WEBVTT 1 00:00:02.370 --> 00:00:07.769 Jorge Pullin: Okay. So our speaker today is for Tsultanian. We'll speak about the black hole to Whitehole transition. 2 00:00:09.120 --> 00:00:16.300 Farshid Soltani: Thanks all again. Hi, everyone. I'm Fashid Sultani. I'm a Phd. Student at the University of Western Ontario. 3 00:00:16.350 --> 00:00:21.189 Farshid Soltani: and today I'll talk about the status and the recent advancements in the Black to White or transition. 4 00:00:22.350 --> 00:00:32.860 Farshid Soltani: The talker is divided in 3 parts. In the first one I will introduce the phenomenon of the black to whiter transition, and I will give the physical intuition behind it. 5 00:00:33.530 --> 00:00:39.290 Farshid Soltani: The second part deals with the construction of an effective metric to describe the space-time. 6 00:00:39.410 --> 00:00:44.300 Farshid Soltani: and in the last part that we'll analyze the quantum physics responsible for this phenomenon. 7 00:00:45.600 --> 00:00:55.970 Farshid Soltani: So what we want to do with the black to whiter transition is to analyze a space-time of a black hole, taking into account the quantum gravitational effects. 8 00:00:56.640 --> 00:01:03.790 Farshid Soltani: So to do this we should start from the classical space Tampa black Hole, and see where quantum radial effect are relevant there. 9 00:01:04.410 --> 00:01:13.240 Farshid Soltani: So let's consider the conformal diagram reported in Slider, which describes, A black hole for the fragrational collapse. 10 00:01:13.270 --> 00:01:19.219 Farshid Soltani: The star is represented in light gray, and the horizon of the black hole is represented by the dashed line. 11 00:01:19.920 --> 00:01:29.319 Farshid Soltani: If you also consider semiclassical effects. We will have hoping radiation production. Outside the horizon, and this will reach future non-infinity. 12 00:01:30.180 --> 00:01:33.639 Farshid Soltani: Given this! The horizon will also shrink. In time. 13 00:01:34.650 --> 00:01:36.170 Farshid Soltani: in this space time 14 00:01:36.200 --> 00:01:45.139 Farshid Soltani: quantum gravitational effects. Cannot be neglected in 3 separate regions, so which for simplicity, I would call regions A, B and C 15 00:01:46.000 --> 00:01:58.909 Farshid Soltani: region A is the subregion. Of the interior vacuum of the black Hole. Where the curvature of space-time, which is a plankton value due to the presence of the classical curvature 16 00:01:59.360 --> 00:02:06.359 Farshid Soltani: region B over. Here is the sub region surrounding the horizon at the end of the operation process. 17 00:02:07.100 --> 00:02:19.380 Farshid Soltani: where the horizon which the plan can scale, and so the semiclassical approximation of hooking calculations is no longer valid. So the dynamics at this point of the horizon will be. 18 00:02:19.810 --> 00:02:27.120 Farshid Soltani: yeah. Control the by quantum gravity. Finally, Regent C is the sub region in the interior of the style 19 00:02:27.370 --> 00:02:31.240 Farshid Soltani: where the density of the collapsing matter becomes Planck Young. 20 00:02:32.930 --> 00:02:38.329 Farshid Soltani: the physics of Region A and C has been extensively studied. The World traveler question for you. 21 00:02:38.590 --> 00:02:40.349 Farshid Soltani: You yeah, get around a lot. 22 00:02:41.400 --> 00:02:53.810 Jorge Pullin: If if you, if you give it, invite a talk and say, Japan, and they pay for your local accommodations. Does that mean you can't use a tourist visa, and you have some kind of work visa, that kind of work. 23 00:02:53.950 --> 00:02:55.140 Farshid Soltani: What it does. 24 00:02:55.570 --> 00:02:57.250 Jorge Pullin: Most places it does 25 00:02:57.570 --> 00:03:01.850 Farshid Soltani: might be. I can hear. I'm trying to figure that out. It's not until 26 00:03:01.870 --> 00:03:12.159 Jorge Pullin: late January. No, not not in tourists. If if you're a tourist, or if you're attending a conference, you don't need to be sound trying to figure out whether they're paying my local expenses messes that up, and 27 00:03:12.330 --> 00:03:13.889 Farshid Soltani: probably your microphone is on 28 00:03:15.080 --> 00:03:15.850 incident. 29 00:03:16.490 --> 00:03:18.189 Jorge Pullin: I'll keep Googling. I thought you would. 30 00:03:18.210 --> 00:03:42.890 Jorge Pullin: In general, I have never done that for countries like Japan. I think that's the plan. But we'll see whether we can get it fixed. 31 00:03:43.040 --> 00:03:44.640 Jorge Pullin: One rare room. 32 00:03:45.970 --> 00:03:46.760 Jorge Pullin: Yeah. 33 00:03:47.230 --> 00:03:47.909 so on. It 34 00:03:48.520 --> 00:03:51.559 Jorge Pullin: don't want to be that guy in trouble 35 00:03:53.310 --> 00:03:54.110 Jorge Pullin: probably been. 36 00:03:54.570 --> 00:03:59.209 Jorge Pullin: No, no, there's a lot of things happen in this sort of 37 00:03:59.420 --> 00:04:13.469 Jorge Pullin: was supposed to make me host, but I think he's forgotten to do it. I can't control his mic. 38 00:04:13.820 --> 00:04:15.630 Jorge Pullin: It was easy once I had it, but it wasn't. 39 00:04:22.190 --> 00:04:29.069 Hal Haggard: They just try to go on. Yeah, let's try to go on, and I'll I'll keep trying to reach him. I'm sorry for this. 40 00:04:29.130 --> 00:04:40.669 Farshid Soltani: Yeah, no worries alright. So, as I was saying, the physics of the quantum regions. Aac has been extensively started in the niche, both in this community and the others. 41 00:04:40.880 --> 00:04:45.830 Farshid Soltani: The same is not true for the physics of Region B of the horizon at the end of the operation. 42 00:04:45.920 --> 00:04:51.719 Farshid Soltani: This is not because the people are not interested in this physics, but in fact. 43 00:04:52.010 --> 00:05:04.709 Farshid Soltani: in in the detail. There are a lot of works about poking information but the physics of this reason is just very difficult to analyze. So that's why there are less works of this 44 00:05:06.110 --> 00:05:15.900 Farshid Soltani: hooking initial proposal for the physics of the horizon at the end of the evaporation. Now was the complete evaporation of the black hole and the disappearance of the horizon. 45 00:05:16.200 --> 00:05:26.680 Farshid Soltani: While this is very problematic for different reasons. So this picture kind of stuck, and is still very used in a different works, especially in the particle physics community 46 00:05:27.470 --> 00:05:31.030 Farshid Soltani: in our community. The consensus is that the 47 00:05:31.380 --> 00:05:39.259 Farshid Soltani: the quantum region will be regularized. Quantum gravitational effects and space-time will continue beyond the this region. 48 00:05:40.290 --> 00:05:50.399 Farshid Soltani: This quite a big picture is formalized. In the Azteca border parigigma. Where this space timer, this diagram, is not 49 00:05:50.410 --> 00:06:00.270 Farshid Soltani: an actual confirm a diagram, so there is no concrete metric assigned to it just serves as a relative picture for what we expect. The 50 00:06:00.570 --> 00:06:03.140 Farshid Soltani: space-time of a black hole to look like. 51 00:06:03.310 --> 00:06:06.280 Farshid Soltani: so in the question. 52 00:06:06.560 --> 00:06:07.729 Farshid Soltani: yeah, sure. But 53 00:06:08.060 --> 00:06:16.060 Jerzy Lewandowski: so what is difference between the status of region A and the status of region? C. 54 00:06:17.510 --> 00:06:19.700 Farshid Soltani: Yes. 55 00:06:19.800 --> 00:06:21.160 Farshid Soltani: Major, aid. 56 00:06:21.920 --> 00:06:30.299 Jerzy Lewandowski: No, no. Sorry. I wanted to ask to compare the 2 quantum regions, which means the region P. And region. 57 00:06:30.570 --> 00:06:39.809 Jerzy Lewandowski: see? It seems that both of them suffer quantum properties, and they are not any longer classical. 58 00:06:40.700 --> 00:06:50.630 Farshid Soltani: Yes, they. This property is the same in the 2 of them, but the physics underlying it is different. And if you see actually from the 59 00:06:50.850 --> 00:07:03.100 Farshid Soltani: like calls in these 3 regions, you see that the onset of the gravitational effects are disconnected between each other, so it is fair to assume that the they can. They could be described separately. 60 00:07:03.280 --> 00:07:07.970 Farshid Soltani: and then check up austerity, that the physics we get that is consistent between the 3. 61 00:07:08.890 --> 00:07:17.380 Jerzy Lewandowski: Okay. But then why do you assume that the region a is any better, and it is still can be considered as classical. 62 00:07:17.900 --> 00:07:22.010 Farshid Soltani: No, I don't. I will analyze all 3 of these regions. 63 00:07:22.540 --> 00:07:23.900 Jerzy Lewandowski: I see. Okay, thank you. 64 00:07:24.500 --> 00:07:28.770 Farshid Soltani: No worries. Thank you for the question. So 65 00:07:29.460 --> 00:07:34.790 Farshid Soltani: you see, in this paradigm the quantum region integrate 66 00:07:35.180 --> 00:07:43.039 Farshid Soltani: is assumed to be described by a regular quantum. Geometry and space-time can continue beyond it 67 00:07:43.300 --> 00:07:54.579 Farshid Soltani: also, since also, at the end of the horizon evaporation. The the quantum physics of the horizon is regular. Space-time can continue around data, and we have a unique asymptotic region. 68 00:07:55.980 --> 00:08:10.890 Farshid Soltani: The black to white or space-time. Is a concrete implementation! Of concrete magic! Inside the the paradigm! So the magic was firstly proposed in 2,015. By Harvard and Rovelli. 69 00:08:11.250 --> 00:08:24.330 Farshid Soltani: and they constructed an explicit metric. Covering the full space timer, except the quantum region interact. So what they consider is collapsing. New shell of matter 70 00:08:24.610 --> 00:08:37.239 Farshid Soltani: in red. In the lower part of the diagram, and the black hole interior is represented by the light grey region. Bounded by the collapsing shell. The quantum region in that gray and the dust dropping horizon! 71 00:08:38.039 --> 00:08:41.649 Farshid Soltani: There is no metric describing the quantum region. 72 00:08:41.730 --> 00:08:53.260 Farshid Soltani: and it is only assumed that the the quantum geometry of this region is regular, and and it interpolates between the past geometry of the black hole to our future geometry of a white hole. 73 00:08:53.790 --> 00:08:58.129 Farshid Soltani: Once again. This is all done in a unique asymptotic region. 74 00:08:59.920 --> 00:09:08.430 Farshid Soltani: Now the quantum physics of the horizon, as we said, is surely relevant at the end of the population process where the horizon is plaun. 75 00:09:08.760 --> 00:09:11.149 Farshid Soltani: However, this is not the only option. 76 00:09:11.470 --> 00:09:27.730 Farshid Soltani: A different possibility is that the the planning gravitational effects near the surrounding the horizon, which are locally neglectable, can pile up during time. And they might trigger, the transition of the horizon. Before the end of the operation process. 77 00:09:28.570 --> 00:09:32.690 Farshid Soltani: This is not a necessary assumption for the black-to-water transition model. 78 00:09:32.830 --> 00:09:36.819 Farshid Soltani: but it is an assumption that hacker delivery make. For simplicity. 79 00:09:36.990 --> 00:09:51.489 Farshid Soltani: actually, what they do is they consider a scenario in which the quantum transition of the horizon is triggered long before the quantum, the evaporation process might have had any effect on the classical geometry 80 00:09:52.560 --> 00:10:02.059 Farshid Soltani: to make this assumption. They're able to construct an explicit metric. Giving this confirmal diagram in the slide? Which solves eccentric questions. 81 00:10:02.230 --> 00:10:05.750 Farshid Soltani: And I want to point out that this is a highly non-trivial result 82 00:10:05.840 --> 00:10:09.790 Farshid Soltani: just by assuming the existence of a quantum region in the space time. 83 00:10:10.170 --> 00:10:21.829 Farshid Soltani: All the rest of the geometry is an exact solution of classical general relativity. implementing A concrete representation of the ashtray of the paradigm. 84 00:10:22.410 --> 00:10:31.399 Farshid Soltani: This result, together with the analysis of the quantum region that we performed, shortly give strong critical evidence in favor of this scenario. 85 00:10:32.920 --> 00:10:50.669 Farshid Soltani: How the metric is actually constructed is well explained by these diagrams. The region numbered one. Which is in the past. Of the collapsing shell. Is a portion of Minkowski space-time. And the same is true for each of in the future of the expanding shell 86 00:10:50.870 --> 00:11:04.399 Farshid Soltani: region 2 and 3 are portion, different portion of cruise, color, space, time, and Region 2 is represented by the portion in the bottom, right, figure, and region 3 in the top, right 87 00:11:04.630 --> 00:11:10.259 Farshid Soltani: on all borders. Between these 4 regions the junction conditions are satisfied. 88 00:11:10.780 --> 00:11:17.689 Farshid Soltani: and since the union of region 2 and 3 is localism to cruise color. This is a 89 00:11:17.740 --> 00:11:20.879 Farshid Soltani: exact solution of Einstein's equations. 90 00:11:21.870 --> 00:11:27.249 Farshid Soltani: Now this is the beginning of the black to auto transition. Where are we now? 91 00:11:27.350 --> 00:11:44.950 Farshid Soltani: So unexpected? Metric. That improves. The Hague Valley space time was recently constructed. And as you can see here from the diagram of this geometry, while the Hague Valley space-time considered the quantum region. The 3 different quantum regions as a unique 92 00:11:45.410 --> 00:11:52.999 Farshid Soltani: region which was unspecified here. The interior of the black color which correspond to region A and C 93 00:11:53.100 --> 00:12:00.279 Farshid Soltani: mostly is described of an effective metric, while the only unspecified region remains rich. On B. 94 00:12:01.430 --> 00:12:24.649 Farshid Soltani: This improves a lot. Our understanding of the physics of the black to white or transition, and, as you can see, this metric was also found independently from the black to white, original space time. So this also says that our study of the interior quantum geometry of a black hole is consistent with the black to white transition. 95 00:12:25.830 --> 00:12:26.730 Farshid Soltani: Now. 96 00:12:26.930 --> 00:12:38.590 Farshid Soltani: erez agmoni to analyze the quantum physics of region BA speed from a framework was developed, and a concrete transition amplitude for the transition of geometry was 97 00:12:39.210 --> 00:12:53.459 Farshid Soltani: constructed. Now this transition amplitude is still too complex. To be analyzed. But we hope that we will be able to do it in the next years. What we were able to do is to analyze both analytically and numerically. 98 00:12:53.520 --> 00:13:02.050 Farshid Soltani: erez agmoni, the spin from transition amplitude for the original habitable space-time, and I will comment on these results in the last section. 99 00:13:03.220 --> 00:13:12.640 Farshid Soltani: Please complete the the introduction to the back to water transition. Now let's see how we can construct. The effective geometry that describes it. 100 00:13:13.690 --> 00:13:18.070 Farshid Soltani: to get a concrete metric. We will start from a concrete classical model. 101 00:13:18.120 --> 00:13:28.580 Farshid Soltani: and since the open time is not a model, is the prototypical example of a black hole formation by gravitational collapsing. We will take this model a starting point. 102 00:13:28.710 --> 00:13:39.819 Farshid Soltani: and here, classically, the style is modeled as aospatially symmetric. Homogeneous! Anisotropic! Dust field! And exterior geometry is given by usual 103 00:13:39.840 --> 00:13:41.380 Farshid Soltani: spy. Should geometry 104 00:13:42.400 --> 00:13:54.650 Farshid Soltani: we can get back to our 3 different quantum regions. And, as I was saying before, I say, these are separate regions, because the onset of quantum variational effects in these 2 regions. 105 00:13:54.840 --> 00:13:55.890 Farshid Soltani: He's a 106 00:13:56.410 --> 00:14:11.000 Farshid Soltani: cultural disconnected. So instead of studying this region as a whole, we can just study them separately and then check up austerity, that the the physics we get is consistent. So we will study all these 3 separately and see what we get them. 107 00:14:12.320 --> 00:14:23.450 Farshid Soltani: As I was saying, at the starter region, A. And C were studied extensively in our community, especially in the context of look, quantizations of symmetrized models. 108 00:14:23.540 --> 00:14:39.290 Farshid Soltani: and we will make use of different results. That are obtained in this context. For a review of all these investigations! And all the references to this works! You can check the recent review by ashtray on meadow and see. 109 00:14:40.500 --> 00:14:49.770 Farshid Soltani: So let's start the analysis of the quantum region in the inside of the star. So what we call Region C. The Castica case. Is pretty simple. 110 00:14:49.780 --> 00:14:59.109 Farshid Soltani: The geometry is described by this Lander, and here, since we assumed that the matter, the collapsing matter is homogeneous and isotopic dust. 111 00:14:59.180 --> 00:15:05.500 Farshid Soltani: The line element is basically the same line element of our cosmological Flrw. W. Scenario. 112 00:15:06.200 --> 00:15:09.719 Farshid Soltani: The only degree of freedom is the scale factor. A. 113 00:15:10.180 --> 00:15:17.660 Farshid Soltani: And we know what equations of motion it satisfies. It satisfies the Friedmann equation which we can solve. But to get 114 00:15:18.190 --> 00:15:35.580 Farshid Soltani: a plot for the scale factor now in a cosmological scenario, the scale factor gives the size of the universe. In the case of this interior of the style, it just gives the size of the style. So this plot basically gives us the plot of the physical radius of the star. In time it collapses. 115 00:15:36.130 --> 00:15:44.720 Farshid Soltani: as you can see in the classical theory. The star keeps collapsing indefinitely until it reaches a single point in which its physical radius goes to 0. 116 00:15:46.110 --> 00:15:57.039 Farshid Soltani: Now following from the similarity reduced models. And mostly from look quantum pathology. We know that we can get an effective metric discovered in this region. 117 00:15:57.360 --> 00:16:02.140 Farshid Soltani: Which takes into account the first of their corrections coming from component effects. 118 00:16:02.510 --> 00:16:17.140 Farshid Soltani: The line element described in this geometry stays the same, but the Friedmann equation is modified in this way. When the parameter rho c, which is called the critical density, is a parameter of quantum nature, the dimensions of a density and 119 00:16:17.520 --> 00:16:18.809 Farshid Soltani: plankton pay you 120 00:16:19.380 --> 00:16:41.240 Farshid Soltani: once again, this equation can be solved to find the quantum corrected scale factor and the plot of iter is represented in orange in the diagram, so you can see how in this quantum corrected metric the physical radius of the style start by collapsing, but then it doesn't reach a single pointer which listed a minimum. Then it bounces and starts to increase 121 00:16:42.230 --> 00:16:47.360 Farshid Soltani: this, of course, the usual bouncer in loop quantum cosmology. 122 00:16:48.110 --> 00:16:57.029 Farshid Soltani: These techniques were applied, but were applied. In the context of the open image and the model learned recently in Kelly, Santa Cruz, and Africa. 123 00:16:58.340 --> 00:17:01.419 Farshid Soltani: This gives us the physics of the integral of the style. 124 00:17:01.570 --> 00:17:07.309 Farshid Soltani: Now we want to see what happens in the vacuum exterior region to the style. What we call the region. A. 125 00:17:07.930 --> 00:17:12.710 Farshid Soltani: The classical case, as we said, is the usual spark shield as reported here. 126 00:17:13.079 --> 00:17:14.830 Farshid Soltani: and I want to know that 127 00:17:15.069 --> 00:17:30.059 Farshid Soltani: erez agmoni, in the symmetry model most of the time for the analysis of this region, the vacuum interior of Black Hole for simplicity. It's usedometry between this region and the cosmological kantos visa space time. 128 00:17:30.750 --> 00:17:48.539 Farshid Soltani: This is fine when you want to study the true nature of the singularity, or a first approximation of the physics of the interior region. But in our case, when we need to study the dynamical collapse model, where we need to describe consistently the interior and exterior of the vehicle in the vacuum region. 129 00:17:48.880 --> 00:17:51.299 Farshid Soltani: We cannot use this symmetry, so we need to 130 00:17:51.720 --> 00:18:02.679 Farshid Soltani: remain with the standard special case and the effective metric for this geometry can be found in the same way. It was done in Cali, Santa Cruz, and Munson, having 131 00:18:03.610 --> 00:18:13.229 Farshid Soltani: once again the line element stays the same. But the defining function F is gets a correction term that goes as one over R to the 4, 132 00:18:13.350 --> 00:18:19.539 Farshid Soltani: and there's a capital, a parameter, which is really related to just the inverse of the critical density. 133 00:18:19.890 --> 00:18:22.090 Farshid Soltani: and controls the quantum effect. 134 00:18:22.250 --> 00:18:34.359 Farshid Soltani: All the quantum correction to the classical geometry are represented. Read in this slide you can see, since capital A is much smaller than the mass of the star squared 135 00:18:34.630 --> 00:18:44.159 Farshid Soltani: the quantum correction outside the horizon. I will be negligible. And so in that syntactic region exterior to the black hole. The geometry is basically steep sparsion. 136 00:18:44.480 --> 00:18:57.579 Farshid Soltani: However, this is not true for the interior. The interior is highly affected by this correction, and we get the culture structure, which is much more similar to the cultural structure of the interior of a charged black hole. 137 00:18:58.230 --> 00:19:10.640 Farshid Soltani: You see, starting from the exterior asymptotic region to the black Hole, we can enter the outer horizon, and we find ourselves in a dropped region which is bounded an inner and outer horizon. 138 00:19:10.750 --> 00:19:18.089 Farshid Soltani: If we still go inside into the inner horizon. We are in a non-trapped region where the style antibodies Bouncer. 139 00:19:18.420 --> 00:19:26.759 Farshid Soltani: This is not the end of the story. We can still go in the future of it. We enter a non-tech region which is bounded by a different in another horizon. 140 00:19:27.050 --> 00:19:32.119 Farshid Soltani: and then we can go out in a second asymptotically talk to each one deeper from the first one. 141 00:19:34.580 --> 00:19:35.440 Farshid Soltani: Now. 142 00:19:35.710 --> 00:19:52.190 Farshid Soltani: erez Agmoni, this geometry for the exterior region was, find, independently from the interior region of the style, however, it turns out that they are exactly compatible. In fact, in Lebanowski and others, and Babur and Pavlovsky, it was shown that 143 00:19:53.060 --> 00:20:06.970 Farshid Soltani: the induced metric and ecstasy curvature on the boundary, on the style that from the 2 sides exactly match. In this scenario. also modern days, it would actually show that the effective metric for the exterior 144 00:20:06.980 --> 00:20:14.200 Farshid Soltani: is actually the unique, staggering symmetric metric having an IP surface at the Gona killing vector field. 145 00:20:14.520 --> 00:20:19.949 Farshid Soltani: That exactly satisfies the junction conditions with the ideal effectiveness of the style. 146 00:20:21.410 --> 00:20:36.390 Farshid Soltani: So this concludes the analysis of the quantum model. However, we still know that we need to take into account the pitch of the horizon. In fact, as soon as hawking evaporation process is considered 147 00:20:36.710 --> 00:20:45.749 Farshid Soltani: qualitatively the path of space-time. Shaded in gray here will not be a good approximation of the physics of a black hole. 148 00:20:46.770 --> 00:20:50.049 Farshid Soltani: Now, one way to describe it could be to just 149 00:20:50.110 --> 00:21:04.709 Farshid Soltani: erez agmoni and analyze it as we did before region A and region C, so just by using symmetry to small as an effective metric. However, to do this, we will need to account for walking radiation and its better action on the metric, and this is a very difficult calculation 150 00:21:05.170 --> 00:21:21.140 Farshid Soltani: instead. What we will do is just to assume as hypothetical that what happens at the end of the evaporation process is a transitional geometry of from traffic horizon to anticipate horizon consistently what we found in the interior 151 00:21:22.080 --> 00:21:32.719 Farshid Soltani: and then construct the space time of starting from this open image, neither model so to actually get a concrete metric. For a space timer 152 00:21:32.760 --> 00:21:37.970 Farshid Soltani: as architecture. Valid leader, we will neglect the poking evaporation processor. 153 00:21:38.740 --> 00:21:40.130 Farshid Soltani: This is not the 154 00:21:40.940 --> 00:21:58.640 Farshid Soltani: because we need to do it. Focusing the space time. Just for simplicity. And even if the evaporation process could change the quantitative physics. Of the metric! It would not change the positive picture of the global spacetime. And that's what we interested in. 155 00:21:59.770 --> 00:22:10.020 Farshid Soltani: So we will assume. That the transition of the horizon is together after a certain amount of time. At the about punch time here, so symbolized by these 156 00:22:10.040 --> 00:22:22.509 Farshid Soltani: surface here. And we also want to get a unique asymptotic region. So we need to cut the exterior region before it reaches non-infinity, and this is done with a constant time surface over here 157 00:22:23.640 --> 00:22:38.920 Farshid Soltani: next. We know that the open 9 minus 90 model is actually symmetric under the time invention with respect to the time at which the bounds happen. So we can keep this symmetry post in our space time since we are neglecting hooking the evaporation. 158 00:22:39.170 --> 00:22:43.380 Farshid Soltani: So we get the a symmetric construction in the upper part of the space time. 159 00:22:43.800 --> 00:22:50.989 Farshid Soltani: Now, the region we don't trust is the one bounded by the blue lines, so we can just get rid of it. And we can identify 160 00:22:51.040 --> 00:22:53.580 Farshid Soltani: the 2 time surface. 161 00:22:53.590 --> 00:22:58.520 Farshid Soltani: the two-time surfaces on past and future, which are isometric by construction. 162 00:22:58.550 --> 00:23:04.510 Farshid Soltani: And this gets us today black to white or spacetime. And it's effective metrics. And now 163 00:23:05.000 --> 00:23:17.670 Farshid Soltani: this construction seems easy when you just take lines, cut pieces of space-time and put them together. There are actually a lot of mathematical details that I will not go very into, but they can be found in the paper cited about here. 164 00:23:19.480 --> 00:23:32.509 Farshid Soltani: So we now have an effective metric. That describes the full space-time of the black water transition, even the interior of the black Hole. Except the quantum region in which there is the physics of the horizon! 165 00:23:33.590 --> 00:23:44.129 Farshid Soltani: I want to stress that this is not just a qualitative space-time of something. We think the space time of the black Hole might look like a. There is a concrete metric representing this. 166 00:23:45.280 --> 00:23:47.300 Farshid Soltani: a question we might ask is, 167 00:23:47.350 --> 00:23:53.559 Farshid Soltani: how do we trust this metric to represent the physical space-time of a black hole? So 168 00:23:53.870 --> 00:24:03.419 Farshid Soltani: we should think of this metric the same way we think of the schematic of an open standard model in the classical theory, so the open name is not a model 169 00:24:04.950 --> 00:24:16.280 Farshid Soltani: does not describe the quantitative physics of a black hole from the gravitational collapse. It considers matter collapsing just as a homogeneous any dust. 170 00:24:16.430 --> 00:24:28.180 Farshid Soltani: and it's vaguely symmetrical, you know the purpose to rotate, so it doesn't get the quantitative picture corrected, but it is an accurate description of the qualitative physics of the 171 00:24:28.580 --> 00:24:37.440 Farshid Soltani: of our collapsed information of a black hole. And so this is the same that this space time does. for the quantum gradation artifics of a blackboard. 172 00:24:39.000 --> 00:24:41.649 Farshid Soltani: So we had our explicit metric 173 00:24:42.490 --> 00:24:49.279 Farshid Soltani: for the Blackwater transition. Now it's time to actually analyze. The physics! Inside of region. P. 174 00:24:51.310 --> 00:24:52.200 Farshid Soltani: So 175 00:24:54.320 --> 00:25:02.709 Farshid Soltani: when we think of quantum geometry in general. We don't think of something that can be described with the classical concept of metric 176 00:25:03.050 --> 00:25:04.679 Farshid Soltani: and racially corrected. 177 00:25:04.830 --> 00:25:11.630 Farshid Soltani: However, it turns out that in very specific scenarios, like the idea of the black hole, we just studied 178 00:25:12.560 --> 00:25:23.579 Farshid Soltani: the quantum geometry. One of the properties of the quantum geometry is that it is well approximated by an effective metric. So we can use the classical concept. That 179 00:25:23.620 --> 00:25:35.849 Farshid Soltani: is not to say that the the quantum theory is not relevant. In this part of space-time, in fact, to get the effective medicare that satisfies effectively the page answer. 180 00:25:35.900 --> 00:25:41.310 Farshid Soltani: we need to go to the quantum theory. It's just a peculiar property of the quantum geometry there. 181 00:25:42.170 --> 00:25:43.790 Farshid Soltani: So one possibility 182 00:25:44.410 --> 00:25:52.849 Abhay Vasant Ashtekar: could I ask a question? Yes, II think that there is a very dramatic thing about this region be 183 00:25:53.110 --> 00:25:58.849 Abhay Vasant Ashtekar: if I look at the hawking radiation, if you are ignoring hawking radiation here. But if I looked at the hawking radiation. 184 00:25:59.030 --> 00:26:03.480 Abhay Vasant Ashtekar: then, in fact, at this late times it is getting extremely ultraviolet. 185 00:26:04.190 --> 00:26:07.589 Abhay Vasant Ashtekar: And so what is coming out of your region be 186 00:26:08.030 --> 00:26:12.300 Abhay Vasant Ashtekar: to scry between these 2 you you all find you beats now 187 00:26:12.420 --> 00:26:14.180 Abhay Vasant Ashtekar: is something good that is going to be 188 00:26:14.380 --> 00:26:21.059 Abhay Vasant Ashtekar: tremendously quantum mechanical. So I'm not clear that this effective metric description 189 00:26:21.170 --> 00:26:24.040 Abhay Vasant Ashtekar: should be valid here, so can you tell me why you 190 00:26:24.050 --> 00:26:30.889 Abhay Vasant Ashtekar: I mean I can say that. Well, but that may be true, but I just see what happens that that I'm happy. But if you think that 191 00:26:31.110 --> 00:26:34.359 Abhay Vasant Ashtekar: there is any reason to believe that effective metric is valid 192 00:26:34.460 --> 00:26:41.979 Abhay Vasant Ashtekar: in this region which is bounded by the region B and the and then Skype Sky plus, which is, you will find New Beta. 193 00:26:42.310 --> 00:26:54.969 Farshid Soltani: I would like to understand why. I mean, II think that is the deepest problem. So I would like to understand why. No, no, I agree what you said, which would be 194 00:26:55.250 --> 00:27:03.409 Farshid Soltani: whatever want to say, and I will comment on this, that it's just that it's a possibility we don't know what is there? We shouldn't exclude it. But 195 00:27:03.570 --> 00:27:10.480 Farshid Soltani: there's a certain possibility that the the pump in German be would be deeply want to. 196 00:27:11.050 --> 00:27:14.369 Abhay Vasant Ashtekar: Okay, thank you. Yeah, we are the same name. Thank you. 197 00:27:14.830 --> 00:27:16.690 Farshid Soltani: Yeah. So. 198 00:27:16.810 --> 00:27:32.749 Farshid Soltani: as I was saying, one possibility is that the uneffective metric might be given there. Describe this region. But there's also another possibility, as we were just saying, that the quantum Germany there is deeply quantum, and no classical concept of metric can be given, and it doesn't make any sense. 199 00:27:33.560 --> 00:27:37.000 Farshid Soltani: So to comment further on visa 200 00:27:38.190 --> 00:27:39.120 Farshid Soltani: the way 201 00:27:39.870 --> 00:27:57.030 Farshid Soltani: some suggestion that they could not be given any regular metric inside of vision. B. Any effective metric. And it's a different arguments. From the one I was saying. So the arguments for the non-existence of a regular metric inside of vision B. Were more 202 00:27:57.340 --> 00:28:15.410 Farshid Soltani: dramatical. In the sense that you see from the left side of this region there are 2 sets of inner and outer horizons. That come into Region B, and they don't come out from the left boundary. So this means that in some way these horizons need to end inside this region. 203 00:28:15.560 --> 00:28:21.300 Farshid Soltani: There were some arguments that this could not be possible. using an effective concept of metric. 204 00:28:22.250 --> 00:28:32.400 Farshid Soltani: What I want to say is that it turns out that this is not true, in fact. The effective metric we constructed. For the space-time in the exterior region. B can be 205 00:28:32.820 --> 00:28:37.240 Farshid Soltani: naturally and most importantly, regularly 206 00:28:38.540 --> 00:28:53.489 Farshid Soltani: extended inside of the region. B, and as you can see from this diagram. This is how trapped an anti-tap region behavior. So take, for example, the trapping inner and upper horizon. So, and soon as they enter the P. Region, start to 207 00:28:53.510 --> 00:29:04.769 Farshid Soltani: go towards each other, and they meet the second pointer, thus closing the truck region, which is now a compact regional space time. The same happens to the untapped up region in the future. 208 00:29:05.040 --> 00:29:18.690 Farshid Soltani: and the rest of the B region is really only a non top region which serves as a sort of connection between the non top region in the interior of the backward, where the start bounces and the non dropped exterior asymptot region. 209 00:29:19.820 --> 00:29:24.529 Farshid Soltani: Also, you can see from the diagram on the right how curves of custom radios behave. 210 00:29:26.140 --> 00:29:27.030 Farshid Soltani: Now 211 00:29:27.210 --> 00:29:53.320 Farshid Soltani: here, I'm not saying that this is an effective metric for the Be region. In fact, we have no physical motivation for it, and we are not even sure that there should be an effective metric, as we will say before, this is just a proof of concept for the possible existence of an effective metric inside this region. So there are regular metrics that describe this region. We don't know if there's physical or there should be a metric at all in this region. 212 00:29:53.840 --> 00:30:00.609 Jerzy Lewandowski: A question about a question about the behavior of the are equal, constant surfaces. 213 00:30:00.630 --> 00:30:07.729 Jerzy Lewandowski: so so are they killing horizons in, in, in inside this gray region. 214 00:30:07.930 --> 00:30:14.780 Jerzy Lewandowski: No, no, the keeping symmetry is broken inside this region. So this 215 00:30:17.130 --> 00:30:18.710 Farshid Soltani: they're not now? No? 216 00:30:18.880 --> 00:30:22.089 Jerzy Lewandowski: Oh, I see. So they are like dynamical horizons. 217 00:30:22.240 --> 00:30:23.620 Farshid Soltani: Yes, yes. 218 00:30:24.490 --> 00:30:26.490 Jerzy Lewandowski: Umhm, okay, thank you. 219 00:30:27.430 --> 00:30:28.680 Farshid Soltani: Thank you for the question. 220 00:30:30.350 --> 00:30:32.160 Abhay Vasant Ashtekar: But but time like right? 221 00:30:33.110 --> 00:30:39.560 Farshid Soltani: Yes, this is a true conformer diagram. So the light cone is always 45 degrees. And yeah. 222 00:30:40.130 --> 00:30:47.149 Abhay Vasant Ashtekar: yeah, but I mean, Mike, my point is that it's not only region B, but everything that is causally related to Region B. 223 00:30:47.420 --> 00:31:05.900 Abhay Vasant Ashtekar: We don't really know that the metric is is is going to be classical. So this is just a side remark. I just wanted to say that because the metric is not classically classical in that region, then it would not be classical in A to the future of that region, either. So I think I just wanted to mention that because we are focusing only on Region BI was making a 224 00:31:06.730 --> 00:31:08.440 Abhay Vasant Ashtekar: like, you still want? 225 00:31:08.470 --> 00:31:11.120 Farshid Soltani: Yeah, this is just 226 00:31:11.290 --> 00:31:36.419 Farshid Soltani: what we get out of the effective equations individuals, a, M and and C, and the the metric because stuck for next year. But then this metric needs to be checked. The fields of the quantum region in B needs to be checked, and it needs to have the correct properties to get this based and out of it. There's also the possibility that quantum effects leaked in the future and all the future of the B region. And it's the quantum data is a possibility. 227 00:31:37.050 --> 00:31:37.800 Abhay Vasant Ashtekar: Thank you. 228 00:31:38.590 --> 00:31:39.330 Farshid Soltani: Yes. 229 00:31:39.780 --> 00:31:48.480 Farshid Soltani: So in any case. even if if there is effective metric for each, and B, or it is a deep quantum region. 230 00:31:48.490 --> 00:31:52.769 Farshid Soltani: This PIN from frameworker can describe it. And so let's see how we do it. 231 00:31:53.570 --> 00:32:03.220 Farshid Soltani: The black-to-while metric. In the exterior of the quantum b region. Depends on 4, 3 parameters. The mass, M. Of the collapsing star 232 00:32:03.300 --> 00:32:14.759 Farshid Soltani: erez agmoni the bounce time, capital T, which is related to the proper time. Experienced by a distant observer from the moment in which the black hole is formed to the moment in which the white hole disappears. 233 00:32:15.140 --> 00:32:23.440 Farshid Soltani: and then 2 advanced times. The alpha and the beta that defines location and size. Of the quantum region people. 234 00:32:24.470 --> 00:32:36.179 Farshid Soltani: Interestingly. the 2 parameters, MB. Alpha D. Beta. I lock up parameters. that is a local observer can study them analyzing the local geometry around him. 235 00:32:36.570 --> 00:32:39.619 Farshid Soltani: However, the bounce time T 236 00:32:39.690 --> 00:32:56.649 Farshid Soltani: is a global parameter, so a lot of observer cannot measure it studying the geometry around them. But it can only be studied by decent observer calculating its proper time. From the formation of the black order that the appearance of the black order 237 00:32:56.960 --> 00:33:08.770 Farshid Soltani: this parameter, if you want to think about it is very similar to the radius of a cylinder. If you study the local geometry of the cylinder, you cannot see the radius. But if you study globally, the radius, you know, is a parameter of the geometry. 238 00:33:10.170 --> 00:33:11.030 Farshid Soltani: So 239 00:33:11.140 --> 00:33:23.450 Farshid Soltani: once we have this 4 dimensional geometry, this induces a three-dimensional geometry on the boundary of the P region. And this basically gives the initial state of the trans quantum transition of geometry and the final state. 240 00:33:24.110 --> 00:33:34.949 Farshid Soltani: So this is really a standard transition of geometry calculation. So any tentative theory of quantum gravity that wants to describe the real border should be able to describe this process. 241 00:33:36.070 --> 00:33:39.090 Farshid Soltani: Let's see how the spin from framework does it. 242 00:33:39.460 --> 00:34:04.010 Farshid Soltani: So the state of the right spin for model for continuity is the generalized Eprl Kkl model, and it is defined on the discrete setting. So the continuum limit of spin for models is still another question. So all the calculations are done in the discrete settings. So the first thing we need to do is discretize the boundary geometry of our region. 243 00:34:04.900 --> 00:34:26.199 Farshid Soltani: Erez agmoni there is no unique or really correct way to do it from a practical point of view. What you want to do is to take a discretization which is refined enough to get enough degrees of freedom of the phenomenon. But you also want that discretization which is simple enough for the transition amplitude to be computed and analyzed. So you need a balance between these 2. 244 00:34:27.820 --> 00:34:40.230 Farshid Soltani: In any case, once you define a discretization, you can take its dual picture and get a graph gamma. the one for the specific geometry we got is represented in the picture. 245 00:34:40.420 --> 00:34:48.590 Farshid Soltani: and the notes of the graph are represented as colored sphere. However, the details of this construction are not relevant. I will not comment on them. 246 00:34:49.719 --> 00:35:03.900 Farshid Soltani: The point is, once we have the graph, gamma, we can define the space. Of spin networks. Over this graph. And this will give me the boundary, Hiba space. Of the theory in which the spin compensation, amplitude is defined 247 00:35:05.000 --> 00:35:24.780 Farshid Soltani: erez Agmoni also given the graph and the discrete geometry that we have from the continuous dimensional geometry. We can then define a unique coherent state in the Banda Hub space that describes, peaked on the classical, discrete geometry we found. So this gives initial and finance data for the quantum transition. 248 00:35:26.050 --> 00:35:37.779 Farshid Soltani: Once this is done, we need to get a spin form. That describe the quantum transition of geometry once again. There's no unique way to define the spin form. And it 249 00:35:37.910 --> 00:35:47.169 Farshid Soltani: it comes down once again, just to a balance between refinement. To get an activities of freedom for the phenomenon and simplicity for the corporations to be manageable 250 00:35:48.180 --> 00:35:54.130 Farshid Soltani: once a concrete spin form is defined. We can get the 251 00:35:54.190 --> 00:36:00.090 Farshid Soltani: spin from transition amplitude right here for the phenomenon. Now the transition amplitude 252 00:36:00.340 --> 00:36:05.940 Farshid Soltani: for this specific space timer was explicitly computed in the references at the top of the slide. 253 00:36:06.600 --> 00:36:14.100 Farshid Soltani: Unfortunately, this is a very complicated object, and it was not possible to analyze it right away, but, as you will see in the next slide, the 254 00:36:14.490 --> 00:36:15.910 Farshid Soltani: The. 255 00:36:15.920 --> 00:36:26.120 Farshid Soltani: We were just able to analyze it, the the spin from for the original hug at the valley space timer. So we hope that we can. We can get to these more refined spin forms in the next year. So 256 00:36:27.200 --> 00:36:34.020 Farshid Soltani: before moving on to these results. I wanted to mention. What this transition up to the actual means? 257 00:36:34.270 --> 00:36:37.840 Farshid Soltani: so for the physics of Region B. What we know is that 258 00:36:38.040 --> 00:37:02.649 Farshid Soltani: there might be in theory many different viable options. For what happens in region B, the black to water position is one of them. There might be others so ideally. What we want to study with this transition amplitude is the probability for the black to white organization to be realized instead of the others. This is something we don't have control over. So it's something that we cannot get with this framework. 259 00:37:02.950 --> 00:37:16.399 Farshid Soltani: However, what we can get is we can restrict ourselves. To the subspace! Of black to white hole scenarios! So, as you see, there are 4 free parameters. So the black to Western transition can actually happen 260 00:37:16.730 --> 00:37:32.579 Farshid Soltani: in many different ways. Depending on the values of these parameters. So we can restrict. On this start pace. And ask questions. About which one of this particular completion of parameters is most proper, more problem than the others. So this transition amplitude 261 00:37:33.680 --> 00:37:39.070 Farshid Soltani: allows us to study this space of parameters. So this is a well-defined quantity 262 00:37:39.440 --> 00:37:44.800 Farshid Soltani: and normalizable, and we can ask a lot of questions with it. For example, we can ask 263 00:37:44.880 --> 00:38:01.779 Farshid Soltani: erez agmoni is the transition amplitude suppressed for microscopic values of the mass. M. So the transition to happen only at the end of the evaporation process, or there is a non-vanishing probability, also microscopic masses. So this transition could happen at any time. 264 00:38:02.490 --> 00:38:12.200 Farshid Soltani: Erez agmoni. We can also ask, what is the probability? What is the average pounce time of this model, we can ask all possible questions regarding these parameters. 265 00:38:13.140 --> 00:38:23.209 Farshid Soltani: This question rain did ask, for the speed, from transition, amplitude of the original algebra space timer and results were recently obtained. So I will comment on this. 266 00:38:23.830 --> 00:38:27.229 Farshid Soltani: Hi, can I ask a quick question? Yup, sure. 267 00:38:27.510 --> 00:38:40.180 Deepak Vaid: So how one of the parameters that you have is is is M. That's the mass right? Correct? So so I mean, how exactly is the mass encoded in the definition of this 268 00:38:40.460 --> 00:38:42.950 Deepak Vaid: of the spin-form state. 269 00:38:43.350 --> 00:38:57.759 Farshid Soltani: Yeah, the 4 dimensional geometry depends on the master. So when I get the boundary geometry of the P region, this will also depend on the master. So the value of my transition amplitude depends on the mass of this coherent state right here. 270 00:38:58.370 --> 00:39:02.119 Farshid Soltani: So we get a different answer for different values of the month. 271 00:39:03.550 --> 00:39:07.719 Deepak Vaid: No, I guess I guess what I'm trying to understand is that like I mean. 272 00:39:08.380 --> 00:39:12.580 Deepak Vaid: if if I if I look at individual vertices in the spin form. 273 00:39:14.200 --> 00:39:24.389 Deepak Vaid: or if I just look at the spin form, state independent of the background, geometry. can you assign a sense, a notion of mass to that to that graph state. 274 00:39:27.810 --> 00:39:30.860 Farshid Soltani: No, the concept of mass come from the understate. 275 00:39:32.370 --> 00:39:33.880 Farshid Soltani: There's been from 276 00:39:34.710 --> 00:39:41.429 Farshid Soltani: describe the geometry. I don't have a way to assign a concept of mass there. 277 00:39:42.010 --> 00:39:44.499 Farshid Soltani: It surely must be encoded in some way. 278 00:39:46.450 --> 00:39:49.230 Farshid Soltani: I don't know how to define it from the outset. Yeah. 279 00:39:49.740 --> 00:39:51.060 Deepak Vaid: okay, thank you. 280 00:39:51.310 --> 00:39:52.170 Farshid Soltani: No worries. 281 00:39:56.930 --> 00:39:58.480 Farshid Soltani: Alright. So 282 00:39:59.640 --> 00:40:18.920 Farshid Soltani: erez agmoni the spin form for the quantum region in the space timer was constructed Velenski in 2,016, and this is the spin form they used. As you can see, it's much simpler than what the one I showed in the last slide. So this is why we were able to get 283 00:40:19.210 --> 00:40:24.220 Farshid Soltani: to analyze this transition. Amplitude is also true, however, that 284 00:40:24.230 --> 00:40:33.779 Farshid Soltani: this spin form needs to capture the degrees of freedom, not only of the physics of the B region. But really of the full, complete quantum region that really 285 00:40:34.040 --> 00:40:45.409 Farshid Soltani: erez agmoni. So this means that a lot of degrees of freedom needs to be described by these quite simple spin form with only 2 vertices and no internal faces. So while this is fine. The 286 00:40:45.740 --> 00:41:00.830 Farshid Soltani: erez agmoni that's from numbers we get out of it should just be considered as a rough idea of of what matter is, if we then will be able to analyze also more complex platforms and confirm this results. It would be a strong, a stronger analysis. 287 00:41:01.960 --> 00:41:20.589 Farshid Soltani: So the analysis of this Pinfo model was initiated by Christopher and Ambrosio in 2,018, and the main results that I'm presenting here were already found. However, there were some technical details that were left open, and so these were recently taken care of in Christa. Do the office. 288 00:41:21.450 --> 00:41:36.459 Farshid Soltani: What they find is that the probability for this transition to happen goes as the exponential of the negative ratio of the square, of the mass, of the collapsing, the matter, and the square of the plank mass. So this means that when the mass is macroscopic. 289 00:41:36.480 --> 00:41:44.229 Farshid Soltani: this transition is highly suppressed. In fact, as you can see, the lifetime of the process. Processed exponential. Of the 290 00:41:44.440 --> 00:41:57.280 Farshid Soltani: erez agmoni ratio, of the square mass of the collapsing matter and the spur of the drug master. So this time is a very long time before the transition can happen if we don't consider the hope evaporation process, in fact, much longer. 291 00:41:57.640 --> 00:41:59.550 Farshid Soltani: that they're hoping evaporation time. 292 00:41:59.870 --> 00:42:15.039 Farshid Soltani: and this is great. This is an actual, genuine prediction of the model. The assumption that we're made of neglecting Ok. Evaporation. Turns out to not be correct. And this is given by this prediction here made with the spin from framework. 293 00:42:16.850 --> 00:42:21.330 Farshid Soltani: This results were also recently confirmed numerically by the work of pizza. 294 00:42:22.670 --> 00:42:33.519 Farshid Soltani: So this numerical confirmation was also for this just 2 vertex vertex model, or Yes, okay. 295 00:42:34.870 --> 00:42:41.009 Farshid Soltani: yes. All the results for now are just this simple speaking. which is already a great result of 296 00:42:43.370 --> 00:42:53.310 Farshid Soltani: so, but I hope I convey them in this talk. Is that the the black to Whitehall transition? Is a very natural scenario for the physics at the end of evaporation process of a black hole. 297 00:42:54.440 --> 00:43:03.129 Farshid Soltani: and we were able to construct an effective metric. For the space timer that also takes into account the the quantum geometry of the interior of a black hole. 298 00:43:04.300 --> 00:43:18.540 Farshid Soltani: We've also seen how the spin from formalism is perfectly able to describe. The quantum transition of geometry happening inside the spontane region, and is also able to get out estimates, physical estimates for the 3 parameters of the model. 299 00:43:19.940 --> 00:43:26.509 Farshid Soltani: This is all nicer. However, this should not be seen as the end pointer. This is really just the starting point for more refined analysis 300 00:43:26.570 --> 00:43:50.029 Farshid Soltani: erez agmoni. In fact, just to mention a few of them. We've just seen how the Spin form transition amplitude told us that the most probable scenario for the black to water. Transition is this transition of the horizon happening at the end of the evaporation process. So we should really work to implement better the poking evaporation process in the context of the black to transition. 301 00:43:50.470 --> 00:43:58.939 Farshid Soltani: Our starting point, our first step was done in my team, the soil of La in very 19. But more work need to be done 302 00:43:59.160 --> 00:44:18.310 Farshid Soltani: erez agmoni. Also it is interesting how, in the interior region of a black hole, now we have an inner horizon. So this designer horizons classically, as soon as you are the ingoing and outgoing matter streams up, I bay dynamical objects. So it will be interesting to study how these quantities behave in the context of the 303 00:44:18.630 --> 00:44:22.179 Farshid Soltani: effective quantum geometry and effective equation of motion 304 00:44:22.900 --> 00:44:39.260 Farshid Soltani: erez agmoni. Secondly, we've seen how we got the first result for the spin from calculations, and this is greater. It would be very nice if you would also try to go in the next step and be able to analyze more complex transition amplitudes, and confirm these results. 305 00:44:40.450 --> 00:44:54.010 Farshid Soltani: Furthermore, everything I said applies only to the stakeholder symmetric case. We know that physical black holes rotate. So it will also be good to be able to generalize this model. With the addition of the angular momentum. 306 00:44:55.070 --> 00:45:11.450 Farshid Soltani: Finally, an interesting point is that the transition of geometry in the quantum field region was often compared with a handling phenomenon in non-relativistic quantum mechanics. But there are some very clear similarities between the 2. 307 00:45:11.470 --> 00:45:20.110 Farshid Soltani: It will be interesting to to see to what extent. These 2 scenarios are similar, and to get a clearer picture about this. 308 00:45:20.400 --> 00:45:22.950 Farshid Soltani: With this I conclude. Thank you. 309 00:45:24.660 --> 00:45:29.100 Hal Haggard: thank you, Farsheid. Thank you for your time management. 310 00:45:32.110 --> 00:45:33.220 Carlo Rovelli: Yes. 311 00:45:33.700 --> 00:45:40.079 Hal Haggard: we'll begin with questions. I see that Ding has already raised his hand, ding, feel free to unmute and ask. 312 00:45:40.640 --> 00:45:41.850 Ding Jia: thank you. 313 00:45:42.080 --> 00:45:50.539 Ding Jia: Very nice talk. I like it very much. I have a question about the second bullet point. It's an existential question. 314 00:45:50.700 --> 00:46:02.269 Ding Jia: what does it mean to have an effective metric? And what is it good for? So I have another notion of effective metric which is a start with a quantum path. Integral. 315 00:46:02.440 --> 00:46:07.520 Ding Jia: impose some boundary conditions I solve for the relevant set of points 316 00:46:08.060 --> 00:46:14.989 Ding Jia: this gives me one or multiple effective metrics and know what it is good for, because 317 00:46:15.010 --> 00:46:17.849 Ding Jia: maybe the whole path integral, is hard to evaluate. 318 00:46:17.890 --> 00:46:34.129 Ding Jia: And I used these saddle points as my leading other approximation to the passenger. So for this notion of the effect of metric, I know its meaning. Do I understand correctly that you're using a different notion of effective, effective metric. And if so, 319 00:46:34.160 --> 00:46:38.290 Ding Jia: what's the what's the what's its meaning of life? 320 00:46:38.510 --> 00:46:44.019 Farshid Soltani: Yeah. The meaning is so you can start from the quantum theory of the geometries, or let me go back to. 321 00:46:45.610 --> 00:47:01.720 Farshid Soltani: So, for example, here, from for the interior physics of the style, you can take the classical physics. Then you can go into the quantum theory of this geometry, and then you can define a coherent state on the classical state. Then you can 322 00:47:02.580 --> 00:47:09.710 Farshid Soltani: follow the quantum dynamics of these quantum state. And you can realize that 323 00:47:09.710 --> 00:47:32.669 Farshid Soltani: the the main peak of these coherence data satisfy some effective equations which are the one gives here. So this really quantum coherence data whose coherence remains to all the way to the collapse. And then what happens later, and so I can describe effectively the physics of the peak of these quantum state to these effective equations. 324 00:47:33.460 --> 00:47:40.760 Farshid Soltani: So the true theory is still quantum. But I can get an approximation of what happens. By studying just these physics here. 325 00:47:42.300 --> 00:47:45.650 Ding Jia: in comparison to the other notion of effective metric. 326 00:47:47.040 --> 00:48:04.440 Farshid Soltani: I'm not familiar with the notion you gave the way I see it is that there's a lot of different way to get approximation of the physics of this region. So there might be 2 different approximations that get right different sort of physics. And that's okay. Just get 327 00:48:04.970 --> 00:48:10.819 Farshid Soltani: more pages of different physics that then can put together and see the clear picture. 328 00:48:11.550 --> 00:48:16.119 Ding Jia: Do I understand correctly that for your notion of effective metric 329 00:48:16.200 --> 00:48:20.710 Ding Jia: you require, you know, some time evolution for it to be meaningful. 330 00:48:22.480 --> 00:48:23.740 Farshid Soltani: And 331 00:48:25.650 --> 00:48:28.100 Farshid Soltani: yes, you choose. 332 00:48:28.630 --> 00:48:32.080 Farshid Soltani: You need to choose a sort of 333 00:48:32.490 --> 00:48:33.510 Farshid Soltani: and 334 00:48:33.580 --> 00:48:40.009 Farshid Soltani: time field or time evolution you want to study doesn't need to be. 335 00:48:40.420 --> 00:48:44.549 Farshid Soltani: And in particular, then we can start evolution. That specific 336 00:48:45.110 --> 00:48:46.940 Farshid Soltani: times you've chosen. Yes. 337 00:48:48.510 --> 00:48:50.770 Ding Jia: and the year notion of effective metric. 338 00:48:50.850 --> 00:48:57.349 Ding Jia: You only need to know the initial boundary condition. You don't know. You don't need to know anything about the future boundary condition. 339 00:48:58.660 --> 00:48:59.520 Farshid Soltani: Correct. 340 00:49:00.840 --> 00:49:02.589 Ding Jia: I see that's a very special 341 00:49:02.950 --> 00:49:05.859 Ding Jia: type of effective measure. But I understand it. No, thank you. 342 00:49:06.570 --> 00:49:07.720 Farshid Soltani: Thanks for the question. 343 00:49:08.870 --> 00:49:09.820 Hal Haggard: Yurik. 344 00:49:11.620 --> 00:49:16.630 Jerzy Lewandowski: okay. So my question is about this. 345 00:49:16.660 --> 00:49:20.219 Jerzy Lewandowski: a surface on which the surface. 346 00:49:20.310 --> 00:49:24.649 Jerzy Lewandowski: the surface quantum state is defined, so 347 00:49:24.930 --> 00:49:38.569 Jerzy Lewandowski: there is a ambiguity in fixing the surface. so how S. Sensitive is the result? deformations of this surface. 348 00:49:38.950 --> 00:49:53.850 Farshid Soltani: Yeah, so this really is not a problem of this specific kind of geometry. The problem of what is the pound? I didn't quantum mechanics. So it's the same problem. And 349 00:49:54.200 --> 00:49:59.429 Farshid Soltani: in theory one expect that by choosing different 350 00:50:00.080 --> 00:50:03.760 Farshid Soltani: Panda is you should get the same physics. Out of it. 351 00:50:03.840 --> 00:50:17.880 Farshid Soltani: Erez agmoni! The only way to prove this in our context is to prove, different boundaries for this region. Calculate the transition amplitude, get out results and then compare them, and they should get out to be compatible. 352 00:50:18.080 --> 00:50:23.100 Farshid Soltani: Please. Of course, sir. out of the question right now. But that's the idea. And that's the hope. 353 00:50:28.530 --> 00:50:30.230 Jerzy Lewandowski: Okay, thank you. 354 00:50:31.180 --> 00:50:31.890 Farshid Soltani: Thank you. 355 00:50:32.150 --> 00:50:42.860 Abhay Vasant Ashtekar: Have a question. Yeah, II just couldn't raise my hand somehow. Something went wrong. Yeah, I just a quick, quick question would just do it. I would like to understand better 356 00:50:43.280 --> 00:50:51.200 Abhay Vasant Ashtekar: the relation between your slide 2021 and then 22, basically 2021 seems to be much more elaborate. 357 00:50:51.630 --> 00:50:58.420 Abhay Vasant Ashtekar: With lots of vertices and lots of is that right? That a lot many vertices here? 358 00:50:58.430 --> 00:51:06.879 Farshid Soltani: Yeah, yeah, this is quite a more complex. Here we have 14 vertices 28 notes 359 00:51:07.310 --> 00:51:09.699 Abhay Vasant Ashtekar: So what is known? In that that case. 360 00:51:10.670 --> 00:51:23.659 Abhay Vasant Ashtekar: what is known in that case many notes. And yeah, what what is known yet? Because you just went to the simplified model and told us what is known. 361 00:51:23.890 --> 00:51:28.199 Abhay Vasant Ashtekar: But in this case, you just set up the problem. But I didn't understand what exactly was shown. 362 00:51:28.580 --> 00:51:51.730 Farshid Soltani: Yeah. So we we've shown that we can get a transition ampute out of it, though we have computed a well defined transition amplitude that we have when we're trying to analyze it is, of course, a very complicated object. So we still haven't been able to get any physics out of it. But the hope is to do the same. The same process we need for the most simplified model also for these more complicated transition output. 363 00:51:52.330 --> 00:51:54.129 Abhay Vasant Ashtekar: and there is no 364 00:51:54.870 --> 00:51:59.630 Abhay Vasant Ashtekar: is there any signal at all that the limitations of the simplified model might go away like 365 00:52:00.310 --> 00:52:07.060 Abhay Vasant Ashtekar: what? Sorry for the simplified model, you know, one gets this results which stays at the 366 00:52:07.290 --> 00:52:22.170 Abhay Vasant Ashtekar: you know that the probability is exponentially suppressed and very, very large. Is there any reason to see that with inclusion of board vertices improves that slightly, or which way it goes, or Internet? That is very signature like on that. 367 00:52:23.240 --> 00:52:29.669 Farshid Soltani: this something we're working on. And we want to do, we want to confirm this results. 368 00:52:30.040 --> 00:52:31.089 Abhay Vasant Ashtekar: Okay, thank you. 369 00:52:31.610 --> 00:52:32.420 Farshid Soltani: Thank you. 370 00:52:34.970 --> 00:52:37.000 Hal Haggard: Are there further questions 371 00:52:39.730 --> 00:52:40.849 3453 Deepan Betal: I had a question. 372 00:52:41.180 --> 00:52:44.379 Hal Haggard: Yes, please go ahead. 373 00:52:46.990 --> 00:52:56.149 3453 Deepan Betal: There is a description from the does the description from the black hole to Whitehole transition change? If you are near the if you're near the cosmological bounds. 374 00:52:57.530 --> 00:53:03.640 3453 Deepan Betal: I mean either after the bounce or before the bounce. If if you have primordial black hole or a black hole which is 375 00:53:03.890 --> 00:53:06.499 3453 Deepan Betal: going into the bounce in, the lady knows. 376 00:53:10.100 --> 00:53:32.219 Farshid Soltani: So this is not something I'm worked on them. So I'm not sure but we're actually very interested in these. In our group. Francesco, we are working on, what? The the presence of these kind of reminisce through the bouncing cosmological bouncer to mean both to ecological bounce up, and to this kind of object. And this is still work in progress. But it's a very interesting scenario. Yes. 377 00:53:33.070 --> 00:53:40.849 3453 Deepan Betal: thank you, and add one more question, though. In the, in the bouncy cosmology there has the. There is a stimulated particle creation, or something like that. 378 00:53:40.950 --> 00:53:45.769 3453 Deepan Betal: Is there something similar in the black hole to White Hole transition that we have? So 379 00:53:45.810 --> 00:53:49.319 3453 Deepan Betal: some kind of particle creation other than hopping radiation is happening? 380 00:53:49.730 --> 00:54:04.190 Farshid Soltani: Yeah, I'm sure there is. It is a very highly dynamic zoom field region, and I'm sure that you study, and it's something that should be studied better. After it's not easy to get the calculations done. 381 00:54:05.830 --> 00:54:12.510 Hal Haggard: I'll return to you. Just I'm gonna give Carlo a chance to ask a first question. Carlo, please go ahead. 382 00:54:18.410 --> 00:54:19.870 Farshid Soltani: Commuter. Still. 383 00:54:20.600 --> 00:54:23.680 Western: there are cameras. Okay. Can you hear me? 384 00:54:23.930 --> 00:54:25.450 Hal Haggard: Yes, yes. 385 00:54:25.510 --> 00:54:38.560 Western: Okay. So this is not a question. It's it's an attempt to to throw clarification. I hope it doesn't. I don't. I don't create confusion. For she was so crystal clear and everything. 386 00:54:38.610 --> 00:54:52.910 Western: II want to. Some point of I mentioned. Don't you expect in the future of the transition to still have a quantum quantum? So something quantum with the metric, a a spread in the metric? 387 00:54:53.400 --> 00:55:02.749 Western: A that I would like to try to offer a classic issue about that. 388 00:55:02.800 --> 00:55:15.500 Western: that was yes, but the and this Co. Actually compatible with the fact that in the past of the quantum region there that we don't question marks. 389 00:55:15.560 --> 00:55:17.420 Western: there's a classical metric 390 00:55:17.440 --> 00:55:21.740 Western: in the following sense. There are 391 00:55:21.990 --> 00:55:27.900 Western: 2 ways to think about quantum mechanics. One is to see the wave function. It evolves and just follow the evolution of the wave function. 392 00:55:28.580 --> 00:55:34.410 Western: the other is that and if you think of just any quantum phenomenon, the laboratory 393 00:55:34.860 --> 00:55:47.700 Western: you compute the probability for one or the other of alternative. what? What did the Copenag interpretations call measure measurement outcomes. 394 00:55:48.070 --> 00:55:51.209 Western: or in the many world interpretation is called 395 00:55:51.370 --> 00:55:58.149 Western: declared branches. So the probability of this or that to happen. So imagine you have a 396 00:55:58.450 --> 00:56:05.360 Western: you have an atom that decays you compute the probability for it to decay in some time, for instance. 397 00:56:06.050 --> 00:56:11.499 Western: And then in in in standard, the laboratory quantum mechanics 398 00:56:11.550 --> 00:56:21.250 Western: you treat what happened later. Completely classical. You have a Geiger counter that has clicked at some time. So you say, okay. So from this point on, II forget by quantum theory. 399 00:56:21.370 --> 00:56:28.769 Western: II have a classical solution, or certain Geiger counters as as as click the time specific time. T. 400 00:56:29.220 --> 00:56:36.129 Western: But the the theory tells me that there's a probability distribution about one of the other things happening 401 00:56:37.100 --> 00:56:49.110 Western: so this is another way of think about quantum mechanics instead of thinking forever away function evolving. You think that at some point you you can go back to the classical approximation. 402 00:56:49.150 --> 00:57:03.640 Western: But what remains with you? Different alternatives might have happened. And this is the way quantum mechanics is treated here. So the the the quantum mechanical physics is relevant in the gray region 403 00:57:03.760 --> 00:57:10.860 Western: after that. There's a classical theory. But the predictions about what happened, that classical theory is probabilistic. 404 00:57:11.160 --> 00:57:23.719 Western: So there could be one or the other of different things happening. And in particular there could be one of the other of different, for instance, parameter t the global parameter t that that 405 00:57:23.870 --> 00:57:29.989 Western: that first it introduced 12 different values. 406 00:57:30.210 --> 00:57:54.920 Western: So the intuition that wait a moment there should be something quantum later on. It's not contradicted by this situation here is that the the the probability assigned by this model to to to the global feature of the classical metric outside to the parameters side does not have not a a spread. So that's where the the 407 00:57:55.220 --> 00:57:57.480 Western: the, the, the 408 00:57:57.840 --> 00:58:08.220 Western: th, the later effect of what mechanics come in, which might be relevant for thinking like unitarity in sky, plus or things like that, or to be sorry, plus or like that. So this 409 00:58:08.740 --> 00:58:33.559 Western: I thought this was always the I mean for she started introducing this as a as a realization of the with dashikar bourgeois paradigm. At the beginning you can think at the Black Hole in the standard way which you think at the at, at the quantum phenomena in the laboratory in which you you just say quite to effect, or 410 00:58:33.580 --> 00:58:56.419 Western: for some time after, after I go back to classical theory, of course, remembering that there's probably solution in in in Copenhagen terms is like there was a measurement, or in a in a in many world terms. There was a was a different branches possibilities. So I hope this, you know, helps bring it together different. See that they're compatible. 411 00:58:57.330 --> 00:59:00.180 Abhay Vasant Ashtekar: II kind of agree with you, Carol, but I mean. 412 00:59:00.370 --> 00:59:08.870 Abhay Vasant Ashtekar: you have said before, you know that there's a heiser, Buck Cut, and so on. But you know there is no management that is taking place here. There's no heiser back cut. So what you said just now is that 413 00:59:09.050 --> 00:59:13.399 Abhay Vasant Ashtekar: you know these are just various probabilities. But the problem is that if, in fact. 414 00:59:14.400 --> 00:59:18.990 Abhay Vasant Ashtekar: the situation extremely quantum mechanical. then 415 00:59:19.690 --> 00:59:23.279 Abhay Vasant Ashtekar: it's not. I mean, if, in fact, it turns out 416 00:59:23.410 --> 00:59:33.120 Abhay Vasant Ashtekar: that the proven distribution is sharply peaked. so that at classical geometry is a good approximation. 417 00:59:33.830 --> 00:59:36.799 Abhay Vasant Ashtekar: then I think these pictures have some intuitive meaning. 418 00:59:36.990 --> 00:59:41.209 Abhay Vasant Ashtekar: but if it turns out that in fact, the classical geometry has 419 00:59:41.230 --> 00:59:44.220 Abhay Vasant Ashtekar: really, I mean the the things are fluctuating so widely 420 00:59:44.430 --> 00:59:50.600 Abhay Vasant Ashtekar: that that is just a mistake to say that, you know there is a there's a classical geometry there. 421 00:59:50.610 --> 00:59:53.599 Abhay Vasant Ashtekar: Yeah, it's just it's it's just like. 422 00:59:53.790 --> 00:59:59.790 Abhay Vasant Ashtekar: you know, just like you did. You know a black hole? It's just a mistake to say that. Well, it's almost flat, it's not. 423 00:59:59.960 --> 01:00:11.820 Abhay Vasant Ashtekar: And so th it it all depends on what the the final answer is, if you like, if, in fact, it is quite a mechanical, and the state is widely oscillating and widely wiggling, and so on, so forth. 424 01:00:12.100 --> 01:00:19.370 Abhay Vasant Ashtekar: Then we can still say that. Well, I just said, but I agree with you that that you can still say that 425 01:00:20.170 --> 01:00:27.139 Abhay Vasant Ashtekar: that there is a priority for this to happen, that to happen, etc., etc. But then the classical pictures don't be deemed very much. 426 01:00:27.290 --> 01:00:33.460 Abhay Vasant Ashtekar: and my concern always has been, as you have told you, as we discussed before is really that in this region? 427 01:00:33.730 --> 01:00:36.320 Abhay Vasant Ashtekar: I mean that 428 01:00:36.530 --> 01:00:40.860 Abhay Vasant Ashtekar: if I look at the hawking radiation, don't ignore it. If I look at the hawking radiation. 429 01:00:41.050 --> 01:00:42.140 Abhay Vasant Ashtekar: Then 430 01:00:42.360 --> 01:00:45.520 Abhay Vasant Ashtekar: at at the kind of end point of the 431 01:00:46.260 --> 01:00:55.700 Abhay Vasant Ashtekar: when the black hole has shrunk to a plant boss, or something like that. At that case. At that time the the the radiation is really very ultraviolet. The temperature is extremely high. 432 01:00:55.850 --> 01:00:58.329 Abhay Vasant Ashtekar: and then what comes out to the black hole? 433 01:00:58.650 --> 01:01:03.960 Abhay Vasant Ashtekar: The output to this, this transition surface is really 434 01:01:03.970 --> 01:01:09.730 Abhay Vasant Ashtekar: is is faced out, and that is how we sort of try to make sense of unitarity. 435 01:01:09.950 --> 01:01:19.049 Abhay Vasant Ashtekar: That, that I enough of those more should have very, very stretched out, and the matching of that II think it's very, very hard to make the matching of that using any classic concept 436 01:01:19.090 --> 01:01:20.220 Abhay Vasant Ashtekar: near 437 01:01:20.480 --> 01:01:24.469 Abhay Vasant Ashtekar: the region U alpha u beta on sky plus. 438 01:01:25.030 --> 01:01:28.879 Abhay Vasant Ashtekar: And and I think that that that is my main concern. Basically. 439 01:01:28.900 --> 01:01:35.559 Abhay Vasant Ashtekar: I think this region D is extremely small, but still you all find you beats are very close to each other in some ways, in some sense. 440 01:01:35.630 --> 01:01:37.529 Abhay Vasant Ashtekar: to me. I think 441 01:01:37.970 --> 01:01:47.009 Abhay Vasant Ashtekar: II mean II completely agree that we should do everything we can by saying, Well, let me make this assumption and see what happens. I I'm I on, come same as you about this. 442 01:01:47.340 --> 01:01:49.070 Abhay Vasant Ashtekar: II really feel that 443 01:01:49.180 --> 01:01:55.580 Abhay Vasant Ashtekar: that can somehow, heart of a problem is to understand the true content nature of what is happening in this 444 01:01:55.670 --> 01:02:00.670 Abhay Vasant Ashtekar: u alpha u beta little label of that. So I just wanted to set. 445 01:02:01.170 --> 01:02:06.500 Abhay Vasant Ashtekar: II agree there is no absolute contradiction. But the question is of usefulness, of such a picture 446 01:02:10.090 --> 01:02:13.650 Hal Haggard: any response from Western? If not, can you mute the mic 447 01:02:16.270 --> 01:02:18.910 Hal Haggard: and ding? Why don't you go ahead with your question. 448 01:02:19.930 --> 01:02:27.369 Ding Jia: Thank you. Again, the question about regularity and effective geometry, effective metric. 449 01:02:27.710 --> 01:02:29.890 Ding Jia: Do you insist that 450 01:02:30.010 --> 01:02:34.320 Ding Jia: an an effective metric has to be nancing or regular. 451 01:02:34.570 --> 01:02:43.199 Ding Jia: I ask this question because, for example, previously you were mentioning that in quantum cosmology, you think of a wave function evolving in time. 452 01:02:43.360 --> 01:02:55.060 Ding Jia: and you think of the effective geometry as where the wave function is picked. Now, I don't know any reason in principle to rule out the possibility that of a unitary evolution for the wave function. 453 01:02:55.160 --> 01:02:59.929 Ding Jia: The wave function is picked along a singular bus trajectory. 454 01:03:00.230 --> 01:03:09.010 Ding Jia: So the question is. do you consider this as an open possibility that for your effective geometry you have a a singular geometry. 455 01:03:09.930 --> 01:03:12.569 Farshid Soltani: Mathematically I would say, I agree with you. 456 01:03:12.580 --> 01:03:21.999 Farshid Soltani: my physical point of view. I don't see how to make sense of a single id, so I don't expect the the we would find one in any of these scenarios. 457 01:03:22.100 --> 01:03:25.329 Farshid Soltani: but from a mathematical point of view, I think yes, you're right 458 01:03:25.760 --> 01:03:31.130 Ding Jia: from a physical point of view. If I have a unitary wave function 459 01:03:31.420 --> 01:03:33.870 Ding Jia: will function evolving humanitarian. 460 01:03:34.170 --> 01:03:39.739 Ding Jia: I can just do out in the quantum mechanics. There's no I don't see any apparent 461 01:03:40.120 --> 01:03:45.579 Ding Jia: difficulty in making sense of the physical predictions, because I have a units are evolving wave function 462 01:03:49.190 --> 01:03:52.419 Farshid Soltani: so you wouldn't have any difficulty in 463 01:03:52.540 --> 01:04:01.280 Farshid Soltani: explaining physically what is happening until you reach a single id. But when to reach the single point. How do you explain physically? What is the secret? Id. 464 01:04:02.100 --> 01:04:12.690 Ding Jia: if you're doing quantum mechanics, what you do is do measurements. You assign probabilities to measurement outcompers. Even if the peak of the wave function is singular. 465 01:04:13.140 --> 01:04:20.960 Ding Jia: the probabilities are still meaningful to some. To one they will be all the conditions you want. I don't see any difficulty there. 466 01:04:26.180 --> 01:04:31.739 Farshid Soltani: Okay, I'm not sure it might make sense. So I need to think more about this, I think. 467 01:04:32.070 --> 01:04:38.380 Farshid Soltani: yeah. it's really just a matter of if this singular id means something physically, or is it just? 468 01:04:39.060 --> 01:04:47.339 Farshid Soltani: it happens to be like these and detective jump description is normally about there. And I think he's finding the quantum theory that it might make sense, I guess. 469 01:04:48.250 --> 01:04:49.550 Ding Jia: Okay, thank you. 470 01:04:51.970 --> 01:04:54.120 Hal Haggard: Any additional questions. 471 01:04:55.510 --> 01:05:05.830 Hal Haggard: If not, I had a follow-up question on Abi's question when you were on slides 2021. This is the more refined spin foam model. 472 01:05:06.230 --> 01:05:25.510 Hal Haggard: Ii understand that you're very interested in confirming the results that people have already seen in spin phone models. But I wondered also if you've thought about additional questions that we'll be able to address with this more refined spin phone model. Are there other observables that you might be able to probe? 473 01:05:26.440 --> 01:05:28.920 Farshid Soltani: Yeah, the main. 474 01:05:29.450 --> 01:05:49.390 Farshid Soltani: So basically, this is much more complex, not only to get more degrees of freedom, but also because we are starting a different space timer than the original one. And so now the topology of the quantum region is different, and a discretization of this topology turns out to be much more difficult to find than the original model one. So this 475 01:05:49.670 --> 01:05:59.050 Farshid Soltani: to find a topology which seems tractable with nice symmetries already takes A much more complicated structure. And so from these. 476 01:05:59.300 --> 01:06:19.550 Farshid Soltani: erez agmoni, these are really 2 different model. Your original proposal just 2, 3 parameters, M. And this pounce time. Here we also have these new parameters that define the quantum region. So surely with this new 2 parameters we can probe differently the quantum region, only the horizon. So we can ask questions about how big should this region be? 150? 477 01:06:19.550 --> 01:06:29.559 Farshid Soltani: How is the actual time? Only this transition? So these 2 parameters surely allows us to have much more control over the quantum region and its properties. 478 01:06:32.110 --> 01:06:36.389 Hal Haggard: Thank you. Next last, call for questions. 479 01:06:38.110 --> 01:06:41.410 Hal Haggard: If there are none, let's thank Farshi again. Thank you very much. 480 01:06:41.880 --> 01:06:42.800 Farshid Soltani: Thank you. 481 01:06:44.280 --> 01:06:45.040 Farshid Soltani: Thanks.