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#5minphysics 

Lawrence Krauss
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Classical Black holes didn't seem that strange, but when general relativity and quantum mechanics are introduced they become stranger, as exemplified by Hawking Radiation. All this leads to 3 paradoxes: 1. time appears to stop at the event horizon, 2. Black Hole evaporation appear to violate a central tenet of quantum mechanics, 3. If black holes radiate at some finite temperature, then something very strange must be happening near the event horizon, which is inconsistent with the fact that a classical observer notices nothing strange when they fall through. I try and show how all this arises in a 15 min #15minphysics episode.

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28 апр 2020

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Комментарии : 71   
@stavrosmaiden
@stavrosmaiden 4 года назад
I love the fact that #5minphysics is always more than 5 minutes!! Thanks Lawrence!!!
@TheresaCoughy
@TheresaCoughy 4 года назад
Stay safe Lawrence , thanks for this series of vids.
@Rog5446
@Rog5446 4 года назад
This is the first time I've agreed with an eminent physicist, I also think it's a mystery.
@sphinxtheeminx
@sphinxtheeminx 4 года назад
How I laughed at 2.05 when he speaks about 'getting on to the mysteries' - like the preceding two minutes hadn't ruined my mind with the unmysterious stuff I'm not equipped to compute.
@woody7652
@woody7652 4 года назад
We need to spread more light on black holes! Mindboggling stuff, thank you, professor.
@RobertCleggRC
@RobertCleggRC 3 года назад
"Dimmer and Dimmer": That's when the movie Dumb and Dumber travels to an event horizon.
@josejoseph1985
@josejoseph1985 4 года назад
Best teacher! No bs!
@haimkohan9241
@haimkohan9241 4 года назад
Fascinating. Thank you for doing these videos and congratulation on finishing the manuscript for a new book!!
@lkrauss1
@lkrauss1 4 года назад
thanks
@Ohotoho
@Ohotoho 4 года назад
This was very interesting.
@olafgusten2671
@olafgusten2671 4 года назад
just find out that you have a youtube channel, and your #5minphysic are didactic as well refreshing. Thanks for making us able to grasp complex ideas, making your field of work more a tangible for us. continue the great work.
@naturediary7651
@naturediary7651 4 года назад
Thanks again Lawrence, you explained in beautifully clear way these 3 paradoxes around Black Holes which make viewing this video so interesting. I'm really looking forward to your new book being published. Take care. Doug
@Bazzo61
@Bazzo61 4 года назад
Fascinating paradoxes. I'd read that the entropy of a black hole was proportional to its area but now I understand why - thank you. Looking forward to reading your new book.
@paulc96
@paulc96 4 года назад
Hi Prof. Krauss, Thanks for another interesting Talk. I am a bit surprised that you didn't mention Leonard Susskind's "Holographic Principle", which I think is quite amazing. And it could even be correct !! All the best, Paul C.
@ahmedsyed3436
@ahmedsyed3436 4 года назад
Thank you Dr. Krauss for explaining complex topics to a layman like me. 🙂
@xyz-ns7ym
@xyz-ns7ym 3 года назад
Great 👍
@user-rt5nc9ch5t
@user-rt5nc9ch5t 4 года назад
I'm Russian and never heard the term "Frozen Star" especially applied to Black Holes. Maybe it is due to the fact that I'm a chemist and not physicist, but I read a lot of physics and cosmology related books in my time. And btw big thanks for your greatly entertaining content.
@lkrauss1
@lkrauss1 4 года назад
thanks. I have been told by some colleagues that this was the term that was used.. at least early on, in Russia.
@kavionic279
@kavionic279 4 года назад
Oh no! I have read this many times for many years, and it sounds like such a great name for the phenomena that it had to be true. And hey, I read it on the internet so it couldn't possibly be wrong! And now it turns out it might be a myth? My world is falling apart! But thanks for clearing it up. Better to be right and disappointed than wrong :-) Now I must at least check it out deeper before I get all worked up about it again.
@Petrov3434
@Petrov3434 4 года назад
Penrose and Hawkins collaborated on black holes (Penrose was a mentor of Hawkins at Cambridge). They both concluded that information is lost in a black hole (which have enormous entropy). Later, under much pressure, Hawkins reversed himself -- Penrose stayed firm that information is lost... In our (any) galaxy almost all entropy is concentrated in its enormous black hole in its center... Of course -- I understand less and less the more I try to understand the subject... ;-))
@nadeemqadir9364
@nadeemqadir9364 4 года назад
You are great Sir
@amreshyadav2758
@amreshyadav2758 4 года назад
great explanation 👍
@markmd9
@markmd9 4 года назад
I love paradoxes even if I'm not a physicist, here's my thoughts: The explosions are the creators of information - Big Bang created the fundamental particles and stars and supernovae created heavier elements. While the black holes are the erasers of information - an object falling into it will break into molecules, molecules into atoms, atoms into plasma, plasma into neutrons and neutrons into quarks, quarks into energy and all the information is lost in this work of decomposition. If to imagine and observer falling into a black hole his time will begin to slow down until it stops. What does this mean - "there is no time"? It means he is dead! and he not even realized it. Of course there can't be any talking about firewalls with dead men.
@eduverse1948
@eduverse1948 4 года назад
This video itself experienced time dilation. A 15 minute video was time dilated and became an hour long video in my frame of reference. That's because I took a lot of notes. Thanks professor.
@sirwilliamkarl5591
@sirwilliamkarl5591 4 года назад
Glad to hear there's a new book coming. Still months away I'd guess...?
@sunshineconch5377
@sunshineconch5377 4 года назад
I'm going to have to watch this one again. Didn't get my head fully wrapped around it the first time.
@abhikrishnaravi6539
@abhikrishnaravi6539 4 года назад
Hlo Mr Krauss , In any of the coming videos of #5minphysics can you please explain the recent attempts to solve the theory of everything, including the string theory . I hope for it.
@GEMSofGOD_com
@GEMSofGOD_com Год назад
Never heard a single "frozen star" in Russia, and I'm the center of Russian academia
@ShadowZZZ
@ShadowZZZ 4 года назад
that is what stephen hawking explained in his bestseller "a brief history of time". also there are many different postulated solutions to the black hole entropy paradox
@AnishDharmakkan
@AnishDharmakkan 4 года назад
Last :'( Thoroughly enjoyed this series. Thanks @Lawrence Krauss
@gilbertengler9064
@gilbertengler9064 4 года назад
I understand that energie is conserved, but I have problems to understand why information should be conserved. If a person dies, his body still has all the molecules present when alive containing all the energy, but what happens with all the knowledge you (eventually) had in your brains, what happens with the millions of patterns of reactions that was perfectly orchestrated going on in living cells and tissues? This information is simply gone in a second (or minutes) and what is here conserved?? Thanks for your excellent explanations!
@AbcDef-tl2kq
@AbcDef-tl2kq 2 года назад
Every paricle creates a ripple in space time since muon is 200 times heavier it allows us to detect back ground gravitational wave.similary if there is much heavier or equal weight particle it will behave similar to muon g2 experiment.
@kvaekvae2257
@kvaekvae2257 4 года назад
does an object, which falls into black hole, eventually reach speed of light.. ? how far into and what happens when it can't accelerate any more? does frame dragging happen?
@RobertCleggRC
@RobertCleggRC 3 года назад
In the case of time travel, where does the information of the previous world's events go? Has it been destroyed? If so, how does the time traveler remember it? Shouldn't he be forced to forget? The paradox: We all have memories of worlds that never existed or can never tell when time travel occurs because no one can remember it.
@va2601
@va2601 4 года назад
Lawrence, in your next video can you explain a little bit about why the black holes are so cold? I mean at the event horizon is cold near absolute zero not at the outer skirts of the black hole or i am wrong?
@vk6uu
@vk6uu 4 года назад
Good question. I thought as you compress mass it got hot.
@alleneverhart4141
@alleneverhart4141 4 года назад
Given Hawking Radiation, I've always puzzled how anything moves beyond the event horizon, since gravitational time dilation is asymmetric, where time upstairs runs fast and infinitely fast as the event horizon is approached. It would seem to me that anything falling in would reach the event horizon just as the black-hole reached the end of its life. Now, if that were true, then we wouldn't need quantum gravity because the singularity never occurs and there's no information paradox because the information never crosses the event horizon. Does that make any sense?
@londonhottt
@londonhottt 4 года назад
Krauss isnt the entralpy just the area pie*r^2?? Because r=2m so m=r/2 and m^2=r^2/4 which when plugging it into 4*pie*m^2 the 4 cancels out??
@martinkaufmann4067
@martinkaufmann4067 4 года назад
Thanks for the explanations. But one question: The velocity of a body at the event horizon, regardless of the size of the black hole, is always the speed of light, isn't it? Otherwise, light could escape at the event horizon. But how can something with mass move with the speed of light? That would require an infinite amount of energy?
@lkrauss1
@lkrauss1 4 года назад
escape velocity is c, but objects can fall in with speed less than c, or hover just outside the event horizon with engines on full throttle.
@GEMSofGOD_com
@GEMSofGOD_com Год назад
Why are you so assured that thermal radiation does not contain information? It may look hard to extract much, but it's certainly something, and it's something that's brighter than absolute blackness. No paradox, really.
@ankuryadav4591
@ankuryadav4591 4 года назад
Sir how to ask right question and how we can practice it ?
@robertmolldius8643
@robertmolldius8643 2 года назад
One Lawrence minute is 3,19 minutes to me.😄😄👍🇸🇪
@kvandos
@kvandos 2 года назад
So if a guy falls into the black hole, and his time stops, viewing it from the outside, would he view the outside world faster? and ultimately opposite of time stop, time instant, so instantly the universe continues until the black hole starts to evaporate where it has a mass that light can escape and this guys internal clock “continues” Like this guy makes a time warp from when his internal clock stops till it continues when black holes starts to evaporate. So like it’s instant for him but billions years for us?
@nylehaywood2471
@nylehaywood2471 4 года назад
YA
@RobertCleggRC
@RobertCleggRC 3 года назад
Faster Than Light: I have an object that I would like to accelerate beyond the speed of light. I start with two objects accelerating them both near the speed of light. Object A started accelerating before Object B. As Object A nears the speed of light, I open a temporal causality loop and bring Object A into a collision bath with Object B. Can I push Object B over the speed limit of light this way?
@frognik79
@frognik79 4 года назад
I love how you hate string theory. You, Brian Cox and Jim Al-Khalili are my favorite science presenters. When are you going to make/be in a science documentary?
@husainahmed7884
@husainahmed7884 4 года назад
What is the fundamental problem in Quantum theory of gravity, i mean is this related to quantizing gravitational field and can all the information stored inside black hole be represented by wavefunction?
@lkrauss1
@lkrauss1 4 года назад
in part.. there are many problems..
@arfeltayona798
@arfeltayona798 3 года назад
Prof. I have an unpublished paper on the conservation of information in the blackhole...
@brucefulper4204
@brucefulper4204 4 года назад
I ALMOST followed him........Violater of quantum mechanics!
@RobertCleggRC
@RobertCleggRC 3 года назад
Imagine a future where the first actual time travel is to take place. The time-traveling scientist and the world scientific team is dreadfully scared of altering the future. So when the scientist visits the past, she is instructed to make a trivial change, a 360 degree rotation of a small object. Upon return to the present, nothing has changed. Has the universe had to split off a universe that is an exact duplicate of the current one minus some small energy or inertial change? Or was that energy change an equal and opposite reaction to the energy in the scientist? Either way, the world is identical except for the 2 seconds it took to rotate a small object back to an original position. And what about the energy it must take to re-create the world in another time slice or dimension just because a little object was spun around? How do you account for all that energy?
@haimkohan9241
@haimkohan9241 4 года назад
I watched the video a few times. Feel like writing my reflections, maybe it will help me to understand the paradoxes. If I understood the first paradox correctly, after the black hole evaporated it continues forming.... Didn't really understand the second paradox, doesn't information always disappear. When I burn a paper on which I wrote something, didn't the information disappear. In other words, why disappearance of information is a problem in quantum theory. Third paradox, The equation says that there is some temperature at infinite distance, hence at the event horizon the temperature must be (infinite?) very high, but since the acceleration near the event horizon is very small a person falling into a black hole should not feel anything strange.... (Did I get it right? :).
@lkrauss1
@lkrauss1 4 года назад
re information paradox.. if one measured every photon coming from the burning, and every atom in the ash, one could in principle, though not in practice, reconstruct what was on the paper.. for the black hole that is not possible even in principle..
@haimkohan9241
@haimkohan9241 4 года назад
@@lkrauss1 incredible!! fascinating world!!
@gordosimmins2727
@gordosimmins2727 4 года назад
Due to time dilation 5min of his time appeared to take 15min of our time because he's so "heavy." ba dum, pish!
@flyonbyya
@flyonbyya 4 года назад
Isn’t the eternal loss of information that Hawking postulated the basis of the disagreement, and indeed the concession Hawking finally made to Preskill?
@lkrauss1
@lkrauss1 4 года назад
yes
@mikebailey519
@mikebailey519 4 года назад
Crawling on the planet’s face. Some insects call the human race. Lost in time, lost in space and meaning.
@doctorspockARTS
@doctorspockARTS 4 года назад
He got 5minutes of physics to fit into 15minutes. 5m=15m\p. Where m is minutes and p is physics
@hbshagor
@hbshagor 4 года назад
Are these theories or facts?
@lkrauss1
@lkrauss1 4 года назад
some theories.. some facts
@_John_Sean_Walker
@_John_Sean_Walker 4 года назад
💃🔴
@SsspraakForsskkarring
@SsspraakForsskkarring 4 года назад
Our universal professor is just like a jesus , yet he deals with reality and has nothing in to do with a jesus. I just paradoxed myself in my pants😇
@georgekanev6644
@georgekanev6644 4 года назад
Absolute space and absolute time do not exist in real universe that is number one wrong in GR. Number two is implementation the Lagrangian function over the bending of the space in Einstein manner which is wrong because the GR is kinematic characterization where absent accelerations and therefore energy transferring. Number three is accepting the velocity of light as absolutely constant in absolutely space which is wrong again because the last doesn’t exist as well! All these parameter are in force only in one separately space in development which means that these constants also are change but very slowly in unison with the slowing changing by the space itself! About the “black hole” conception: Let begin with the nature of particle-antiparticle. All what we know about this phenomenon is that antiparticle is mirror image of respectively particle, but what is the essence nature of this dualism particle antiparticle? The answer comes from the essence of the field and polarization of the space in accordance with the USM www.kanevuniverse.com part I. Let see also page 195 to 198 USM where is given convincingly explanation of the nature question of antiparticle, which in summarizing fashion is the following: Antiparticle it is particle escaping from its own polarization space to the contrary one so quickly that there it isn’t tame to reverse its kinematic parameters, which immediately follows by annihilation. It is obviously that some form of common existence even in some not proved as a physical medium fantasy like a black hole it isn’t possible. Let remember again what should to be the black hole conception according to general relativity: Never forget the definition of black hole according to general relativity and it is place in the space where nothing can escape and anything stream in! Sensible person immediately ask you..where all these come in like masses, energies and soon, and you cannot give him reasonable answer…… What is the first: the revolving disc, which may hasn’t any mass, but which has tangential velocity and therefore bend the space around itself, or the spherical mass which has or hasn’t tangential velocity but we accuse that this mass bend the space and creates the so called space time curvilinear tensor? Gravity is dynamically characterization (centripetal acceleration) but the bending is kinematical characterization, so obviously we must to remind again the following: Brian, it’s OK! All of us I believe know very well special theory of relativity and of course the general one, but these theories are correct about the time when they wеre invented by Einstein and especially if I may to use the word of Einstein himself (how it is possible of course), he very much doubt about the problem with the absolute space existence. He approximate said that if the space is distances between the objects only, that doesn’t obstruct the existence of the absolute space, and it for the time was correct. By then the essence of the field, that he accepted, it is the bending of the space only and these bending can organize through some tensor of deformations. For that the general theory of relativity needs absolute space, because the effect of member √(1-v^2/c^2 ) is very weak if the velocity is between the two close objects. Einstein said the following: If we have one revolving disc and if we put tangentially on the periphery a meter length, then this meter will shrink according to the member above, but if we put this meter at the radius it remain the same. So if we divide the perimeter by the diameter of this disc we cannot obtain the number (π). That is why the space is bending, but to be possible this bending to explain the quantity of the gravitational field, there is needed velocity close to the velocity of light, which practically is very rarely on the Universe. So Einstein proposes the following experiment: He said if we have one flat table and if begin to arrange safety matches in square form and if we shifting a little one of them, the difference will be insignificant, but if we continues with the arrangement endlessly then the bending will be so big that the curvet line can close into the circuit. So Einstein is needs endless absolute space independently existing, where act the physical processes. The connections between the times, also is known, but there is importantly that the times to have common beginning. So let pass towards the theory USM www.kanevuniverse.com Namely from part I and part II it is seen that the distances between the cell of the matter, which is the orbital system, is equilibrium between the centripetal and centrifugal forces and this movement creates the field itself: g=±(v.c)/r ln(1±v/c) . So if these forces absent then the space disappears, because the field disappears and because of that the masses also disappear. So remains nothing, which (if You read the theory) passes into absolute nothing. So the absolute space doesn’t exist. Now about the times: If You read the theory You can see the coefficient of connection between the times in the two most close spaces, for instance Our space and Subspace, and this coefficient is equal to:〖10〗^31 folds. So when in our space passes one second in the subspace passes 〖10〗^31 seconds. So in the subspace there are 〖10〗^31 beginnings……. Where is the common beginning about the two times? Obviously the time in the USM is quantity of movement like multiplication between force (which means acceleration or the same field) and passed road and obviously the time it isn’t real dimension, but because of the thickening of the micro cosmos and expanding of the macro cosmos this quantity of movement does represent the energy and this coincides with the essence of the time in general theory of relativity. But let’s stop here because the lecture becomes very long. Other and many more in: www.kanevuniverse.com Obviously such thing like black hole cannot exist physically, because conception of point where the centripetal attraction can be endlessly is mathematically related but not physical phenomenon, because there is disturbed at least the rule of energy preservation. So what is the essence of greatness attraction forces in some point of the universe where we indeed observe such phenomena? The answer is in USM www.kanevuniverse.com and especially material called supmaterial which can create the joromachine www.kanevuniverse.com see the density (gravity) and possibility of common magnetic moment! G.Kanev
@sleepersciscience-magicfin7098
@sleepersciscience-magicfin7098 4 года назад
👽If you take for example a one milimeter material from black hole and put him to our galaxy, everything colapse to this black hole, huge black hole is only empty space gravity cold colaps around very density to the paradox, when you cannot to see this material but only empty cold space like us around "nothing black density orb" and thats your theory before. You can to made gravity in your spaceship but this technology is in this time too danger for human race. Youre welcome
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