"Black Holes, Hawking Radiation and the Structure of Spacetime," Juan Maldacena, IAS

[Music] so today our speaker is one nasty in maldacena who is one of the most renowned theoretical physicists in the world so it's a real privilege to hear from him today so Juan got his undergraduate and his master's degrees in Argentina in bariloche in bariloche in argentina and then came to princeton university to do his PhD actually we were contemporaries and know each other from graduate school and then he went on at the end of his PhD to write a magisterial PhD thesis on indeed black holes and the structure of space-time were questions related to black holes and the structure of space-time in the 20-some years since then juan has written many many many seminal papers in the quantum theory of gravity about the nature of space about the nature of time the physics of black holes the very early universe really transformed our understanding of theoretical physics in the process so it's a privilege to hear from him today and there you go thank you [Applause] ok it's a it's a privilege to be here I've been having a lot of fun here in the Aspen send center for physics discuss in physics actually have a connection to Hein spatial that comes with a funny story our house was Burger Bird someone broke into our house and the police dispatched the police went in and then we were not there the police reported that they found a woman there that claimed to live there in our house and we said no insure that referee she's not she's not living there it's not none of us but it turned out that the police make many mistake and went to the wrong house three houses over that's the house of Elaine pages that's a fine spacious wife okay anyway so this is a talk about black holes in the structure of space-time and yeah it's not work you know I forgot to put in the same sorry so first I'll give you a very short outline so general relativity predicts black holes rush I found this solution people were very confused about the solution Einstein was confused about the solution and it took many years to really understand the solutions I think thought that the the were unphysical solutions and then eventually was understood that they were unavoidable solutions that arise when you put too much matter in a small region of space-time then and they were called black holes then Hawking realize they're actually not black you can have red black holes white black holes and try to understand that so even the name was wrong so black holes have been always source of confusion and and also source of new physics surprises and so Hawking thought that this phenomenon implied that black quantum mechanics is incompatible with gravity and then through the methods of string theory we think that black holes are seen from the outside at least are compatible with monta mechanics and this led also to some relationship between quantum mechanics and the space-time geometry that we'll be reviewing but there are still many confusions that remain and recently they were interesting papers highlighting those confusions ok so let's start with the basics there is something called the principle of relativity which is a few hundred years old that says that an observer traveling with constant velocity observes the same laws of physics as an observer at rest you have two observers if each is in his or her own laboratory they cannot notice whether one is moving or they stationary now Einstein put a new twist in this principle by saying that there is one aspect of the laws of physics which is that the maximum velocity for signal propagation is the speed of light and that maximum velocity should be the same for all observers so it's the same principle but with one new element and this element has an interesting consequence so imagine that you have two observers and they are both trying to this is some light signal now from your intuition you would think that this one would see the light signal propagating faster than this one right if that's not your intuition I'm not explaining this clearly so it seems that it would be impossible for naively we would say that it would be possible for this observer to see this propagating at the same speed as this one and indeed you need something quite radical for that to be the case you need that the time that this of that time runs more slowly for this observer and then he can see the light propagating at the same distance in addition the observer is kind of contracted in the direction of propagation that's why I drew it this way so that's what Einstein derive from this principle this principle of relativity and this is what is called special relativity the Einstein theory of special relativity implies this in particular and it implies some other things for example there is the famous twin paradox imagine two twins that are born at the same time and then one twin travels very far and the time time flows slowly for him and then they go back and when they go back the one that was travel very far is younger now you might say well how do I know which of the one was the one who travel and there is a difference between these two twins and one difference is that this this one felt some acceleration so we could apply the special relativity formulas while they were moving with constant velocity there was some moment when they faced some acceleration and so the one that felt some acceleration is a little younger now in in that we have the following setup that the two twins are born one goes away and comes back and when they meet again they they die okay that's the rule sorry for the bad bit let's say this is the rule now which of the two twins would you rather be would you rather be this twin or that twin I think you clearly would rather be this twin who had a longer life okay now it turns out that even elementary particles prefer this so it's a principle in physics that says that any elementary particle tries to travel in a way that maximizes its own proper time so the time it experiences as long as possible so that's the principle of maximal life or maximal experience time that and particles try to move in this way and that's why particles that's why that's how we explain that particles move along straight lines so the lesson of this is that space and time form a single entity which is space-time and the time we measure depends on how we move so what an observer perceives a space or as time is different but they all perceive the same combination which we call space-time and particles move in straight line that space-time to maximize their lifetime so that's flat space now we go into some topic which looks a bit different at first that's gravity and we'll find the relationship to space-time later so gravity of course the intuition is that heavier objects fall faster but Galileo realized that everything falls in the same way once we remove the effect of air resistance and this this observation led to Einstein what he called his happy thought so his Kappa thought was the following was that when you fall freely it looks as if gravity appears it looks as if you're floating so view the image he used was that if you are in an elevator and the elevator is following the you would feel that you're floating in the middle of elevator so it looks as if gravity has disappeared free for for you and the reason is that well one explanation Galileo's explanation would be to say that both the elevator and you are falling in extend exactly the same way and he iced and promoted this to a kind of new physics law which he calls the equivalence principle so the idea that when you're falling freely it seems that gravity disappears that's what it says it's just the same as the happy thought and the idea is that the gravity should obey this principle somehow the theory of gravity should obey this a new principle and so well that we see this with the astronauts they're both somehow orbiting the Earth in exactly the same way the astronauts and the spaceship and they feel weightless and he realized that this principle led to the idea of general relativity and to the idea that gravity is due to the geometry of space-time gravity's due to the geometry of space-time and that if you have a heavy object it produces some curvature so the space-time is somehow curved and then if you have a second light particle it would follow the trajectory of maximal lifetime in that curved space-time okay so now when we say that gravity deforms the shape of space-time we usually picture this somehow the spaces deform right and that's that correct but in addition something very important and will be very important for what we're going to say is that also the the way time flows is deform so imagine you have a person in the top floor of a building and a person in the lower floor of the building each one has a clock these are two identical clocks made in the exactly same way then what will happen is that the clock in the bottom of the building will go a little more slowly than the clock in the top of the building and this is a very tiny effect for an ordinary building so it's a part in a 10 to the 15 so you need a super good clock to do this but people have this clock so there there's a Colorado they have the NIST they can make clocks that can be detect the different in difference in height of three centimeters so so now we again we can have the something similar to the twins paradox we can have a person who stays near high gravitational field will be younger right and that person is accelerating more is feeling a force of gravity I think we say and same effect that we had when he was traveling and then coming back now ShoreTel very soon after Einstein proposed his equations sure shall we solve these equations in the outside of a massive spherical body so imagine you have a massive spherical start and outside the star there is no matter and you can solve the equations Einstein's equations outside the star and this is a full geometry and this geometry in particular will tell us how time flows for an observer who's sitting at a fixed radial position so for example if we have someone sitting at the surface of the star it its clock will run a little more slowly than the clock very far away right where there is so this feels some weight also this observer feels a certain weight The Observer very far away feels no wait now you can imagine that the star is smaller but with the same mass imagine that same star and we make it smaller and smaller so we're going to do that we're going to follow this process of making the star smaller and smaller so make it a little smaller then the person will feel a larger weight and that his time will run a little more slowly and then something very surprising happen which is that if you make this are smaller than a certain radius smaller than a certain size it looked as if the person would feel here an infinite weight someone's sitting at that position will feel an infinite weight and his cloak or her clock would stop completely okay and this is what surprised Tyne Stein and thought that this was something unphysical that in a real physical process this with this will never happen and not only Einstein but most of the people thinking about this thought in the beginning thought that this was some unphysical feature but yeah the total mass of the star is the same yeah we are taking the same mass and we're making small it's smaller and smaller yeah any other questions well now something we should realize is that those those observers were not falling freely right remember Einsteins happy thought the the idea was that if you fall freely gravity disappears so a question is what happens with those people if they were where they were to fall freely and it turns out that what happens is that they actually fall freely and they can go through that surface where someone who would be sitting at fixed radial position would feel an infinite way if you fall freely you don't feel anything special as you go through that through that part of the space line so there is the earth this is the same diagram of that geometry we have the outside geometry we had the surface that is now called the price on the surface where static observer would feel an infinite weight but the falling observer doesn't feel anything special and then when you go through that you find a new region of the geometry and the new region of the geometry has a slightly different character it looks like a collapsing universe it looks like a Big Crunch universe and that whole region of space-time collapses into what we call a singularity so region where the space-time curvature becomes very large and where if you fell there you would be destroyed so your head would go in one direction your feet in another direction so it's not a pleasant process but the important point here is that you don't feel anything at the horizon you feel something a little later so you fall in and go through the horizon and one problem is that once you go through the horizon it's called horizon because once you go through it there is no way of going back out so no matter what rocket you have you cannot even a little musk cannot make your rocket that can go out of this black hole so because the the singularity this space-time looks like a Big Crunch and the similarities in your future in the same way that you cannot travel to the past you cannot avoid falling into a singularity so singularities in the future and it's not it's not really we should not think of it as inside the black hole like in a special point it's really in the future of the that region now there is an isle nice an allergy that was proposed by bin row which is to think of this space-time as a river so imagine you had a river where we have water flow into a waterfall so waterfall would be analogous to the singularity and then the on this river there are some fish and the fish can travel at some maximum velocity that maximum velocity is analogous to the velocity of light so here in this region the velocity of the water is less than the velocity of light and if a fish swims in that direction that fish can swim upstream and can avoid falling into the singularity but a fish that is sitting at this at this point the velocity of the river becomes equal to the velocity the maximum velocity at which the fish can swim and if a fish is swimming they would just stay there that's analogous to these clocks that stopped at disposal some special position there and if a fish happens to trap to to go into this region of the river where the velocity of water is bigger than the velocity of light the fish cannot do cannot avoid falling into the singularity or the waterfall but something important is that if you are a fish in this river and let's say it's a muddy river you cannot see the shore you cannot see the banks of the river then you you don't realize that you pass this point there is nothing special at this point in the river so a few things were learned once is that once you cross the horizon you cannot get out and then another thing that well took some time to understand what was eventually understood is that the start can collapse into a black hole so you have a very massive star it can collapse into a black hole and also that there are objects in the sky that seem to be black holes the black holes we are talking about so this black holes we are talking about here a row Shasta solutions mathematical solutions of licensure questions but we think that there are objects in the sky which are actually those physical objects described by those equations and the real black holes that we think exists in the universe come in two types some are produced by the collapse of massive stars that have some sizes that range between ten and hundred kilometers and then there are black holes at the center of galaxies which have a much bigger size they have a size of the solar system they are very massive and so you can ask that you can ask how do we see them so when one method is that when you have a black hole and some matter falls into a black hole the matter becomes hot as it falls into a black hole and amid certain characteristic radiation that one can see and astronomers interpreted as a signature of a black hole and more recently people have observed the gravity waves produced when two black holes collide and this sickness of gravity waves are in Nice agreement with what you expect from Einstein theory so these are this is an example of the first process so we have here this is for a very big black host of the size of a galaxy so here we have the galaxies and in the center we have some amplified image here this is four hundred light years the black hole would be a very tiny dot there in the center the size of the solar system is just a few hours so four hundred light years is much bigger but here we see the matter falling in some of the matter falls into the black hole it heats up it some of it comes out as Jets and so on and so you have this very compacts very small object producing this huge humongous structures in the galaxies this is one one type of black holes and most recently a couple of years ago there are this gravity wave detectors there are a couple here in the US there is one in Italy and this one black holes collide they produce gravity waves and this gravity waves can be detected by this gravity wave detectors and the shape of the gravity waves is exactly the one that is predicted from Einstein theory if you assume that the two objects that collide are black holes so this is currently one of the best evidences for black holes because they this the shape of these gravity waves is sensitive to the geometry very close to the horizon of the black hole now maybe I should ask for questions now and because now we're going to start discussing some more theoretical aspects yeah this this is an this is an artist restaurants know these are these are actual actual pictures yeah okay any other question yeah that's a more complicated Astrophysical question that I don't know but the idea is that some of the particles that fall in eventually it's like they bounce back and they go up in that the black hole is spinning that's why there is a special axis and some particles end up going in that those directions oh yes yes they become one black hole yeah they once they collide they soon become one spinning black hole yes yes yes yes yeah go around the black hole so if you don't cross the horizon outside the fries from the geometries the same as the geometry outside the massive body so we were to replace for example the Sun by a black hole we would continue orbiting that black hole the same way that the earth is orbiting the Sun and you could get closer but you have to end well because if you go through the horizon then you can't come back well there is some some some singularity in the interior you could call it the RIP in spaces originally where the curvature is very large yeah but that's inside the horizon so we don't see it from the outside from the outside we see a kind of hole a bottom like a well imagine Waterworld right very deep and you can throw things in the chest fall in nothing happens but if you were they got one that fell in then something would happen to you that was like really an event like well I I don't know the details of that so of the of this high-energy gamma rays I think one theory is that they could be produced by explosions of stars maybe they are produced by some black holes there is some some connection between high energy this high energy cosmic rays and active galactic nuclei which are this black holes that I shown in the previous transparency yeah so I don't have a detailed answer to your question yes yes yes yes yes yes no we don't we don't have we don't have mathematics of this Christ what happens to you when you fall in so I mean that yep we can say that you will die because for that you're done yeah because for because the the mathematics is holes close enough to the singularity where the gravity forces are big enough for you to die but you can ask whether what happens afterwards is there another region of space-time afterwards thus time and and so on and we don't have an exact description of the interior of the black hole so that's where configuration from this very simple equation interesting equation you cannot have a situation where the two black holes collide and all their and initial energy is emitted in two gravity waves in part the tradition of the background is emitted into gravity waves they cannot be all of it so so far we've discussed the black classic black we find the new surprise and that's that we can have white black holes so found the black holes any variation the radiation the temperature of the radiation increases as the size decreases smaller black hole the black hole is putter and with a mean radiation with short temperature and if it is small enough you can see bread and if it's even smaller you can see why he reported the temperatures for black holes for various masses so if you had a black hole which had the mass of the Sun roughly which is these are the docs Astrophysical the black holes that are produced by astrophysics the temperature will be very timing this is a very very tiny temperature these are degrees Kelvin about absolute zero and this temperature is so small that it cannot be measured this effect has not been measured in black holes that have been produced so you can ask what about the black hole which black hole will make white line we have to have size which is comparable to the wavelength of light and so without drop if you have the size of a bacterium such a black hole very pretty big master and that would look quite and you will actually be able to see so if you had such a black poet would be very tiny white light so now let me explain a little bit why so and this is the answer to your question so why why is this the case so the idea is that we stick contradictory particles can be created and destroyed and even in the vacuum itself and but somehow this food is enforced by some policeman the quantum uncertainty principle which says that they cannot measure the energy in very short times so they cannot make precise measurements of the energy over very short times so we're very short times you can't have some negative energies and the policeman cannot really check that the energy so they allow those things to exist this is a rough picture so in in flat space they can exist very long for the negative and can exist for short time and they should quickly identity but in the presence of something else for these our web server is more like momentum so it's something that could be negative so this is different from the inside is offset with negative energy so sum is negative energy from the point of view of the oxide is perfectly legal and this policeman has no problem with it and allows it to exist and this is roughly the mechanism by which God and so I can fall in and the other one can go up now this is likely the black hole emits radiation induces mass we have a finite lifetime so a black hole of the mass of the Sun or beer will live much longer than the age of the universe a black pool that is made with an option than ordinary massless a kilogram we operate in design much much shorter than a quadratic per second and within the amount of an amount of energy worse than any people the process can be very quick at the very end and if you have the quality of the money then it might be evaporating now finally there could be very tiny black hoss producing particular accelerators and those would be carried by these processes no no no black holes were detecting any particle accelerator currently working but this is just a very conservative okay any questions so far yes could you have to reverse you had a negative on energy on the inside and positive on the outside doesn't work well no because the policeman outside really checks positive that the energies are positive outside [Music] I mean you could have a tiny process where you have a little bit of negative energy outside that you have to quickly it would be like to think only that that we completely turn this fact that the black possum evaluation is some interesting critical problems very frankly described described really two problems one question is information so how do you explain temperature temperature goes back to the 19th century and emotional microscopic constituents so the air is colder because the molecules in the air are moving faster so that's how explain blanket in physics and it's the same for anything that is called some is called their constituents their elementary moving faster than the same object minutes ago so so the question roughly the question is what is moving in a black pot why what are this elementary constituents that give rise to the temperature concept concept which is called entropy society more subtle concept which tells us how many microscopic configurations the system has so for example in the case of the molecules they are having how many positions that can be and this you can calculate you can in principle matter in an ordinary system by measuring it flows by knowing how heat flows in and out of the system at various temperatures you can actually measure this entropy how many states or microstate microscopic configuration the system has those those are standard formulas so called statistical so for the black poll we have the mass and talking gave us a formula for the temperature as a function of the mass from this we can calculate this heat flows and we can calculate the entropy and one finds that the entropy is equal to the area of the horizon which turns out to be the so-called blank line so it's the very tiny leg 33 centimeter this is very very small our size is the minimum size we can measure experimentally but that minimum size is to the Planck length it's a very tiny line we we can't currently examine those tiny legs but what this is saying is that if you have an option for a microscopic area to say one centimeter square then this would be a huge entropy it's an entropy which is much bigger than the entropy of any object with the same area but what something interesting is that now we have a interpretation of that saying area and all the time before which is that we come to it as a consequence increases now this is perhaps one of the most important laws in all of physics so entropy is a measure of disorder you are very used to the fact that left alone the store there always increases in what entropy that's the general bottom line a mixing that disorder they're always in prison and the area law comes from Einstein's equations so this should be somewhat surprising because excess equations are deterministic equations they are equations that they didn't know anything about this order apparently they are just to give some initial conditions to evolved and classical equations from a nevertheless now when we asked about the constituents of a black hole they don't depend on this specific matter that we have as we saw before configuration black depend on how you made it so they're universal purposes of gravity and space-time and so by understanding the consequence of a black hole to think that we understand something about the structure and nature of space and it's [Music] so that was one department I haven't taught you what is for citrus are you now I'd like to describe for you the second so that is that we can form a black hole in in different ways and so we can form black put different kinds of stars or you can throw information books etcetera but the black hole will evaporate emitting radiation and in speculation is well if you look perfectly thermal and feature person apparently apparently independent of the in fact mechanics if you form an object in different ways issue the operator he came in also in different ways different ways could be very subtle and cookie almost almost missed English word but there should be at least in principle some way to distinguish so if we take a book and you burn it so the first approximation you just have some smoke and it would be you apparently lost the information about the book but if you managed to gather a small in principle some very advanced civilization might be able to figure out what was in the head at least according to the standard standard mention physics and the question is whether the laws of physics that applied to gravity are also of the same nature and sure to answer this type of questions we really need to have a theory that puts together quantum mechanics and gravity theory is called string theory so I won't give you in theory under construction the theory of quantum gravity is a theory about the quantum mechanics of space-time and it reduces quantum theory under ordinary circumstances or lower inertia so long distances because many other features are not going to discuss but one feature I'm going to discuss is the universe's which come negative curvature and I'll try to discuss this in more detail now but the main point is that the set theory that describes the quantum mechanics of space-time and also it's a tear in the construction we don't know all the college features so there are some questions we cannot answer for example the question I was asked about the what happens exactly in here okay [Music] but we are projecting that negatively curved surface two-dimensional two-dimensional flat surface of the screen so it was about the far away or deformed there they're smaller today something similar happens when you project the surface of the earth on a map the regions near understand the protection the regions near the North Pole and South Pole there and then it is you have a gravitational theories in the space-time pasta dish a button occupations that gravity part of the thing another that can be described in terms of the theory the particles today mean on the contrary the particles living on the boundary are very strongly another picture of the same thing space-time potential there is the temperature and entropy of the platform comes from the temperature and entropy of these movies of particles based on exactly now this this description would have a kind of imagine geometry we have particles are live near the boundary you have some geometry that comes some batteries out of their interactions and this looks a little strange and I try to explain this with an another and another G so it would be an analogy to imagine a sentence now you can and this way you are interpreting the sentence right so whenever you see your friends when you're prank here's the sentence is interpreting the sentence in this way you automatically are doing this in your brain to interpret the sentence and not only you have knowledge I also have some done business relations between parts of the sentence for peace and also some concepts related to commerce and so we have these various correlations within the sentence younger relations so the idea is that the kind of interpretation on this thing is giving us how the information in this encoder this structure of some smaller objects in some bigger and bigger and bigger structures design is capturing the information present at different length scales and then there could be some long-range correlation between specific words that the worsen had before and those particles propagate that's exactly the picture we have a picture like this but a quantum mechanical version please and that is how we understand the merchants of this so we say the letters time doesn't make any sense okay contract - in the words of the dark dark oh now the air person is the amount of ignorance that you have and the area growth is related to the fact that the factory area grows is related to the factor if you change the sentence randomly you are done but now I'm actually produced by a reversible process so I think that is what's actually produced by an encoding process like similar to the encoding process processes that your computers do when you send the credit cards over the internet and so on the computers take that number and they mess it up the producer thinks that [Music] and let me just illustrate so they will not be able to decode but if you knew the algorithms you will be able to decode the sentence we would reverse the process and recover the original sentence and that's another words to the idea that the commission the loss of physics of the boundary change the stake of the system at the boundary and it's the dose of physics are reversible so it's analogous to the laws of physics are analogous to an encryption process they can be they can be somewhat complicated but they are reversible and in principle we can undo the formation and in principle recover the original information and that we can do in the boundary theory because okay maybe that's no different when you see boundaries at the scene is a horizon yeah so in this in order to have a precise description you need to put this on there very far away we only know how to do this in a precise way when the boundaries very far away since at the end of the universe you have a very very big difference and the boundaries at the end of the universe it would be desirable to be able to do this for smaller bounder let's say you take the black pole and you just with the boundary of the price we don't currently know so we can describe not only the black hole but the whole space-time with the black power [Music] I said the theories of particle particle the batter is from the interaction this so you can use now the interior space time to learn about this particles in the boundary so in that that analogy we think about the boundary theory as the particles that live in our space hands could be a system of ways from interacting particles expert a five-dimensional at university I turns out that in this way the products that might be complicated in the boundary theory my become simple in the interior so the complicated quantum mechanical problem in the boundary Theory can become a simple problem in handstand gravity so a simple problem is organized in X equation I sent equations are little indicated but it's easier to solve Einstein's equations than to solve quantum math equations of quantum physics so it's another way that they are getting information of the was some phases of quantum matter nuclear physics also some connections between blackboard presence and the loss of my hands he said that the boundary would have some fluid and that fluid obeys the looks at the dynamics and it turns out that the lots of other dynamics are contained within offense equations so Einstein's equations with a black horizon you can find you bet so now I would like to talk a bit about the connection between entanglement and geometry but other questions okay so we're going to decide up topic so that's out that in this discussion called entanglement you place the important growth contracting the statement you try to discuss only one example of entanglement entanglement is correlation between two quantum systems this a correlation which has bit stronger than classical correlations but which is the solution [Music] the distribution far away here is the best position Bryson is this for a second the interior is this region here you can come from the outside here the advantage of these pictures is the light rays are percent represented as 45-degree line so if you are someone traveling in this space-time you always have to move at the speed which is not now that's one cold and then we have a second black hole horizon and the final thing is that this is like cost-share an interior so we have so they can be [Music] [Music] in this a form of correlation with mechanics so there is geometric connection for entanglement in order to try to explain this and try to again go back to an analogy so let's imagine the we have again the same sentence here we have the sentence in Spanish now here are the correlations between the letters are different right - we have some variations of short distances so these are the correlations of Spanish to us understand the correlations that English castles right but both have this structure meaning of the sentence is the same that we have a common number sentence means that we work through an analysis some kind of analysis of the sentence concise between the sentence in English and the sentence in Spanish and this is how we think about the fact that there is a connection in space between these two black holes will generate now I said that this black hole is not enough for the typical science fiction story but in order to explain what the weird aspects of this blog post out I miscalculations have I'll try to give you another science fiction story imagine that we are in some advanced time in the future civilization and attack each other but their families don't like each other and Juliet in some faraway galaxy Drummond tribute are very very smart and very ingenious and what they do is they change the title precisely in this way for this they need very highly advanced technology that we don't happen very carefully how they would do that but let's imagine they did that so after they do that then they decide to jump into their respective blackboards then let's focus not in the bottom part of the picture so the families see them jumping into blackboard and disappeared behind the black horizon so their families could say that they committed suicide because they fell into a black college and that's the narrator of the story would also say that but if we have this platform we the experience is different they fall into the black pots and they actually meet in the interior because the theory is common and so they and then we can live together for a while and then unfortunately they died at the sink right now there's a way to rescue them now from the outside and so there are still many mysteries so conclusions I hope to have transmitted to you that black holes are fascinating objects where the geometry of space-time is performing in dramatic way black holes and quantum mechanics gives interesting theoretical challenges and string theory describes a cosmic insist from the outside we don't know the inside of each window and space time is an effective approximate concept which seems to arise from more elementary particles even in the bounder space time and this is the current picture that we can use to describe and we also mentioned that the tiny quantum mechanical properties and fundamental role in determining the structure of a [Applause] tankman hood like to say entanglement wouldn't be possible I mean not a lot of penises behind some data from the electrons will see we have one you would know it's been and then if one crosses over the we do not then be able to inaudible at least have some idea about a some of the information that's India you can get direct access to it you know where it is based online partly you do have within your grasp if you will yeah so if you're not too in terminal States and you throw one into a black hole the outside state is still in on a very basic level would you just define space-time connective language are you asking why you use the word space-time you climb a space together no I'd like you to define it okay so space that space-time is a geometric concept and it's defined in terms of the points in space-time so we find a point in space-time it's an event something that happens at the place in space and some time so for example the start of this talk was an event it happen here and it's a particular time the end is another point in helping that some other time and so on when so we often represent space time in space is one dimensional three dimensional just one dimension to visualize this means since this could be from again let's say the start of a job today in this location then we move in that direction so in that direction there is another building here is the other building at that moment the buildings exists a long time so buildings are trying some protectors in space time and the protector of the building that was over there if I got on a traffic light here I would send a signal to the other building the other person in there didn't see the same the signal propagates along all these points in the space-time so this is the deposition of space-time is a collection of events with some causal relation between them so some are to the future of others and also some distances so it's very similar to the definition will be pretty entertaining space you were talking about black balls having lifetimes yes are they on and then off or did they become black holes and then yeah so the idea is that the black cross forms and then it starts emitting Hawking radiation because it the Muscogee radiation induces mass become smaller and smaller and smaller and then in the final processing it means more initial more cotton and faster and it's a big qualitative in quantum optics for weird entangled photons at an earlier time those photons came from a common point yamanori you you seem to eat when you talk to black holes being in fact you are you find that at some earlier time that it's two black holes came from the saia's yes in order to produce them in an entangled way you would have to have a you have to have a common origin so for example when I told the story of Romeo and Julia I said that they exchanged entangled pairs so he produced entangled pairs and then send them to each other and then I'm assuming they have any northern wonderful quantum computers that allow them to form the black holes in any desired stage we don't have such [Music] yeah yeah because the action you show that night with and coming out mentioned that palaces going for our meat Levi yes yes yes they fun preference but they fall into a black hole day I mean the point is that there are lots of particles phony name yep and they're forming a gas in the guts the gas gets compressed and well I mean there are lots of particles so they bump into each other huh yeah yeah he's like many people try to rush out of the room [Applause] [Music]

Channel: Aspen Physics

Views: 4,380

Rating: 4.7611942 out of 5

Keywords: ACP, Aspen Center for Physics

Id: R5monjFomwU

Length: 67min 21sec (4041 seconds)

Published: Fri Aug 24 2018