin pointed out). But, if my clock comes to a complete stop, then for me an entire eternity outside of the horizon will fly by at infinite speed. That can't happen because the horizon will still continue to have time intervals as a possible future collision with another black hole would register. Therefore, my clock could never come to a complete stop.
@@chriskennedy2846 I am not a proponent of time travel but look at some QM paradoxes, including delayed choice quantum eraser, and work of people like Aaronov and Vaidman, maybe others as well. Looks like the wave function is propagating forward and backword in both time directions. Not sure if this prooves anything but is strange at least :)
@@tiamnikSabine Hossenfelder has a pretty good video on this "DCQE & time travel" being a misinterpretation of the physics. And, as the commenter above stated, a BH merger would still have to register as "forward in time", even though the far-observer's clock would appeared to run at infinite speeds. Something has to give there, as both cannot be true... And because of all of the logical breakdowns of time travel and causality, I think it's safe to say that TT isn't possible. Obviously no one can prove that (especially not a novice like me), but it takes a lot more leaps in rationale to accept it than it does to reject it.
This wasn't actually the sort of content I was in the mood for, but I've such respect for Arvin that when the algorithm suggested it, because it was him, I knew it would be good...
Arvin Ash is one of those fine channels you can confidently click the up-thumb before the video starts :)
In relativity, it is required that all identical clocks tick away at the same rate, everywhere, and under all circumstances of motion. There is no such thing as "time stopping".
@@aaaa8130 Excellent question. The first step fundamentally is experimentally determining if the gravitational field is a metric field (measurements of Local Position Invariance, Local Lorentz Invariance, Weak Equivalence). A metric field does not affect matter with such effects as differences in elapsed proper time being due to geometry (clocks traversing different spacetime distances). All measurements to date are consistent with the gravitational field being a metric field.
Once the experimental data is established the rate at which time lapses is given by the norm of the vector tangent to a world-line. Given a world-line expressed in arbitrary spacetime coordinates, X(τ), with tangent vector U=dX/dτ, the rate is then g(U,U)=1, which is a constant.
Fascinating I love to learn about blackholes, to rap my head around blackholes I like to think of them in 2D and 3 Dimensions
12:51 That's incorrect, because the "r" coordinate is not a physical distance, it is only a coordinate ( that is spacelike outside the horizon and timelike in the interior).
Actually, in GR textbooks , the "r" coordinate is usually called " the areal radius" , because it is defined by the surface area of cocentric spheres.
The reason why tidal forces are weaker near the horizon for more massive Black Holes is that they're inversely proportional to r^3 {~M/(r^3)}.
The so called " surface gravity" ( this is a GR technical term, it's not the "gravitational force" on the horizon!) is κ= 1/4M ( for the simple non rotating, non charged BHs), where M is the total mass of the Black Hole.
And R_schwarz goes a M, so the tidal “force” at the horizon falls as mass to the fourth….and for a ten million solar mass black hole, the forth power is….big.
i like how you deskribed the singulaity so much
U are simply aweseom ,
I've watched this documentary called Interstellar where a guy enters a black hole and finds himself behind a bookshelf in his home on Earth. He is able to push individual books out of the shelf and he can see his daughter on the other side of the shelf but for some unclear reason, he cannot exit from behind the shelf into the room. All this happens after he drove his car at a high speed (with a flat tire), smashing full grown corn plants in a corn field,, while there's a famine and there's a road like ten meters away.
“Documentary” 🤣
The craziest thing about the journey into the black hole is similar to when people die and return(NDE) They say they feel like they are falling one way or another, and they see light from around them and above them and then a deep blacker than black hole below them... I really believe that the mind is a reflection of the universe...
Arvin, I learned something.
Great video... a question, please if you read this Mr. Arvin Ash: Are you going to release some video about your visit to Copenhagen Atomics? Thank you as always.
Yes, that's coming. It will be a full video on molten salt reactors.
Arvin,
Could you make a video on the theoretical physics of the possibility of the existence of parallel universes? It will be appreciated by many of your subscribers.
Considering the information in this video it appears that gravity is the dominating force in the universe. It stands apart from the other forces and it is considered to be week in comparison, but in reality it governs the behavior of the other forces through its influence on the curvature of space. It is simultaneously both the weekest and the strongest force depending on the curveture of space. At quantum level everything is a wave by necessity. Two waves has a much higher probability to interact then two particles considering there size. Particles represent interaction. Between interactions everything propagates as a wave. Light propagates by interacting with itself via the electric and magnetic field. The elapsed time between interactions is directly linked to the curvature of space or the strength of gravity if you will. Gravity squeezes both the fields and the atoms together using pressure. This results in decreased elapsed time between interactions. At the singularity of a black hole the fields are compressed to an infinitesimal smal size so interaction is no longer possible, or there is no elapsed time between interactions. The singularity represents the perfect quantum state, no space no time, or all space all time. It is space that gives rise to time or in other words the separation of the fields gives rise to space which is controlled by gravity which in turn dictates the passage of time, the creation of space/time. The flow or passage of time depends on the strength of gravity in every given point in space. The present is universal. There is a reason why the Schwarzschild radius doubles as the mass doubles yet the force of gravity grows linearly with mass.
@Arvin - How about Higgs field switched off inside the black hole? And all infalling particles (dust) will be massless. And singularity can be visualized as a ball of massless particles occupying a single state.
This space-time bending thingy is mind bending. While I find it fascinating, I can never really wrap my mind around it.
Love the out of nowhere "Bullshit" @ 09:53!!!
Out of character, Arvin! Jk, you're the man👍
I've watched so many of these videos on theory and this is probably the best one yet... where is your video on time travel? I don't see it in the description
4:51 Really well made presentation so far.
(I am not a physicist)
Q. Infinitely small volume for the mass? Or a flaw in relativity?
Why does something that exhibits properties of mass(energy) have to be a tangible substance? If it is just the illusion/appearance of matter and does not truly exist to begin with then that nothing can be compressed to an infinitely small volume. There is also the problem with the illusion of a static volumes (distance across the void) created by the extremes of space, time and 'c'. Depending upon the point of perspective if time stops, the void appears infinitely large. Time stops near and within the singularity and the void becomes infinitely large. I know this is just a brief comment, but hopefully some see the issue as you have stated.
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6:00 I am not sure about this explanation. (But there is an ambiguity in the flipping of space and time that you will explain following).
I would expect that looking back after crossing the event horizon would offer the appearance of emerging from a single point and progressing toward an infinite void ahead. In some sense emerging from an undefinable central[ish] location and expanding outwards toward the (unreachable) inner edge of a spherical void. aka maybe like emerging from a big bang(big emergence) into what may appear as an infinite void (universe). Factoring in the flipping of space time effects this description, so I will watch on :)
[edit] At 15:47 this theory is confirmed. (See a basic analogy below).
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13:45 It's an interesting point, but we have already established that the gravity at the event horizon is that even light cannot escape, but I will accept that the "gradient" of that gravity may be spread over a far greater distance meaning a large object would experience much the same gravity between it's closest and furthermost points.
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19:09
So, a little different to the outcome suggested here. Time travel = Unlikely (I agree).
This applies to both our universe as well as the idea of a black hole universe, although very loosely.
At or near the event horizon I can accept a concept of Space and Time flipping places, but this is more of an "illusion" of the reality rather than a physical reality.
As I said above, the illusion (for that object) would be of emerging from a difficult to define point in space and/or time. The progression would be toward what would appear as an infinite void with the singularity(appearing to be) at the outer limits of that void. Ultimately as we move toward a smaller and smaller section on the surface of that singularity, the gravitational force may decrease. But ultimately we may never reach that singularity due to 'c' and time dilation. This could all take many billions of years from the perspective of the object allowing for the other objects to combine into galaxies etc along the way.
Sounds a little familiar :)
Emerging (at the extremes of space and time) from some undefinable place inside the void and progressing toward an unreachable event horizon (or singularity?).
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Another thing I am having difficulty with, but not directly related to the context of this video is this concept in physics that everything including time is derived from the void and matter.
What if it is the other way around? What if everything (the void and what we call matter) is derived from time? What if the void in which mater and our cosmos appears to exist is nothing more than an illusion or emergence (Very real illusion for us inside) created out of the tensions in the progression of time?
If time has no physically definable property at zero time, then it does not have to exist in any particular medium. Once time begins and progresses (at an equivalence of 'c') it leaves in it's wake the appearance of a physical void. We have just created the 3D void from nothing. It appears to be infinite as we can never catch up to or view the leading edge of time or the illusion of the void that it has created.
What about energy and matter in this void?
We have many hints from things such as the humble photon which exist in a single place in the void, but 2 separate places in time. There is a tension between the 2 places in time. Can the very existence of the photon or it's energy just be an expression of that tension in time?
We can also slip over to the problem with quantum entanglement.
2 particles existing in distant locations in the void, yet information seams to travel instantly across that distance, but what if both share the same place in time. Both are "Locked" into the same expression of time without any separation. This is somewhat the opposite of the photon that exists in the single location in the void, and different places in time.
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I think there is too much emphasis on the physical objects of the void, and too little emphasis on the role that time plays. Yes I know, we only have the physical as a tangible way of studying these things, but if we alter our position from "time emerging from the existence of the void" to "the void emerging from the existence of time" many of the paradoxes and problems in physics begin to have plausible pathways to answers.
As a thought experiment, change the common 4 dimensions and our use from:
(1st, 2nd, 3rd) the 3D void then 4D (time that some how emerges from the former),
and replace it with.
0D (zeroth dimension (time). Non physical) and then 1st, 2nd, and 3rd (the physical 3D void) as what emerges from the the 0D.
We could say time-space instead of space-time :)
Thank you.
Hi Arvin, thanks for this great video. Could you discuss the very controversal position of the UA-cam channel Dialect. He published few days ago another excellent video about one important aspect of the Einstein's theory which that he based his whole theories on one important assumption: that the 2 way measurement of speed of light is the same on its way from and back to the signal emitter. But if we assume that the speed of light can vary....well the time dilution and lenght contraction don t exist anymore and time becomes absolute again! This has been tackled 60 years ago already. It would be interesting to hear your toughts on this.
Imagine if you fire a laser pulse at a target, would you think the pulse would be detected at a time when its light is expected to reach based on it moving at the speed of light (the correct answer) or at a totally random time because light speed can vary (the wrong answer)?
Great !!! Finally someone is been to a black hole 👏👏
Fascinating! What made of singularity inside the blackhole? Is this point of singularity is ending or beginning of another space?
Einstein said: “To those of us who believe in physics,” he wrote in 1955 to the family of a friend who had recently died, “this separation between past, present, and future is only an illusion, if a stubborn one.”
It's always the Present everywhere in the Universe. Time doesn't flow. It is Entropy that accounts for change. Travelling to the Past is not possible because the Past has "no location." The configuration that is called the Past been undergoing constant transformation and its current configuration is what we call the Present. At least, that what I think.
I think Kip Thorne has the best hypothesis of the singularity, that matter/energy in the quantum sense transforms into space/time energy. This solves virtually all of the problems of the singularity because the matter/energy is being transformed into something that is not infinitesimally small.
I may be way off, but I'm thinking about the spacetime diagram. We always remove a spatial dimension to make it easier to visualize the time dimension and the worldine looks like a 3 dimensional cone. But I think about adding that other dimension back into the diagram and what would that look like. Obviously we can't visualize 4 dimensions, but it seems like it would still appear to expand outward, but in every direction simultaneously since we can't observe a fourth spatial dimension. That sounds a lot like Hubble's law. Everything in the universe is moving. Maybe the expansion of the universe is just the universe moving through time. Is that a thing, or am I way off? Maybe he addressed this in the video, I was too busy typing this.
amazing
listening to your explanation my visualization of the singularity goes like this, the singularity has a physical "point" but it is not a physical "object" when something passes through/comes into contact with the singularity itself, it will be get "folded" in a sense, like my brain pictures folding a piece of paper evenly until it cant be folded anymore but combine that with like a whirlpool in water, so ur folding in a circular formation overlapping over itself until u fold out of existence
WoW! It definitely makes my daily problems look infinitesimal small
Wonderful video, Arvin. So, instead of finding one outside the event horizon, as in Author Clarke's "Neutron Tide", we'd find that star mangled spanner near the singularity.