0 00:00:02,820 --> 00:00:08,790 Jorge Pullin: Okay, so our speaker today is that Wilson was going to speak about black hole collapse and bounced and effective move quantum gravity. 1 00:00:13,590 --> 00:00:13,950 Jorge Pullin: It. 2 00:00:15,179 --> 00:00:25,380 Edward Wilson-Ewing (UNB): Right. Thank you very much. Um, so what I'll tell you today is some work that I've been doing with two students that you envy Jared Kelly and Robert Santa Cruz and you can find 3 00:00:26,730 --> 00:00:27,750 Edward Wilson-Ewing (UNB): The papers. 4 00:00:28,830 --> 00:00:32,100 Edward Wilson-Ewing (UNB): That my talks based on on the archive at these two numbers. 5 00:00:33,840 --> 00:00:52,350 Edward Wilson-Ewing (UNB): Okay, so my goal today is to explain the basic ideas and results. So especially what goes in to the calculation and what comes out. I won't spend so much time on the details of the intermediate calculations and I'll just refer you to the papers for those details. 6 00:00:54,450 --> 00:00:54,780 Edward Wilson-Ewing (UNB): Okay. 7 00:00:56,070 --> 00:01:09,300 Edward Wilson-Ewing (UNB): So, as I think everyone here knows black holes were in the most promising places to explore and potentially even test any theory of quantum gravity and there are three topics that are 8 00:01:10,560 --> 00:01:18,780 Edward Wilson-Ewing (UNB): Three reasons for that, that stand out among several others. So first of course in classical general relativity black hole contains a curvature singularity. 9 00:01:19,170 --> 00:01:24,030 Edward Wilson-Ewing (UNB): And we'd expect the quantum gravity affects would become important in the vicinity and possibly resolve that singularity. 10 00:01:24,630 --> 00:01:33,240 Edward Wilson-Ewing (UNB): Second, there's the famous information last problem. So if you use quantum field theory on a curve background. If you create a black hole. 11 00:01:34,170 --> 00:01:44,760 Edward Wilson-Ewing (UNB): By collapsing some matter that's in a pure state, then the black hole will act as a black body and it appears to evaporate to mix state of Hawking radiation. 12 00:01:45,150 --> 00:01:58,860 Edward Wilson-Ewing (UNB): So the question is, Can quantum gravity somehow restore unitary in this process. And finally, there have been some recent suggestions that perhaps quantum gravity affects could cause a black hole to transition to a white hole. So, this 13 00:01:59,790 --> 00:02:13,560 Edward Wilson-Ewing (UNB): Is built in, in part on results in the porn cosmology, where we see that we have a cosmic bounce. And so the idea is perhaps something similar could happen inside a black hole where you'd have a star that collapses. Once a black hole and then bounces and comes back out. 14 00:02:14,730 --> 00:02:29,760 Edward Wilson-Ewing (UNB): So our goal in this work is to use elocution LTC techniques to study quantum route effects and black holes in general and to hopefully have something to say about these different problems. 15 00:02:31,410 --> 00:02:39,780 Edward Wilson-Ewing (UNB): Okay. So the general framework that all follow in this talk is that we're going to look at spherical symmetric last whole space times 16 00:02:40,170 --> 00:02:43,740 Edward Wilson-Ewing (UNB): So this is really short. So we're not looking at career. There's no angular momentum here. 17 00:02:44,400 --> 00:02:52,470 Edward Wilson-Ewing (UNB): And and how we're going to do this is we're going to start by imposing spherical symmetry. The classical both in the constraints and the syntactic structure. 18 00:02:53,460 --> 00:03:04,110 Edward Wilson-Ewing (UNB): Then we're going to further simplify the problem by gauge fixing the different more physical constraint began at the classical level. So these first two steps, make no reference at all to quantum gravity. 19 00:03:05,700 --> 00:03:14,610 Edward Wilson-Ewing (UNB): Then the third step is that will include salami corrections in an effective framework and this is going to build on the work by a lot of people, the list here is by no means exhaustive. 20 00:03:14,970 --> 00:03:27,780 Edward Wilson-Ewing (UNB): Have only listed the papers that we follow the most closely the literature here is huge. And there are a lot of other important papers here which I just don't have a place to write down. Then once we have 21 00:03:28,980 --> 00:03:29,220 Edward Wilson-Ewing (UNB): Our 22 00:03:30,780 --> 00:03:39,510 Edward Wilson-Ewing (UNB): Hamiltonian constraint, then we can find and solve the effect of equations emotion and see what we get. So that's the general process that will follow here. 23 00:03:41,010 --> 00:03:46,590 Edward Wilson-Ewing (UNB): What we do is that we start with vacuum space time. So the first half of my talk will really be focusing on a vacuum space time 24 00:03:47,010 --> 00:03:53,280 Edward Wilson-Ewing (UNB): But a quite interesting result is that the space time that we get when we focus on a vacuum of space time is incomplete. 25 00:03:53,730 --> 00:04:00,030 Edward Wilson-Ewing (UNB): And this will be a little bit clearer as we go on. But really, what happens is that we have a hole in the middle. Something's missing. 26 00:04:00,840 --> 00:04:18,780 Edward Wilson-Ewing (UNB): And what we were what we did is that we added a dust field and this lets us do two things. First, let's a steady the collapse. So we're no longer just looking at stationary solution to the effective equations emotion, but we can look at the collapse of some matter. 27 00:04:20,460 --> 00:04:36,420 Edward Wilson-Ewing (UNB): And on top of that, with this were able to describe the entire platform space time including that whole that shows up when you only look at the vacuum case. So in this framework, it seems that it's essential to include matter if you want to be able to describe the full space time 28 00:04:39,090 --> 00:04:53,160 Edward Wilson-Ewing (UNB): Okay. So let me start here with just some basic information about the variables that will use. So if we work with a strictly symmetric metric, we can always put it in this form. 29 00:04:53,790 --> 00:05:06,000 Edward Wilson-Ewing (UNB): We have some laps function. Here we have some shift vector here that only isn't the radial direction and then we have some functions in front of the radio part and some function for the angular part 30 00:05:06,930 --> 00:05:13,170 Edward Wilson-Ewing (UNB): And as I mentioned, we impose the aerial gauge which means that we're taking this part, considering it equal to x squared. 31 00:05:14,160 --> 00:05:22,740 Edward Wilson-Ewing (UNB): So this cage fixes the different more physical constraint. We're only left the scale or constraint and it also imposes the relationship between the shift and the laps. 32 00:05:24,420 --> 00:05:35,070 Edward Wilson-Ewing (UNB): Okay, now here of course have introduced this little piece. So what is be be captures the extremes of curvature in the angular directions. So this is essentially 33 00:05:36,330 --> 00:05:48,150 Edward Wilson-Ewing (UNB): A component of the extrovert connection in the angular directions. And in this case, it only captures the extremes of curvature its conjugate variable is the insights triad. 34 00:05:49,920 --> 00:05:50,490 Edward Wilson-Ewing (UNB): Which 35 00:05:51,570 --> 00:05:55,290 Edward Wilson-Ewing (UNB): In this case turns out to be the square root of f and g. So, this is the densities triad. 36 00:05:56,610 --> 00:06:09,900 Edward Wilson-Ewing (UNB): That is conjugate to this component of the connection. Okay, now we're in vacuum spherical symmetry to start. So after we fix the aerial gauge. We only have to face space variables that remain. 37 00:06:10,980 --> 00:06:12,570 Edward Wilson-Ewing (UNB): Be an EV, and of course 38 00:06:13,710 --> 00:06:20,760 Edward Wilson-Ewing (UNB): We have circle cemetery, but we still have a degree of freedom in the real direction. So both of these qualities depend on x. 39 00:06:24,210 --> 00:06:39,450 Edward Wilson-Ewing (UNB): As I already mentioned also we have one scanner constraint which is left and of course the exact form isn't so important. The main point is that it only depends on be an EB and then pecs and the rubber meets the premier 40 00:06:40,530 --> 00:06:54,120 Edward Wilson-Ewing (UNB): Okay. And then finally, if we want to study the dynamics of the system, we can extract the equations emotion from the Hamiltonian constraint which is just integrating the scale or constraint over the radio. 41 00:06:55,980 --> 00:06:59,040 Edward Wilson-Ewing (UNB): Coordinate with weighted by some laps function. 42 00:07:00,510 --> 00:07:08,280 Edward Wilson-Ewing (UNB): Okay, so this is he basic classical framework that we want to take and pad. Hold on me corrections to 43 00:07:11,160 --> 00:07:29,580 Edward Wilson-Ewing (UNB): So the key step here is that we want to express be this component of the astral Roberto connection in terms of its parallel transport among edges of a minimal length which is proportional to Planck length. So here delta is the area gap. And so we're going to take a 44 00:07:31,020 --> 00:07:36,540 Edward Wilson-Ewing (UNB): Look, and consider the parallel transport along edges with a minimal length given by the square root of the area. 45 00:07:37,410 --> 00:07:42,900 Edward Wilson-Ewing (UNB): So this has to be done, both in scale or constraint and also for the relation between and 46 00:07:43,800 --> 00:07:59,520 Edward Wilson-Ewing (UNB): And the shift vector. So if I just go back one slide. If you remember, here we had this relationship between the shift in the radial direction and the laps and we have a be here. So that means that if I want to gamble to 47 00:08:00,630 --> 00:08:18,840 Edward Wilson-Ewing (UNB): Promote this expression to an operator and a quantum theory, I have to somehow replace this component to be also. So, of course, we're very familiar from the quantum cosmology of doing this in the scale or constraint here. But in this case, we also have to do it in this relation here. 48 00:08:20,850 --> 00:08:23,190 Edward Wilson-Ewing (UNB): Okay, so this is 49 00:08:25,200 --> 00:08:39,900 Edward Wilson-Ewing (UNB): The process have to fall to introduce our Columbia corrections. How do we do this well we create our, our edges and we just take the parallel transport along those edges. Now, a key point here, and this is something that was pointed out some time ago. 50 00:08:41,220 --> 00:08:48,210 Edward Wilson-Ewing (UNB): When the introduction of the improved dynamics is that when we talk of the length of an edge, of course. 51 00:08:49,170 --> 00:08:53,370 Edward Wilson-Ewing (UNB): We're referring to a physical length. We're not referring to a quarter length. So if we ask that the link 52 00:08:53,940 --> 00:09:03,090 Edward Wilson-Ewing (UNB): That the only to the edge be let's say Planck length, then we're really referring to the physical length of that edge being the planck length and not some coordinate length being equal to the planck length. 53 00:09:04,110 --> 00:09:10,770 Edward Wilson-Ewing (UNB): So here I have considering the tonal transport of my 54 00:09:11,970 --> 00:09:18,690 Edward Wilson-Ewing (UNB): Of be in the angular directions. So, for example, like it just take it in the theta direction. 55 00:09:19,440 --> 00:09:25,200 Edward Wilson-Ewing (UNB): And my metric tells me that the physical length is related to the court length theta in this way. 56 00:09:25,710 --> 00:09:41,610 Edward Wilson-Ewing (UNB): So if I require that my physical length be of the order of the square root of delta. That means that my court length is related to the square root of delta in this way. So this is really just using the new bar dynamics from cosmology and extending it to 57 00:09:43,410 --> 00:09:50,040 Edward Wilson-Ewing (UNB): To the black hole space time. And so if I do this, and I get this substitution for be that looks like this. 58 00:09:51,270 --> 00:10:01,320 Edward Wilson-Ewing (UNB): And here I want to take this substitution and put it back in to the scale or constraint and replace the whatever be shows up I replace it by this quantity here. 59 00:10:03,210 --> 00:10:16,710 Edward Wilson-Ewing (UNB): Okay, I just want to mention two quick technical points. These aren't so important going forward. But just for those of you who know this very well I'm, what I'm doing here is I'm really following what's known and lukewarm cosmology, as the Caleb quantization. 60 00:10:17,760 --> 00:10:26,040 Edward Wilson-Ewing (UNB): And another important point is here, I really am calculating the password exponential when I'm evaluating the parallel transport. 61 00:10:26,610 --> 00:10:36,600 Edward Wilson-Ewing (UNB): What happens is that because of spiritual symmetry as I integrate along an angular direction this path ordering just trivializes so it's very easy to handle 62 00:10:37,470 --> 00:10:46,320 Edward Wilson-Ewing (UNB): If I were to take the peril transferring the radio direction course then because my connection would depend on the radio coordinate this path where he would not trivialize 63 00:10:46,770 --> 00:10:51,810 Edward Wilson-Ewing (UNB): So this would be much more complicated, but this is one of the reasons why we did the gauge fixing earlier. 64 00:10:52,380 --> 00:11:04,140 Edward Wilson-Ewing (UNB): Through the gauge fixing we now only have the components of the connection left that aren't angular direction. And in this case we can really calculate the full payroll transport explicitly and very easily. 65 00:11:04,620 --> 00:11:14,340 Edward Wilson-Ewing (UNB): If we were to do it in the radio direction. This will be much more complicated. So that's one nice effect of doing this gauge fixing is that simplifies the problem significantly for us. 66 00:11:15,990 --> 00:11:17,160 Parampreet Singh: It. Can I ask you a question. 67 00:11:17,460 --> 00:11:18,120 Edward Wilson-Ewing (UNB): Yes, please. 68 00:11:18,480 --> 00:11:28,740 Parampreet Singh: So if I understand now your strategy correctly. So first we are doing the aerial gauge fixing so we are not worried about the radial coordinate and how do we call them is over there. But in addition 69 00:11:29,520 --> 00:11:35,820 Parampreet Singh: We are only considering the wholeness of extrinsic curvature on even on this aerial gauge so 70 00:11:36,060 --> 00:11:37,560 Parampreet Singh: That's right. If one doesn't do that. 71 00:11:38,640 --> 00:11:47,220 Parampreet Singh: Then this. I'm not sure. Like how you got this formula like are you driving it explicitly from the Hamiltonian constraint standing on the quantum Hamiltonian constraint. 72 00:11:47,580 --> 00:11:55,890 Parampreet Singh: Or you're using it as a tumble, like many people, many people use because I was worried about what happened to the spatial curvature part 73 00:11:56,880 --> 00:12:00,000 Parampreet Singh: Raven to the k quantization because we know that if we do the 74 00:12:00,690 --> 00:12:04,710 Parampreet Singh: Loop Quantum cosmology are gonna close model than this tumble doesn't apply. 75 00:12:06,420 --> 00:12:07,980 Edward Wilson-Ewing (UNB): Right. So, here what we're doing. 76 00:12:08,280 --> 00:12:09,600 Edward Wilson-Ewing (UNB): Is we're 77 00:12:09,780 --> 00:12:23,610 Edward Wilson-Ewing (UNB): Calculating the the parallel transport, as you say, of the extremes of curvature in the angular direction. And here we're really are calculating the password exponential. And all of that is just that just so happens that trivializes do just vertical symmetry. 78 00:12:25,110 --> 00:12:35,040 Edward Wilson-Ewing (UNB): Now you're right that there is some spatial curvature here and what would happen. It's exactly the same thing as a loop quantum cosmology. If we included the spatial curvature 79 00:12:35,610 --> 00:12:41,070 Edward Wilson-Ewing (UNB): Then we would get something which is not almost periodic in the connection. And so then I wouldn't know how to represent it in the quantum theory. 80 00:12:43,290 --> 00:12:49,770 Edward Wilson-Ewing (UNB): But we still the scanner constraint still knows about the spatial curvature, of course. 81 00:12:51,960 --> 00:12:58,800 Parampreet Singh: So the scanner constraint knows about the spatial curvature only because of those extra terms which you didn't hold on a minute. Right. 82 00:12:59,040 --> 00:12:59,430 Edward Wilson-Ewing (UNB): That's right. 83 00:12:59,520 --> 00:13:11,460 Parampreet Singh: Well, the spatial coverage. So, too. So to put it the way you said it to put it correctly, the spatial curvature piece in your Hamiltonian constraint is not does not know about quantum geometry affects 84 00:13:11,610 --> 00:13:13,260 Edward Wilson-Ewing (UNB): X plus. Correct. Yeah, okay. 85 00:13:14,910 --> 00:13:22,470 Edward Wilson-Ewing (UNB): So of course, ideally, we'd like to include those also but then I'm not sure how to eventually construct a quantum theory with that. 86 00:13:23,040 --> 00:13:29,700 Parampreet Singh: But just one last point, like I know it's technical for everyone. But didn't you tried like the way like it was done. 87 00:13:31,740 --> 00:13:36,960 Parampreet Singh: Like in a PSP paper or what Cory cheon crummy did later with like this. 88 00:13:38,640 --> 00:13:41,190 Parampreet Singh: Using the shaker connection itself as an operator. 89 00:13:42,540 --> 00:13:49,710 Edward Wilson-Ewing (UNB): Um, yeah, so you can also do something like that, um, this just turns out to be easier. 90 00:13:50,850 --> 00:13:56,010 Edward Wilson-Ewing (UNB): But also I mean if you remember in the paper that we wrote on this, we found that 91 00:13:56,640 --> 00:14:08,880 Edward Wilson-Ewing (UNB): In in lukewarm cosmology, at least. I mean, I don't know if this is true for black holes, but certainly in cosmology. It seems that the Caleb quantization is closer to the F quantization than the quantization is 92 00:14:09,690 --> 00:14:10,890 Parampreet Singh: Yes, I know that. Yeah. 93 00:14:10,920 --> 00:14:17,220 Edward Wilson-Ewing (UNB): Yeah. So in that sense, I would prefer to work with the K quantization and the eight quantization here. 94 00:14:18,540 --> 00:14:24,300 Edward Wilson-Ewing (UNB): In any case, the F quantization. I'm not sure how to do that because you'll definitely get something which is not almost periodic in the connection. 95 00:14:25,470 --> 00:14:26,040 Parampreet Singh: Okay, thank you. 96 00:14:26,760 --> 00:14:27,120 Parampreet Singh: No problem. 97 00:14:27,990 --> 00:14:29,010 Edward Wilson-Ewing (UNB): Are there any other questions. 98 00:14:33,120 --> 00:14:34,110 Edward Wilson-Ewing (UNB): Okay, so 99 00:14:35,310 --> 00:14:52,080 Edward Wilson-Ewing (UNB): Here the the main point is that we're able to really express be in terms of the parallel transport and we're using the improved or new board dynamics to do this. Okay, now I want to say a few words about this because there's been a lot of work. 100 00:14:53,160 --> 00:14:58,050 Edward Wilson-Ewing (UNB): On this topic in the context of black holes and we're going at it from a slightly different 101 00:14:58,740 --> 00:15:03,120 Edward Wilson-Ewing (UNB): Perspective than what a lot of other people have done. And so I want to compare and contrast, a little bit. 102 00:15:03,840 --> 00:15:17,790 Edward Wilson-Ewing (UNB): So this very same URL scheme was first proposed by Boomer van der Sloot quite some time ago and they applied in the contest key sex FaceTime, and that of course describes the black hole interior in GR 103 00:15:18,810 --> 00:15:27,120 Edward Wilson-Ewing (UNB): But it turns out that if you use this choice and control ski Sachs, you get unacceptably large effects of the horizon, so of course for large black hole that 104 00:15:27,810 --> 00:15:32,970 Edward Wilson-Ewing (UNB): Space Time permission, the pricing is very small and you would expect the classical JIRA would be a good approximation there. 105 00:15:33,810 --> 00:15:42,960 Edward Wilson-Ewing (UNB): And what they found is that, on the other hand, that's not at all what happened. They got very large corrections at the horizon, even if the temperature was small and so 106 00:15:43,770 --> 00:15:59,940 Edward Wilson-Ewing (UNB): We think, and that this problem is probably due to the fact that they were using courts that are coming on the horizon. Now what the improve dynamics scheme is really doing is that it's asking you to identify a physical length. 107 00:16:01,140 --> 00:16:18,660 Edward Wilson-Ewing (UNB): Of an edge with the planck length, but if you take the full autonomy in a direction that becomes know that physical length, necessarily becomes zero. And if you're trying to force this zero to be equal to the planck length, it's not so surprising that you could run into some inconsistency. 108 00:16:19,740 --> 00:16:20,280 Edward Wilson-Ewing (UNB): So, 109 00:16:21,300 --> 00:16:25,050 Edward Wilson-Ewing (UNB): Our perspective on this is that the issue that 110 00:16:26,850 --> 00:16:35,190 Edward Wilson-Ewing (UNB): arose in Boomer vendor suits work was not so much of their choice from you bar was incorrect, it was rather that they were trying to use it for corns that became know 111 00:16:35,760 --> 00:16:44,670 Edward Wilson-Ewing (UNB): And when you have these coins that become know you're essentially forcing this physical length, which tends to zero to be equal to the planck length and you have some tension there. 112 00:16:46,110 --> 00:16:46,470 Edward Wilson-Ewing (UNB): So, 113 00:16:46,500 --> 00:16:47,550 Parampreet Singh: It can I make one comment. 114 00:16:47,850 --> 00:16:57,270 Parampreet Singh: Yes. Is this is I don't think like there is anything. I'm sorry to say, but I don't see any new insight here like this was, this is already known in literature. 115 00:16:57,930 --> 00:17:05,940 Parampreet Singh: If you look at my paper with Aunt and Joe like a few years back we had pointed out, essentially, that the bomb of understood approach fails. 116 00:17:06,330 --> 00:17:18,000 Parampreet Singh: Precisely because one is trying to apply Mubarak scheme at the coordinate singularity and in my paper right away and how we are also we have commented on the same thing. So you're completely right that literature already supports your point. 117 00:17:19,320 --> 00:17:20,040 Edward Wilson-Ewing (UNB): I'm happy with that. 118 00:17:22,590 --> 00:17:32,850 Edward Wilson-Ewing (UNB): Okay. And so this is why. Now I'm trying to keep the same new bar scheme but now work with coordinates that cover the whole FaceTime 119 00:17:33,600 --> 00:17:41,670 Edward Wilson-Ewing (UNB): Right. So instead of trying to adapt and move our scheme. I'm going to instead say okay, you know, let's keep that same URL scheme. But now let's use courts that don't become know anywhere. 120 00:17:42,360 --> 00:17:48,420 Edward Wilson-Ewing (UNB): So this is, if you like. It's perhaps not a new insight, but this is the motivation behind what we're doing here. 121 00:17:50,970 --> 00:17:51,960 Edward Wilson-Ewing (UNB): Okay, and 122 00:17:53,220 --> 00:18:00,360 Edward Wilson-Ewing (UNB): So let's continue on this theme this issue of having these no coordinates we can avoid that by using horizon Pearson coordinates. 123 00:18:00,810 --> 00:18:12,870 Edward Wilson-Ewing (UNB): And there's been some literature on this also. So chimney and Tang did some murkiness in 2012 and then very recently can be Neil meadow and pulling also worked on this. And of course, our work is also going this exact same direction. 124 00:18:14,160 --> 00:18:27,360 Edward Wilson-Ewing (UNB): One issue though with the first work but union Tang was that they didn't have a closed algebra. So if you look at the constraint algebra between they're effective Skyler. And if your constraints that algebra didn't close so that obviously was a problem. 125 00:18:28,680 --> 00:18:34,410 Edward Wilson-Ewing (UNB): And I think that this is due to the fact that they were using a point along the approximation, the radial direction. 126 00:18:35,190 --> 00:18:46,410 Edward Wilson-Ewing (UNB): And of course, this is an in some ways a reasonable approximation to try because this means you don't have to evaluate this path or exponential, which becomes very messy very quickly. 127 00:18:47,580 --> 00:18:53,160 Edward Wilson-Ewing (UNB): But it seems to me that this approximation. Although tempting just doesn't work. In this case, so 128 00:18:53,850 --> 00:19:02,670 Edward Wilson-Ewing (UNB): From my point of view, I think that if you take this new our scheme and you apply it to the full space time. And so here I mean both the interior and the exterior of the black hole. 129 00:19:03,000 --> 00:19:08,970 Edward Wilson-Ewing (UNB): We don't just restrict to contest the sax, then I think there are three ways that we could 130 00:19:09,600 --> 00:19:14,880 Edward Wilson-Ewing (UNB): Hope to get a close constraint algebra. So the first one is just to avoid using the point. Hello enemies approximation. 131 00:19:15,270 --> 00:19:30,030 Edward Wilson-Ewing (UNB): And instead, evaluate the password or exponential X for the connection components in the radial direction. Now this to me, I think, is ideal, but it also seems very hard. So to start, I didn't want to go down that route. 132 00:19:31,650 --> 00:19:40,620 Edward Wilson-Ewing (UNB): Another way that you could approach this problem is to try different combinations of constraints. So again, being in Poland. Some time ago showed how you could 133 00:19:41,940 --> 00:19:55,740 Edward Wilson-Ewing (UNB): redefine the constraints and get them the billion set of constraints and this lends itself to a very nice treatment, which was done recently by can't be any old metal and poor but and 134 00:19:56,790 --> 00:20:03,180 Edward Wilson-Ewing (UNB): Please forgive me, correct me if I'm wrong, but as far as I understand, this works very well and vacuum. But I think it's harder to include matter in this case. 135 00:20:04,650 --> 00:20:12,090 Edward Wilson-Ewing (UNB): Now our approach is different. We're going to oppose the gauge. So the different Mormonism, the aerial gauge to fix it. If you're more for some constraints in our case. 136 00:20:13,740 --> 00:20:18,150 Edward Wilson-Ewing (UNB): And the advantage of this is that in this case it will be easy to add in a matter of field. 137 00:20:20,250 --> 00:20:20,640 Edward Wilson-Ewing (UNB): Okay. 138 00:20:22,080 --> 00:20:23,070 Edward Wilson-Ewing (UNB): Um, let me 139 00:20:24,540 --> 00:20:33,900 Edward Wilson-Ewing (UNB): Go back to where we were. So we had found the Islamic corrections and we wanted to add them back into the scale of constraint. And so this gives us 140 00:20:35,010 --> 00:20:37,680 Edward Wilson-Ewing (UNB): The effect of scale or constraint, they show you here. 141 00:20:38,760 --> 00:20:40,230 Edward Wilson-Ewing (UNB): The details don't matter. 142 00:20:41,580 --> 00:20:46,500 Edward Wilson-Ewing (UNB): The point is that from this of course we can derive the equations emotion that were interested in and then solve them. 143 00:20:48,450 --> 00:20:59,430 Edward Wilson-Ewing (UNB): Okay. Now, of course, we fix the different Sufism fix the arrow gauge. So that gets rid of a few more physical constraints, but we still have an entry looking straight algebra between the scale or constraint in itself. 144 00:21:00,000 --> 00:21:14,010 Edward Wilson-Ewing (UNB): And what's nice is that with this modification. So with these salami corrections here. We still have a constraint algebra that closes, of course, the, the algebra is different. We have this extra term here compared to what happens classically 145 00:21:15,270 --> 00:21:20,520 Edward Wilson-Ewing (UNB): But we have a consistent theory with an algebra. The closest so that's that's an important point here. 146 00:21:21,990 --> 00:21:27,000 Edward Wilson-Ewing (UNB): Now remember that we also had to update the relationship between the laps and the shift. 147 00:21:28,140 --> 00:21:28,500 Edward Wilson-Ewing (UNB): So, 148 00:21:28,530 --> 00:21:29,730 Abhay Vasant Ashtekar: But in the 149 00:21:29,820 --> 00:21:31,800 Abhay Vasant Ashtekar: classical limit you probably get exactly 150 00:21:32,910 --> 00:21:34,140 Abhay Vasant Ashtekar: What you should get right in this 151 00:21:34,410 --> 00:21:36,870 Edward Wilson-Ewing (UNB): Absolutely. So the classical limit you take 152 00:21:36,930 --> 00:21:49,560 Edward Wilson-Ewing (UNB): The square root of delta two zero. So this cosine goes to one. And then here, this square root of delta over x cancels this x over square root of delta and you get back the classical result absolutely right. 153 00:21:49,950 --> 00:21:50,190 Like 154 00:21:52,800 --> 00:21:54,750 Edward Wilson-Ewing (UNB): I'm okay so 155 00:21:55,980 --> 00:21:59,340 Edward Wilson-Ewing (UNB): And this form of the constraint Alger was actually quite suggestive. 156 00:22:00,360 --> 00:22:18,060 Edward Wilson-Ewing (UNB): Because the classical form, which I've given right here you can rewrite in terms of the shift vector by using the classical relationship between the shift in the laps. And so what we did is that we updated the relationship between the shift in the laps in this way. 157 00:22:19,080 --> 00:22:24,090 Edward Wilson-Ewing (UNB): So that if we then use this relationship to re express this 158 00:22:26,580 --> 00:22:28,440 Edward Wilson-Ewing (UNB): This term here in terms of 159 00:22:29,490 --> 00:22:47,250 Edward Wilson-Ewing (UNB): This shift and the shift vector like this, using this relation then we get something that looks exactly like the classical case. So, here there is some ambiguity in the exact choice that you make. And we're, we're, guided by this resemblance to make this choice. 160 00:22:49,530 --> 00:22:49,830 Okay. 161 00:22:53,310 --> 00:22:54,420 Edward Wilson-Ewing (UNB): So now. 162 00:22:55,170 --> 00:22:56,400 Parampreet Singh: Can I ask a question. So 163 00:22:56,430 --> 00:23:06,780 Parampreet Singh: Yes, please. Like you already had a very natural choice between x and n right when you did polymerization of be so essentially you are 164 00:23:07,980 --> 00:23:10,650 Parampreet Singh: Multiplying by one and then calling that one as cosine 165 00:23:12,030 --> 00:23:16,890 Edward Wilson-Ewing (UNB): Um, well, in some sense, I would few this 166 00:23:18,870 --> 00:23:24,240 Edward Wilson-Ewing (UNB): I think that it's a will be shouldn't assume that we have the same substitution everywhere. 167 00:23:24,990 --> 00:23:36,090 Edward Wilson-Ewing (UNB): Right. I mean, in one case, something is coming from the field strength. And in the other case, there is a relationship between your look for your garage multipliers. So it's not obvious to me that you should necessarily do the same substitution everywhere. 168 00:23:36,720 --> 00:23:38,400 Edward Wilson-Ewing (UNB): Okay, another night. 169 00:23:38,520 --> 00:23:57,570 Edward Wilson-Ewing (UNB): Sorry, let me just mention quickly. This is exactly the same relation that can be Neil meadow and Poland gut and they chose it for a different reason. Which I thought was, was quite interesting and their point is that in the scale or constraint, you have this sign squared term here. 170 00:23:58,620 --> 00:24:09,510 Edward Wilson-Ewing (UNB): And so what that means is that when you act with it, you will act, you will shift by twice to to to spatial steps. 171 00:24:10,560 --> 00:24:17,700 Edward Wilson-Ewing (UNB): And here, if you only have a sign you only move by one. And so then your, your lattices in the quantum three won't quite match up. 172 00:24:18,180 --> 00:24:28,410 Edward Wilson-Ewing (UNB): But if you include this cosine term here, then again, you'll shift by two steps in the spatial direction. So there's like a consistency there to sorry you're gonna say something else. 173 00:24:28,860 --> 00:24:37,260 Parampreet Singh: Yes, and maybe then I'm just confused. So, earlier you also the relationship of Annex and and right and I thought you said that replace be by 174 00:24:38,430 --> 00:24:47,100 Parampreet Singh: Expert scooter of telltale sign of delta V by x. So I assume that you are doing that at that step itself, but you are not doing that, you're not 175 00:24:47,130 --> 00:24:47,910 Edward Wilson-Ewing (UNB): No, no. 176 00:24:48,180 --> 00:24:48,540 Parampreet Singh: Okay. 177 00:24:49,050 --> 00:24:56,250 Edward Wilson-Ewing (UNB): No, I'm doing that for the effect of scale or constraint here and then I still have to do it for that relationship between X Men. 178 00:24:58,680 --> 00:25:00,420 Edward Wilson-Ewing (UNB): And that's what I'm doing at this step here. 179 00:25:03,270 --> 00:25:06,690 Carlo Rovelli: Do you mind that is super simple technical thing that just to 180 00:25:06,690 --> 00:25:07,020 Further 181 00:25:08,160 --> 00:25:18,720 Carlo Rovelli: X X X X squared. This is the area of this of the of the proportion to the area of the of the sphere suicide. Correct. Yeah, so the question is, it connects to be negative. 182 00:25:19,920 --> 00:25:20,220 No. 183 00:25:23,640 --> 00:25:25,470 Edward Wilson-Ewing (UNB): I don't see how that would come out. 184 00:25:26,820 --> 00:25:28,080 Edward Wilson-Ewing (UNB): This the data follow 185 00:25:28,140 --> 00:25:37,800 Carlo Rovelli: The topology here is necessarily that if you follow if you continuously follow shrinking here. You cannot continue more than that. You don't have another side so 186 00:25:38,700 --> 00:25:39,630 Edward Wilson-Ewing (UNB): Yeah, I 187 00:25:40,740 --> 00:25:46,650 Edward Wilson-Ewing (UNB): I don't think that's actually an input, but then when I solve the equations emotion that's just what comes out, I guess. 188 00:25:48,600 --> 00:25:55,890 Edward Wilson-Ewing (UNB): If something else came out, I would have been a bit surprised, to be honest. But I don't think that's a requirement at this stage. 189 00:25:56,340 --> 00:26:06,600 Edward Wilson-Ewing (UNB): So I think, in principle, you could have negative access but that would. I'm not sure how I would interpret that. And it doesn't seem to be relevant for the solutions that we find 190 00:26:09,240 --> 00:26:10,710 Parampreet Singh: Okay, can I ask one final question. 191 00:26:10,950 --> 00:26:11,580 Edward Wilson-Ewing (UNB): Yes, please. 192 00:26:11,670 --> 00:26:23,700 Parampreet Singh: I don't know like what was done in Germany Olmedo Poland paper, but are you saying that in both the papers, the strategy which one follows, is that okay like one polarizes be and 193 00:26:24,750 --> 00:26:35,910 Parampreet Singh: One rights being in terms of the only the sign function in the Hamiltonian constraint. But, but when one has to relate, an expert and one has to use a very different polymerization 194 00:26:37,230 --> 00:26:39,840 Edward Wilson-Ewing (UNB): I wouldn't call it very different. I mean, they're very closely related. 195 00:26:40,320 --> 00:26:48,030 Parampreet Singh: Well, they are who they are. Well, they are closely related only in the classical theory. Well, if you will go near the bounce. This will give very different effects, um, 196 00:26:48,420 --> 00:26:55,020 Edward Wilson-Ewing (UNB): Well, I mean, in both cases, we have the same Ubar framework, right. I'm not choosing new barn one case and you're not in something else. I mean, these are 197 00:26:55,680 --> 00:26:56,070 Parampreet Singh: The different 198 00:26:56,790 --> 00:27:02,970 Parampreet Singh: So your lettuce is different, even if you are choosing the same new bar your lettuce lettuce structure is changing the other single 199 00:27:03,000 --> 00:27:03,870 Edward Wilson-Ewing (UNB): Why is that, sorry. 200 00:27:05,070 --> 00:27:08,190 Parampreet Singh: Because this seems to give you a different angle than the other one. 201 00:27:08,940 --> 00:27:11,010 Edward Wilson-Ewing (UNB): No, because remember this is saying squared. 202 00:27:13,560 --> 00:27:17,730 Edward Wilson-Ewing (UNB): So sign squared will have exactly the same spacing sign times cosine 203 00:27:19,260 --> 00:27:24,990 Edward Wilson-Ewing (UNB): That's the argument that can be in your middle polling make to precisely to make this choice. 204 00:27:26,130 --> 00:27:27,630 Parampreet Singh: And I might not 205 00:27:28,650 --> 00:27:42,630 Parampreet Singh: Like I hope I'm not making any mistake. But isn't this the very similar thing which is also done in the hybrid quantization when they are doing the perturbations to introduce this cosine to define the the buying the McConnell society equation. 206 00:27:43,950 --> 00:27:48,540 Edward Wilson-Ewing (UNB): Um, it could be I'd have to check to to see you. 207 00:27:49,800 --> 00:27:52,350 Parampreet Singh: Okay. Okay. Thanks. Thanks for the clarification. 208 00:27:53,190 --> 00:28:09,510 Abhay Vasant Ashtekar: So excited. I mean, I think that confusion I maybe I'm just confused. Yeah, I think the confusion was coming because you already defined what is an x and then an x, you already chosen to be equal to minus n times be divided by gamma and then you chose be to be something 209 00:28:11,190 --> 00:28:20,070 Abhay Vasant Ashtekar: So that would just give you the relation between x and then to be exactly what you wrote, except for the costs delta B or B do are the X to appear. 210 00:28:20,730 --> 00:28:23,190 Edward Wilson-Ewing (UNB): Right, so I probably should have been a little bit clearer. 211 00:28:23,250 --> 00:28:25,020 Edward Wilson-Ewing (UNB): Few slides back I think everybody's 212 00:28:25,200 --> 00:28:33,090 Edward Wilson-Ewing (UNB): Busy here this this substitution is really for the scale or constraint. And the idea here is that you know we have some 213 00:28:33,840 --> 00:28:38,430 Edward Wilson-Ewing (UNB): Coming from lukewarm cosmology. We have some field strength. We want to evaluate it by going around the loop. 214 00:28:39,090 --> 00:28:46,650 Edward Wilson-Ewing (UNB): And when you have a spatial curvature. It's hard to go around the loop. But you say, Okay, let me just take the transport in one direction. 215 00:28:47,430 --> 00:28:57,690 Edward Wilson-Ewing (UNB): And that leads to this type of substitution. And so I'm just taking the exactly the same framework that we use in LTC and then applying it here. 216 00:28:58,530 --> 00:29:08,070 Edward Wilson-Ewing (UNB): In LTC usually we don't include a lapse. Sorry, we don't include a shift vector we just set that equal to zero. And my point here is that we shouldn't 217 00:29:08,130 --> 00:29:11,760 Edward Wilson-Ewing (UNB): Just assume that we're going to do exactly the same substitution to relate those two things. 218 00:29:13,050 --> 00:29:13,830 Edward Wilson-Ewing (UNB): Instead, 219 00:29:14,880 --> 00:29:29,100 Edward Wilson-Ewing (UNB): What we're doing here is we're saying, Okay, we have this constraint algebra, and I'd like to make it look as much as possible at the classical one and is there a way to do that. And the answer is yes. And it's through this relationship here. 220 00:29:30,660 --> 00:29:47,580 Abhay Vasant Ashtekar: But I guess statement is that in going from the classical theatre effective equations you met two assumptions, one has gays fixing and one is this an X right now and to have a contradiction with each other unless cause of delta V or X multiplier Ibiza, good one. 221 00:29:49,290 --> 00:29:52,440 Edward Wilson-Ewing (UNB): Um, well, I'm not sure they're in contradiction. 222 00:29:53,490 --> 00:29:59,640 Edward Wilson-Ewing (UNB): I mean, there's a choice that has a need, right, because if if I have if I have this relation 223 00:30:00,210 --> 00:30:01,500 Edward Wilson-Ewing (UNB): Right and the classical theory. 224 00:30:01,920 --> 00:30:03,480 Edward Wilson-Ewing (UNB): How can I want to be able to 225 00:30:03,840 --> 00:30:04,770 Edward Wilson-Ewing (UNB): Could say okay, I want to 226 00:30:05,040 --> 00:30:11,520 Edward Wilson-Ewing (UNB): Promote this to something to where I can say, okay, what is this in the quantum theory, I have to make some choice here. 227 00:30:12,060 --> 00:30:22,380 Edward Wilson-Ewing (UNB): And I agree there's a choice to be made. Right. So there's some freedom and how you do it. But if I want to promote this relationship 20 quantum theory have to do something here. Yeah. 228 00:30:22,860 --> 00:30:25,200 Abhay Vasant Ashtekar: I understood 229 00:30:26,700 --> 00:30:31,440 Abhay Vasant Ashtekar: One other question. Good. So yeah, let's see. So can you go back to the next. The next slide that you are using 230 00:30:32,280 --> 00:30:32,610 Edward Wilson-Ewing (UNB): This one. 231 00:30:35,250 --> 00:30:38,580 Abhay Vasant Ashtekar: The one that you are actually short showing not. I just know with the 232 00:30:39,600 --> 00:30:44,040 Abhay Vasant Ashtekar: Next equal to minus and I'm the concert. Yeah, that one up here so 233 00:30:49,170 --> 00:30:50,430 Abhay Vasant Ashtekar: Yeah, so the point is that 234 00:30:52,470 --> 00:30:57,180 Abhay Vasant Ashtekar: So you achieving and is always positive. And next can be both positive and negative. Is that what is that 235 00:30:57,210 --> 00:31:00,540 Edward Wilson-Ewing (UNB): Yes, that's right. Yeah. OK. OK. OK. 236 00:31:01,470 --> 00:31:08,010 Parampreet Singh: OK, and maybe like I can make one final comment like because like it has really very much clarified what I was asking so 237 00:31:08,580 --> 00:31:15,930 Parampreet Singh: You see, like, I can understand, like, if you do the extensive curvature quantization or the key quantization. Then you got this be to sign 238 00:31:16,470 --> 00:31:25,110 Parampreet Singh: Lambda be kind of a thing. But the main question is who gives us this relation between x and n this is essentially a zoom and 239 00:31:25,740 --> 00:31:31,350 Parampreet Singh: natural thing to assume would have been knowing you understand technical difficulties. I'm not objecting to this stuff. 240 00:31:31,680 --> 00:31:41,700 Parampreet Singh: But naturally one would have assumed that what we assumed what we considered for be going to sign lambda be, I don't know whether it was derived or put put as a thumb rule, we should use 241 00:31:42,360 --> 00:31:43,620 Edward Wilson-Ewing (UNB): So so so the 242 00:31:45,390 --> 00:31:47,790 Edward Wilson-Ewing (UNB): So this, this is 243 00:31:49,170 --> 00:31:53,460 Edward Wilson-Ewing (UNB): Derived that exists exactly the same level as the LTC Caleb quantization. 244 00:31:53,730 --> 00:31:55,020 Parampreet Singh: Okay, so it was the right 245 00:31:55,680 --> 00:31:57,660 Edward Wilson-Ewing (UNB): Exactly the same level. Yes. 246 00:31:57,810 --> 00:32:02,940 Parampreet Singh: So the natural thing to do would be that if there is a relationship between x and and we would just plug in this be 247 00:32:03,330 --> 00:32:10,860 Parampreet Singh: But right now, you're saying that, well, we'll let us look at the different markets and constraint and the structure of the lattice motivates that 248 00:32:11,670 --> 00:32:28,470 Parampreet Singh: If I would have chosen and next exactly guided by what you did earlier as a calculation, then I will be in a mess. I won't be able to do the for the computation. So I should use a different polymerization for be here, right. So, that is what is the confusion which are ban high yet. 249 00:32:29,430 --> 00:32:41,160 Edward Wilson-Ewing (UNB): Right, so what what I'm saying here is that we have two places where we have to, I mean polymer eyes be to have a theory which then we can promote to a quantum theory. 250 00:32:42,840 --> 00:32:51,810 Edward Wilson-Ewing (UNB): And for the scanner constraint and falling exactly the same procedure hasn't lukewarm cosmology and for the relationship between the laps and the shift. 251 00:32:52,380 --> 00:33:04,320 Edward Wilson-Ewing (UNB): There is no guidance from the club cosmology, right, because they're the shift is always zero. So what do I use for guidance. Instead, I tried to mimic the structure of this constraint algebra as much as possible. 252 00:33:05,610 --> 00:33:05,940 Edward Wilson-Ewing (UNB): But 253 00:33:06,240 --> 00:33:08,490 Parampreet Singh: You would agree right there is a multitude of choices. 254 00:33:08,520 --> 00:33:10,470 Edward Wilson-Ewing (UNB): Once you give up that little late. Absolutely. There's a 255 00:33:11,280 --> 00:33:16,110 Parampreet Singh: Multitude of choices and there is only one fine tune choice which gives you what you are asking for. 256 00:33:17,400 --> 00:33:21,000 Edward Wilson-Ewing (UNB): Well, any choice is fine tuned mean if you make a choice, right. 257 00:33:22,050 --> 00:33:23,970 Edward Wilson-Ewing (UNB): You're picking something. Yeah. 258 00:33:25,620 --> 00:33:39,870 Abhay Vasant Ashtekar: I think I think what he's saying is that in the effective theory right if I just look at the space level. I just have one constraint, because you have fixed the different models of constraints disappeared. Right. 259 00:33:39,930 --> 00:33:49,050 Abhay Vasant Ashtekar: There's only one constraint and so they affect the city, you can forget about this an x is equal to, blah blah blah, that we got up here, right, this relation that is at the bottom of the transparency. 260 00:33:49,920 --> 00:34:01,110 Abhay Vasant Ashtekar: And the level of the face face. I don't need to know what is an x, because it's so what Eddie saying is that at the level of face to face, and just rephrasing what is it I'm sorry but to 261 00:34:01,500 --> 00:34:02,160 Edward Wilson-Ewing (UNB): Go ahead please. 262 00:34:02,790 --> 00:34:05,280 Abhay Vasant Ashtekar: And so what he's saying is that 263 00:34:06,660 --> 00:34:12,870 Abhay Vasant Ashtekar: At the face base level. I don't have to say anything about annex so he has chosen that be by the 264 00:34:14,400 --> 00:34:15,150 Abhay Vasant Ashtekar: By the 265 00:34:16,500 --> 00:34:29,910 Abhay Vasant Ashtekar: Key alanna me and that is the end of it, and you can just solve the problem at the space level and I'm acted, but there is still a second issue, which is that you're got some trajectory in the face space. And how do you connect them to the space time metric 266 00:34:30,900 --> 00:34:31,110 Edward Wilson-Ewing (UNB): Right. 267 00:34:31,140 --> 00:34:32,190 Edward Wilson-Ewing (UNB): And, you know, 268 00:34:34,020 --> 00:34:37,860 Abhay Vasant Ashtekar: And he's saying that, well, logically, this is an independent choice. 269 00:34:38,880 --> 00:34:48,420 Abhay Vasant Ashtekar: And it is, it can be made in order so that the cluster algebra is exactly that. I mean, somebody might argue and say that, well, no. I mean, you can just let the costs of delta be 270 00:34:49,590 --> 00:34:50,940 Abhay Vasant Ashtekar: Delta is be or x 271 00:34:51,960 --> 00:35:03,270 Abhay Vasant Ashtekar: As it is, so that the constraint algebra has a slightly modified with the classical you make you get the right answer, but he put in. I mean, this is a choice. And as I had said let's see what happens with respect to the choice. 272 00:35:04,410 --> 00:35:04,770 Edward Wilson-Ewing (UNB): Yeah. 273 00:35:07,500 --> 00:35:15,390 Edward Wilson-Ewing (UNB): Okay, um, let me continue because I, I would like to get through a few other things. Um, so anyway, so this is 274 00:35:16,770 --> 00:35:17,310 Edward Wilson-Ewing (UNB): The 275 00:35:17,820 --> 00:35:18,990 Edward Wilson-Ewing (UNB): Effect of three. I'll be using 276 00:35:19,350 --> 00:35:21,120 Edward Wilson-Ewing (UNB): So this is the 277 00:35:22,380 --> 00:35:32,940 Edward Wilson-Ewing (UNB): Effect of scale or constraint. This will give me the equations emotion which we can solve. And then from once we have solved the equations emotion, then we can reconstruct 278 00:35:33,900 --> 00:35:40,830 Edward Wilson-Ewing (UNB): The space time and in part to use this to figure out what the shift factories. When we get the metric. Okay. 279 00:35:41,760 --> 00:35:55,560 Edward Wilson-Ewing (UNB): So if we look for a stationary solution we can solve the effective dynamics explicitly analytically for pain Libby goals friendly coordinates where we set the shift equal to one and that gives this metric here. 280 00:35:57,240 --> 00:36:03,360 Edward Wilson-Ewing (UNB): And here RS is equal to is just a short short radius of to GM the classical social radius. 281 00:36:05,430 --> 00:36:20,790 Edward Wilson-Ewing (UNB): Okay, um, as you can see right away. This solution is only valid for x greater than some minimal value just because you have this square root. And if you want to make sure that the square root of this as well defined. You need to make sure the x is greater than this X Men. 282 00:36:22,200 --> 00:36:24,990 Edward Wilson-Ewing (UNB): This X Men lies well within the short short radius. 283 00:36:27,870 --> 00:36:33,510 Edward Wilson-Ewing (UNB): And I want to stress that, of course, this is one solution that we get for payment, the goals around like coordinates. 284 00:36:33,870 --> 00:36:42,540 Edward Wilson-Ewing (UNB): You can make other choices for the laps. And one thing that we did is that we wanted to make contact with results by Gambino meadow and Poland, and so we also 285 00:36:43,050 --> 00:36:50,880 Edward Wilson-Ewing (UNB): Checked setting the labs equal to this, which is what they, the choice that they made and their paper and we get exactly what they get. 286 00:36:51,360 --> 00:37:01,200 Edward Wilson-Ewing (UNB): So there's a nice concordance of results here. So if you if you follow their approach, which is really to villainize the constraints or if you follow our approach, which is to gauge fix 287 00:37:01,470 --> 00:37:02,640 wolfgang wieland: Then at the end of the day that 288 00:37:02,970 --> 00:37:05,100 Edward Wilson-Ewing (UNB): You get these two results which match. 289 00:37:08,940 --> 00:37:20,490 Edward Wilson-Ewing (UNB): Okay. And I want to go through the details of this FaceTime, one by one by do want to mention a few important points. So the first one that I thought was interesting. 290 00:37:20,940 --> 00:37:29,730 Edward Wilson-Ewing (UNB): Is that if you have a mass a black hole or in quotation marks here black hole with a mass which is less than the plank mass, there is no horizon. 291 00:37:30,300 --> 00:37:40,560 Edward Wilson-Ewing (UNB): So if you want to get a horizon, you need a mask greater than the plank last and here when I say horizon. I'm just talking about a killing horizon. 292 00:37:43,710 --> 00:37:56,850 Edward Wilson-Ewing (UNB): Okay, so that's the first point. The second point is that this solution has on our horizon and also inner horizon. So if you have, you know, a large black hole, you'll have an outer horizon. 293 00:37:58,050 --> 00:38:00,150 Edward Wilson-Ewing (UNB): Here we're late concepts over 294 00:38:01,380 --> 00:38:09,120 Edward Wilson-Ewing (UNB): This is essentially at the classical value of the short short radius. There are some small corrections which her you know quite suppressed. 295 00:38:11,580 --> 00:38:25,950 Edward Wilson-Ewing (UNB): By for at least for a large black hole. And you also inner horizon. When the light cone tips over again. And then in between X Men and X, enter your, your particles move both in words and opens 296 00:38:27,990 --> 00:38:33,780 Edward Wilson-Ewing (UNB): And here, this gray region is the region, which were the solution just doesn't exist. 297 00:38:36,840 --> 00:38:52,260 Edward Wilson-Ewing (UNB): And finally, the curvature and variants are bounded and I've given the their balance here um this result isn't so surprising because we've cut off the space time. You can't get to x is equal to zero here. So this is nice, but perhaps not. 298 00:38:53,460 --> 00:38:59,040 Edward Wilson-Ewing (UNB): Super convincing at this stage because really, we've just cut off the space time here. 299 00:39:01,410 --> 00:39:04,170 Edward Wilson-Ewing (UNB): Okay, so this is what we get. We look at the vacuum solution. 300 00:39:06,360 --> 00:39:06,900 Edward Wilson-Ewing (UNB): And 301 00:39:08,400 --> 00:39:16,290 Edward Wilson-Ewing (UNB): In some ways is quite nice. We see that we get some quantum gravity effects exactly in the region where we would expect this is exactly 302 00:39:17,100 --> 00:39:26,070 Edward Wilson-Ewing (UNB): So this region here is exactly the region where the freshman curvature is of the Planck scale. So these curvature effects turn on exactly where we want them to 303 00:39:26,940 --> 00:39:33,000 Edward Wilson-Ewing (UNB): The effects at the horizon are miniscule very, very small. They're essentially suppressed by 304 00:39:33,540 --> 00:39:45,120 Edward Wilson-Ewing (UNB): The array gap divided by the shore shield radius squared. So the effects of the horizon are very small and they turn on exactly where we expect them to be where the Christian Skylar according to GR would reach the Planck scale. 305 00:39:46,440 --> 00:39:55,050 Edward Wilson-Ewing (UNB): Okay, but there is a problem in that this region here just we don't have a solution for that space. I'm just kind of ends sharply. 306 00:39:56,640 --> 00:39:57,120 Edward Wilson-Ewing (UNB): And 307 00:39:57,780 --> 00:39:58,350 Edward Wilson-Ewing (UNB): That is 308 00:39:59,400 --> 00:39:59,820 Abhay Vasant Ashtekar: Very 309 00:40:00,000 --> 00:40:05,970 Abhay Vasant Ashtekar: Good. So is that a Kobe just singularity, or what. What does it mean to say it ends or there's a metric become complex or 310 00:40:06,270 --> 00:40:07,740 Edward Wilson-Ewing (UNB): The metric becomes complex 311 00:40:07,950 --> 00:40:09,240 Abhay Vasant Ashtekar: Microbiome complex. So, 312 00:40:10,290 --> 00:40:13,710 Edward Wilson-Ewing (UNB): If we look here, this term here becomes negative. 313 00:40:14,910 --> 00:40:15,180 Abhay Vasant Ashtekar: Okay. 314 00:40:16,710 --> 00:40:17,190 Carlo Rovelli: Ed. 315 00:40:17,580 --> 00:40:18,000 Edward Wilson-Ewing (UNB): Yes. 316 00:40:18,870 --> 00:40:32,100 Carlo Rovelli: I'm confusing. Once again, the this again. The, the doubling of x and the side effects. What happened is in the selection solutions that we have been studied the effective solutions is that if you follow x 317 00:40:33,510 --> 00:40:41,790 Carlo Rovelli: Namely, the, the area of this year's you come from large, you get to a minimum size. 318 00:40:42,840 --> 00:40:49,740 Carlo Rovelli: And then the space time continues and and the girls again. So there is no 319 00:40:51,210 --> 00:40:59,640 Carlo Rovelli: There's no region of space time with x less than some x minimum. But that's not the end of the world. So just that continues. 320 00:41:00,720 --> 00:41:06,120 Carlo Rovelli: I mean, you can have a model that shrinks and gets the minimum and then opens up so you can have a 321 00:41:08,250 --> 00:41:22,290 Carlo Rovelli: I'm just on the one hand, it seems that this is very similar to the geometry that we have. But the other hand, you seem to be describing differently is saying that something stops there, and especially that x is unique because in 322 00:41:23,520 --> 00:41:29,670 Carlo Rovelli: In if you get if you go to this page fixing that you started the very beginning was a G. Geez, x squared. 323 00:41:31,530 --> 00:41:50,730 Carlo Rovelli: Then x has the two points in space time we're access same value and they connected smooth three so so Max minimum or you just catching this possibility out a priori or no. Is it what what's going on here. It's me, confusing about the geometry. 324 00:41:51,510 --> 00:41:55,860 Edward Wilson-Ewing (UNB): Um, maybe I think it might be easier if I continue a little bit 325 00:41:56,070 --> 00:41:58,290 Edward Wilson-Ewing (UNB): And we'll see what happens when I add matter. 326 00:41:59,010 --> 00:42:12,330 Edward Wilson-Ewing (UNB): Okay, so I'm not going to just rule out that there could be some, you know, perhaps surprising geometries that come out here. But in any case, at this stage, my first instinct was okay we need to add matter. 327 00:42:13,800 --> 00:42:22,380 Edward Wilson-Ewing (UNB): And we were able to do that. And we got some quite interesting results, which I think will will address your questions and if they don't, please come back to that. 328 00:42:23,640 --> 00:42:24,750 Parampreet Singh: Can I ask a question. 329 00:42:25,080 --> 00:42:29,280 Parampreet Singh: Yes, please. So what happens when I said perfect share. Is it is it bounded or 330 00:42:30,540 --> 00:42:40,050 Edward Wilson-Ewing (UNB): Um, yeah, so that should be captured in the question Skyler and and that will be bounded here. But of course, we're only going up to X Men here. 331 00:42:41,160 --> 00:42:41,730 Parampreet Singh: Know what 332 00:42:42,120 --> 00:42:43,920 Parampreet Singh: But you could compute your sigma square right 333 00:42:44,760 --> 00:42:51,480 Edward Wilson-Ewing (UNB): Yeah, I don't think we did that, but I would expect it to be bounded, but I don't think we did the calculation. 334 00:42:52,500 --> 00:42:53,640 Okay, thanks. 335 00:42:56,970 --> 00:42:58,980 Johannes Münch: I have another question. 336 00:42:59,310 --> 00:42:59,760 Edward Wilson-Ewing (UNB): Yes, please. 337 00:43:01,410 --> 00:43:21,900 Johannes Münch: Um, I would also comment on on what Carlos said basically, I think the choice of gauge already basically exclude the possibility of bounce here, right, because usually this bouncing balls, you have this error rate is as a function of a parameter. And you see that the derivative can zero 338 00:43:22,950 --> 00:43:29,220 Johannes Münch: At the bounce. So you cannot so so this function has essentially two branches and you cannot inverted because 339 00:43:30,300 --> 00:43:40,530 Edward Wilson-Ewing (UNB): Well, I think, I think this is based on looking at the Kentucky sex space time where you're really viewing it as some sort of cosmological 340 00:43:41,250 --> 00:43:57,180 Edward Wilson-Ewing (UNB): Model, where the value of the scale factors tells you how big the space time is here. I want to be able to describe the interior and exterior and I would like to be able to you know put an observer at any value of x. At any instance of time. 341 00:43:57,900 --> 00:43:59,760 Edward Wilson-Ewing (UNB): And so here, x is just 342 00:44:00,000 --> 00:44:02,160 Edward Wilson-Ewing (UNB): Increasing as you move outwards. 343 00:44:04,140 --> 00:44:08,970 Johannes Münch: Yes, I'm fine with this so might my let me rephrase extra 344 00:44:10,260 --> 00:44:26,820 Johannes Münch: So is actually the second solution to your equations which might be due to different choice of the science somewhere which you might lose X Men to to your current solution where you can interpret one as the black home branch and device as the white one branch. 345 00:44:27,960 --> 00:44:28,140 Right. 346 00:44:31,140 --> 00:44:31,470 Right. 347 00:44:32,790 --> 00:44:33,330 Edward Wilson-Ewing (UNB): I 348 00:44:34,500 --> 00:44:39,060 Edward Wilson-Ewing (UNB): Don't think so, but I'd have to check in detail. 349 00:44:40,110 --> 00:44:40,440 Okay. 350 00:44:41,670 --> 00:44:47,310 Carlo Rovelli: Yeah, but I would be interested in that because that's the that the geometry. 351 00:44:48,600 --> 00:44:55,080 Carlo Rovelli: That we are studying so whether it, it matches with your, your way of computing it 352 00:44:55,170 --> 00:45:02,700 Edward Wilson-Ewing (UNB): I think. But, but, again, let me let me add in matter because I think this will change the perspective, at least it did for me. 353 00:45:02,820 --> 00:45:04,230 Edward Wilson-Ewing (UNB): But yes. 354 00:45:05,010 --> 00:45:07,320 Carlo Rovelli: I mean tell me shut up. If you want to go ahead 355 00:45:07,620 --> 00:45:08,160 Edward Wilson-Ewing (UNB): No, it's okay. 356 00:45:09,720 --> 00:45:16,860 Carlo Rovelli: I think that the problem. What happened with the matter is is nothing to do with the problem. What happens when the 357 00:45:17,910 --> 00:45:27,510 Carlo Rovelli: Small curvature is more radius is. I mean, if you if you just look at the standard. The black hole pedals diagram of the one with the singularity. 358 00:45:27,930 --> 00:45:39,180 Carlo Rovelli: I mean, there's one point to a macro arrives and then there's a huge horizon. So there's a huge region where our becomes small fire very far away from Latin. So there's a problem. What happens with small are 359 00:45:40,680 --> 00:45:41,040 Edward Wilson-Ewing (UNB): So, 360 00:45:41,100 --> 00:45:42,300 Carlo Rovelli: Mike independent of ladder. 361 00:45:42,630 --> 00:45:49,830 Edward Wilson-Ewing (UNB): Right. So my argument, and I'll be coming to this in a second is that this whole region here has to contain matter. 362 00:45:51,570 --> 00:45:56,910 Carlo Rovelli: So that that excludes the models. We've been studying in my side. Right. 363 00:45:58,410 --> 00:46:02,190 Edward Wilson-Ewing (UNB): Well, as far as I understand you've been looking at vacuum solutions right 364 00:46:02,490 --> 00:46:04,350 Carlo Rovelli: We have global picture. 365 00:46:05,520 --> 00:46:20,490 Carlo Rovelli: Matches the matter is somewhere and there's about matter bounce. But then there is a region where you just cross through the singularity far away from matter, no matter whatsoever. And you go from the tropical. Tropical region is just look at that one far away. 366 00:46:21,600 --> 00:46:32,610 Carlo Rovelli: Then it's a little. It's a little Kentucky sucks. If you want, you wait for the rise on away from the, from the matter which is look there, but there is a position there without matter. 367 00:46:35,040 --> 00:46:36,750 Edward Wilson-Ewing (UNB): So what we find is a little different. 368 00:46:36,990 --> 00:46:44,310 Edward Wilson-Ewing (UNB): Okay. Yeah. So I think there are some similarities, which are interesting, but there are also some differences. So let me, let me try to explain 369 00:46:44,340 --> 00:46:59,130 Abhay Vasant Ashtekar: I think it just is different because then I know but you know horizon, you've got all these things which which was which all these effective space times that in a web in considering coverage because it in don't have these you know horizon is a completely different global structure. 370 00:47:00,390 --> 00:47:01,530 Yeah yeah 371 00:47:02,550 --> 00:47:09,900 Edward Wilson-Ewing (UNB): Okay, so for for us, at least when we, when we got this. We thought, okay, maybe we should add matter and see what happens in that case. 372 00:47:10,290 --> 00:47:19,110 Edward Wilson-Ewing (UNB): Are we able to fill this hole or is there or should we look for something else entirely different, but if we add matter what happens. 373 00:47:19,740 --> 00:47:26,430 Edward Wilson-Ewing (UNB): Now, we had some motivation behind this. I want to explain the motivation and this very is very much a hand waving argument. 374 00:47:26,790 --> 00:47:36,240 Edward Wilson-Ewing (UNB): But what's nice is that we'll see in just a little bit that this hand-waving argument becomes very precise. So if we have a gravitational field. Let's say black hole. 375 00:47:37,380 --> 00:47:47,130 Edward Wilson-Ewing (UNB): Normally we would say, okay, well, there has to be some sort of sort of source now hysterical symmetry. We don't have any gravitational waves. So the only source possible ism is 376 00:47:47,640 --> 00:47:53,520 Edward Wilson-Ewing (UNB): Now, classically, of course, you can just say, okay, we put my mass at the origin. And I have some delta function source. 377 00:47:54,480 --> 00:48:02,070 Edward Wilson-Ewing (UNB): But if you think from porn gravity and say, look, quantum cosmology that you could have an upper bound on the density of your matter field. 378 00:48:02,520 --> 00:48:24,540 Edward Wilson-Ewing (UNB): Of the Planck scale, then that means that if you have a compact object of some mass capital M, it has to have some extent. And specifically, it has to extend at least to a minimum radius given by this mass divided by maximal density and taking the cube root. And if we look at what happens. 379 00:48:25,620 --> 00:48:30,510 Edward Wilson-Ewing (UNB): Here. Sorry for X Men, that is exactly where this shows up. 380 00:48:31,740 --> 00:48:35,880 Edward Wilson-Ewing (UNB): So this suggests that maybe matter plays an important role here. 381 00:48:38,130 --> 00:48:42,150 Edward Wilson-Ewing (UNB): Okay, but I want to stress this is just a hand waving argument to motivate this 382 00:48:43,620 --> 00:48:45,900 Edward Wilson-Ewing (UNB): So to explore this, what we did is we added 383 00:48:46,710 --> 00:48:47,400 Parampreet Singh: Some question. 384 00:48:47,730 --> 00:48:48,270 Edward Wilson-Ewing (UNB): Yes, please. 385 00:48:48,600 --> 00:48:57,420 Parampreet Singh: Okay, so I have some issues with all this arguments. The point is, like, first of all, it gives us who gives us this our bond roll less than Rafi 386 00:48:57,930 --> 00:48:59,970 Edward Wilson-Ewing (UNB): So prompt. This is just motivation. 387 00:49:00,810 --> 00:49:01,980 Parampreet Singh: Okay, but I'm just 388 00:49:02,070 --> 00:49:08,880 Parampreet Singh: I'm here. I don't know when he started regularly. So I will make this precise in a minute, but at this stage is really just to motivate 389 00:49:09,030 --> 00:49:12,090 Edward Wilson-Ewing (UNB): Heading matter if you think that the argument is week. That's okay. 390 00:49:13,110 --> 00:49:21,540 Parampreet Singh: No, no. Well, let me just ask my question first point is that even if you have rule, less than Rosie, even if you assume that like 391 00:49:21,960 --> 00:49:28,710 Parampreet Singh: From el que se that maybe that could occur. And if you asked arguments. Okay, let us look at the Yankee one, for example, they are also 392 00:49:29,400 --> 00:49:44,940 Parampreet Singh: Row was less than Rosie, but the main role played in the space times even if the matter is present is by a nicer trapeze. We know that. So you will never reach row close to Rosie and your X Men, even with the same argument will be very large. 393 00:49:45,480 --> 00:49:55,290 Edward Wilson-Ewing (UNB): Sure. So what that means is that this if you include some and I saw trapeze or something else, then what you're essentially doing is you're making this even bigger. 394 00:49:57,450 --> 00:49:59,640 Parampreet Singh: No, you don't have to include a nicer properties are already there. 395 00:50:00,210 --> 00:50:00,570 Abhay Vasant Ashtekar: Sure. 396 00:50:01,140 --> 00:50:03,330 Abhay Vasant Ashtekar: If but if you apply that in the argument. 397 00:50:03,630 --> 00:50:04,980 Edward Wilson-Ewing (UNB): This makes this even bigger. 398 00:50:06,360 --> 00:50:15,600 Edward Wilson-Ewing (UNB): Right, because you're making row smaller, so you're making you know this whole thing together bigger. So you're saying that actually we need to include matter even further up 399 00:50:16,260 --> 00:50:17,610 Parampreet Singh: Absolutely, yeah. 400 00:50:17,640 --> 00:50:35,520 Edward Wilson-Ewing (UNB): So, so yes. Either way, um, it really suggest that we should include matter to try and understand what's happening here, at least, and I, again, I don't want to spend too much time on this because it's not a central point. This is just, you know, a motivational argument. 401 00:50:35,820 --> 00:50:43,560 Parampreet Singh: No, but I think it's an important point. So let me just summarize the technical points so far. So the point is, like, we made certain good choices. 402 00:50:44,160 --> 00:51:01,200 Parampreet Singh: We did K quantization. We then meet certain choice of Annex and an end. We ended by saying, well, now if I do not include matter, things don't work. My metric becomes complex below X Men, so I should go back to the square one and redo the analysis with matter. Isn't that what we're doing. 403 00:51:01,470 --> 00:51:01,830 Yeah. 404 00:51:06,330 --> 00:51:06,660 Yeah. 405 00:51:08,310 --> 00:51:13,260 Edward Wilson-Ewing (UNB): And again, so. So this is just, you know, motivation and 406 00:51:13,410 --> 00:51:16,410 Edward Wilson-Ewing (UNB): I'm going to make it precise in a second and how this argument really does work. 407 00:51:17,340 --> 00:51:27,360 Edward Wilson-Ewing (UNB): In more detail. And so what we did is that we added a dust field. Um, we use the dust time gauge which means that we set 408 00:51:28,530 --> 00:51:37,830 Edward Wilson-Ewing (UNB): We, we, we use the dust field as the clock and this sets the laps equal to one this is on top of the arrow gauge, of course. And then we get a true Hamiltonian 409 00:51:38,490 --> 00:51:53,550 Edward Wilson-Ewing (UNB): And the equations emotion or essentially the El que or some version of El que je effective equations for LTV space times in panel of eagles friendly coordinates. And when I say Pelham eagles turn like whereas I just mean that the lapses equal to one. 410 00:51:56,790 --> 00:52:04,020 Edward Wilson-Ewing (UNB): Okay, so here is the true Hamiltonian after we've added the dust field and we use it as a relational clock. 411 00:52:05,490 --> 00:52:16,440 Edward Wilson-Ewing (UNB): Of course, it's no longer constrained right this is a true Hamiltonian and the energy density of the dust field is related to the value of this effective Hamiltonian 412 00:52:18,600 --> 00:52:29,460 Edward Wilson-Ewing (UNB): Um, let me go through this quickly because it's not so important we get some equations emotion their exact form is important. The point is, I want to show you that we have equations emotion for general LTV space times 413 00:52:30,360 --> 00:52:41,160 Edward Wilson-Ewing (UNB): But what we do. We don't. I mean going and solving all the LTV space times. Is it a little ambitious to start. So we said, Okay, let's just look at the simplest model that we can think of, which is open hammer Snyder collapse. 414 00:52:42,450 --> 00:52:50,820 Edward Wilson-Ewing (UNB): And so this is a star of some radius L and L is dynamical right so we have a star which is going to collapse. So l will get smaller and smaller. 415 00:52:51,600 --> 00:53:02,910 Edward Wilson-Ewing (UNB): And the energy density of the dust field is zero outside of the star and it's constant inside. And of course, as the star collapses this density will increase. So the question is what happens dynamically 416 00:53:04,770 --> 00:53:22,500 Edward Wilson-Ewing (UNB): Now we can take the LTV equations emotion and apply it for this system and see what we get. So what I'm going to tell you. Next is not something I'm putting in by hand but it's a derivation of these results from the LTV equations here. 417 00:53:23,910 --> 00:53:48,210 Edward Wilson-Ewing (UNB): And so this is the equation that we get for how L evolves and as you can tell this is exactly the effective Freeman equation for LTC so it seems to me a very nice convergence of ideas where we're applying the same methods that we do and lukewarm cosmological spherical cemetery. 418 00:53:49,290 --> 00:53:59,580 Edward Wilson-Ewing (UNB): And this gives us some very general equations for LTV space times. But if we apply it in a context where you would expect the QC equations to work. 419 00:54:00,390 --> 00:54:10,650 Edward Wilson-Ewing (UNB): And of course the open hammer Snyder model is exactly such a case, because the interior modeling as a space with a homogeneous space. 420 00:54:11,220 --> 00:54:25,530 Edward Wilson-Ewing (UNB): than you'd expect to recover the LTC equations emotion that's exactly what we get. And what I want to stress is that we get everything exactly the same, even the value of the critical energy toasty here in matches exactly with LPC 421 00:54:27,120 --> 00:54:35,460 Edward Wilson-Ewing (UNB): Okay, we can also find explicit solutions for all of the other terms. I'm not going to show that here. I'll just refer you to the paper. If you're interested in the details. 422 00:54:35,760 --> 00:54:43,200 Edward Wilson-Ewing (UNB): But what we see is that there's events. So you have a star, it collapses, it reaches a minimal radius. And then it bounces up 423 00:54:46,950 --> 00:54:47,520 Edward Wilson-Ewing (UNB): Now, 424 00:54:47,850 --> 00:54:54,840 Edward Wilson-Ewing (UNB): Another interesting thing, and this is where I'm making precise what I put the hand waving argument I gave earlier. 425 00:54:55,200 --> 00:55:09,900 Edward Wilson-Ewing (UNB): Is that you can solve for the radius of the star Lt. And you can see, okay, what is this minimal value and it's minimal value turns out to be exactly X Men, where the vacuum solution ends so 426 00:55:10,980 --> 00:55:16,530 Edward Wilson-Ewing (UNB): The way that I interpret these results. Is that your vacuum solution goes up to a point. 427 00:55:16,980 --> 00:55:26,790 Edward Wilson-Ewing (UNB): And inside that point, you need matter. But if you include matter, then you're guaranteed that your solution will extend at least that far. So of course before when you start. It's big and it's just starts to collapse. 428 00:55:27,300 --> 00:55:33,420 Edward Wilson-Ewing (UNB): It's much bigger than X Men, but the smallest point it reaches is X Men and then it bounces back out again. 429 00:55:36,660 --> 00:55:38,100 Parampreet Singh: It can make a very small point 430 00:55:38,430 --> 00:55:38,940 Edward Wilson-Ewing (UNB): Yes, please. 431 00:55:39,000 --> 00:55:46,950 Parampreet Singh: Isn't this coincidence, precisely because of sorry I won't say like, this is a coincidence, precisely because of we are working with a K quantization. 432 00:55:47,400 --> 00:56:03,330 Parampreet Singh: And you did exactly the same polymerization, which led to the X Men similar polymerization, which is done in elk. You see what especially flat model. And if you would have chosen to include spatial curvature in quantum gravity affects then this coincidence will not offer 433 00:56:04,860 --> 00:56:16,890 Edward Wilson-Ewing (UNB): Right. So here I agree, we have to keep in mind that we're we're comparing apples with apples and we're doing the same Luke quantization. So if, if we were to do 434 00:56:17,790 --> 00:56:27,630 Edward Wilson-Ewing (UNB): As you say, let's say in a loop quantization, then you may not expect them to match because there are some quantization ambiguities. But my point here is that, at least to me. 435 00:56:27,990 --> 00:56:41,490 Edward Wilson-Ewing (UNB): It was surprising that we do this in spherical symmetry and we get some very general equations and then we reduced down to this case we get exactly what we would have gotten admittedly following the same quantization procedure, but still we get exactly the same thing. 436 00:56:42,210 --> 00:56:46,080 Edward Wilson-Ewing (UNB): No, but I would have expected. Maybe some small corrections, but that doesn't even happen here. 437 00:56:46,410 --> 00:56:52,530 Parampreet Singh: Nobody but the point is, like, once we assume the aerial cage and once we take the cake quantization, we are essentially in the same system. 438 00:56:53,160 --> 00:56:55,200 Edward Wilson-Ewing (UNB): No, no, no, no, no, no. 439 00:56:55,260 --> 00:56:57,660 Abhay Vasant Ashtekar: This, this particular metric is completely different system. 440 00:56:57,780 --> 00:57:06,300 Parampreet Singh: Know, obey. That is, it is true. It is true, it is asparagus metric. It's a completely different system, but the quantization effects are essentially what are done in specially flannel QC 441 00:57:07,530 --> 00:57:18,240 Edward Wilson-Ewing (UNB): Well, I mean, I'm following the same procedure. I agree. I mean, the whole point here is to use the same input and then see you know do we get something that comes out, which is consistent right 442 00:57:18,630 --> 00:57:19,740 Edward Wilson-Ewing (UNB): I'm definitely not 443 00:57:20,010 --> 00:57:24,780 Edward Wilson-Ewing (UNB): Building everything from scratch and become very much using work that's been done before. There's no question 444 00:57:25,950 --> 00:57:26,940 Suddhasattwa Brahma: But here. 445 00:57:27,300 --> 00:57:39,090 Edward Wilson-Ewing (UNB): I mean, classically, I have all these quantities that depend on x, right, everything has an x dependence, right, if you look at the equations of motion. Here I have all these spatial derivatives here in here. 446 00:57:39,840 --> 00:57:47,520 Edward Wilson-Ewing (UNB): Right, so the fact that, then when I look at some limit where I have a homogeneous matter field I recover exactly the same. 447 00:57:48,960 --> 00:57:52,560 Edward Wilson-Ewing (UNB): Equations emotion I, for me, it was, it was a nice result. 448 00:57:55,230 --> 00:58:03,960 Abhay Vasant Ashtekar: Not by me. This got totally unexpected so i don't i don't think it is that something that I would have seen it just from the metrics, you're using. So 449 00:58:07,050 --> 00:58:08,670 Suddhasattwa Brahma: Can I ask a quick question. This is true, though. 450 00:58:08,970 --> 00:58:22,380 Suddhasattwa Brahma: So it's so if just to build on this question. If you include special curriculum shouldn't expect equals one cosmology. If you're really doing Oppenheimer Snyder for the interior like wouldn't expect that effect to be, I mean, forget 451 00:58:23,640 --> 00:58:24,780 Edward Wilson-Ewing (UNB): Yes, you're right. 452 00:58:24,900 --> 00:58:31,800 Edward Wilson-Ewing (UNB): So here I haven't studied that yet because there's so much to be done here. I mean, here I'm giving you what we've done so far. And there's a lot to be done. 453 00:58:32,280 --> 00:58:43,890 Edward Wilson-Ewing (UNB): Here I made a choice here just to simplify things, and I chose that Eb is equal to x. So that's a choice that you can make when you're looking for a certain solution. 454 00:58:44,070 --> 00:58:45,720 Edward Wilson-Ewing (UNB): And then that corresponds to the flat. 455 00:58:45,960 --> 00:58:46,890 Edward Wilson-Ewing (UNB): Open hammer cider. 456 00:58:47,220 --> 00:58:48,930 Suddhasattwa Brahma: Yeah. Thank you. Yeah. 457 00:58:49,020 --> 00:58:49,500 Edward Wilson-Ewing (UNB): So you're right. 458 00:58:49,830 --> 00:58:52,260 Edward Wilson-Ewing (UNB): I would be interesting to see what happens if we put in 459 00:58:53,100 --> 00:58:55,260 Edward Wilson-Ewing (UNB): Another choice which would give something that 460 00:58:55,260 --> 00:58:56,580 Suddhasattwa Brahma: Would be closed. Yeah. 461 00:58:57,270 --> 00:59:11,910 Parampreet Singh: And I think like just to add to both of your commands like Adams and and and Romans comment like first like to. I was. I didn't meant to say like the system. The same. But I thought you understood, like what I meant like the condition procedure, the main steps. 462 00:59:12,600 --> 00:59:13,410 Parampreet Singh: Of similarities 463 00:59:13,740 --> 00:59:14,850 Parampreet Singh: The second point was like 464 00:59:15,210 --> 00:59:21,000 Edward Wilson-Ewing (UNB): Sorry if I misunderstood you I hear, I agree that the quantization steps are very similar. I mean, very much followers 465 00:59:21,240 --> 00:59:21,660 Parampreet Singh: But just 466 00:59:21,810 --> 00:59:23,400 Parampreet Singh: To just to clarify the word 467 00:59:23,520 --> 00:59:34,110 Parampreet Singh: For bromance. Like if one has to include key code one in this case, then the right quantization to do will be the A quantization. In the first step, not the key quantization to make to repeat the similar arguments. 468 00:59:35,400 --> 00:59:39,270 Edward Wilson-Ewing (UNB): While you could do either. Right. And then you could compare with the K or the a little quantization. 469 00:59:39,480 --> 00:59:44,940 Parampreet Singh: Yeah, but then you won't get you won't get the agreement, what you have, if you do K and then k equal to one here. 470 00:59:46,320 --> 00:59:46,860 Edward Wilson-Ewing (UNB): Um, 471 00:59:48,330 --> 00:59:51,810 Edward Wilson-Ewing (UNB): I'm not sure. I mean, it's certainly possible. Yeah. 472 00:59:55,740 --> 01:00:00,180 Edward Wilson-Ewing (UNB): Okay, so. So what we find in this case is that we get a bounce. 473 01:00:01,620 --> 01:00:02,220 Edward Wilson-Ewing (UNB): And 474 01:00:03,630 --> 01:00:10,230 Edward Wilson-Ewing (UNB): And what we really have is we have some collapse or we have a collapsing star it reaches a minimal radius. And then it starts to bounce back up. 475 01:00:12,180 --> 01:00:21,570 Edward Wilson-Ewing (UNB): Okay. And here, um, this model really gives us, I think, a very nice and explicit realization, but transition from a black hole. 476 01:00:21,840 --> 01:00:28,290 Edward Wilson-Ewing (UNB): To and here and being very careful what I say something which isn't some ways similar to a white hole which is generated by quantum gravity effects. 477 01:00:28,680 --> 01:00:33,150 Edward Wilson-Ewing (UNB): And also, as you notice that the title I have white hole in quotation marks. 478 01:00:33,660 --> 01:00:49,920 Edward Wilson-Ewing (UNB): So why am I doing this. Why am I not seeing away whole. Well, the reason is it's not exactly a white hole. There are some very important similarities but it's not a white hole as you would see in the classical GR textbook. So the reason for that is that if you look at the space time 479 01:00:50,940 --> 01:00:54,060 Edward Wilson-Ewing (UNB): Someone who's outside doesn't notice 480 01:00:55,500 --> 01:01:06,810 Edward Wilson-Ewing (UNB): What's happening inside. So here, if you're if you reach the outer horizon, right, which is essentially the sword shield radius for large black hole. This is still a trap surface. 481 01:01:07,350 --> 01:01:22,620 Edward Wilson-Ewing (UNB): So an observer in here is moving towards the left. This is still trapped the differences inside the star which here I'm showing in grey you have observers, which are anti trapped. So you have a sort of white hole like region here. 482 01:01:23,700 --> 01:01:26,610 Edward Wilson-Ewing (UNB): But this part still looks like a black hole. 483 01:01:27,660 --> 01:01:35,730 Edward Wilson-Ewing (UNB): So in some ways, you have the similarity with white hole, but it's not a white whole space time at all. 484 01:01:36,840 --> 01:01:47,370 Edward Wilson-Ewing (UNB): And of course as the system evolves. After the bounce rate. So you have your, your star which collapses and bounces in the balls outwards. So, then your 485 01:01:48,480 --> 01:01:59,910 Edward Wilson-Ewing (UNB): Radius of this matter field is slowly moving outwards and once it passes the outer horizon there won't be a black hole anymore in the sense that there's no longer under horizon. 486 01:02:01,590 --> 01:02:04,050 Edward Wilson-Ewing (UNB): Okay, so this is the general picture of what's happening. 487 01:02:06,660 --> 01:02:11,820 Edward Wilson-Ewing (UNB): I'm almost out of time. So let me just quickly say a few things about this. 488 01:02:13,800 --> 01:02:15,450 Edward Wilson-Ewing (UNB): I showed you some explicit 489 01:02:18,210 --> 01:02:22,440 Edward Wilson-Ewing (UNB): Equations. So some explicit analytic solutions for 490 01:02:23,460 --> 01:02:27,090 Edward Wilson-Ewing (UNB): I couldn't show them to you. But in the in our paper we have some explicit analytic solutions for 491 01:02:27,900 --> 01:02:35,280 Edward Wilson-Ewing (UNB): If we go back here for Eb be an annex, and this is explicit solutions for the open hammer slider model. 492 01:02:35,760 --> 01:02:52,470 Edward Wilson-Ewing (UNB): Now, when we do this we're neglecting these edge effects at x is equal to L and that's perfectly fine, because in the open hammer Snyder model as it collapses all the fields are continuous. They're not necessarily differentiable at the boundary, but they are continuous now. 493 01:02:52,530 --> 01:02:53,310 After 494 01:02:54,420 --> 01:03:04,020 Edward Wilson-Ewing (UNB): After the bounce. What you see here is that you have an anti trap region here and attract region here and there's clearly a discontinuity between the two. 495 01:03:04,710 --> 01:03:16,680 Edward Wilson-Ewing (UNB): So what that means is you have to include these edge effects. Now, so that means that, okay, we had some nice solutions which were very simple for the pre bounce. But after the bounce. We have to be a little more careful. 496 01:03:19,470 --> 01:03:26,490 Edward Wilson-Ewing (UNB): And in particular, you can check that this be here is discontinuous at x is equal to hell. 497 01:03:27,600 --> 01:03:36,000 Edward Wilson-Ewing (UNB): And so to understand how L moves outwards. We can't just use the open hammer Snyder equations anymore. We have to use the full LTV effect of equations. 498 01:03:37,680 --> 01:03:40,950 Edward Wilson-Ewing (UNB): Okay. And these of course are a lot harder to solve. 499 01:03:42,240 --> 01:03:52,350 Edward Wilson-Ewing (UNB): So I won't go through the details here, but if you just do a back of the envelope calculation. This suggests that this discontinuity really slows the expansion of this wave front. 500 01:03:52,950 --> 01:04:09,660 Edward Wilson-Ewing (UNB): And it suggests that the lifetime of the black hole would be around M squared over and plank. Now this is a very rough back of the envelope estimation. So we really need to do further work To check to see if this is correct or not. But this is what the first 501 01:04:11,940 --> 01:04:25,470 Edward Wilson-Ewing (UNB): First explorations indicate and I just want to mention here that when I talk about the lifetime of a black hole. I'm assuming that both the formation of the black hole. So you have a collapsing star, presumably, that's an energetic event. And then when the 502 01:04:26,610 --> 01:04:31,290 Edward Wilson-Ewing (UNB): The wave front comes out again. That's also an energetic event that will send out photons. 503 01:04:31,650 --> 01:04:42,840 Edward Wilson-Ewing (UNB): So I'm saying, Okay, we have some distant observer. That's really far away and he sees some photons that are emitted as the star collapses and forms of black hole and then you see some photons again when the way in front 504 01:04:43,800 --> 01:04:56,310 Edward Wilson-Ewing (UNB): Of the matter field reaches the horizon, or just passes the horizon and more photons are emitted and so he's measuring the time between the photons that he receives from the collapse and then from the expansion from a distance. That's very far away. 505 01:04:59,430 --> 01:04:59,760 Edward Wilson-Ewing (UNB): Okay. 506 01:05:00,780 --> 01:05:09,060 Edward Wilson-Ewing (UNB): So I'm almost done. I just want to say a few things about the ramifications for the information last problem. So if this is the correct lifetime. 507 01:05:09,510 --> 01:05:18,150 Edward Wilson-Ewing (UNB): Then I think this would have some quite interesting ramifications for the information loss problem. So first, we don't have any singularity. So there's no no place for information to just 508 01:05:18,660 --> 01:05:33,150 Edward Wilson-Ewing (UNB): You know, and or be lost entirely and there's no eternal event horizon, behind which information can just hide forever. So those are two places where people sometimes think, oh, this is one way that information loss could happen. Well, these just aren't available in this space time 509 01:05:35,190 --> 01:05:43,740 Edward Wilson-Ewing (UNB): Now, on top of that people often argue that the potential information loss becomes a real problem after half of the black hole has evaporated. 510 01:05:44,850 --> 01:05:51,240 Edward Wilson-Ewing (UNB): And the idea is that, okay, you have a black hole and you have some hockey radiation and as hockey radiation goes on. 511 01:05:52,020 --> 01:05:55,380 Edward Wilson-Ewing (UNB): You'll have some entanglement between the hockey radiation what's left of the black hole. 512 01:05:56,280 --> 01:06:01,950 Edward Wilson-Ewing (UNB): And this is fine until all of a sudden, there are more degrees of freedom in the hotkey radiation and in the black hole. 513 01:06:02,340 --> 01:06:08,250 Edward Wilson-Ewing (UNB): And then you would expect that you'd have to have some purification for the entertainment entry to decrease since the 514 01:06:08,880 --> 01:06:11,490 Edward Wilson-Ewing (UNB): number of degrees of freedom in your black hole is getting smaller and smaller. 515 01:06:12,450 --> 01:06:20,340 Edward Wilson-Ewing (UNB): And the page. Time for a black hole. If you just look at the standard quantum field theory calculation would be MQ over m squared. 516 01:06:20,970 --> 01:06:28,650 Edward Wilson-Ewing (UNB): So if the black hole lifetime, because we calculated here is only M squared over and playing so much shorter 517 01:06:29,340 --> 01:06:41,040 Edward Wilson-Ewing (UNB): Then this would say that the Hawking evaporation process is a sub leading quantum fact, of course, it's still there, but it's just much slower and there's not enough time for information loss to become a problem in this case. 518 01:06:43,380 --> 01:06:55,140 Edward Wilson-Ewing (UNB): Okay, I'm out of time. So let me just conclude very quickly. So what we did is that we drive some LPG effective equations with hello on me corrections for 519 01:06:56,490 --> 01:07:00,870 Edward Wilson-Ewing (UNB): For strictly symmetric space times, both in vacuum and with a dust field. 520 01:07:01,560 --> 01:07:10,620 Edward Wilson-Ewing (UNB): In vacuum. We get solutions that agree with what was found by can be neoliberal in Poland, following the different approach. So I think this is quite nice. We have these different approaches that give the same result. 521 01:07:11,430 --> 01:07:15,420 Edward Wilson-Ewing (UNB): We find an enterprise and also minimum radius, where the vacuum solution breaks down. 522 01:07:16,440 --> 01:07:29,730 Edward Wilson-Ewing (UNB): So then we added a dust matter field. And not only can we know describe the entire space time there is no minimum inner you know X Men were the solution, because then I can go all the way down to x equals to zero. 523 01:07:31,380 --> 01:07:46,320 Edward Wilson-Ewing (UNB): And what happens is I have a collapse. I have a bounce and then as it comes out. I have a shockwave and as I just finished saying we estimate the lifetime of the black hole to be m squared over complaint. 524 01:07:48,180 --> 01:07:49,290 Edward Wilson-Ewing (UNB): Okay, um, 525 01:07:50,370 --> 01:08:02,760 Edward Wilson-Ewing (UNB): Let me just put up some open questions. Of course there. There's a huge number of things that still need to be explored. And these are just some of them. It's some of the ones that I've been thinking about the most. But it's by no means an exhaustive list or tons of other ones. 526 01:08:03,840 --> 01:08:06,150 Edward Wilson-Ewing (UNB): So thank you all for listening. 527 01:08:15,540 --> 01:08:16,320 Carlo Rovelli: I have a question. 528 01:08:17,190 --> 01:08:17,970 Edward Wilson-Ewing (UNB): Well, please. 529 01:08:19,080 --> 01:08:30,120 Carlo Rovelli: So in 2222 comments, more, more than questions I had that this is this is very nice. Thank you very much. I mean, very solid. As always, when you do things the first comment is about em square 530 01:08:31,140 --> 01:08:43,320 Carlo Rovelli: It's just, I mean I'm I'm super happy of seeing and square coming can can be coming back because m square. I mean, then the lifetime of box goes whole n square 531 01:08:44,700 --> 01:09:00,090 Carlo Rovelli: It's a, it's a possibility, how and I pointed out that there's just a dimensional hand waving argument that says that it is possible on quantum gravity dimensional argument that things happen and square 532 01:09:00,600 --> 01:09:01,110 Carlo Rovelli: And so 533 01:09:01,890 --> 01:09:06,510 Carlo Rovelli: It was a it was a, we were very excited because, of course, there is a 534 01:09:06,900 --> 01:09:17,460 Carlo Rovelli: There's other phenomenology. That could be related to him square. I mean, for Jessica has explored that there is even some some astrophysical search for em square phenomenon and black holes. 535 01:09:18,360 --> 01:09:32,040 Carlo Rovelli: Primordial black holes exploding today if if the lifetime is I'm square could give a good give up several things. So it's fantastic and very happy that this is reinforced I was losing hope of em square 536 01:09:33,210 --> 01:09:42,480 Carlo Rovelli: Because of spin form calculations that were saying, No, no, no. It says, It's too early for for something to happen when you look at the at the quantum gravity horizon. 537 01:09:43,230 --> 01:09:51,600 Carlo Rovelli: But I want to. So recently I was just, you know, thinking no no no black holes are going to stay there, all, all VM in Cuba life. 538 01:09:52,140 --> 01:10:01,440 Carlo Rovelli: But, but, but it's nothing solid in in in our results in fact i i from, from the point of us being forms. I think it's a 539 01:10:02,370 --> 01:10:16,500 Carlo Rovelli: There are indications from Cuba, but but but it would be fantastic on for quantum gravity and for for observations, if they were MS clear phenomena, but that's the first comment. The second comment is that yeah i mean 540 01:10:17,730 --> 01:10:27,030 Carlo Rovelli: By put it very clearly that the kind of model. You're doing it differs from a transition across the 541 01:10:28,410 --> 01:10:34,140 Carlo Rovelli: The Singularity without Makar that has been exploring in various ways in in in other ways. 542 01:10:35,460 --> 01:10:48,270 Carlo Rovelli: But, but, you know, but but God is complicated. And then of course the, the choice of of coordinates in which we are kind of make things very, very, very, very different. So 543 01:10:49,410 --> 01:10:50,100 Carlo Rovelli: I think 544 01:10:51,210 --> 01:10:58,650 Carlo Rovelli: I'm particularly impressed by your matter part and by the appearance of this pseudo pseudo 545 01:11:00,360 --> 01:11:01,170 Carlo Rovelli: HTC 546 01:11:02,400 --> 01:11:13,680 Carlo Rovelli: Friedman equation that we appears here that that that's very surprising and the fact that it can be described the bounce the bounce. It's remarkable perhaps 547 01:11:14,790 --> 01:11:22,440 Carlo Rovelli: Perhaps things could stay together if if we look, I would like to see 548 01:11:23,880 --> 01:11:45,210 Carlo Rovelli: Somehow the full in a pot is is on the basis of that of the full space time. I mean, the full Council structure of the space time that comes out, comparing with a one that comes from other from other analysis, then we do these things is not. I mean, I understand that. 549 01:11:46,500 --> 01:11:53,040 Carlo Rovelli: Understand the beauty of doing rigorous system that some simplification that you can 550 01:11:54,330 --> 01:12:02,790 Carlo Rovelli: That you can do exactly understand the strength of that, of course, very well. But, but at the end of the day, physicists complicated. I mean, 551 01:12:03,240 --> 01:12:15,030 Carlo Rovelli: Black was a complicated thing there is a star that collapses. There's a part that bounces. There's a you can go get to the singularity far away from the star days arise. So there's a lot of pieces. And it seems to me that each one is treated in an approximation. 552 01:12:16,170 --> 01:12:26,160 Carlo Rovelli: And we have to be flexible enough to see the various it's about pick up the right hint from each one of these models that the second, the second comment. 553 01:12:27,480 --> 01:12:35,280 Edward Wilson-Ewing (UNB): Yeah, and I agree with both. And let me just add one other comment. I think that, you know, there's a lot of things that are going to be explored right i mean 554 01:12:36,180 --> 01:12:47,670 Edward Wilson-Ewing (UNB): For even what what I'm presenting here. This is very much. You know what first few steps in this direction. And there's more to be done. And there's more to be done in other directions to mean 555 01:12:47,910 --> 01:12:50,610 Edward Wilson-Ewing (UNB): The more we do it, the more the more will learn for sure. So 556 01:12:52,410 --> 01:12:54,870 Carlo Rovelli: Thanks very nice, very nice presentation. Thank you. 557 01:12:55,830 --> 01:13:03,420 Francesca Vidotto: Look at which one would be the first thing to do in this list of open questions in order to go ahead with this one. 558 01:13:03,480 --> 01:13:09,450 Edward Wilson-Ewing (UNB): Um, well, I can tell you what I'm doing. I'm doing I'm working on the third and fourth ones. 559 01:13:11,610 --> 01:13:25,590 Edward Wilson-Ewing (UNB): Um, but, you know, I think that's something that each person will have their own answer to. And I think any progress in any of these questions will be very, very helpful, but I'm personally currently working on the third and fourth 560 01:13:28,800 --> 01:13:30,630 Abhay Vasant Ashtekar: Okay, so, hooray asked me to 561 01:13:34,080 --> 01:13:39,030 Abhay Vasant Ashtekar: To take you to share the session because he has a class to teach. Let me see what 562 01:13:41,310 --> 01:13:46,620 Abhay Vasant Ashtekar: Participate right. I think it should die as a question. So does a comment or question. Thanks. 563 01:13:48,330 --> 01:14:02,940 Suddhasattwa Brahma: So kinds of a nice presentation. So my question is very related to this to this relating the last to the shift like you know you introduce this cost cosine function or not. So the first question is, if you do not include that cosine in that relationship. 564 01:14:03,960 --> 01:14:11,130 Suddhasattwa Brahma: Does that affect your equations of motion. Does that affect the square root factor that comes in. Later on, which excludes part of your space for the backend system. 565 01:14:12,270 --> 01:14:19,530 Edward Wilson-Ewing (UNB): Okay, so it doesn't affect the equations emotion. But what it does do is that it affects the metric that you extract afterwards. 566 01:14:21,540 --> 01:14:23,940 Edward Wilson-Ewing (UNB): Because, of course, to know the metric you need to know what the shift. 567 01:14:23,940 --> 01:14:24,480 Edward Wilson-Ewing (UNB): Vector is 568 01:14:25,170 --> 01:14:25,770 Suddhasattwa Brahma: Yeah, that's 569 01:14:26,880 --> 01:14:28,890 Suddhasattwa Brahma: The metric in a way that this region is not 570 01:14:29,970 --> 01:14:35,070 Edward Wilson-Ewing (UNB): Right. So what happens actually is a little bit surprising if you just put in 571 01:14:36,330 --> 01:14:45,480 Edward Wilson-Ewing (UNB): The sign but term by itself without the cosine, you just end up there's there's some cancellation that happens in unit back with the classical solution. 572 01:14:48,060 --> 01:14:54,990 Edward Wilson-Ewing (UNB): So that there's certainly some ambiguity, what you want to do there. But if you make the choice of 573 01:14:56,490 --> 01:15:03,450 Edward Wilson-Ewing (UNB): Of just sign of, you know, square delta be horror x divided by that. 574 01:15:04,620 --> 01:15:06,420 Edward Wilson-Ewing (UNB): Then you just get back the classical solution. 575 01:15:07,320 --> 01:15:09,450 Abhay Vasant Ashtekar: But how can I get back to classical solution because 576 01:15:10,470 --> 01:15:12,210 Edward Wilson-Ewing (UNB): There's some cancellations. That happened. 577 01:15:12,750 --> 01:15:15,840 Abhay Vasant Ashtekar: So, so all the delta goes away everything else. 578 01:15:16,230 --> 01:15:17,550 Abhay Vasant Ashtekar: Yeah, it is. 579 01:15:18,090 --> 01:15:20,040 Edward Wilson-Ewing (UNB): It's a little surprising. Yeah. 580 01:15:20,700 --> 01:15:22,410 Abhay Vasant Ashtekar: It's not surprising be shocking. 581 01:15:24,630 --> 01:15:24,930 Abhay Vasant Ashtekar: Okay. 582 01:15:27,450 --> 01:15:29,580 Abhay Vasant Ashtekar: Let's see. I think this has a question. 583 01:15:31,350 --> 01:15:31,620 Abhay Vasant Ashtekar: Right. 584 01:15:32,490 --> 01:15:34,110 Suddhasattwa Brahma: Yeah, I'm trying to lower my hand. 585 01:15:34,140 --> 01:15:34,380 Yes. 586 01:15:37,020 --> 01:15:38,430 Johannes Münch: Yes, I have another question. 587 01:15:39,090 --> 01:15:39,390 Please. 588 01:15:40,650 --> 01:15:51,720 Johannes Münch: So this x. So you have this metro space time and you have this exterior non metro space time and the exterior space time has a column horizon. That's right. 589 01:15:53,220 --> 01:15:53,820 Edward Wilson-Ewing (UNB): Um, 590 01:15:56,310 --> 01:15:56,940 Edward Wilson-Ewing (UNB): So, 591 01:15:58,050 --> 01:15:59,940 Edward Wilson-Ewing (UNB): Do you mean the enterprise or the horizon. 592 01:16:01,050 --> 01:16:01,440 Johannes Münch: Outer 593 01:16:02,340 --> 01:16:06,930 Edward Wilson-Ewing (UNB): Right. So this is just the usual outer horizon. That's essentially at the short short radius. 594 01:16:08,490 --> 01:16:10,620 Edward Wilson-Ewing (UNB): Plus some very small quantum gravity affects that we can 595 01:16:10,620 --> 01:16:11,220 Edward Wilson-Ewing (UNB): Neglect here. 596 01:16:11,970 --> 01:16:17,040 Johannes Münch: So, so some little bit more about the fact because because if you just 597 01:16:18,090 --> 01:16:27,840 Johannes Münch: Think about the exterior space time basically the horizon should be a causal horizon and once you met I came across this causal arising never can come back. Right. 598 01:16:28,290 --> 01:16:29,880 Edward Wilson-Ewing (UNB): So if you remember for for 599 01:16:29,910 --> 01:16:31,200 Edward Wilson-Ewing (UNB): For a test field. That's true. 600 01:16:32,220 --> 01:16:46,110 Edward Wilson-Ewing (UNB): But if you have matter which is back reacting, then that's. And again, remember that the equations emotion here, not the equations emotional GR so the the intuition developed in GR just isn't 601 01:16:47,280 --> 01:16:53,670 Edward Wilson-Ewing (UNB): Clickable stuff. So, it is true that if you have a causal horizon and you have a test particle, then it'll never come back up. 602 01:16:54,780 --> 01:16:58,830 Edward Wilson-Ewing (UNB): But here we have a matter of field which is very much back reacting on the geometry. 603 01:17:01,020 --> 01:17:11,100 Johannes Münch: Yeah. Yes. I'm not completely sure about this because there wasn't a paper on black hole collapsed by boy. Well done to other collaborators, I 604 01:17:11,730 --> 01:17:22,470 Johannes Münch: Forgot fortunately in 2004 or six or something around this where they actually counted the same problem that they had a space site or they had matter which was bouncing 605 01:17:23,040 --> 01:17:39,360 Johannes Münch: But they were not able to describe how the bounce proceeds. Once you reach the horizon again. So you're personalizing your bounce and then you reach it again. And then I was not sure how they were not sure how to proceed afterwards and 606 01:17:40,380 --> 01:17:51,450 Edward Wilson-Ewing (UNB): Right. So I'd have to check that paper and detailed to to fully answer that. But here I mean we do know how to proceed, because we have these equations emotion here. 607 01:17:52,650 --> 01:18:02,280 Edward Wilson-Ewing (UNB): So the, the only question is, we have to solve them, which of course is easier said than done. I mean, these are quite complicated. Especially if you have some sort of discontinuity. 608 01:18:03,720 --> 01:18:07,860 Edward Wilson-Ewing (UNB): So in principle we know to do in practice. We're working on it. 609 01:18:10,140 --> 01:18:17,640 Edward Wilson-Ewing (UNB): But the point here is that it's absolutely true that if you have a test particle once it passes the horizon. It's not coming back. 610 01:18:18,660 --> 01:18:21,870 Edward Wilson-Ewing (UNB): But here you have a matter of field which is very much backtracking on the geometry. 611 01:18:22,890 --> 01:18:27,990 Edward Wilson-Ewing (UNB): And furthermore, not according time science equations right these are modified 612 01:18:29,550 --> 01:18:32,100 Johannes Münch: Yes, but but still you have the effective 613 01:18:33,210 --> 01:18:39,840 Johannes Münch: FaceTime, which on the line. Yeah. Like, like the mathematics of differential geometry, so on. 614 01:18:41,070 --> 01:18:48,240 Johannes Münch: And so I'm not sure if it's really a thing of the equation of more human. Rather, the notional causal writing things like this. 615 01:18:48,990 --> 01:19:06,060 Abhay Vasant Ashtekar: So let me just rephrase what you on this is saying and see if this makes sense to you so you only see saying that, well, but I mean you if in fact you're saying that there is a giving horizon. So there's another vector field. And there's a killing horizon. Right. 616 01:19:07,140 --> 01:19:09,180 Abhay Vasant Ashtekar: So it's, it's a standard sure to it. 617 01:19:10,590 --> 01:19:24,900 Abhay Vasant Ashtekar: And then the the killing records tangential to the know service, then the statement, he's saying is that, then whatever is inside just by causally because you're gonna you're gonna metric here and the causal structure of that metric would be such that 618 01:19:26,070 --> 01:19:28,260 Abhay Vasant Ashtekar: Whatever is sort of on the one side 619 01:19:29,280 --> 01:19:30,630 Abhay Vasant Ashtekar: Could never get out 620 01:19:31,620 --> 01:19:36,450 Edward Wilson-Ewing (UNB): Okay, I'm here. I think I should be careful when I speak of 621 01:19:37,530 --> 01:19:40,290 Edward Wilson-Ewing (UNB): This powder horizon, hear me and apparent horizon. 622 01:19:41,430 --> 01:19:44,550 Edward Wilson-Ewing (UNB): We don't have a killing vector because this is a dynamical space time 623 01:19:46,260 --> 01:19:48,090 Abhay Vasant Ashtekar: Why is it that it's outside the matter it 624 01:19:48,570 --> 01:19:54,960 Edward Wilson-Ewing (UNB): Well, the matter of strengths that say out here right amount of stress very far out collapses in and then eventually bounces back in 625 01:19:55,260 --> 01:20:00,000 Abhay Vasant Ashtekar: I think people got interested in the picture that you have here, which is that, well, the matter is actually collapsed in 626 01:20:00,630 --> 01:20:01,080 Abhay Vasant Ashtekar: And then 627 01:20:01,470 --> 01:20:06,540 Abhay Vasant Ashtekar: Then is there that out the horizon is still there. If. What's the matter is actually 628 01:20:07,590 --> 01:20:17,160 Abhay Vasant Ashtekar: collapsed in and if there is out of horizon there then just by cause of structure if it is a minus, plus, plus, plus signature metric. And there's a closet structure, then whatever is so to say inside 629 01:20:18,570 --> 01:20:29,430 Abhay Vasant Ashtekar: It would mean, is this like an adequate right i mean what it is you cannot tell drivers that boundary. So that is this question. So I don't think it has to do with the equations of butchering, this is 630 01:20:29,610 --> 01:20:30,750 Carlo Rovelli: It cannot pick 631 01:20:31,350 --> 01:20:45,510 Edward Wilson-Ewing (UNB): Yeah, I mean, let me just say something, I'll let Carla jump in. After but here again I agree that if you have a test particle once it passes your outer horizon is not coming back. There's no question about that. It's when you have 632 01:20:47,370 --> 01:20:52,920 Edward Wilson-Ewing (UNB): A minor field which is back reacting on the geometry and then your geometry can change. 633 01:20:54,690 --> 01:20:59,070 Edward Wilson-Ewing (UNB): And then it will be able to to come back out. 634 01:21:00,810 --> 01:21:02,130 Edward Wilson-Ewing (UNB): Sorry, Carla. You want to say something. 635 01:21:03,420 --> 01:21:18,840 Carlo Rovelli: Yes, something along these lines. The, the, what you said is correct. I think what am I saying is that if you just look a little bit outside X outer just on an outside this if you assume that you are in in 636 01:21:21,000 --> 01:21:23,070 Carlo Rovelli: In the classical fully in the classical 637 01:21:24,660 --> 01:21:28,200 Carlo Rovelli: Approximation, then there's no way to to to 638 01:21:30,120 --> 01:21:39,240 Carlo Rovelli: I mean the outside parties counseling closed. There's nothing that can come in. But I think the point is that your patients here my violate the classical artists and equations one 639 01:21:39,480 --> 01:21:40,080 I don't even 640 01:21:41,100 --> 01:21:45,330 Abhay Vasant Ashtekar: Know, no. But there's nothing to the eastern equation it is just different to john because he was saying. 641 01:21:45,750 --> 01:21:57,210 Carlo Rovelli: No, no, but yeah. By then, then the then, the point is, what is not a spacetime on weekdays a dynamic because it's a dynamic space time itself. So it's a it's going to change according to 642 01:21:57,210 --> 01:22:00,150 Abhay Vasant Ashtekar: Show. So it just the diagram is misleading. That's all. 643 01:22:00,660 --> 01:22:01,830 Carlo Rovelli: Yeah yeah yeah 644 01:22:03,480 --> 01:22:04,020 Abhay Vasant Ashtekar: He's a little bit 645 01:22:04,230 --> 01:22:17,130 Carlo Rovelli: If one if one if one reads status as right as a council structure on which the star is expanding stories is moving, then it doesn't work, but that's 646 01:22:17,220 --> 01:22:18,360 Carlo Rovelli: I think we shouldn't blow ready 647 01:22:19,260 --> 01:22:21,750 Edward Wilson-Ewing (UNB): Here. Sorry. The late calls really meant just for test particles. 648 01:22:23,160 --> 01:22:23,430 Abhay Vasant Ashtekar: So, 649 01:22:23,880 --> 01:22:25,050 Edward Wilson-Ewing (UNB): This instance of time. 650 01:22:27,270 --> 01:22:31,740 Abhay Vasant Ashtekar: Because the light goes, I'm not. They don't refer to it as particles like guns. I just like guns. 651 01:22:34,050 --> 01:22:38,520 Abhay Vasant Ashtekar: Though I think the statement is basically that this is going to be 652 01:22:39,930 --> 01:22:46,140 Abhay Vasant Ashtekar: Probably an isolated horizon for a little while because you know the matter is inside all the way that you're drawing here. 653 01:22:47,790 --> 01:22:49,920 Abhay Vasant Ashtekar: But then the statement is a mattress coming out. 654 01:22:52,050 --> 01:22:52,470 Abhay Vasant Ashtekar: And before 655 01:22:52,710 --> 01:22:52,980 Edward Wilson-Ewing (UNB): I mean, 656 01:22:55,980 --> 01:22:56,370 Abhay Vasant Ashtekar: Sorry. 657 01:22:57,210 --> 01:23:03,360 Abhay Vasant Ashtekar: Yes. Like, like, like the white space time. Is it going to be in fact that the is going to be 658 01:23:04,740 --> 01:23:09,780 Abhay Vasant Ashtekar: So you aren't as it's going to be now for a little while, but the statement is that the end matter is going to come out. 659 01:23:09,960 --> 01:23:13,650 Abhay Vasant Ashtekar: Yeah, it comes out the matter comes out and then it becomes a 660 01:23:15,390 --> 01:23:29,610 Abhay Vasant Ashtekar: Dynamical horizon, and that is why there is a good chance that scribe will be complete and salsa. So this picture up here is is this is not incorrect busy misleading in the sense that at this is our time, it is true that there is something now. 661 01:23:31,020 --> 01:23:32,970 Edward Wilson-Ewing (UNB): If you prefer that this is 662 01:23:33,090 --> 01:23:34,740 Edward Wilson-Ewing (UNB): What it looks like an instance of time. 663 01:23:35,040 --> 01:23:37,560 Edward Wilson-Ewing (UNB): Exactly. And as time evolves. This will change. 664 01:23:37,860 --> 01:23:45,900 Abhay Vasant Ashtekar: Exactly. And it changes qualitatively. What's the matter comes out when it becomes dynamic, is that okay yeah honest because if you're done, then where to go to the next question. 665 01:23:46,440 --> 01:23:49,440 Johannes Münch: Yes, thank you. All right. 666 01:23:50,250 --> 01:23:53,310 Abhay Vasant Ashtekar: I think Danny Lee has a question or comment. Yeah. 667 01:23:53,340 --> 01:24:00,840 Daniele Pranzetti: Hi ahead, I'm sorry. I missed the first for me. So maybe you said this, but I just went on this and be better how you derive your effect of equations because 668 01:24:01,470 --> 01:24:12,450 Daniele Pranzetti: I seen derivatives there. So it seems to me you're taking some parameters to zero or mean some discrete skills to zero or how can the relative 669 01:24:13,290 --> 01:24:15,120 Edward Wilson-Ewing (UNB): Right, so here 670 01:24:17,160 --> 01:24:23,070 Edward Wilson-Ewing (UNB): What I did is I just look at circle symmetry. So, of course, there's some x dependence right some real dependence. 671 01:24:24,510 --> 01:24:33,000 Edward Wilson-Ewing (UNB): And I'm not looking only at the inside. I'm looking at the full space time with both the interior of the horizon and the exterior 672 01:24:34,170 --> 01:24:36,120 Edward Wilson-Ewing (UNB): And after that I gauge fixed 673 01:24:37,320 --> 01:24:44,040 Edward Wilson-Ewing (UNB): So, and by gage fixing here. I mean specifically setting this term here to be x squared. 674 01:24:45,330 --> 01:24:48,360 Edward Wilson-Ewing (UNB): And then after that I include the whole on me corrections. 675 01:24:49,860 --> 01:24:51,360 Edward Wilson-Ewing (UNB): I'm not sure if that answers your question. 676 01:24:51,960 --> 01:24:56,820 Daniele Pranzetti: I mean, because usually every derivatives in the classical myth thing becomes a discrete 677 01:24:57,120 --> 01:24:58,350 Abhay Vasant Ashtekar: Different. No, no, no. 678 01:24:59,100 --> 01:25:12,240 Edward Wilson-Ewing (UNB): I'm remaining at the effect of level here so I haven't. So you're right. The next step that I would do, which we haven't done here. But what the next step would be to them to securitize and then define the quantum theory and lattice. 679 01:25:12,900 --> 01:25:16,350 Daniele Pranzetti: Okay, so there's some direction, basically you're taking this continuous in some so this 680 01:25:18,270 --> 01:25:20,790 Edward Wilson-Ewing (UNB): Is not one treating all of the directions is continuous. 681 01:25:22,530 --> 01:25:26,640 Edward Wilson-Ewing (UNB): But anyway, yeah, at the quantum level, I would have to, you know, introduce a lattice. 682 01:25:28,650 --> 01:25:37,920 Daniele Pranzetti: So yep only one squeaked in a parameter in this game, you're seeing or these are the only one delta, not like a date on this fear there is no delta, there is no grass. 683 01:25:38,460 --> 01:25:42,000 Edward Wilson-Ewing (UNB): That's right, because of the gauge fixing that have done now. 684 01:25:42,030 --> 01:25:43,680 Abhay Vasant Ashtekar: I think there's confusion at a 685 01:25:45,210 --> 01:25:55,170 Abhay Vasant Ashtekar: Minus, minus three level, so to say. So these are the 50 questions a lot. Look, Congress biology, for example, right. So it's not that one is actually taking some 686 01:25:56,130 --> 01:26:10,140 Abhay Vasant Ashtekar: One is not he is not doing like things that various people like are doing when they're coming from Luke condom guy with you to do Congress Margie by introducing some some some state there and some code and states and discreet state and then 687 01:26:10,170 --> 01:26:10,530 Edward Wilson-Ewing (UNB): I read 688 01:26:10,770 --> 01:26:18,450 Abhay Vasant Ashtekar: The market. So he's not doing that at all. So the statement is this is really proceeding as in look Congress mythology in which you first have just 689 01:26:19,020 --> 01:26:30,000 Abhay Vasant Ashtekar: The medicine, this, this, this really super space right of the where everything just depends on our so it gets particular symmetric media super space and one just start from there. One doesn't try to come 690 01:26:30,570 --> 01:26:38,340 Abhay Vasant Ashtekar: This quantization from a flow theory and therefore everything is continuous from the beginning, the effective date and an end date. Yeah. 691 01:26:38,400 --> 01:26:45,300 Edward Wilson-Ewing (UNB): That's right. And of course, I mean an interesting open problem would be to see how to do that to start from the full theory and then come down. 692 01:26:46,440 --> 01:26:57,750 Daniele Pranzetti: Okay, but also even from that point of view, you still recent like in your model by your true discrete as parameters. Right. Also on the sphere, even though you you down the road from the food theory. 693 01:26:58,650 --> 01:27:00,690 Edward Wilson-Ewing (UNB): So it sounds to what you mean the to the screeners 694 01:27:01,020 --> 01:27:07,830 Daniele Pranzetti: Me like there is the Epson Epson next if you want an extra associated to links on the sphere and act transistor radio links. 695 01:27:08,070 --> 01:27:09,120 Abhay Vasant Ashtekar: That are links. 696 01:27:09,540 --> 01:27:13,440 Daniele Pranzetti: Yeah, but I mean the justification for introducing the parameters. 697 01:27:13,530 --> 01:27:21,030 Edward Wilson-Ewing (UNB): So, so here what happens is that because of the gauge fixing. I only have to take his enemies in the angular directions. 698 01:27:21,330 --> 01:27:25,200 Daniele Pranzetti: Okay, so it's like taking the other option to zero best really kind of 699 01:27:25,440 --> 01:27:35,580 Edward Wilson-Ewing (UNB): I'm not really because because of the gauge fixing the connection in the real direction is then rewritten in terms of the connection and the aerial directions are in the angular directions. 700 01:27:36,930 --> 01:27:38,820 Edward Wilson-Ewing (UNB): So there's there's some mixing here. 701 01:27:41,040 --> 01:27:44,850 Daniele Pranzetti: Okay, so you only have one parameter that determines that is quickness. 702 01:27:44,940 --> 01:27:49,980 Edward Wilson-Ewing (UNB): That's right, basically. Yeah. And that's essentially what we set to 703 01:27:51,030 --> 01:27:54,750 Edward Wilson-Ewing (UNB): That we set that physical length to be equal to the square where the recap. 704 01:27:56,880 --> 01:28:01,320 Edward Wilson-Ewing (UNB): Okay, so. So again, I mean, this is very much following he LTC 705 01:28:02,370 --> 01:28:06,990 Abhay Vasant Ashtekar: Is best. Not a thing. It doesn't this cretinous but just to think of there was constant calamitous nondescript this 706 01:28:07,020 --> 01:28:07,440 Yeah yeah 707 01:28:08,580 --> 01:28:11,160 Daniele Pranzetti: But so you have only one on one, two parameters. 708 01:28:11,190 --> 01:28:12,330 Edward Wilson-Ewing (UNB): That's right, yeah. 709 01:28:14,490 --> 01:28:16,320 Abhay Vasant Ashtekar: Okay Kong Zang has a question. 710 01:28:19,020 --> 01:28:22,110 Cong Zhang: Yes, I just have a small question about 711 01:28:22,110 --> 01:28:33,240 Cong Zhang: This minimal value of this x. So here, your explanation about this minimum value is data. So this minimal value is the end of the vacuum solution. 712 01:28:33,720 --> 01:28:50,880 Cong Zhang: So my question is, it is possible that here you have this minimum value of x, just because that this x is not a GU to coordinate in your effective space time which cannot cover the whole space time 713 01:28:52,290 --> 01:29:00,000 Edward Wilson-Ewing (UNB): I mean, that's certainly a possibility in general. And then this is what both Carlo and Johan us were suggesting earlier and 714 01:29:01,380 --> 01:29:16,710 Edward Wilson-Ewing (UNB): At first, that something that's truly worth looking into. But from at least my point of view, the fact that when we add in matter we get rid of that issue completely to me suggests that this is more a question of trying to 715 01:29:17,850 --> 01:29:25,260 Edward Wilson-Ewing (UNB): You know, treat has vacuum of space time where you really should have some matter content. So the fact that it goes away so nicely. 716 01:29:25,980 --> 01:29:40,800 Edward Wilson-Ewing (UNB): When you add in a matter of field to me suggests that this is really just an artifact of, you know, looking only the vacuum case when you add in matter, then this, this goes away. But I agree that a priori, that could be a possibility. Absolutely. 717 01:29:42,600 --> 01:29:45,420 Cong Zhang: OK. OK, I see. Thank you. Thank you, you 718 01:29:47,370 --> 01:29:48,900 Johannes Münch: Have a comment on this. 719 01:29:50,490 --> 01:29:50,790 Abhay Vasant Ashtekar: Guy. 720 01:29:52,530 --> 01:29:59,040 Johannes Münch: And I think in the so I think it's not really a matter, matter of matter on me because 721 01:29:59,550 --> 01:30:13,080 Johannes Münch: I think in the moment where you go to the young, the bounce and you have increasing x. Again, you essentially implicitly assume that your, your white hole in quotation marks branch is essentially the same one as the black hole branch. 722 01:30:13,500 --> 01:30:14,160 You know, it's nothing. 723 01:30:16,080 --> 01:30:22,110 Edward Wilson-Ewing (UNB): Because it's moving up much more slowly, it collapses in a timescale. That's essentially the mass 724 01:30:23,220 --> 01:30:26,880 Edward Wilson-Ewing (UNB): And the expansion as is slower, right, sorry. 725 01:30:27,420 --> 01:30:32,520 Johannes Münch: That's the metric timescale, I'm just talking about the solution outside the matter. 726 01:30:33,630 --> 01:30:34,140 Carlo Rovelli: I think 727 01:30:34,380 --> 01:30:34,980 Carlo Rovelli: The solution. 728 01:30:35,490 --> 01:30:36,570 Edward Wilson-Ewing (UNB): The matter is stationary 729 01:30:39,300 --> 01:30:40,410 Yes, but but 730 01:30:43,770 --> 01:30:45,630 Johannes Münch: It's hard to explain. Okay. 731 01:30:46,230 --> 01:30:46,530 Edward Wilson-Ewing (UNB): Go ahead. 732 01:30:49,560 --> 01:30:57,390 Johannes Münch: So I think at the moment you you go beyond the minimum value because if you think about postcard diagrams, you essentially have to 733 01:30:58,230 --> 01:31:09,120 Johannes Münch: So you can write down to the collapse of the classical black hole is drawing a shorter course Costco diagram and then draw the line of matter in this diagram right and 734 01:31:10,620 --> 01:31:14,970 Johannes Münch: So, so your exterior space time is only valid up to this dynamic line of 735 01:31:16,860 --> 01:31:29,100 Johannes Münch: The outermost shell of your columns. Right. And in the moment it hits the singularity, or in your case that the minimal value. That should be the the singularity. Yes, so that the 736 01:31:29,850 --> 01:31:46,290 Johannes Münch: Time like surface which classically is the singularity, but it's now your, your minimal value this X Men. And then the question is how you proceed. And I think you just implicitly just mimic the same exterior space time 737 01:31:50,760 --> 01:31:53,220 Johannes Münch: Can you follow roughly what I'm trying to say. 738 01:31:53,310 --> 01:32:05,430 Edward Wilson-Ewing (UNB): Um, well, let me, let me try to tell me if my answer is not for my answer your question, but so what we have is that we have me. Can we just go back here. 739 01:32:08,400 --> 01:32:11,730 Edward Wilson-Ewing (UNB): We have these equations emotion and we have 740 01:32:12,960 --> 01:32:21,990 Edward Wilson-Ewing (UNB): Our hardest field and we can just solve these equations emotion. Right. So, what, what I do is I say, I'll give you some initial conditions. 741 01:32:22,470 --> 01:32:35,370 Edward Wilson-Ewing (UNB): Right, have a star that has some radius. And that's vacuum outside. So these are my initial conditions and then I just let the system evolve using these equations emotion. 742 01:32:37,020 --> 01:32:41,010 Edward Wilson-Ewing (UNB): And what happens is that the star will contract. 743 01:32:42,210 --> 01:32:47,400 Edward Wilson-Ewing (UNB): It will reach some minimum value and then we'll bounce and it'll come back out again. 744 01:32:49,470 --> 01:32:59,070 Edward Wilson-Ewing (UNB): Now the equations emotion are easy to solve for the contract in part because the edge effects are negligible and you can throw them away. 745 01:33:00,270 --> 01:33:04,380 Edward Wilson-Ewing (UNB): For the expanding case, it's much harder solve. And so we're working on that right now. 746 01:33:05,820 --> 01:33:16,770 Edward Wilson-Ewing (UNB): But this is very much just a question of right we have some equations, emotional, we can solve them. And then from once we've solved equations emotion, then we can reconstruct the space time 747 01:33:19,050 --> 01:33:20,010 Yes. Okay. 748 01:33:22,950 --> 01:33:24,930 Johannes Münch: So, so if you think about it, but 749 01:33:26,340 --> 01:33:41,130 Johannes Münch: I'm not sure if it's really to to summarize my comment I'm not really sure if you can avoid this. The second branch of all these white, black and white for solutions by just adding metal finishing my calling. But I have to study your, your, your work in more detail to understand 750 01:33:42,870 --> 01:33:49,110 Edward Wilson-Ewing (UNB): Thank you. No problem. If there's something that you know you think is worth discussing, please let me know. 751 01:33:50,310 --> 01:33:51,390 Abhay Vasant Ashtekar: Okay, just go. 752 01:33:52,770 --> 01:34:05,790 Francesca Vidotto: I have a question regarding the expanding face so you know that this is an ongoing work. So probably you don't have it yet an answer, but I just wanted to put something on the table to think about maybe for the future. 753 01:34:06,510 --> 01:34:19,140 Francesca Vidotto: So when thinking about expanding face. We had a lot of discussions with the people in Murray, the like he's been in general versa longer I and so on. And he brought his word about the fact that 754 01:34:20,520 --> 01:34:30,990 Francesca Vidotto: It's very important to know what is the speed of the expansion and it will be preferable to have a very quick especial rather than this low one because we, the 755 01:34:32,040 --> 01:34:41,190 Francesca Vidotto: For this function is not fast enough, then there is the problem of a possible recall apps. So any stability of the day. Wait, old face. 756 01:34:42,540 --> 01:34:53,640 Francesca Vidotto: On your face, whatever you want to call it. So I always think about this expanding face as being a dynamic of processing which have also the mantle be taken into account. 757 01:34:54,780 --> 01:35:10,830 Francesca Vidotto: So these changes a lot to the the picture. So usually when all these instability arguments are discussing that nobody's discussing the fact that that, in fact, if you have an expansion. There is a lot of math of that coming out. 758 01:35:11,640 --> 01:35:20,910 Francesca Vidotto: From the riser. So yeah, maybe two things to think about. One is the speed in general and they're all of matter. Yeah. 759 01:35:21,060 --> 01:35:29,880 Edward Wilson-Ewing (UNB): I agree with both of those points. Um, and, but let me just add to that, there are usually there are two differences, I think. 760 01:35:30,360 --> 01:35:34,650 Edward Wilson-Ewing (UNB): In in what we're doing and the usual calculations for these white hole instabilities 761 01:35:35,430 --> 01:35:45,210 Edward Wilson-Ewing (UNB): The first one is you say is that matter. Right. That's a big difference. And the second one is that usually when they talk about this white hole instability. It's a true white holes FaceTime 762 01:35:45,570 --> 01:35:55,020 Edward Wilson-Ewing (UNB): And here, that's not exactly what we have right we have, you know, some region which which is trapped at least for some period of time and then another region which is anti trap. So there are some differences. 763 01:35:55,920 --> 01:36:02,670 Edward Wilson-Ewing (UNB): And how these all combine. I'm not sure yet. But yes, this is certainly something that we're looking at. 764 01:36:06,990 --> 01:36:11,100 Abhay Vasant Ashtekar: Okay, so God Moses, the Lord is had anybody else has any questions or comments. 765 01:36:14,730 --> 01:36:15,900 Abhay Vasant Ashtekar: Yeah. JOHN Jonathan 766 01:36:16,530 --> 01:36:22,560 Jonathan Engle: Yes, so maybe this is a very simple question. Um, since you have a model of 767 01:36:23,640 --> 01:36:25,890 Jonathan Engle: Oh, I see. I think I've answered my own question. I was wondering why 768 01:36:25,890 --> 01:36:27,300 Jonathan Engle: Don't see any Hawking radiation. 769 01:36:27,720 --> 01:36:37,830 Jonathan Engle: So, the better. But I guess the point is that you're just using effective equation. So you're really treating the matter quantum mechanically, but I mean it would be interesting. One could also see Hawking radiation in a model like this, but that's 770 01:36:38,430 --> 01:36:40,560 Edward Wilson-Ewing (UNB): Probably not. Yeah, I would love to do that. 771 01:36:40,590 --> 01:36:41,460 Jonathan Engle: Yes, yeah. 772 01:36:41,550 --> 01:36:42,240 Edward Wilson-Ewing (UNB): I don't have to 773 01:36:45,330 --> 01:36:45,690 Jonathan Engle: Talk. 774 01:36:46,230 --> 01:36:47,640 Edward Wilson-Ewing (UNB): Thank you so 775 01:36:48,300 --> 01:36:48,750 Good. 776 01:36:51,270 --> 01:36:52,680 Abhay Vasant Ashtekar: Good Jonathan, you're done. Right. 777 01:36:54,150 --> 01:36:55,140 Jonathan Engle: Yeah. Yes. 778 01:36:55,710 --> 01:36:56,790 Abhay Vasant Ashtekar: Okay, you can move the hand. 779 01:36:57,690 --> 01:36:57,900 Abhay Vasant Ashtekar: Yes. 780 01:36:57,990 --> 01:36:58,800 Very quick 781 01:36:59,850 --> 01:37:00,810 Abhay Vasant Ashtekar: Okay punches. 782 01:37:02,730 --> 01:37:05,250 Francesca Vidotto: And follow up with that in order to study. 783 01:37:06,540 --> 01:37:09,150 Francesca Vidotto: Okay, you may want to check the work of 784 01:37:11,280 --> 01:37:19,830 Francesca Vidotto: Get into. So look at this, the treatment is a classical one. So it should be applicable to what you are doing. 785 01:37:20,370 --> 01:37:21,480 Edward Wilson-Ewing (UNB): Okay, I'll take a look at that. Thank you. 786 01:37:24,600 --> 01:37:34,110 Abhay Vasant Ashtekar: But I mean that is basically patching white space times. So I think you could pass the space time to she wanted but 787 01:37:35,280 --> 01:37:42,510 Abhay Vasant Ashtekar: could not do scale of field. Is it just completely difficult in sort of classical scale of field is sort of the scale of field collapses for the 788 01:37:43,680 --> 01:37:44,550 Abhay Vasant Ashtekar: Does collapse. 789 01:37:45,090 --> 01:37:53,970 Edward Wilson-Ewing (UNB): Right. So that's something I'm thinking about, um, I, I don't have an answer yet because I haven't gotten very far with this, but this is definitely something that's on my plate. 790 01:37:55,050 --> 01:37:59,220 Abhay Vasant Ashtekar: Because that would then also, you know, in some sense, the natural part to the Hawking. 791 01:37:59,760 --> 01:38:01,380 Abhay Vasant Ashtekar: Radius. Right. Absolutely. 792 01:38:01,770 --> 01:38:06,510 Abhay Vasant Ashtekar: And also, anyway. I mean, that's the fundamental level, we shouldn't be talking about so that 793 01:38:08,070 --> 01:38:12,060 Abhay Vasant Ashtekar: And just to sort of summarize. I mean, you know, of course, you arrived at this particular 794 01:38:14,130 --> 01:38:26,730 Abhay Vasant Ashtekar: Calculations falling seven steps in some ways I mean you want you to do the first the vacuum case. And then you realize that somehow there is a issue. And then that issue sort of naturally led you to look at the 795 01:38:27,900 --> 01:38:33,810 Abhay Vasant Ashtekar: The collapsing situation. But of course, logically, you could just forget about the first part altogether. 796 01:38:34,410 --> 01:38:41,670 Abhay Vasant Ashtekar: Absolutely, absolutely. Logically, you can just say that, well, I mean, you know, it's important is much more realistic to talk about all these things. 797 01:38:41,940 --> 01:38:53,190 Abhay Vasant Ashtekar: Not about studying black hole, but really the collapsing black hole because I know that Hawking radiation etc refers to collapse. And so what could actually just look at the collapsing backhaul and then see see what happens. 798 01:38:53,880 --> 01:38:54,330 Edward Wilson-Ewing (UNB): Absolutely. 799 01:38:55,080 --> 01:39:04,080 Abhay Vasant Ashtekar: The baby. And then from that perspective, then what will happen if we had looked at this white space times like this Martinez. 800 01:39:05,700 --> 01:39:06,810 Abhay Vasant Ashtekar: Is looking at 801 01:39:07,680 --> 01:39:08,940 Edward Wilson-Ewing (UNB): Well, I'm 802 01:39:10,200 --> 01:39:11,670 Edward Wilson-Ewing (UNB): Vida is dust is it 803 01:39:12,330 --> 01:39:14,970 Abhay Vasant Ashtekar: No, it's not like it's not it's not a strict 804 01:39:15,660 --> 01:39:18,750 Edward Wilson-Ewing (UNB): Um, I think you need a different action. 805 01:39:18,780 --> 01:39:26,010 Edward Wilson-Ewing (UNB): Because this dust is necessarily time. Like I said, I'm so I would expect that you could do it. 806 01:39:26,430 --> 01:39:27,480 Abhay Vasant Ashtekar: But yeah, because if I 807 01:39:27,480 --> 01:39:29,280 Edward Wilson-Ewing (UNB): Had to go back a few steps and the data. 808 01:39:29,520 --> 01:39:33,510 Abhay Vasant Ashtekar: Just started Einstein's equation, right. We don't have to go back to the action. This 809 01:39:34,620 --> 01:39:36,030 Abhay Vasant Ashtekar: Because, you know, after all, your okay 810 01:39:36,630 --> 01:39:39,750 Edward Wilson-Ewing (UNB): Well, the thing is, let me just mention here. 811 01:39:40,890 --> 01:39:42,750 Edward Wilson-Ewing (UNB): Here we're really using the desktop gauge 812 01:39:43,680 --> 01:39:59,910 Edward Wilson-Ewing (UNB): So we're using the dust as o'clock I that I imagined wouldn't be possible or for an oldest right so i think that you could probably adapt it, but I'm not sure. I mean, I would require a little bit of work. 813 01:40:00,900 --> 01:40:01,620 Abhay Vasant Ashtekar: That will just make 814 01:40:02,700 --> 01:40:05,670 Abhay Vasant Ashtekar: Connections with what Francesco said, Yeah. 815 01:40:07,170 --> 01:40:08,820 Abhay Vasant Ashtekar: Okay, so I don't see any further. 816 01:40:08,910 --> 01:40:11,220 Carlo Rovelli: By. Can I make a note is a known physics. 817 01:40:12,360 --> 01:40:13,050 Carlo Rovelli: Point system. 818 01:40:14,550 --> 01:40:22,590 Carlo Rovelli: In this this meeting emerged from from the older telephone one. So, so we're used to not look at one another, but I would like to 819 01:40:24,690 --> 01:40:37,770 Carlo Rovelli: Bind that video that zoom doesn't is not overcharged everybody keeps the video on and it's much more pleasant to give a talk. If you see the faces of people, so I 820 01:40:38,400 --> 01:40:46,350 Carlo Rovelli: I would invite me, of course. Everybody's free, but I would invite people to show up their faces. It's nice to see France, of course, be unmuted. But with video on 821 01:40:47,670 --> 01:40:59,610 Abhay Vasant Ashtekar: It just a lot of times, you know, the internet connection is unstable and if the video is on the question more data bank and so a lot of people like me. We keep it off, just because of the 822 01:41:00,810 --> 01:41:02,490 Abhay Vasant Ashtekar: Instability good mix. 823 01:41:03,150 --> 01:41:14,040 Carlo Rovelli: Right, right, if you have, if you have a connection problem, of course, I understand, and people may have reasons but it's, I just, you know, it's nice to see faces for those who have good connections, but 824 01:41:14,820 --> 01:41:19,320 Abhay Vasant Ashtekar: Okay, so thank you very much again and and I guess this is the 825 01:41:21,180 --> 01:41:28,650 Abhay Vasant Ashtekar: I mean, I guess we'll, we'll get get back in touch Horry and others will get back in touch, about the next meeting and topics so 826 01:41:29,940 --> 01:41:32,460 Abhay Vasant Ashtekar: Thank you everyone for all your questions and comments I 827 01:41:32,700 --> 01:41:36,690 Edward Wilson-Ewing (UNB): Was very, it was very enjoyable to to give this talk. So thank you.