ICTS Big Questions: A Journey into the Quantum Universe with Subir Sachdev - By International Centre for Theoretical Sciences
Transcript
00:08 | and hello everyone and welcome . Good , good evening | |
00:14 | . Good afternoon , Good morning . Uh , to | |
00:17 | every uh , to all of you who could join | |
00:19 | us today . Uh , we're meeting at a rather | |
00:22 | terrible time in India , as you know , and | |
00:26 | uh , I think many of us have been very | |
00:29 | stressed about situation , the well being of our family | |
00:35 | members , friends and have been tragedies everywhere . It's | |
00:39 | , it's a , it's a kind of a really | |
00:42 | unfortunate period we are going through , but , but | |
00:46 | I thought that we should nevertheless free ourselves on , | |
00:51 | rather not be chained to this uh , to this | |
00:54 | depressing uh , situation that's unfolding around us , but | |
01:01 | perhaps take our mind for a little while , at | |
01:04 | least to something more eternal and more uh , um | |
01:09 | , which will live long past all of us . | |
01:12 | Uh , so , uh , so this is why | |
01:15 | we have today's big questions , cities and uh , | |
01:22 | it's a great pleasure to welcome process to be such | |
01:26 | thing uh from from Harvard to , to to this | |
01:32 | episode , as you know , we we started this | |
01:36 | last year during the lockdown and this is uh a | |
01:39 | bit so we really sort of completing the first year | |
01:42 | of uh this and we have really ventured into many | |
01:48 | different domains uh starting from cosmology , the very big | |
01:53 | and so on and and also the very small , | |
01:55 | the particle physics Fatima then into the world of the | |
01:59 | mind with uh with Syria uh last time into the | |
02:05 | mathematical universe with uh with Angel . Uh today , | |
02:11 | it's a number , very fascinating universe that should be | |
02:14 | able to take us into uh which is the quantum | |
02:18 | universe . Let me just share my slides one minute | |
02:22 | . I just have a little bit of uh this | |
02:25 | thing where where is it ? Okay , yeah , | |
02:29 | okay , so so severe is uh so we'll we'll | |
02:34 | really have a session and so we will hopefully disentangle | |
02:37 | quantum mechanics for us by entangling us into it . | |
02:42 | Uh but uh severe is the hurtle smith professor of | |
02:47 | physics at Harvard . He has is really a pioneering | |
02:51 | physicist and uh numerous recognitions and uh I just wanted | |
02:57 | to pick out the direct medal which cites his pioneering | |
03:00 | contributions to many areas of theoretical condensed matter physics and | |
03:04 | then goes on to list uh really impressive list of | |
03:10 | contributions . The largest on saga price of the american | |
03:14 | uh Physical society is the fellow of the National Academy | |
03:17 | of Sciences and so on and it goes on . | |
03:21 | Uh He has again been a pillar of support for | |
03:26 | I . C . T . S . Uh through | |
03:28 | uh by being part of our international advisory board for | |
03:33 | a very long time , has been helping us in | |
03:37 | as we grow our faculty in different areas , especially | |
03:42 | in condensed matter physics . Um Some beers work has | |
03:45 | been pioneering . It's it's very I think amongst contemporary | |
03:51 | theoretical physicists it's very unusual to have someone like severe | |
03:55 | because uh in any era of specialization where people sort | |
04:01 | of find their nation sort of uh focus on that | |
04:05 | superior has has enormous breath . And this has uh | |
04:12 | we have seen this repeatedly uh in some ways it's | |
04:17 | uh he has brought ideas from string theory from the | |
04:21 | physics of black holes to bear on questions in strongly | |
04:25 | interacting systems , strongly interacting materials and I'm sure you'll | |
04:31 | hear about that from him today . But he has | |
04:33 | also gone the flow has gone the other way . | |
04:37 | So one of the models which is currently very influential | |
04:40 | in string theory for understanding the physics of black holes | |
04:44 | and features like quantum chaos and so on , is | |
04:47 | a model proposed by uh severe that such a week | |
04:51 | I have model which uh has uh has been a | |
04:57 | very uh very uh important model in that it is | |
05:02 | solvable and it's you're able to actually see many features | |
05:06 | which are otherwise normally , which would be out of | |
05:10 | reach uh , to uh , to a sort of | |
05:13 | analytical understanding . And so this has influenced things of | |
05:17 | course , in condensed matter physics , but as I | |
05:19 | said , the ideas have flown the other way . | |
05:22 | So it's very unique to have someone who's sort of | |
05:25 | taken ideas from string theory to subject at first very | |
05:29 | far removed , like condensed matter physics and vice versa | |
05:33 | , head in the flow in the other direction as | |
05:37 | well . So , uh , so this this is | |
05:40 | part of the reason why I think Siberia is uh | |
05:43 | and at the heart of a lot of this is | |
05:45 | the is the phenomenon of quantum entanglement uh which he | |
05:51 | will take us through today . And uh , so | |
05:54 | , uh , but before , before I hand over | |
05:58 | to severe , uh , I just want to mention | |
06:02 | of course uh CTS fundraising thanks to all who could | |
06:07 | contribute to our annual fundraising and you can continue to | |
06:11 | help uh as we build our I . C . | |
06:14 | T . S . Endowment . And a very important | |
06:17 | way in which you can help our efforts . Especially | |
06:19 | now with these with this lockdown is to connect us | |
06:24 | , connect me with potential supporters and val vicious anywhere | |
06:28 | across the world and of course spread the word amongst | |
06:31 | your circles uh for people who might want to be | |
06:35 | engaged with I . C . T . S . | |
06:36 | Uh So thank you again for all your support and | |
06:40 | for showing up at such a critical moment . But | |
06:44 | I hope you will find it uh nevertheless accelerating . | |
06:48 | So uh so the pilot onto the pilot service for | |
06:53 | the journey ? Yeah . Okay . I hope you | |
06:57 | can hear me and see my screen and see the | |
07:01 | yellow green circle . That's all right rajesh . Yes | |
07:04 | . Yes . Okay . Well thank you very much | |
07:07 | strategies for that . Very , very kind introduction . | |
07:11 | Uh , I must say I should also say a | |
07:14 | few words about the incredible work that you rajesh and | |
07:19 | also spent a warrior have been doing . And uh | |
07:23 | , uh , not only doing high quality physics , | |
07:26 | uh , in India , but also at the same | |
07:28 | time building this incredible institution CTS , which I I | |
07:32 | love to visit partly because it's it's the town that | |
07:36 | I went to school in Bangalore . Uh , and | |
07:41 | I hope the situation in Bangla is going to improve | |
07:43 | soon . And uh , I look forward to my | |
07:45 | next visit to see you . Okay . So , | |
07:50 | so I'm really flattered to be asked to talk on | |
07:52 | big questions . That's not the way I approach my | |
07:55 | research . Normally I just think about some tiny little | |
07:58 | question and then maybe later on it has something back | |
08:01 | in some other question . But so I started , | |
08:04 | you know , thinking about how to phrase how to | |
08:07 | present some of the things I've been working on , | |
08:10 | some big context . So I'm going to go really | |
08:12 | big inspired by rajesh . So forgive the , you | |
08:16 | know , the reach . But anyway , I think | |
08:17 | it be found anywhere to connect this up too , | |
08:20 | other big questions in the history of physics . So | |
08:24 | let me begin , uh , by , by Newton | |
08:27 | . So we've all heard of uh , in high | |
08:29 | school and the Newton's laws of motion . Well , | |
08:32 | they were probably not due to him . I think | |
08:35 | most of them are understood before what we learned in | |
08:37 | high school . But what was really new to Newton | |
08:40 | was something uh , also something more remarkable . What | |
08:46 | do you show for the first time that the same | |
08:48 | laws of motion apply to the planets on planetary scales | |
08:54 | , which is about a trillion meters . That's the | |
08:57 | , roughly the size of the solar system . Uh | |
09:00 | , as they applied , you know , two apples | |
09:02 | falling on earth exactly the same laws . The laws | |
09:07 | were exactly the same . You could by computing the | |
09:09 | motion of the planets , uh , then reduce how | |
09:13 | fast an approval for . And this was really a | |
09:16 | very big thing . It was really the first time | |
09:18 | that , that , you know , people understood that | |
09:23 | what's happening in the heavens , it's also what's happening | |
09:25 | on the Earth . It's the same , it's the | |
09:26 | same laws . Uh , and so newton scan , | |
09:30 | very vast distance scale , from Julian meters , uh | |
09:35 | , to about a meter . And of course , | |
09:38 | and everything in between . And as far as people | |
09:41 | learned over the next 200 years , everything worked perfectly | |
09:45 | . So , in some sense , Newton has , | |
09:47 | some people thought , you know , that was the | |
09:49 | end of physics . What else is there to do | |
09:52 | ? Of course , that's not true at all . | |
09:54 | Uh and you can say the physics in the , | |
09:57 | you know , the 20th century and the 21st century | |
10:00 | is about extending the reach of this range , or | |
10:05 | to even larger scales and smaller scales . And and | |
10:10 | that's kind of what I'm gonna try to do today | |
10:12 | , just quickly . Uh so let's keep going to | |
10:15 | even smaller and smaller scales from an apple to a | |
10:19 | dust particle to even smaller scales , uh , grains | |
10:25 | of pollen . People could see that things worked exactly | |
10:28 | the same . Newton's laws were still okay Up until | |
10:32 | around the early 1900s , when people started to understand | |
10:37 | that in fact , mutants didn't apply at a scale | |
10:41 | , which is around 10 to 3 to minus 10 | |
10:44 | m , 1/10 of a nanometer , uh , which | |
10:48 | is the size of a hydrogen . And so in | |
10:50 | a hydrogen atom , you have an electron uh in | |
10:55 | in the right to food picture going around like a | |
10:58 | planet around the nucleus , which is positively charged proton | |
11:03 | . Um And initially people started to apply newton's laws | |
11:06 | of motion to this electron also , but it became | |
11:10 | very clear , especially , you know , from observations | |
11:15 | that I won't have time to go through , that | |
11:17 | this simply did not work . Uh So there was | |
11:20 | just again , a plethora of observations started with the | |
11:23 | so called black , black black body spectrum and various | |
11:27 | measures of spectra of atoms and so on and so | |
11:31 | forth . Uh And then uh you would say there | |
11:34 | was a big event , almost as big as Newton's | |
11:37 | discovery of the universal law of gravitation , Which was | |
11:42 | the discovery of the quantum theory uh by shorting and | |
11:45 | Heisenberg in 1925 . So there was a new theory | |
11:49 | which could describe perfectly uh we know today not just | |
11:53 | the structure of a single heritage and item , but | |
11:55 | partisan molecules , you know big molecules D . N | |
11:59 | . A . And so on . So and even | |
12:02 | big crystal and solids as we talk about nature . | |
12:06 | So and this theory initially seemed like a small deviation | |
12:10 | some correction to nutrients framework . But soon it became | |
12:14 | clear that it was something much more radical . Introduced | |
12:18 | a whole new idea into physics and into our theory | |
12:21 | of the universe that didn't exist at all in the | |
12:25 | new Newtonian formulation . And this is the idea of | |
12:29 | the principle of superposition . So I'm sure most of | |
12:33 | you've heard about the famous cat which is both dead | |
12:36 | and alive . That's of course just uh you know | |
12:40 | nobody's ever achieved that uh would be very very difficult | |
12:44 | to have such a proposition of a life can that | |
12:47 | cat ? But it just makes the basic point which | |
12:51 | can be achieved in uh in much smaller objects , | |
12:54 | is that you could have a physical system which is | |
12:57 | in two distinct states , for example , an electron | |
13:01 | , uh , you know , at one position and | |
13:03 | in a different position , you could make a state | |
13:07 | of the electron , which is in fact in both | |
13:10 | states at the same time . So you can superimpose | |
13:13 | , you can take two distinct physical states and make | |
13:17 | another state , which is the sum or difference of | |
13:19 | them are actually more any linear combination and add and | |
13:23 | subtract states . So that's really the if you when | |
13:26 | you when you dig down into what's going on in | |
13:28 | the quantum theory , it took a few years to | |
13:31 | appreciate this . That's really what the heart of everything | |
13:36 | , the principle of superposition . Uh So once people | |
13:41 | understood this , you can now ask the converse question | |
13:44 | . Now , we've gone on to very small scales | |
13:45 | and you've discovered this principle . Uh no , let's | |
13:49 | go back up and scale things up , not just | |
13:52 | up to a cat all the way to the solar | |
13:55 | system and even beyond it , is this still apply | |
14:00 | ? Uh So the short answer is there , as | |
14:02 | far as we know today , the answer is yes | |
14:04 | . And I'll try to give you some flavor of | |
14:07 | the type of questions people have been addressing uh to | |
14:10 | to to go from the small to the large now | |
14:13 | . Um All right , so let's just take that | |
14:17 | one step at a time . So here I'm going | |
14:19 | to take two electrons , not one electron . Uh | |
14:22 | So the very simple picture of a hydrogen atom is | |
14:25 | an electron that's orbiting around uh the item , but | |
14:28 | it also spin on spins on its own axis . | |
14:31 | Uh And it turns out the spin is a very | |
14:35 | simple object corner mechanically . Uh So quickly summarize by | |
14:40 | saying that the electron can only spin clockwise or anti | |
14:44 | clockwise . So there's two possible states of the spin | |
14:46 | of the electron , let's say the alphabet represented spinning | |
14:50 | anti clockwise counterclockwise and the down arrow representing spinning clockwise | |
14:57 | . Okay , so now let's take two electrons , | |
15:00 | as you'll find in the hydrogen molecules with these two | |
15:02 | protons and two electrons . A very simple description uh | |
15:08 | of the state of every hydrogen molecule that's out there | |
15:13 | is this particular state . Uh And this state is | |
15:17 | a superposition now again for in principle of to physically | |
15:20 | distinct states . And the state on the left uh | |
15:24 | is an electron that spending the first electron on the | |
15:27 | left adam is fitting . That's a counterclockwise and the | |
15:31 | electron on the right items spinning clockwise . But there | |
15:35 | is another distinct state . But the electron on the | |
15:38 | left adam is spinning clockwise and the one on the | |
15:41 | right edge and spinning counterclockwise . So these are two | |
15:44 | distinct states . And you know , in principle , | |
15:46 | if I could do a clever enough experiment , I | |
15:49 | could go in and measure which direction is this electron | |
15:52 | spinning . Uh And you know , I could either | |
15:56 | see a clockwise or counterclockwise electron . But the actual | |
16:00 | state of the electron is the superposition of these two | |
16:04 | distinct states . It's really in both at the time | |
16:07 | and until you look at it , you don't know | |
16:10 | which one is it ? It's really involved . Uh | |
16:13 | Okay , so but you do have something strange emerging | |
16:17 | here , which is the start of what we call | |
16:19 | entanglement . If you measure this electron and you find | |
16:23 | that it's that is up or counterclockwise , then the | |
16:28 | other one necessarily is clockwise . So there is a | |
16:35 | perfect correlation between the orientations , but you can't tell | |
16:39 | which one of which one is up and which one | |
16:41 | is done , but you're sure that one is up | |
16:43 | , the other star . And it's only the act | |
16:45 | of measurement that determines which is which . Alright , | |
16:49 | so that's you know , now the same idea of | |
16:51 | superposition already started trying to starting a song . Very | |
16:55 | , very strange in for a single molecule . But | |
17:00 | this is no question that this is what happens . | |
17:03 | Ah So the world corn of entanglement is a modern | |
17:07 | world . I'm not sure exactly what it entered our | |
17:10 | lexicon , but this paper were Einstein , Podolski and | |
17:13 | Rosen . I don't think they use it in this | |
17:15 | paper either , but they put their they really pointed | |
17:19 | out the essence and the mystery of entanglement . So | |
17:23 | one way to state their argument is , imagine you | |
17:26 | have this uh hydrogen molecule and you do a very | |
17:30 | clever experiment where you separate the two atoms and their | |
17:35 | electrons without disturbing them without disturbing the spin in particular | |
17:39 | . That's very hard to do . But imagine you | |
17:41 | could do it in principle , you can do that | |
17:44 | . And this particular adam put the , you know | |
17:46 | , with me in boston and principal and the other | |
17:48 | one would be in Bangalore . Ah The corner mechanics | |
17:52 | would say that they're still entangled , that they're still | |
17:56 | correlated . Uh And nobody knows whether the electron and | |
18:00 | electron in Bangalore Is up and the one in Boston | |
18:04 | is down or vice versa . In fact , it's | |
18:06 | not even determined . It it's only the act of | |
18:10 | measurement which will because of the way you perturb the | |
18:13 | system . This is kind of like the uncertainty principle | |
18:16 | in action that will determine which is open , which | |
18:19 | is down . So it could be this way or | |
18:22 | that way we don't know , they're still entangled . | |
18:25 | Uh And it's only the measurement of an electron which | |
18:28 | determines the state of the other electron . So this | |
18:33 | is something that in fact E . P . R | |
18:35 | . Found unacceptable . And they pretty much said in | |
18:38 | the title of the paper , something is wrong with | |
18:40 | . Quantum mechanics are incomplete . Is a precise where | |
18:43 | they use this can't possibly be the case . Uh | |
18:47 | The theory is bizarre and it seemed like you know | |
18:53 | , something was traveling instantaneously from boston to Bangor . | |
18:57 | Okay , so the answer is this is in fact | |
19:00 | what happens uh Nothing is traveling instantaneously . The concept | |
19:05 | we have to then accept is that the entanglement or | |
19:09 | the concept of a quantum state is not a local | |
19:11 | concept and the state is not neither in boston northern | |
19:15 | dangle or it's it's really in both places . Uh | |
19:18 | That's really one of the radical ideas that comes out | |
19:22 | of quantum mechanics . Um Okay So now today of | |
19:26 | course there's almost 1935 . Like this is an article | |
19:30 | in New York Times , uh talking about an experiment | |
19:34 | number two electrons , but two photons to be uh | |
19:38 | little lumps of light , 1.3 kilometers apart where they | |
19:42 | did indeed say this , this this does happen . | |
19:44 | And that I think uh now , five years later | |
19:48 | there's much even longer scales . Much better experiments showing | |
19:52 | what people say , spooky action . Einstein called spooky | |
19:56 | action . But again , uh that's a pocket . | |
19:59 | So I don't think you ever use those words , | |
20:00 | but anyway , All right , so that's then a | |
20:06 | description of entanglement . Uh just two particles in this | |
20:12 | . Even in this experiment , we're talking about two | |
20:13 | particles on the very small scale . So let me | |
20:18 | know , change gears completely and go back . Actually | |
20:23 | , strictly speaking , very , very heavy . We | |
20:25 | were talking about single electrons , let's go to very | |
20:28 | , very heavy objects black holes . So , a | |
20:34 | black hole , it's it's so heavy that is full | |
20:38 | of gravitation , is so strong that if some adam | |
20:41 | inside the black hole emitted a being of light , | |
20:44 | the light would start to escape the black hole , | |
20:47 | but then would be pulled back and would never be | |
20:49 | able to go . Uh So there's a horizon beyond | |
20:54 | which uh no , like whatever ever escaped from the | |
20:58 | inside of a black hole , because the gravity of | |
21:00 | photo gravity is so strong , okay . Um and | |
21:05 | and this the existence of black holes and many of | |
21:08 | the properties was really came about from Einstein's theory of | |
21:11 | general relativity , 1918 . Uh and that's before the | |
21:17 | invention of the quantum theory in 1925 . Uh And | |
21:21 | and , you know , it was also , it's | |
21:23 | an amazing theory , but one thing to keep in | |
21:26 | mind , it is not as radical departure from Newton's | |
21:29 | equations as the core . In theory , it can | |
21:32 | be viewed as some kind of correction uh to Newton's | |
21:35 | equations , when things move really fast near the velocity | |
21:39 | of light . Uh it's really the same Newtonian framework | |
21:43 | except you have to uh you know , okay , | |
21:46 | you have to think about curvature of space time , | |
21:50 | but still within the its evolution , natural evolutionary mutant | |
21:54 | . It's not a radical departure like Volunteer was . | |
21:58 | Uh so in particular , Einstein's theory would give you | |
22:01 | this radius of horizon for a mass , M . | |
22:04 | G is Newton's constant and see as the velocity of | |
22:06 | light . This is the only equation I really use | |
22:10 | uh if you plug in here , earth mass , | |
22:13 | you get a radius of nine millimeters . So that's | |
22:16 | how dense you have to make things you predict the | |
22:18 | whole Earth and squeeze it down to nine millimeters for | |
22:21 | the earth to become a black hole . uh so | |
22:24 | this was thought to be completely ridiculous uh in the | |
22:27 | 1920s and 30s and much later , but today we | |
22:31 | know there's lots and lots of black holes out there | |
22:34 | . So now they're going really big . Uh this | |
22:36 | is a picture that actually my wife Lucia pointed out | |
22:39 | to me in the popular press recently Showing 25,000 miracles | |
22:45 | , supermassive black holes . Uh These are black holes | |
22:48 | are a million to a billion times the mass of | |
22:51 | our sun . And each one of these dots represents | |
22:55 | a supermassive black hole at the center of its own | |
22:59 | galaxy . So we can't see the galaxy in this | |
23:01 | particular view because of the frequency at which they're looking | |
23:05 | at it . Uh And each black hole is about | |
23:09 | 10 times larger than a son . Uh and it's | |
23:12 | at the center of its own galaxy . In fact | |
23:14 | , it's almost as bright as the rest of the | |
23:16 | galaxy , and including our own galaxy has such a | |
23:18 | huge black hole at the center of it . All | |
23:23 | right , so , now I've told you about the | |
23:24 | Newtonian Einstein theory of black holes and how they're out | |
23:28 | there . And everything in these and similar observations agrees | |
23:33 | with the predictions of Einstein's theory , but Phyllis being | |
23:37 | Phyllis is they don't stop with just uh you know | |
23:40 | , what's what's possible , They've got what's been done | |
23:43 | the time to think of what could be possible . | |
23:45 | So , so we developed this theory of the very | |
23:47 | small the quantum theory . Uh and so like Newton | |
23:51 | , they're going to try to scale it up all | |
23:53 | the way to black holes . And as is there | |
23:56 | any effect of the quantum theory on black holes , | |
23:59 | Is it going to change anything ? Um And this | |
24:02 | step was really first taken by Stephen Hawking in a | |
24:06 | sense , that was his most important contribution . Uh | |
24:10 | and one way to understand what he did , although | |
24:12 | he didn't phrase it in these terms , is to | |
24:14 | take again take a pair of entangled electrons and imagine | |
24:19 | that somehow you can separate them , we're putting one | |
24:23 | inside a black hole and the other outside of that | |
24:26 | . Then the quantum theory would say that they're still | |
24:29 | they're still entangled . There's no uh just because you're | |
24:33 | , one is inside and outside the black hole , | |
24:35 | it doesn't matter as long as you didn't disturb the | |
24:37 | spin , they're still intact uh and vice versa . | |
24:43 | So , so that's again very bizarre . And one | |
24:46 | of the consequences of this was that black holes turned | |
24:51 | out , okay , this I've already said this quantum | |
24:54 | entanglement between the inside and the outside of black hole | |
24:57 | and a consequence of this entanglement um is that black | |
25:01 | holes actually have a temperature ? Uh They're not just | |
25:06 | disquiet isn't uh body out of it , nothing can | |
25:09 | ever escape . They're ready very , very slowly and | |
25:13 | very low temperature , uh you know , light and | |
25:17 | energy and small particles ah and what hawking computed not | |
25:23 | buy this argument with some related argument that what the | |
25:28 | temperature of every black holders and we call it , | |
25:30 | of course , the hugging temperature . Well from the | |
25:33 | entanglement point of view , you can understand this in | |
25:36 | the following manner . Say I'm outside the black hole | |
25:39 | and I have uh this electron with me . Uh | |
25:45 | you know , it's entangled with the other electron which | |
25:47 | is inside the black hole , but there's no possible | |
25:51 | way I can never figure out over any conceivable time | |
25:54 | uh until the black totally evaporates when we're not going | |
25:58 | to wait that long . What's happening to this one | |
26:00 | ? So that black , that other electron is just | |
26:04 | totally gone . It's beyond the horizon , It's inside | |
26:08 | the horizon . So for me , this electron is | |
26:11 | really not entangled with anybody . Uh it's totally random | |
26:15 | and randomness , you know , is the essence of | |
26:17 | temperature and entropy . That's how things become hard and | |
26:21 | become random . So this electron seems like a hard | |
26:23 | electron to me . And that's roughly how you can | |
26:27 | understand the existence of black hole . All right , | |
26:32 | so this is one of the I think uh this | |
26:35 | is hawking is really greatest discovery um that the corn | |
26:39 | um theory from the very , very small applied to | |
26:42 | the very , very big does have some consequences , | |
26:45 | although in this case the consequences so far are so | |
26:47 | weak that there hasn't been any experiment detecting this consequence | |
26:51 | . But who knows in the future it could well | |
26:53 | be . Uh All right . So now I want | |
26:57 | to uh you know , try to connect the small | |
27:00 | and the big with this entanglement a bit bit more | |
27:04 | so Hawking had of course a very brilliant advance , | |
27:06 | but it was short of a complete theory . Many | |
27:10 | questions it opened up as many questions uh as it | |
27:14 | answered . Uh you couldn't really tell , you know | |
27:17 | exactly how information will be preserved as a black hole | |
27:20 | started radiating away and evaporating uh and what happened when | |
27:25 | it became really small . So there are many many | |
27:27 | complicated questions Hawking's theory raised , which I think the | |
27:34 | community has been a lot of progress on . But | |
27:35 | it's still , I would say there's still many , | |
27:37 | many open questions uh starting , you know , even | |
27:41 | though there's an enormous amount of work since how things | |
27:44 | work . Uh and part of the reason is so | |
27:47 | difficult is that having a complete theory of a black | |
27:51 | hole of entanglement on the scale of a black hole | |
27:55 | is that we have to consider not just to particle | |
27:57 | entanglement , as I'm stanford all skin rosen talked about | |
28:01 | , but multi particle entangled but entanglement for essentially infinite | |
28:05 | number of particles , all of the particles making up | |
28:08 | a black hole . We have to figure out some | |
28:10 | general theory of how they entangled with each other and | |
28:14 | there's really no such plate theory . Uh But this | |
28:21 | problem of multi particle entanglement for over in the last | |
28:25 | , I would say 20 years or so , over | |
28:26 | 30 years and started to appear in other branches of | |
28:29 | physics , which are closer to branches that I work | |
28:32 | on . Many of you may heard about kind of | |
28:35 | computers and in some ways that is what point of | |
28:38 | the building is . It's the way it's a way | |
28:41 | of controlling the entanglement of many particles . Computer scientific | |
28:45 | , all 10 cubits . Uh in a way that | |
28:47 | you could prepare something useful . But controlling entanglement is | |
28:51 | extremely hard because you have to really separate those degrees | |
28:55 | of freedom from everything around them from the environment . | |
28:59 | Uh And and that's really , you know , the | |
29:01 | challenge that the whole thing is facing , whether they'll | |
29:04 | be able to overcome that and uh they're making small | |
29:09 | steps towards that direction . But I would say a | |
29:11 | long way from having some useful calling computer at this | |
29:15 | morning . Ah And finally another place where multi particle | |
29:20 | entanglement appears is in the study of certain materials . | |
29:25 | Sometimes we call them corner materials . These are crystals | |
29:29 | with multiple elements which were on their own display phases | |
29:33 | with multi electron and time when you just make the | |
29:35 | crystal in the lab and the electrons turned out to | |
29:38 | be entangled in some complicated way . Uh And then | |
29:42 | you can study their properties and this is , this | |
29:45 | is usually the world that I live in . So | |
29:48 | here is a very famous example . It's made up | |
29:51 | of these elementary tune barium copper oxide . Uh Here's | |
29:55 | a picture of little pieces of the crystal is the | |
29:58 | structure of the various atoms that repeat themselves in this | |
30:02 | configuration to form a crystal like that . And it's | |
30:05 | what's called a high temperature superconductor . Uh what you | |
30:10 | mean by that is you could take this little uh | |
30:13 | little palette of peroxide uh and different in liquid nitrogen | |
30:19 | . That's what's been done here to this talent here | |
30:22 | and it's placed over a bunch of magnets . Uh | |
30:25 | And then yes , I hope you can see the | |
30:27 | movie . The rest of there's this uh superconducting magnet | |
30:31 | floating over the honoring magnets . Uh and of course | |
30:37 | it fell down because it's got hot once it gets | |
30:40 | above about 100 Kelvin . Uh then then it no | |
30:44 | longer super conducts . All right . So trying to | |
30:48 | does this behavior was discovered around 1987 1988 , just | |
30:53 | when I was starting my career as a physicist . | |
30:55 | Uh , and I've been thinking about such materials ever | |
30:58 | since . Uh , they show what we call the | |
31:01 | phase diagram . This is here on the horizontal axis | |
31:05 | , change the density of electrons in the crystal by | |
31:08 | some clinical means . You're raising the temperature and here's | |
31:12 | the superconductor that I just showed you . But most | |
31:16 | interesting is some regime here that people call the strange | |
31:19 | metal . Strange . Well , because it's strange and | |
31:23 | our current understanding and this strange metal is actually a | |
31:26 | phase where there's complicated multi particle entanglement really at many | |
31:32 | , essentially all scales , uh , in the crystal | |
31:36 | . And that's why the metal behaves in such a | |
31:38 | bizarre way . Okay , so , uh , so | |
31:43 | that's uh , you know , the domain that I | |
31:46 | mentioned here earlier of Corner Materials , where that's an | |
31:50 | actual material which displays faces . A multi electronic entanglement | |
31:55 | . So they are black holes . This Corner computers | |
31:58 | , maybe someday with controlled entanglement here , we can't | |
32:01 | control it , it does what it wants to do | |
32:03 | . And we're trying to figure out what it's doing | |
32:05 | in the corner materials . So , let me just | |
32:09 | finish by mentioning uh the s like a model that | |
32:15 | is frequently mentioned the beginning . Uh So , this | |
32:18 | is a , you know , a model that I | |
32:22 | cooked up in 1993 . Uh just trying to find | |
32:27 | some model of multi particle entanglement from which you could | |
32:30 | say something definite . So , it was really born | |
32:34 | of desperation . I was trying to understand the the | |
32:38 | strange metal phase and is still working on that . | |
32:41 | Uh So we wanted to find some simple , simplest | |
32:45 | model , but you can make some progress . Uh | |
32:49 | and it turns out we're still discovering many features of | |
32:53 | the ceasefire came out through uh and it has some | |
32:56 | very interesting structure of entanglement , uh which is , | |
32:59 | in a sense , scaling variant uh and allows you | |
33:02 | to go from a very small to the very big | |
33:05 | . Uh so has a scaling variant diagnosed structure , | |
33:09 | electrons entangled really , mostly speaking at all distance and | |
33:13 | time scales . And understanding how that happens in this | |
33:16 | model has led to new insights on the physics of | |
33:20 | strange metals . Uh and as Rogers also mentioned uh | |
33:24 | these days and understanding the structure of black holes . | |
33:27 | Okay , so , so what is the heart of | |
33:31 | this uh disability for this simple model to describe such | |
33:36 | very different systems , apart from the fact that it | |
33:38 | involves entanglement ? Well , if you in the original | |
33:43 | variables that you wrote in town , uh it's very | |
33:47 | much motivated by what's happening in that crystal , how | |
33:51 | the electrons are moving around . We try to make | |
33:53 | a model of how the electrons moving around and got | |
33:55 | a strange matter , but over the years , inspired | |
34:00 | in particular by many developments in string theory , uh | |
34:05 | the concept of duality has played an important role . | |
34:08 | So you can take a new dual set of variables | |
34:12 | . Uh so these are describing the same system , | |
34:14 | but in a very different way . And these dual | |
34:18 | sort of variables in fact end up obeying equations which | |
34:22 | are very similar . The equations of Einstein's , the | |
34:26 | combination of Einstein's theory of general activity and for the | |
34:30 | mechanics , and this has led to insights on a | |
34:33 | certain class of black holes . Okay , so let | |
34:39 | me just uh fortunately it turns out I can describe | |
34:42 | it as like a model just in a few pictures | |
34:45 | . It's really that simple . And so I'll close | |
34:48 | with that , show you a picture of it . | |
34:50 | Uh so what you do is you take a bunch | |
34:52 | of positions uh placed randomly and then you put in | |
35:00 | occupy some fraction of them with electrons . So here | |
35:03 | each cripple dark represents an electron . I'm ignoring it | |
35:07 | spin . So it just let me just imagine the | |
35:09 | spins are all up . Um and you put a | |
35:13 | hole bunch of them on these traps and now you | |
35:17 | want the electrons to move around because of the uncertainty | |
35:21 | principle . Uh they want to hop to other places | |
35:24 | just naturally from corner mechanics . That's what you call | |
35:28 | tunneling from one side to the other . Um So | |
35:32 | the electrons , you want them to turn all around | |
35:34 | now , if you just let them turn around as | |
35:37 | they as they wish , Uh then you get a | |
35:42 | metal . So that's been , you know , understood | |
35:43 | for 50 years or even longer . Uh if you | |
35:46 | take a bunch of random positions and allowed uh electrons | |
35:50 | to move around , you get a metal , which | |
35:52 | is not what we want to understand . We understand | |
35:55 | metals extremely well . So what you have to do | |
35:59 | is something just put a little twist , put a | |
36:01 | little restrictions on how they can move . And the | |
36:04 | restriction is that they move in pairs . That's it | |
36:08 | . So , for example , this pair of electrons | |
36:10 | can tunnel uh from here from these two sides to | |
36:16 | these two sides . Now , the electrons are identical | |
36:20 | particles . So you can't distinguish quantum mechanically between this | |
36:24 | tunneling and this tunnel . It could be that this | |
36:27 | one went here and that one went there . They | |
36:29 | really both happened at the same time , effectively . | |
36:33 | And so you can see that what this process leads | |
36:36 | is an entanglement . It generates entanglement even though initially | |
36:40 | it wasn't there . Uh huh . So these two | |
36:43 | can hop around . And and that particular hopping happens | |
36:48 | at some some rate , which depends on exactly the | |
36:51 | environment you put these electrons in , uh and so | |
36:56 | on . So you pick any two sides and you | |
36:57 | allow them to pop that way . And for each | |
37:02 | one of these pig processes , you attach a number | |
37:06 | number roughly tells you often that particular event is going | |
37:11 | to happen and these two let's move here to there | |
37:14 | and in a real crystal , these processes happen . | |
37:17 | And it's a very complicated process to figure out what | |
37:20 | that number is that you're attached to each process . | |
37:23 | Yeah , So our idea , it's ridiculous how simple | |
37:28 | it was . It was to say , okay , | |
37:30 | I don't know what's happening . So to each of | |
37:33 | these processes , just attach a random number , an | |
37:37 | independent random number for every process . So everything that | |
37:40 | can happen is allowed to happen and how often it | |
37:43 | happens is ranked uh huh Amazingly . that gave really | |
37:48 | the first sub model that you could work out completely | |
37:52 | and understand now in great detail the structure of the | |
37:56 | many particle entanglement . Once you allowed these amputees each | |
38:01 | of these processes to have a random number associated . | |
38:05 | Okay , uh so the pair there and each of | |
38:08 | this entanglement is happening with the random aptitude is the | |
38:12 | technical word that we use uh quantum mechanically . Okay | |
38:17 | . Uh I think that's it . So , so | |
38:21 | that's that's what the s like a model . It | |
38:23 | is . It's really has entangled . I got all | |
38:25 | the distances in all times and that allows you to | |
38:29 | describe things that are in a little crystal all the | |
38:33 | way up to black holes . And we're really learning | |
38:38 | a lot these days by connecting the very small to | |
38:41 | the very big , not only by the s like | |
38:44 | a model , but also many other models , including | |
38:48 | , and in particular , this duality that I mentioned | |
38:50 | is something radishes . Uh It's a very brilliant contributions | |
38:54 | recently , more in the context of string theory . | |
38:57 | The duality between these two different ways of looking at | |
39:00 | intact . So thank you Roger . Mhm Thanks a | |
39:05 | lot severe for that , taking us through this vast | |
39:09 | landscape in uh and giving us a glimpse of uh | |
39:14 | one of the things that I think most strikes me | |
39:17 | about these developments that you've been pioneering is the interconnectedness | |
39:22 | of ideas and theoretical physics . How you cannot really | |
39:27 | kind of put firewalls . So to say between different | |
39:30 | areas , ideas , you have to let the ideas | |
39:34 | move around in idea space and they find new homes | |
39:39 | , they find new , remarkable ways . And and | |
39:42 | each time you get these sort of when you view | |
39:45 | things like when you start viewing black holes in terms | |
39:48 | of strange metals , that's just completely mind blowing . | |
39:51 | I mean that you can do that . I mean | |
39:54 | they seem like completely pulls apart but that's I think | |
39:58 | the remarkable thing about physics . Uh So uh so | |
40:04 | please ask your questions about , you can ask on | |
40:09 | the chat , you can unmute yourself and uh you | |
40:14 | can ask , put up your hand and ask to | |
40:17 | be in muted uh etcetera . So , so uh | |
40:23 | let's uh and feel free to talk about , ask | |
40:28 | about anything . As they say that you were afraid | |
40:31 | to ask anything about quantum mechanics , that you were | |
40:34 | always uh that you were very uh mystified by . | |
40:40 | So as you can see the this structure of quantum | |
40:44 | entanglement is is at the heart of a lot of | |
40:48 | things . I think even some of these new materials | |
40:51 | that should be mentioned that uh these are things that | |
40:55 | are likely to sort of appear in our lifetime , | |
40:58 | uh things around us . I'm sure they are going | |
41:03 | to revolutionized technology in the future . So there's a | |
41:09 | question from sign they've about is the duality uh also | |
41:14 | related to the small dissenters duality conjecture from string theory | |
41:19 | . Uh Oh , yes , of course . Yeah | |
41:22 | . So there's there's a duality in string theory is | |
41:25 | sometimes called the dsc F . T duality , uh | |
41:28 | which is , I think it's much more than a | |
41:31 | conjecture today , especially different . Some of the work | |
41:34 | by Rajesh recently , uh it's essentially proven that there's | |
41:39 | a duality between uh uh well , what are called | |
41:43 | informal field theories , So informal field theories are not | |
41:47 | quite strange metals , they're similar , but there is | |
41:51 | another form of matter that's not , doesn't occur in | |
41:54 | the real , in the natural world that easily uh | |
41:57 | with , with long range entanglement . So , Cook | |
42:01 | . And so that's a duality between informal field theory | |
42:04 | and black holes . The duality between the , so | |
42:08 | I came out on black holes is a cousin of | |
42:10 | that . Uh it doesn't have a formal field here | |
42:13 | on one side . I'm exactly the same type and | |
42:18 | yeah , okay . Uh it's in fact it's much | |
42:21 | simpler version of it because it's essentially proven without doubt | |
42:26 | by starting from either side . Uh and uh okay | |
42:31 | , because yeah , the two are similar so now | |
42:37 | , but I , you know , I will say | |
42:39 | in that , although I was able to describe the | |
42:44 | S . Y . K model in a few pictures | |
42:46 | , you have to take a whole year of string | |
42:49 | theory to understand informal field leaders . So it is | |
42:53 | a lot lot simpler . So Roger Banerjee asked how | |
42:59 | do two electrons decide to entangle uh in some sense | |
43:03 | ? Uh uh when when how do they get entangled | |
43:08 | or ? Yeah . Right . So , uh I | |
43:13 | think so , these pictures that I showed were kind | |
43:17 | of misleading . So let me share again . Ah | |
43:22 | , I mean that's the best we can do . | |
43:24 | Right . So I was uh , so you have | |
43:29 | these electrons and I was sort of pretending that things | |
43:33 | are evolving in time , but these electrons sit here | |
43:36 | and then two of them move and the two of | |
43:38 | the others move and so on . But really they're | |
43:43 | all happening at the same time . So the time | |
43:45 | evolution and the slides is totally fake . Uh there | |
43:51 | there's a certain attitude for any pair of electrons to | |
43:54 | entangle . So it's a number that you assigned at | |
43:58 | some point . It depends on how far apart they | |
44:00 | are . How , you know , what's the nature | |
44:03 | of the interaction between them ? There's some electrical forces | |
44:06 | that you have to worry about . So once , | |
44:08 | you know , all those forces , there's a certain | |
44:10 | rate at which they were attacked . And that's true | |
44:14 | for any pair of electrons in the set . And | |
44:17 | what makes this uh you know , quantum problem is | |
44:19 | all of that is happening at the same time . | |
44:21 | It's not as if they're in , these two are | |
44:24 | entangled and the other two are entangling . That's a | |
44:27 | really a newtonian point of view , if you wish | |
44:30 | , if that was the problem because all that very | |
44:32 | easily you could just take write down some kind of | |
44:35 | Markov chain and and just write down some probability distribution | |
44:39 | of the electrons . That is not what happens . | |
44:42 | They really all entangling together at the same time . | |
44:45 | That's what makes multi particle entanglement really complicated . I | |
44:53 | hope I answered that question . Shashi you body . | |
44:59 | Uh by the way , I should mention to you | |
45:02 | severe . Uh Shashi Central and I were all classmates | |
45:05 | in the same year in Physics . Uh Center for | |
45:11 | many of the I T . K . People on | |
45:13 | the skull uh S . PhD but severe . So | |
45:16 | uh uh can actually , well that was a very | |
45:21 | distinguished I thi K class . Uh She asked why | |
45:27 | is it so hard to achieve artificial entanglement in quantum | |
45:31 | computers while easy to find it in natural systems like | |
45:35 | eitC materials ? Uh Well it's because yeah , entanglement | |
45:44 | is always hard to achieve if you want to achieve | |
45:47 | a certain type of the time . So in the | |
45:50 | high dc materials we're just they achieve some sort of | |
45:54 | entanglement which depends on all kinds of details of their | |
45:57 | structure . And we're just trying to figure it out | |
46:00 | , we're trying to measure what's there if you wanted | |
46:02 | to change it and control it to something that we | |
46:04 | want that's extremely hard and that's really what we want | |
46:08 | to do in upon a computer . You know , | |
46:10 | you know , it just studying the entire movement that | |
46:13 | happens to be there . Uh , you want to | |
46:15 | make your own entanglement in a way that does something | |
46:18 | useful for you , uh , in the sense of | |
46:20 | computing something . And to do that , you really | |
46:23 | have to take each each electron and control its entanglement | |
46:29 | very precisely . Uh , and so , you know | |
46:33 | , people have all kinds of ingenious ideas and what | |
46:35 | to do that almost certainly going to make errors . | |
46:38 | So you have to have quite America correction . And | |
46:42 | the current status of things . Is that Even for | |
46:45 | a single electron , No 1s , I made a | |
46:49 | fully what's called a fault tolerant a bit actually , | |
46:54 | you know , they could correct its own entanglement by | |
46:57 | by by some error correction method . So that's a | |
47:00 | very , very challenging problem . But okay , people | |
47:03 | have all kinds of creative ideas and how that will | |
47:06 | move forward . I mean , my my own view | |
47:08 | is that , you know , it's sort of like | |
47:10 | going to the moon . It's it's a very nice | |
47:12 | goal to go to have , you know , people's | |
47:15 | colonies on the moon or something like that . But | |
47:17 | along the way , we're going to discover all kinds | |
47:19 | of amazing things and useful things . And I'm sure | |
47:23 | that's what's going to happen on a computer is nobody | |
47:25 | knows what they're actually going to be useful for . | |
47:28 | I doubt they're going to be useful for , you | |
47:30 | know , fact arising big numbers , which is sort | |
47:32 | of like going to the moon . Uh , but | |
47:36 | there are many other things are going to mars , | |
47:38 | I should say . Yeah , Okay , that's a | |
47:42 | personal point of view . Many , many of my | |
47:44 | closest friends in my department to disagree with me , | |
47:47 | but okay , okay , jesse muted . Uh , | |
47:55 | yeah . On the subject of entanglement , uh , | |
47:58 | wife , uh , says you've piqued our curiosity . | |
48:03 | Do you have an explanation of what results an entangled | |
48:06 | state , meaning ? What's an observation that causes the | |
48:10 | cat to choose whether it's alive or dead ? I | |
48:13 | guess the wave function collapse . Does that that's still | |
48:19 | the mysterious issue that ? Well , I mean , | |
48:22 | so the cat and it depends what you mean by | |
48:24 | the cat . The cat itself , you know , | |
48:26 | just the air molecules . So the cat is breathing | |
48:29 | . Uh , as a cat breeds the air molecules | |
48:32 | , those air molecules are entangling with the cat . | |
48:35 | Uh , so that , in a sense that in | |
48:38 | a sense , will break , you know , so | |
48:41 | if you try to make a superposition of life and | |
48:43 | death cab , you have to get rid of all | |
48:45 | the air and that will kill the cat . Anyway | |
48:47 | , so you really have to totally isolated . Uh | |
48:52 | , and so that , you know , that's just | |
48:54 | a picture that people like to make . I think | |
48:57 | people have made what they call cat states of maybe | |
49:01 | 100 electrons in a very controlled environment in a very | |
49:05 | cold system Where there is essentially no air , nothing | |
49:10 | is an ultra high vacuum uh and under certain conditions | |
49:14 | and you can make a cat states , but you | |
49:16 | know , 700 electrons where all electrons are up and | |
49:21 | the dead cat is all electrons are dull . So | |
49:24 | that's what people call a cat steak . Uh But | |
49:29 | you know , I I I still wanted to show | |
49:31 | the picture because then everybody knows what I'm trying to | |
49:34 | say . Uh huh . But I guess the question | |
49:38 | of the collapse of the wave function is still whatever | |
49:42 | was 100 years ago . Right . I mean , | |
49:45 | that's not something we have . Uh even , Well | |
49:49 | , I would say , I think one view is | |
49:51 | that the collapse of the very function itself is entanglement | |
49:54 | . So when I look at something yeah , my | |
49:57 | brain , I have been entangled with what I'm looking | |
49:59 | at and and since I've entangled with what I'm looking | |
50:02 | at , I'm going to see what I'm entangled with | |
50:05 | , which is one of those things . But this | |
50:07 | raises the philosophical question more about the other me , | |
50:10 | which saw the other part of the State . Well | |
50:11 | , I don't know what to do about that because | |
50:14 | that's not something that I'm observing , you know , | |
50:18 | that gets us into many worlds and so on . | |
50:20 | Right by the way , there's a very interesting graphic | |
50:23 | comic . I was recommending to Seville's wife last time | |
50:27 | we met , I think it's called totally Random and | |
50:31 | it's by I think Geoffrey bob and his uh and | |
50:36 | I think his wife who was the illustrator . But | |
50:38 | it's a graphic novel , you can find it on | |
50:40 | amazon and it explores many of these ideas in a | |
50:44 | very fun way meant for non technical uh audience . | |
50:49 | So Vineet Gupta as quantum entanglement can be used to | |
50:54 | teleport particles . Is this something that can be used | |
50:58 | to transmit information across long distances ? Uh I guess | |
51:02 | it's not more about quantum and I love that , | |
51:06 | correct . So you can the quantum teleportation uh you | |
51:10 | know what uh telephoning actual matter uh for the for | |
51:15 | the second part of the question is the correct way | |
51:17 | to say uh you're really sending part of information . | |
51:21 | So if you have a court of state here , | |
51:23 | you know , if I have an electron sitting here | |
51:26 | and it's in some superposition state is both up and | |
51:29 | down and I don't know exactly what kind of state | |
51:33 | had said , and if I look at it um | |
51:36 | I will uh I will see it either up or | |
51:40 | down and I'll destroy the state just by the act | |
51:42 | of looking at it . But what I can do | |
51:45 | by a very clever protocol without that , I can | |
51:48 | take my electron in a certain state . And it's | |
51:51 | important that I don't know what state it's in . | |
51:53 | I can still send it to from here to Bangalore | |
51:56 | in principle . So that the person uh in Bangalore | |
52:01 | has the same state . The electron in Bangalore has | |
52:04 | the same state that I had here . No electron | |
52:07 | has moved . I could send the information by a | |
52:09 | beam of light or so . Well actually not even | |
52:11 | been back . What requires is that , you know | |
52:16 | , you take this pair , the CpR pair that | |
52:19 | I showed you and you know , so I have | |
52:22 | to go to Bangla or you have to create an | |
52:24 | if you are a pair then I have to come | |
52:26 | back to boston carrying my half of our affair . | |
52:29 | And the person in Bangladesh has the other half . | |
52:32 | So we met for a while . We share this | |
52:35 | if you are there and then I can bring in | |
52:38 | another electron over here and send the information on this | |
52:41 | electron without knowing exactly what states and all the way | |
52:45 | to bang law . And I can be confident that | |
52:47 | Roger stone has the same state that I had before | |
52:50 | in his electron over there . That's what teleportation is | |
52:54 | about . Uh it's not magic . You have to | |
52:58 | have some contacts in the past where you share entanglement | |
53:03 | and then you can use that in the future to | |
53:05 | send one of information . Yeah , yeah . That's | |
53:08 | why it doesn't violate relativity as unit was uh wondering | |
53:13 | . Yeah . Uh so uh annan Rajaram and asked | |
53:16 | once a pair of electrons are entangled , do they | |
53:19 | remain entangled forever ? Or is there a probability that | |
53:23 | they disentangle ? Uh huh . Uh great question . | |
53:29 | Yes , they they can disentangle . I mean you | |
53:33 | have to bring in some other electrons uh and with | |
53:36 | the right sort of interaction , you can disentangle them | |
53:38 | and transfer the entitlement to the other one . Quantum | |
53:41 | teleportation does something like that . Yeah . Yeah . | |
53:47 | Uh this uh from Youtube , there's a question by | |
53:51 | Pierre Luc are different . Strange mental states are always | |
53:56 | distinguishable by scattering experiments . Well , that's a great | |
54:03 | question . Uh I think I would say we're still | |
54:09 | in the process of classifying the different possibilities for strange | |
54:12 | metals . There are many different materials that show strength | |
54:15 | metals . There are similar and different uh to each | |
54:18 | other , but some of the details of different the | |
54:20 | temperature range of which exist and their response to various | |
54:25 | spectral probes is different . Uh And they are curious | |
54:31 | for many of them , although that's still , you | |
54:33 | know , subject of active research . Uh And those | |
54:38 | are also , you know , the theories are similar | |
54:41 | to each other and similar in some ways to get | |
54:43 | us like a model also . Uh But we still | |
54:46 | don't have a full , you know what I would | |
54:48 | say , a definitive classification of strange metals . And | |
54:51 | and and you know , the full taxonomy of this | |
54:53 | , these are the five different kinds and uh this | |
54:57 | is what you'll find this material and that you'll find | |
54:59 | other material . Uh My hope is to reach that | |
55:02 | maybe someday . Uh That's been the goal of my | |
55:06 | research for a while . Yeah . So uh is | |
55:12 | there a there's a question what there's a question probably | |
55:16 | that needs maybe some uh clarification what forces involved in | |
55:22 | quantum entanglement ? Yeah , I guess that's there's no | |
55:25 | real force . Yeah . But uh yeah , I | |
55:29 | mean , I would say it's sort of like , | |
55:31 | let's go back Newton's laws . So Newton's laws have | |
55:34 | kind of two components . Uh one is force equals | |
55:38 | mass times acceleration . And the other is that the | |
55:43 | force of gravity is G . M . One M | |
55:46 | two Harar square . So the forces gravity uh what | |
55:49 | we call the Kinnah Matic part , which is ethical | |
55:53 | that made it applies to any force ethical , then | |
55:55 | they would apply to gravitational forces . Electrical forces in | |
55:59 | principle also the strong and weak forces , if you | |
56:02 | could find them in the right to jane . Um | |
56:05 | So there's the actual force of many different forces in | |
56:09 | the strange metals that I deal with . It's mostly | |
56:11 | almost all electrical forces . Uh But then there is | |
56:16 | a kin dramatic part which tells you how does the | |
56:19 | position and momentum of the particle respond to a certain | |
56:22 | force ? Uh And and that's what quantum mechanics tells | |
56:28 | us . It's independent of what particular force using it | |
56:32 | . It's a statement of the evolution of the quantum | |
56:34 | state for any any force . And I what was | |
56:40 | the precise question ? I think I forgot . I | |
56:43 | think I answered the question . Yeah . So that's | |
56:49 | a sort of a general question from again hurts . | |
56:54 | Do you find yourself making connections of drawing analogy between | |
56:58 | phenomena and physics with other areas of life such as | |
57:03 | philosophy , art or human behavior ? A great question | |
57:09 | . I try to avoid that . You know , | |
57:12 | I think I think I leave the philosophy that the | |
57:15 | philosophers and uh you know , you could say we | |
57:20 | have very narrow point of view . I mean the | |
57:22 | people who make connections between the duality and the concept | |
57:26 | of duality in religion and philosophy . I uh there | |
57:31 | may be I know at some level , but I | |
57:34 | know that Mhm . It's hard to phrase the connection | |
57:38 | in scientific terms , which will actually influence some of | |
57:42 | the things I was thinking about my work . Uh | |
57:46 | But uh yeah , I guess what I would say | |
57:51 | is that uh huh the reality of quantum theory uh | |
57:56 | if you want a more philosophical point of view , | |
57:59 | uh so you know , and these black holes , | |
58:02 | the , you know , the supermassive black holes , | |
58:04 | Galaxies and the electrons and uh it's so incredible and | |
58:10 | so unbelievable that even the most fantastic stories of origin | |
58:14 | and religion don't come to the actual close to the | |
58:16 | truth . It's much more fantastic than anybody even humans | |
58:20 | ever imagined . Uh All the stories of creation are | |
58:26 | just a weak imitation of the actual reality . Okay | |
58:33 | , that sounds really just I'm going to get Yeah | |
58:37 | , but I mean , narrowing things a bit in | |
58:41 | across different areas of physics . Uh I mean , | |
58:45 | how do you find yourself sort of uh thinking about | |
58:49 | something like black holes which was so far away from | |
58:53 | your original uh interest ? How do you find yourself | |
59:00 | thinking about uh making these connections ? Or is that | |
59:06 | sort of organic ? Or is it uh is it | |
59:09 | something you kind of uh when you're when you're hearing | |
59:12 | talks from other areas do you make ? Yeah , | |
59:16 | try to make the connections . Uh Yeah , I | |
59:22 | mean I guess it uh taking back to my own | |
59:26 | uh progress on some of these topics , I mean | |
59:29 | in almost all cases I've been just focused on a | |
59:32 | very narrow what seems like a very narrow question . | |
59:34 | Uh But I you know , try to really understand | |
59:38 | it well and not accept the easy answer and you | |
59:43 | write a paper and then move on to something else | |
59:45 | . You really want to dive into the depth of | |
59:48 | it and start wow trying to make progress and then | |
59:53 | and while you're working this question you kind of be | |
59:58 | open to what else is going on . You know | |
59:59 | , go to lots of seminars in different fields and | |
60:02 | just been listening . Uh and then you know , | |
60:05 | where the conference is talking to people and then every | |
60:07 | now and then suddenly somebody will say something that will | |
60:10 | legal connection . That's typically the way it's happened for | |
60:14 | me . It's not that I'm sitting in my chair | |
60:16 | and trying to think big thoughts . Usually you're , | |
60:18 | you're trying to think those little thoughts and and hopefully | |
60:21 | some connection gets made someday . Yeah . Okay . | |
60:26 | Yeah . So an androgen ramen uh what is your | |
60:30 | prediction for ? How long before we see the first | |
60:33 | practical applications of quantum computing ? Will it be in | |
60:36 | our lifetimes ? I would say , you know , | |
60:40 | define practical uh you know , uh I would say | |
60:47 | within a day , All right , I have a | |
60:49 | lot of friends in this field and you know what | |
60:51 | I say , they'll get upset at me , but | |
60:54 | I got to say what I want . I would | |
60:56 | say now , lifetime maybe . Uh you know , | |
61:01 | we'll understand more about the structure of matter and structure | |
61:04 | of complicated quantum mechanics uh in in the kind of | |
61:08 | materials I was telling you about are more complicated molecules | |
61:13 | that are important in chemical reactions . Uh so , | |
61:17 | so there's a , you know , you know , | |
61:22 | sort of , you know , ordinary computers , classical | |
61:25 | computers that I have found it very , very difficult | |
61:27 | to factories large numbers . And that's one of the | |
61:30 | problems that we hope one of computers that solve . | |
61:32 | But there are other problems that are very , very | |
61:34 | difficult for ordinary computers . And this is like computing | |
61:37 | for McCain's computing the effects of quantum entanglement on physical | |
61:42 | properties of a certain crystal or of a certain set | |
61:45 | certain big molecules . We can't compute it very accurately | |
61:49 | by an ordinary computer because it's uh it's impossibly hard | |
61:54 | uh for reasons I won't go into , but quantum | |
61:58 | computers can simulate some of this . Uh and I | |
62:03 | think so , these quantum simulation task as they fall | |
62:06 | , that's looking , you know , very reachable in | |
62:09 | the neutral in the near term Minnick , you know | |
62:13 | , in the lifetime . I have left as a | |
62:14 | researcher , I think there will be real progress there | |
62:19 | and there's already quite a bit of exciting work in | |
62:21 | that direction even in the last few months . Uh | |
62:26 | and will that have some practical impact ? But , | |
62:29 | you know , it's hard to tell . I I | |
62:31 | think I think eventually it will . I mean , | |
62:33 | if you go back and look at , you know | |
62:36 | , of course , the big story we always like | |
62:38 | to tell the development of transistor and the laser and | |
62:40 | how it launched the electronic revolution that all came from | |
62:44 | advances in quantum physics and understanding uh behavior at corner | |
62:50 | behavior of electrons in materials . And I think there's | |
62:52 | a but you're likely another frontier in that direction that | |
62:57 | could well open up . So so I wouldn't worry | |
63:02 | about , you know , R . S . A | |
63:05 | . Being uh suddenly not not safe . I'm not | |
63:09 | worried about that in my lifetime . But I think | |
63:11 | there could be many other benefits of quantum computing . | |
63:16 | I mean , do you have I mean there are | |
63:19 | many different kinds of approaches people take to building quantum | |
63:23 | computers using superconducting cubits . Or maybe even uh then | |
63:28 | there of course there are the ideas of using topological | |
63:31 | lee protected states . Uh So do you think that | |
63:35 | some of the I mean in some sense , progress | |
63:38 | in understanding uh So do you think like this technologically | |
63:43 | protected states they seem attractive on paper that uh that | |
63:47 | you are kind of protecting that entanglement that you talked | |
63:50 | about in some very rigid paul anthropology ? Do you | |
63:55 | think something like that could eventually materialised ? I think | |
63:59 | so far people are struggling if I'm not mistaken uh | |
64:03 | to realize something like that . Yeah . So so | |
64:08 | my okay . Uh my own view is that the | |
64:12 | topological way of doing things is really the only way | |
64:17 | that will eventually succeed if at all . I think | |
64:20 | the people trying to apology which is the Microsoft group | |
64:23 | uh then what they seem to be much further behind | |
64:27 | right now from google or intel or any of the | |
64:31 | other people using other methods . But the other methods | |
64:35 | , uh you know , they they really are what | |
64:39 | I would say is doing corn and computer science rather | |
64:42 | than one of physics . They're trying to take ideas | |
64:45 | from computer science and how you correct errors and implementing | |
64:48 | them in a series of gate operations . And yeah | |
64:52 | , once you have a whole bunch of sequences of | |
64:55 | data operations , I'm skeptical that the corn and computer | |
64:58 | science model of the real world is actually going to | |
65:00 | work . Once you get a very large number of | |
65:02 | it's okay . That that's a minority point of view | |
65:05 | , I should say . But that's my opinion . | |
65:07 | Uh , there are a few friends of mine who | |
65:09 | would agree with me , I think I would say | |
65:11 | . Uh , but topological way of doing things in | |
65:16 | some ways what they're doing when we're saying it is | |
65:18 | they're putting the corn um , error correction right in | |
65:21 | the hardware . It's a hardware level born american action | |
65:25 | rather than a software level hardware direction . So they're | |
65:28 | really actually carefully studying the entanglement of what actually makes | |
65:33 | a bit rather than taking some gate model that may | |
65:36 | not reflect reality , what actually makes it get . | |
65:39 | They have a they have a theory of what makes | |
65:41 | a bit and then from that theory and their understanding | |
65:44 | of it , you can argued and on the very | |
65:48 | general connect uh huh conditions that they should be parliamentary | |
65:52 | corrections possible . And I mean those arguments I find | |
65:55 | very persuasive , but on the other hand , implementing | |
65:58 | error correction at the hardware level is extremely difficult and | |
66:01 | Microsoft has huge effort trying to do that . We | |
66:05 | still haven't , as I said , no one's fully | |
66:08 | calling America even a single bit , but I would | |
66:11 | say once that's achieved by Microsoft or whoever does it | |
66:14 | , then the road to building an actual point computer | |
66:17 | before easier in the topological direction . That's my view | |
66:23 | . Yeah , just uh for for me also just | |
66:26 | has a total outsider , it seemed like a robust | |
66:29 | way to sort of go about . Uh but but | |
66:35 | I always got the feeling that it's a bit of | |
66:37 | the underdog right now , that yeah , but usually | |
66:40 | it's the underdog that Yeah , yeah , but but | |
66:46 | you know , with the superconducting cubits and the iron | |
66:50 | traps , you can , you can , you know | |
66:51 | , you can make a few Cubans and have them | |
66:53 | do fun things and it looks great . Uh and | |
66:55 | now they're going up with 50 bits , but they're | |
66:57 | very quickly , they're not doing computing . What they're | |
67:00 | doing is quantum simulation . Really ? That's what they're | |
67:03 | all doing right now . Uh Yeah , okay . | |
67:10 | I don't like to say I told you so , | |
67:11 | but I told you so . So Jp Jenna wants | |
67:19 | to know the distance across which quantum entangled phenomena can | |
67:25 | be realized . Uh For instance , other activities on | |
67:29 | earth can be controlled from a distant galaxy , I | |
67:31 | guess in some science fiction is the thing . But | |
67:34 | I guess the science question is how is there are | |
67:38 | there limits to the distances across which quantum entanglement can | |
67:42 | be realized ? Uh No , as far as we | |
67:46 | know , they're orange . I mean you can have | |
67:48 | particles on two sides of a black hole or even | |
67:50 | two sides of a galaxy be entangled with each other | |
67:52 | in principle . But you know about somebody from a | |
67:55 | different galaxy controlling us . There is mm you know | |
68:01 | , unless we we interacted with that galaxy at some | |
68:06 | time deep dark in the past and shared some mutual | |
68:10 | entanglement and that entanglement didn't get destroyed by other preservations | |
68:15 | . Uh there's no way for them to control us | |
68:18 | . I mean they it's not some you know uh | |
68:23 | like star trek or um teleportation from here to that | |
68:27 | . Uh there has to have been some interacts in | |
68:30 | the past which was coherently preserved until today for uh | |
68:35 | for quantum entangled . To be useful for something like | |
68:38 | teleportation . Oh yeah , yeah . I think there's | |
68:44 | one science fiction novel I read that sort of tries | |
68:47 | to take this . I mean , it tries to | |
68:50 | bring it in a little more scientifically like this , | |
68:53 | I think by creating that initial contact and then having | |
68:58 | this other galaxy kind of try to control things on | |
69:02 | earth by the science fiction chinese science fiction writer Session | |
69:06 | lou I think the three body problem uh and it's | |
69:09 | uh equals but anyhow , but that's I think science | |
69:14 | fiction . Um There's another question from Pierre Luc it | |
69:18 | says , are there not already consequences of having gone | |
69:22 | from a classical to a quantum formulation of information theory | |
69:27 | , presumably meaning just that ? Yeah , the rules | |
69:33 | are very different for quantum information and the limits of | |
69:38 | uh quantum information . So are there consequences in uh | |
69:45 | leaving aside quantum computing , I guess ? Uh the | |
69:48 | transmission of information . Right ? Uh Sorry , I | |
69:53 | understand . Excuse me . You are there limits to | |
69:56 | I think it's our the question is are there not | |
70:01 | already consequences of having gone from a classical to a | |
70:06 | quantum formulation of information theory ? I mean , uh | |
70:10 | is that I think that's uh if I can sort | |
70:14 | of read between the lines that uh are there drastic | |
70:18 | consequences ? Are their radical sort of changes uh in | |
70:23 | doing that ? Well , I want the classical information | |
70:28 | theory of Shannon uh is pretty much still valid . | |
70:31 | And uh I think the flow is in more the | |
70:35 | other way people taking ideas from classical information theory and | |
70:39 | helping understand corner of entanglement using classes using information theory | |
70:45 | . And so there's been a huge explosion of working | |
70:48 | using quantum information uh not just for transmission of information | |
70:54 | , but also for even asking questions like what happens | |
70:58 | uh when a black hole evaporates , you know , | |
71:01 | so the kind of thought , you know , I | |
71:04 | suppose you had a black hole and it started radiating | |
71:07 | like Hawking said and eventually started evaporated . And then | |
71:10 | I gave you a different black hole , which only | |
71:12 | differed by Somebody threw 1 , 1 particle into it | |
71:18 | . So these are almost identical black holes , but | |
71:20 | there initial state is slightly different . Could you ? | |
71:24 | By looking at what's coming out , the information that's | |
71:26 | coming out from the radiation tell , uh , which | |
71:30 | black hole had that extra particle thrown in ? Uh | |
71:34 | , So that's one of the deep questions that string | |
71:37 | theorists and others have been sorting out these days . | |
71:39 | And the answer is yes , you can , but | |
71:41 | it's extremely difficult , but at least in principle you | |
71:43 | can . And I think ideas from classical information theory | |
71:47 | have really played an important role in understanding questions of | |
71:50 | this type , correct me if I'm wrong , graduates | |
71:53 | graduates know more about on the nose . So , | |
72:01 | uh , papa has a very interesting question . Does | |
72:05 | the Big Bang imply that everything was entangled in the | |
72:09 | past ? And of course , she says she as | |
72:12 | a non scientist , it's sort of a , uh | |
72:15 | , general question on her . But , but I | |
72:17 | think it's an interesting question , but uh , uh | |
72:22 | , I mean there's questions of inflation , right ? | |
72:24 | So if you didn't have inflation than people who are | |
72:26 | not causally connected at some point , I think there's | |
72:29 | still , uh , I believe there's the visible universe | |
72:34 | , which is the time it takes for light to | |
72:36 | travel , uh , From the Big Bang ? Take | |
72:40 | the time from now to the Big Bang , which | |
72:42 | is 13.6 billion years and you go out 13.6 billion | |
72:46 | years in space , you still , that's our visible | |
72:50 | universe . Who knows what's beyond that ? And in | |
72:53 | principle , I think we could be entangled with anything | |
72:55 | in the visible universe . Yes . Yeah . I | |
72:58 | mean , I guess there's a question of uh , | |
73:01 | like you said earlier about Newton's laws , that's the | |
73:03 | time evolution . But then there's the initial state and | |
73:06 | we still are I mean , there are hypothesis of | |
73:10 | what the initial state was . I mean , there | |
73:12 | are some natural initial states you could consider so called | |
73:16 | bunch Davies vacuum and all the for inflation , which | |
73:21 | would mean that there and and as Super said , | |
73:24 | there's a horizon uh due to the inflation . So | |
73:29 | things in some sense , just like the black hole | |
73:31 | horizon are sort of entangled across that horizon . And | |
73:35 | us as well . So there is a certain sense | |
73:38 | and there's a certain sense in which the spacetime expand | |
73:43 | , inflationary spacetime has a temperature like the black hole | |
73:46 | as the temperature . So in some ways , yeah | |
73:50 | . But but it's , we still don't know whether | |
73:52 | that's really the case or not . I mean this | |
73:54 | are uh these are just ideas about what the initial | |
73:58 | vacuum was like and uh we still don't have a | |
74:02 | theory which tells us uh uh this thing . Uh | |
74:08 | So yeah , but but it's a very valid very | |
74:11 | very interesting question . Uh So uh I shook why | |
74:16 | she asked , I wonder if there's a radical impact | |
74:19 | on causality due to quantum mechanics . We still seem | |
74:23 | to cling to the view that the cosmos is just | |
74:25 | deterministic and principal given sufficient computational ability . Uh That's | |
74:35 | a very good question . Uh um So the equations | |
74:39 | of quantum mechanics are deterministic despite the uncertainty principle uh | |
74:46 | in the sense that and there is no violation of | |
74:49 | causality in the sense that if you knew the corn | |
74:51 | um state At time T0 , then equating the quantum | |
74:57 | mechanics in principle fully determine the corner state in the | |
75:01 | future . Where , in a sense , the uncertainty | |
75:04 | comes in is that it's impossible to know the phone | |
75:07 | um state if I give you a little electron in | |
75:09 | a box and tell you here's your electron . And | |
75:11 | I tell you predict his future . Well your 1st | |
75:16 | 1st choice . Well , let me look at the | |
75:19 | electron to figure out the state right now and then | |
75:22 | I'll predict the future . But but just by the | |
75:24 | act of looking at it , you will destroy the | |
75:25 | electron . On the other hand , if I give | |
75:28 | you an electron , I told you it's in this | |
75:30 | state , I just tell you it's in this state | |
75:33 | and then knowing that you can predict the future of | |
75:35 | the electron . But you have to believe me that | |
75:38 | I told you the truth . There's no way of | |
75:39 | confirming I told you the truth . Okay , so | |
75:42 | that's a very simple way of putting it . Uh | |
75:45 | equations are deterministic , but but there are certain unknowable | |
75:51 | aspect opponent theory that you can't uh fully determined unknown | |
75:55 | state . That's where the uncertainty comes in in a | |
75:58 | sense . Uh but causality uh and determinism are really | |
76:05 | not are still present . It's just harder to implement | |
76:09 | them . Uh huh . So let me just like | |
76:16 | I think we should close very soon . It's quite | |
76:20 | late for uh people . And in fact I have | |
76:24 | to go get my second vaccine . And uh close | |
76:29 | . I just wanted a last work where distinct thought | |
76:32 | from you severe about Uh you mentioned in the last | |
76:36 | 30 years or so , 2030 years is when the | |
76:39 | idea of quantum entanglement in the understanding of various phases | |
76:43 | of matter and materials has really kind of uh come | |
76:48 | center stage . Uh and so uh do you see | |
76:54 | radical new developments in in kind of producing new materials | |
77:01 | or kind of seeing amazing new phenomenon uh coming over | |
77:06 | the horizon ? It is it something that you feel | |
77:10 | is ? Uh I mean I I if I knew | |
77:15 | what was coming on the horizon I do working on | |
77:17 | . Okay , I would know . Uh So it's | |
77:20 | hard to predict , but you can look at the | |
77:22 | recent past and see all the sequence of incredible discoveries | |
77:26 | uh And they don't seem to be you know , | |
77:30 | slowing down in any way . In the past couple | |
77:33 | of years . It was twisted by their graphene , | |
77:35 | There's different compounds showing spin liquid behavior or quite . | |
77:41 | Uh And then now very recently I've been involved in | |
77:44 | some work by Michelle locals group at Harvard and realizing | |
77:49 | a spin liquid using cold atoms and lasers I think | |
77:52 | should grow at actually and I . C . D | |
77:54 | . S . But an important role in that . | |
77:57 | Uh So yeah I think there's you know , I | |
78:04 | would agree with you that uh there's a lot happening | |
78:08 | on the corner frontier in physics all the way from | |
78:12 | materials in the lab to new understanding of very deep | |
78:16 | understanding of going information here , black holes and amazing | |
78:19 | thing is that they are connected in some way . | |
78:23 | Uh So yeah , no I get the sense that | |
78:27 | it's like a tip of an iceberg that one is | |
78:30 | sort of uncovering and so of course much of the | |
78:33 | iceberg room incident . But hopefully it's going to come | |
78:36 | into view in in the in the coming years and | |
78:40 | it's probably an exciting time for young people to be | |
78:43 | getting into the field asking questions about uh this . | |
78:49 | Uh So we just take uh last question from Rather | |
78:55 | Banerjee about what happens to the entangled electron when we | |
79:01 | observe the state of its path . Uh So presumably | |
79:06 | when ? Yeah yeah so that's it will change . | |
79:13 | That's really what E . P . R . Were | |
79:16 | objecting to that . You know if I have a | |
79:20 | pair of entangled electrons and one is the british in | |
79:22 | one of the beef , I just looked at his | |
79:26 | electron . Then my electron will change to a particular | |
79:29 | state that's determined by the consequences of radishes . I | |
79:33 | shouldn't say determined by that's connected to our correlated to | |
79:38 | the consequences of not the consequence connected to what right | |
79:42 | eight observed . But for me to actually make sure | |
79:46 | that uh the entanglement was correct , I would have | |
79:51 | to call up radish and say what did you observe | |
79:53 | ? And rather should tell me what he observed and | |
79:55 | then I would uh see that was consistent . So | |
80:00 | it's so that it does and that information only travels | |
80:03 | the velocity of light or slower . So uh so | |
80:07 | that's when information gets transmitted . So what you can | |
80:10 | do with entanglement is not you can't send information faster | |
80:15 | instantaneously , but you can send it securely . So | |
80:18 | for example , I mean this is a very they're | |
80:20 | better algorithms for this . But uh you know , | |
80:24 | suppose I know that radish and I are entangled . | |
80:27 | I have a pair of electrons that entangled like mine | |
80:29 | is up and this is done and vice a person | |
80:32 | . So then we share this in the past . | |
80:34 | And then Rodgers looks at his electron and it's down | |
80:40 | and I look at my electron and it's up . | |
80:42 | So at this point I know that radishes electron is | |
80:45 | dark And No one else knows this . So I | |
80:49 | can call up Roger , I should say if your | |
80:51 | electron was down uh invest in this company . If | |
80:55 | you're electron was up invest in the other company . | |
80:58 | Uh and no one can tell what I told Roger | |
81:01 | , even if they heard what I told him . | |
81:03 | But I , but Rogers will perfectly understand what I | |
81:06 | said because we share this information . So that's the | |
81:10 | , the way you have the best , very simple | |
81:12 | explanation of corn of photography . You can securely send | |
81:16 | information , but it's , that's not any faster . | |
81:19 | Okay . Yeah . You're muted radish . Sorry . | |
81:27 | Uh , so thanks a lot to be for very | |
81:31 | patiently taking so many questions , spending time with us | |
81:37 | . Uh , such a , such a moment . | |
81:40 | I mean , I hope you get your second shop | |
81:42 | very soon . And , uh , yeah , right | |
81:46 | . You've got your second shot already . Oh no | |
81:48 | , I'm still , yeah . I mean , I've | |
81:51 | got mine my first shot about four weeks ago . | |
81:54 | So , uh , hopefully soon get it . There | |
81:57 | are there are issues shortages . Yeah , But let's | |
82:01 | see how it goes . But , uh , anyway | |
82:03 | , everyone on the call . Please stay safe . | |
82:05 | All the best for you and your families and friends | |
82:09 | and everyone . It's a difficult time . But anyway | |
82:13 | , I hope you got a little respite from that | |
82:15 | . This thing here in this marvelous world of quantum | |
82:19 | mechanics and entanglement . So , uh , good night | |
82:23 | , good day and so on to all and by | |
82:26 | , by severe and uh , hopefully soon in India | |
82:31 | when things thinking hopefully things get better . Uh , | |
82:34 | thank you . All right . Bye bye . Thanks | |
00:0-1 | . |
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ICTS Big Questions: A Journey into the Quantum Universe with Subir Sachdev is a free educational video by International Centre for Theoretical Sciences.
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