 Hello and welcome to NewsClick. Today on Talking Science and Tech, we will be discussing this year's Nobel Prize in Physics and we are joined by Prabir Prakash. So this year's Nobel Prize has been awarded to Roger Penrose, Andrea Guest and Reinhard Genzel for their work on Blackwoods. So Prabir, can you first tell us about more about their work basically and what they have achieved in their work to be awarded this Nobel Prize? Well, I think there are two separate issues in this case. One is that there was a mathematical strategy which Penrose used and in fact he created some specific mathematics or mathematical methods, what's called the Penrose transform, the topological transforms to advance the mathematics of black holes or what is now being referred as black holes, basically what was called a space-time singularity. Now that advance that he did is one element of course of the the Nobel Prize. What Guest and Genzel have done is prove that yes, there is a supermassive object in the center of the Milky Way galaxy. It corresponds to the existence of what a black hole would be like. So there is an experimental confirmation based on data and that data has been collected for nearly 30 years, going back to nearly 30 years and that shows that the two teams independently working have confirmed the existence of a supermassive object, 4 million sun solar masses equivalent to 4 million solar masses at the center of the Milky Way galaxy. So these two put together now go to say yes, that particular object at the center of the Milky Way galaxy is in fact the space-time singularity, in other words a black hole. So this is the two things that have happened. As you know physics has this problem that you may provide a theory, everything may confirm to the theory but unless you also get a prediction in the theory which is verified experimentally, physicists have still the doubt, the niggling doubt maybe this is really not correct, it shows everything confirms what we know but does it actually predict things which we don't know and if there is such a prediction it makes and we find that the prediction is now confirmed by experimental evidence then we can say yes, now we are confirmed that this theory is correct till of course something comes up which is creates anomalies and that's how theories develop even further. So I think Penrose's major achievement was to move beyond what was known and at that point of time though the space-time singularity had been predicted it came out of Einstein's equation. In fact it happened a few months after 1915 Einstein's general theory of relativity equations. There was a German officer of the physicist, he was also an officer in the German army, this is the first world war in progress and he had said one of the implications of Einstein's general equations, general theory of relativity equations was in fact a space-time singularity rising out of the equation and he had given that that's why it's called the Schwartz field singularity, all of that name still is there and a lot of the, a lot of the name nomenclature of the black hole in fact goes back to his name that he was he in fact pointed this out but even Einstein was of the opinion that this is very unlikely that this is not happening nature would find ways to not to do it and one of the arguments that had come up at that it need the mass to collapse in a symmetric way and symmetric collapse of the mass was thought to be something which would not really happen so maybe this apocalyptic apocalyptic prediction of the singularity of a space-time singularity would not arise and something else would happen but what Penrose showed and that's the major advance that he made is that he showed that it doesn't need symmetric collapse that once it had reached a certain stage of collapse and there was a mass of a certain size in a certain space which is the density of the space had reached a certain level and there was an amount of mass and he that equation is really a what mass it is comes from Schwartz field equation or solution of the general theory of relativity and that would ensure that even without symmetry in the symmetric collapse being there it would create a black hole and that was the basic conclusion that Penrose's mathematics shows or mathematical strategy he used showed that he did not need a symmetric collapse provided it had gone beyond a certain point in fact the this black hole formation would be the way it would work what it also showed and Penrose again has to be credited with that it is not only a question of a collapse of a stellar object but it could happen in a dense region of space that if there was a certain amount of mass in a given amount of space then at some point you would get the formation of what he called a trapped surface and this would lead inevitably to a black hole or a singularity getting formed so he had generalized this the equations that he that were there for the black hole formation and showed that it was it is more it is not as specific or it was not as constrained as it was thought earlier and that's the mathematical contribution he made by which he could actually show all of this and this led to as we know Hawking's taking it up extending it to Big Bang the Hawking and Penrose did some work together they have their singularity theorems so all of this were really a major advance in general theory of relativity and I think Penrose and Hawking both have advanced in significant way the general theory of relativity and one of the consequences of course is the basically mathematically showing the existence of singularities would be there and then are finding now black holes in centers of various galaxies and even outside them so black holes now have become much more accepted within physics but when Penrose was working on it it was still still thought to be something which is odd would not really be there it's very unusual it's only a physics speculation but doesn't really exist in nature so all these issues were there so I think that is this is this is what physics what makes physics so interesting that you have an odd mathematical relationship that comes out of certain something else in this case the general theory of relativity and that at some point of time advances physics even further and you talked about how experimental verification is very important for physicists and that is why it took so long for the theory of Penrose and for the theory of Hawking to be recognized it was 55 years ago I think that Penrose had actually done this paper in 1965 and Hawking of course could not even be recognized because he died two years ago so can you also tell us more about the experimental part of this work which has been carried out by the teams of Andrea Ghez and Ryan Gardgen you know first is of course Hawking's big bang theory very extends this whole issue of concept of singularity to say that if we take time backwards this means there would be a singularity space term singularity in time and this means that the world started with the big bang and he was able to show that consistently I mean using mathematics he could show that this was consistent with what we know of physics today so that was his achievement but the consequence of that some experimental verification of the kind we have received for Penrose's conjecture and Penrose's derivations that is still not there so Hawking even if he had been alive the Nobel committee in its wisdom and we have questions on the wisdom on numerous occasions and we can discuss that later the question the issue is that given that it's unlikely that Hawking would have received the Nobel Prize because they would have said given the consistency of the performance of the conservative nature of the Nobel committee they would have said we are still awaiting a verification and obviously in physics a lot of these issues particularly concerning astrophysics are going to be difficult because experiments are not possible in astrophysics you can't really experiment with stars and so on so all you are really reliant on is nature doing an experiment which you can observe so I think that's the problem with astrophysics anything to do with astrophysics takes really long time to provide verification of this kind and in the Einstein himself didn't finally receive his Nobel Prize for General Theory of Relativity even though Eddington had shown that there was experimental basis to believe that there is gravity does bend for instance stellar light light coming from stars and the gravitational force of the sun could be seen to bend star light during an eclipse but even then the Nobel committee gave him the Nobel Prize which they couldn't really stop here become a household name for photoelectric effects so they didn't give him for general theory of relativity and they didn't give him a second Nobel Prize either for general theory of relativity though that's what is you know is most known for at least among the lay audience kept coming back to the Geys and Gensels work on how they plotted this out this had been already pointed out in the 80s that there seems to be a heavy object at the center of the of the Milky Way galaxy and this the black hole problem is that you cannot see it through light you cannot see through electromagnetic radiation so the normal way you observe distant objects is not open to you so the only or only external effect you would feel is that of gravity because it still would have mass and because it has mass that attraction of a heavy object which is which has consumed the mass of say many stars or was heavy to start with then that would be felt in the orbit of nearby stars so the question was that how do we show conclusively the mass of that object which if it exists is there in the center of the galaxy of the Milky Way and what is the size of that mass and also that there is no other electromagnetic observation we can make of that mass so that was that's basically the challenge and both these teams they use two different telescopes they use different calculations both the teams computed one particular star's orbit which was orbiting close to the center the Milky Way center and close in this case of course is still pretty large by our standards but not by the stellar standards so that was the object which one called s or two the other called s2 this is the nomenclature of the same star and they tracked it over a period of something like 20 25 years and they I think started this project in 1990 early 1990s and published results over a period of time showing that that there there is a heavy object which is why it is moving the way it is and the various reasons why you can say it's circling a near a very heavy object because if you see for instance the planets the closer you are to the sun the orbit the is in fact the planet moves faster its rotational rotation is faster and a speed is faster while if you have a more distant planet it's less that's simply because it is the gravitational effect leads to this so this the stellar object seems to be moving fast enough for them to consider consider that this there was a heavy object at the center which was causing this trajectory and both plotted this trajectory and from that try to reduce the mass of the object and both the trajectory and the mass that they calculated both agree very very close to each other in fact the citation that is given for the award has a detailed paper along with it this goal gives the details of what they saw and both of them showed very close to each other that this can only be explained if there is a super heavy object of the size of of the you know gravitational mass of four million solar sorry four million solar masses that is the size that that would be required to explain the trajectory and that's that's what then confirmed that there is a super heavy object which conforms to what the existence of a black hole this is the well committee's citation virtually that this is what we say it's consistent with that and therefore we have experimental proof there is that but you know before that we have had the event telescope last year publish a stunning picture of a black hole and that is even much bigger I think it's 6.5 billion solar masses so it's a huge gargantam black hole and that picture is a stunning picture the first ever picture of a black hole and that was done to last last year by what's called the event telescope so that that all of this now seems to confirm that yes Pedro's calculations are right black holes are not something which are anomalous they do exist and we see now to be reconciled to the conclusion that in most galaxy centers there are these massive black holes why they're there how they're they have been formed we'll leave it to further astrophysicists to talk about but I think the the broad ground has now been laid out that yes stellar collapse above the certain size and that's that was fairly well known could produce a black hole Pedro's had shown that it would not require there is stringent conditions to be satisfied to satisfy to create that black hole and now we know that there are possibly other reasons why black holes can be formed again Pedro's calculation showed that if you have a certain amount of mass in a certain space then that beyond a certain mass it would lead to the density is achieved of a certain amount and that's not very high depending on the mass it is then you could or you would see it collapse into a black hole so all of these results seem to show that you will see many more black holes most centers of the galaxy seem to have bad black holes was ours are supposed to have black holes because it's gravitational collapse but the gravitational energy being emitted is what seems to be powering the quasars so all of this is now entering into a new phase where we have taken now for granted black holes exist they are now even proven according to the Nobel Prize committee and therefore you can therefore give the Nobel Prize for that and we are lucky that Pedro's is alive is 89 it's because if he had died then no Nobel Prize can be given so even if Hawking's big bang theory and there is again enough experimental evidence of that which are which is there but if at some point the well committee decides that yes we have evidence we can now give a Nobel Prize for it they can't give it to Stephen Hawking and because posthumously the well prizes are not awarded so I some people have said well this is also a hat tip to Hawking the prize that he did not receive but he did richly deserve because I think he's been the most well-known name in physics after Einstein at least in our generation so thank you Ruby for joining us today and that's all the time we have keep watching you stick