Jorge Pullin: Okay. So our speaker today is for Tsultanian. We'll speak about the black hole to Whitehole transition.
Farshid Soltani: Thanks all again. Hi, everyone. I'm Fashid Sultani. I'm a Phd. Student at the University of Western Ontario.
Farshid Soltani: and today I'll talk about the status and the recent advancements in the Black to White or transition.
Farshid Soltani: The talker is divided in 3 parts. In the first one I will introduce the phenomenon of the black to whiter transition, and I will give the physical intuition behind it.
Farshid Soltani: The second part deals with the construction of an effective metric to describe the space-time.
Farshid Soltani: and in the last part that we'll analyze the quantum physics responsible for this phenomenon.
Farshid Soltani: So what we want to do with the black to whiter transition is to analyze a space-time of a black hole, taking into account the quantum gravitational effects.
Farshid Soltani: So to do this we should start from the classical space Tampa black Hole, and see where quantum radial effect are relevant there.
Farshid Soltani: So let's consider the conformal diagram reported in Slider, which describes, A black hole for the fragrational collapse.
Farshid Soltani: The star is represented in light gray, and the horizon of the black hole is represented by the dashed line.
Farshid Soltani: If you also consider semiclassical effects. We will have hoping radiation production. Outside the horizon, and this will reach future non-infinity.
Farshid Soltani: Given this! The horizon will also shrink. In time.
Farshid Soltani: in this space time
Farshid Soltani: quantum gravitational effects. Cannot be neglected in 3 separate regions, so which for simplicity, I would call regions A, B and C
Farshid Soltani: region A is the subregion. Of the interior vacuum of the black Hole. Where the curvature of space-time, which is a plankton value due to the presence of the classical curvature
Farshid Soltani: region B over. Here is the sub region surrounding the horizon at the end of the operation process.
Farshid Soltani: where the horizon which the plan can scale, and so the semiclassical approximation of hooking calculations is no longer valid. So the dynamics at this point of the horizon will be.
Farshid Soltani: yeah. Control the by quantum gravity. Finally, Regent C is the sub region in the interior of the style
Farshid Soltani: where the density of the collapsing matter becomes Planck Young.
Farshid Soltani: the physics of Region A and C has been extensively studied. The World traveler question for you.
Farshid Soltani: You yeah, get around a lot.
Jorge Pullin: If if you, if you give it, invite a talk and say, Japan, and they pay for your local accommodations. Does that mean you can't use a tourist visa, and you have some kind of work visa, that kind of work.
Farshid Soltani: What it does.
Jorge Pullin: Most places it does
Farshid Soltani: might be. I can hear. I'm trying to figure that out. It's not until
Jorge Pullin: late January. No, not not in tourists. If if you're a tourist, or if you're attending a conference, you don't need to be sound trying to figure out whether they're paying my local expenses messes that up, and
Farshid Soltani: probably your microphone is on
incident.
Jorge Pullin: I'll keep Googling. I thought you would.
Jorge Pullin: In general, I have never done that for countries like Japan. I think that's the plan. But we'll see whether we can get it fixed.
Jorge Pullin: One rare room.
Jorge Pullin: Yeah.
so on. It
Jorge Pullin: don't want to be that guy in trouble
Jorge Pullin: probably been.
Jorge Pullin: No, no, there's a lot of things happen in this sort of
Jorge Pullin: was supposed to make me host, but I think he's forgotten to do it. I can't control his mic.
Jorge Pullin: It was easy once I had it, but it wasn't.
Hal Haggard: They just try to go on. Yeah, let's try to go on, and I'll I'll keep trying to reach him. I'm sorry for this.
Farshid Soltani: Yeah, no worries alright. So, as I was saying, the physics of the quantum regions. Aac has been extensively started in the niche, both in this community and the others.
Farshid Soltani: The same is not true for the physics of Region B of the horizon at the end of the operation.
Farshid Soltani: This is not because the people are not interested in this physics, but in fact.
Farshid Soltani: in in the detail. There are a lot of works about poking information but the physics of this reason is just very difficult to analyze. So that's why there are less works of this
Farshid Soltani: hooking initial proposal for the physics of the horizon at the end of the evaporation. Now was the complete evaporation of the black hole and the disappearance of the horizon.
Farshid Soltani: While this is very problematic for different reasons. So this picture kind of stuck, and is still very used in a different works, especially in the particle physics community
Farshid Soltani: in our community. The consensus is that the
Farshid Soltani: the quantum region will be regularized. Quantum gravitational effects and space-time will continue beyond the this region.
Farshid Soltani: This quite a big picture is formalized. In the Azteca border parigigma. Where this space timer, this diagram, is not
Farshid Soltani: an actual confirm a diagram, so there is no concrete metric assigned to it just serves as a relative picture for what we expect. The
Farshid Soltani: space-time of a black hole to look like.
Farshid Soltani: so in the question.
Farshid Soltani: yeah, sure. But
Jerzy Lewandowski: so what is difference between the status of region A and the status of region? C.
Farshid Soltani: Yes.
Farshid Soltani: Major, aid.
Jerzy Lewandowski: No, no. Sorry. I wanted to ask to compare the 2 quantum regions, which means the region P. And region.
Jerzy Lewandowski: see? It seems that both of them suffer quantum properties, and they are not any longer classical.
Farshid Soltani: Yes, they. This property is the same in the 2 of them, but the physics underlying it is different. And if you see actually from the
Farshid Soltani: like calls in these 3 regions, you see that the onset of the gravitational effects are disconnected between each other, so it is fair to assume that the they can. They could be described separately.
Farshid Soltani: and then check up austerity, that the physics we get that is consistent between the 3.
Jerzy Lewandowski: Okay. But then why do you assume that the region a is any better, and it is still can be considered as classical.
Farshid Soltani: No, I don't. I will analyze all 3 of these regions.
Jerzy Lewandowski: I see. Okay, thank you.
Farshid Soltani: No worries. Thank you for the question. So
Farshid Soltani: you see, in this paradigm the quantum region integrate
Farshid Soltani: is assumed to be described by a regular quantum. Geometry and space-time can continue beyond it
Farshid Soltani: also, since also, at the end of the horizon evaporation. The the quantum physics of the horizon is regular. Space-time can continue around data, and we have a unique asymptotic region.
Farshid Soltani: The black to white or space-time. Is a concrete implementation! Of concrete magic! Inside the the paradigm! So the magic was firstly proposed in 2,015. By Harvard and Rovelli.
Farshid Soltani: and they constructed an explicit metric. Covering the full space timer, except the quantum region interact. So what they consider is collapsing. New shell of matter
Farshid Soltani: in red. In the lower part of the diagram, and the black hole interior is represented by the light grey region. Bounded by the collapsing shell. The quantum region in that gray and the dust dropping horizon!
Farshid Soltani: There is no metric describing the quantum region.
Farshid Soltani: and it is only assumed that the the quantum geometry of this region is regular, and and it interpolates between the past geometry of the black hole to our future geometry of a white hole.
Farshid Soltani: Once again. This is all done in a unique asymptotic region.
Farshid Soltani: Now the quantum physics of the horizon, as we said, is surely relevant at the end of the population process where the horizon is plaun.
Farshid Soltani: However, this is not the only option.
Farshid Soltani: A different possibility is that the the planning gravitational effects near the surrounding the horizon, which are locally neglectable, can pile up during time. And they might trigger, the transition of the horizon. Before the end of the operation process.
Farshid Soltani: This is not a necessary assumption for the black-to-water transition model.
Farshid Soltani: but it is an assumption that hacker delivery make. For simplicity.
Farshid Soltani: actually, what they do is they consider a scenario in which the quantum transition of the horizon is triggered long before the quantum, the evaporation process might have had any effect on the classical geometry
Farshid Soltani: to make this assumption. They're able to construct an explicit metric. Giving this confirmal diagram in the slide? Which solves eccentric questions.
Farshid Soltani: And I want to point out that this is a highly non-trivial result
Farshid Soltani: just by assuming the existence of a quantum region in the space time.
Farshid Soltani: All the rest of the geometry is an exact solution of classical general relativity. implementing A concrete representation of the ashtray of the paradigm.
Farshid Soltani: This result, together with the analysis of the quantum region that we performed, shortly give strong critical evidence in favor of this scenario.
Farshid Soltani: How the metric is actually constructed is well explained by these diagrams. The region numbered one. Which is in the past. Of the collapsing shell. Is a portion of Minkowski space-time. And the same is true for each of in the future of the expanding shell
Farshid Soltani: region 2 and 3 are portion, different portion of cruise, color, space, time, and Region 2 is represented by the portion in the bottom, right, figure, and region 3 in the top, right
Farshid Soltani: on all borders. Between these 4 regions the junction conditions are satisfied.
Farshid Soltani: and since the union of region 2 and 3 is localism to cruise color. This is a
Farshid Soltani: exact solution of Einstein's equations.
Farshid Soltani: Now this is the beginning of the black to auto transition. Where are we now?
Farshid Soltani: So unexpected? Metric. That improves. The Hague Valley space time was recently constructed. And as you can see here from the diagram of this geometry, while the Hague Valley space-time considered the quantum region. The 3 different quantum regions as a unique
Farshid Soltani: region which was unspecified here. The interior of the black color which correspond to region A and C
Farshid Soltani: mostly is described of an effective metric, while the only unspecified region remains rich. On B.
Farshid Soltani: This improves a lot. Our understanding of the physics of the black to white or transition, and, as you can see, this metric was also found independently from the black to white, original space time. So this also says that our study of the interior quantum geometry of a black hole is consistent with the black to white transition.
Farshid Soltani: Now.
Farshid Soltani: erez agmoni to analyze the quantum physics of region BA speed from a framework was developed, and a concrete transition amplitude for the transition of geometry was
Farshid Soltani: constructed. Now this transition amplitude is still too complex. To be analyzed. But we hope that we will be able to do it in the next years. What we were able to do is to analyze both analytically and numerically.
Farshid Soltani: erez agmoni, the spin from transition amplitude for the original habitable space-time, and I will comment on these results in the last section.
Farshid Soltani: Please complete the the introduction to the back to water transition. Now let's see how we can construct. The effective geometry that describes it.
Farshid Soltani: to get a concrete metric. We will start from a concrete classical model.
Farshid Soltani: and since the open time is not a model, is the prototypical example of a black hole formation by gravitational collapsing. We will take this model a starting point.
Farshid Soltani: and here, classically, the style is modeled as aospatially symmetric. Homogeneous! Anisotropic! Dust field! And exterior geometry is given by usual
Farshid Soltani: spy. Should geometry
Farshid Soltani: we can get back to our 3 different quantum regions. And, as I was saying before, I say, these are separate regions, because the onset of quantum variational effects in these 2 regions.
Farshid Soltani: He's a
Farshid Soltani: cultural disconnected. So instead of studying this region as a whole, we can just study them separately and then check up austerity, that the the physics we get is consistent. So we will study all these 3 separately and see what we get them.
Farshid Soltani: As I was saying, at the starter region, A. And C were studied extensively in our community, especially in the context of look, quantizations of symmetrized models.
Farshid Soltani: and we will make use of different results. That are obtained in this context. For a review of all these investigations! And all the references to this works! You can check the recent review by ashtray on meadow and see.
Farshid Soltani: So let's start the analysis of the quantum region in the inside of the star. So what we call Region C. The Castica case. Is pretty simple.
Farshid Soltani: The geometry is described by this Lander, and here, since we assumed that the matter, the collapsing matter is homogeneous and isotopic dust.
Farshid Soltani: The line element is basically the same line element of our cosmological Flrw. W. Scenario.
Farshid Soltani: The only degree of freedom is the scale factor. A.
Farshid Soltani: And we know what equations of motion it satisfies. It satisfies the Friedmann equation which we can solve. But to get
Farshid Soltani: a plot for the scale factor now in a cosmological scenario, the scale factor gives the size of the universe. In the case of this interior of the style, it just gives the size of the style. So this plot basically gives us the plot of the physical radius of the star. In time it collapses.
Farshid Soltani: as you can see in the classical theory. The star keeps collapsing indefinitely until it reaches a single point in which its physical radius goes to 0.
Farshid Soltani: Now following from the similarity reduced models. And mostly from look quantum pathology. We know that we can get an effective metric discovered in this region.
Farshid Soltani: Which takes into account the first of their corrections coming from component effects.
Farshid Soltani: The line element described in this geometry stays the same, but the Friedmann equation is modified in this way. When the parameter rho c, which is called the critical density, is a parameter of quantum nature, the dimensions of a density and
Farshid Soltani: plankton pay you
Farshid Soltani: once again, this equation can be solved to find the quantum corrected scale factor and the plot of iter is represented in orange in the diagram, so you can see how in this quantum corrected metric the physical radius of the style start by collapsing, but then it doesn't reach a single pointer which listed a minimum. Then it bounces and starts to increase
Farshid Soltani: this, of course, the usual bouncer in loop quantum cosmology.
Farshid Soltani: These techniques were applied, but were applied. In the context of the open image and the model learned recently in Kelly, Santa Cruz, and Africa.
Farshid Soltani: This gives us the physics of the integral of the style.
Farshid Soltani: Now we want to see what happens in the vacuum exterior region to the style. What we call the region. A.
Farshid Soltani: The classical case, as we said, is the usual spark shield as reported here.
Farshid Soltani: and I want to know that
Farshid Soltani: erez agmoni, in the symmetry model most of the time for the analysis of this region, the vacuum interior of Black Hole for simplicity. It's usedometry between this region and the cosmological kantos visa space time.
Farshid Soltani: This is fine when you want to study the true nature of the singularity, or a first approximation of the physics of the interior region. But in our case, when we need to study the dynamical collapse model, where we need to describe consistently the interior and exterior of the vehicle in the vacuum region.
Farshid Soltani: We cannot use this symmetry, so we need to
Farshid Soltani: remain with the standard special case and the effective metric for this geometry can be found in the same way. It was done in Cali, Santa Cruz, and Munson, having
Farshid Soltani: once again the line element stays the same. But the defining function F is gets a correction term that goes as one over R to the 4,
Farshid Soltani: and there's a capital, a parameter, which is really related to just the inverse of the critical density.
Farshid Soltani: and controls the quantum effect.
Farshid Soltani: All the quantum correction to the classical geometry are represented. Read in this slide you can see, since capital A is much smaller than the mass of the star squared
Farshid Soltani: the quantum correction outside the horizon. I will be negligible. And so in that syntactic region exterior to the black hole. The geometry is basically steep sparsion.
Farshid Soltani: However, this is not true for the interior. The interior is highly affected by this correction, and we get the culture structure, which is much more similar to the cultural structure of the interior of a charged black hole.
Farshid Soltani: You see, starting from the exterior asymptotic region to the black Hole, we can enter the outer horizon, and we find ourselves in a dropped region which is bounded an inner and outer horizon.
Farshid Soltani: If we still go inside into the inner horizon. We are in a non-trapped region where the style antibodies Bouncer.
Farshid Soltani: This is not the end of the story. We can still go in the future of it. We enter a non-tech region which is bounded by a different in another horizon.
Farshid Soltani: and then we can go out in a second asymptotically talk to each one deeper from the first one.
Farshid Soltani: Now.
Farshid Soltani: erez Agmoni, this geometry for the exterior region was, find, independently from the interior region of the style, however, it turns out that they are exactly compatible. In fact, in Lebanowski and others, and Babur and Pavlovsky, it was shown that
Farshid Soltani: the induced metric and ecstasy curvature on the boundary, on the style that from the 2 sides exactly match. In this scenario. also modern days, it would actually show that the effective metric for the exterior
Farshid Soltani: is actually the unique, staggering symmetric metric having an IP surface at the Gona killing vector field.
Farshid Soltani: That exactly satisfies the junction conditions with the ideal effectiveness of the style.
Farshid Soltani: So this concludes the analysis of the quantum model. However, we still know that we need to take into account the pitch of the horizon. In fact, as soon as hawking evaporation process is considered
Farshid Soltani: qualitatively the path of space-time. Shaded in gray here will not be a good approximation of the physics of a black hole.
Farshid Soltani: Now, one way to describe it could be to just
Farshid Soltani: erez agmoni and analyze it as we did before region A and region C, so just by using symmetry to small as an effective metric. However, to do this, we will need to account for walking radiation and its better action on the metric, and this is a very difficult calculation
Farshid Soltani: instead. What we will do is just to assume as hypothetical that what happens at the end of the evaporation process is a transitional geometry of from traffic horizon to anticipate horizon consistently what we found in the interior
Farshid Soltani: and then construct the space time of starting from this open image, neither model so to actually get a concrete metric. For a space timer
Farshid Soltani: as architecture. Valid leader, we will neglect the poking evaporation processor.
Farshid Soltani: This is not the
Farshid Soltani: because we need to do it. Focusing the space time. Just for simplicity. And even if the evaporation process could change the quantitative physics. Of the metric! It would not change the positive picture of the global spacetime. And that's what we interested in.
Farshid Soltani: So we will assume. That the transition of the horizon is together after a certain amount of time. At the about punch time here, so symbolized by these
Farshid Soltani: surface here. And we also want to get a unique asymptotic region. So we need to cut the exterior region before it reaches non-infinity, and this is done with a constant time surface over here
Farshid Soltani: next. We know that the open 9 minus 90 model is actually symmetric under the time invention with respect to the time at which the bounds happen. So we can keep this symmetry post in our space time since we are neglecting hooking the evaporation.
Farshid Soltani: So we get the a symmetric construction in the upper part of the space time.
Farshid Soltani: Now, the region we don't trust is the one bounded by the blue lines, so we can just get rid of it. And we can identify
Farshid Soltani: the 2 time surface.
Farshid Soltani: the two-time surfaces on past and future, which are isometric by construction.
Farshid Soltani: And this gets us today black to white or spacetime. And it's effective metrics. And now
Farshid Soltani: this construction seems easy when you just take lines, cut pieces of space-time and put them together. There are actually a lot of mathematical details that I will not go very into, but they can be found in the paper cited about here.
Farshid Soltani: So we now have an effective metric. That describes the full space-time of the black water transition, even the interior of the black Hole. Except the quantum region in which there is the physics of the horizon!
Farshid Soltani: I want to stress that this is not just a qualitative space-time of something. We think the space time of the black Hole might look like a. There is a concrete metric representing this.
Farshid Soltani: a question we might ask is,
Farshid Soltani: how do we trust this metric to represent the physical space-time of a black hole? So
Farshid Soltani: we should think of this metric the same way we think of the schematic of an open standard model in the classical theory, so the open name is not a model
Farshid Soltani: does not describe the quantitative physics of a black hole from the gravitational collapse. It considers matter collapsing just as a homogeneous any dust.
Farshid Soltani: and it's vaguely symmetrical, you know the purpose to rotate, so it doesn't get the quantitative picture corrected, but it is an accurate description of the qualitative physics of the
Farshid Soltani: of our collapsed information of a black hole. And so this is the same that this space time does. for the quantum gradation artifics of a blackboard.
Farshid Soltani: So we had our explicit metric
Farshid Soltani: for the Blackwater transition. Now it's time to actually analyze. The physics! Inside of region. P.
Farshid Soltani: So
Farshid Soltani: when we think of quantum geometry in general. We don't think of something that can be described with the classical concept of metric
Farshid Soltani: and racially corrected.
Farshid Soltani: However, it turns out that in very specific scenarios, like the idea of the black hole, we just studied
Farshid Soltani: the quantum geometry. One of the properties of the quantum geometry is that it is well approximated by an effective metric. So we can use the classical concept. That
Farshid Soltani: is not to say that the the quantum theory is not relevant. In this part of space-time, in fact, to get the effective medicare that satisfies effectively the page answer.
Farshid Soltani: we need to go to the quantum theory. It's just a peculiar property of the quantum geometry there.
Farshid Soltani: So one possibility
Abhay Vasant Ashtekar: could I ask a question? Yes, II think that there is a very dramatic thing about this region be
Abhay Vasant Ashtekar: if I look at the hawking radiation, if you are ignoring hawking radiation here. But if I looked at the hawking radiation.
Abhay Vasant Ashtekar: then, in fact, at this late times it is getting extremely ultraviolet.
Abhay Vasant Ashtekar: And so what is coming out of your region be
Abhay Vasant Ashtekar: to scry between these 2 you you all find you beats now
Abhay Vasant Ashtekar: is something good that is going to be
Abhay Vasant Ashtekar: tremendously quantum mechanical. So I'm not clear that this effective metric description
Abhay Vasant Ashtekar: should be valid here, so can you tell me why you
Abhay Vasant Ashtekar: I mean I can say that. Well, but that may be true, but I just see what happens that that I'm happy. But if you think that
Abhay Vasant Ashtekar: there is any reason to believe that effective metric is valid
Abhay Vasant Ashtekar: in this region which is bounded by the region B and the and then Skype Sky plus, which is, you will find New Beta.
Farshid Soltani: I would like to understand why. I mean, II think that is the deepest problem. So I would like to understand why. No, no, I agree what you said, which would be
Farshid Soltani: whatever want to say, and I will comment on this, that it's just that it's a possibility we don't know what is there? We shouldn't exclude it. But
Farshid Soltani: there's a certain possibility that the the pump in German be would be deeply want to.
Abhay Vasant Ashtekar: Okay, thank you. Yeah, we are the same name. Thank you.
Farshid Soltani: Yeah. So.
Farshid Soltani: as I was saying, one possibility is that the uneffective metric might be given there. Describe this region. But there's also another possibility, as we were just saying, that the quantum Germany there is deeply quantum, and no classical concept of metric can be given, and it doesn't make any sense.
Farshid Soltani: So to comment further on visa
Farshid Soltani: the way
Farshid Soltani: some suggestion that they could not be given any regular metric inside of vision. B. Any effective metric. And it's a different arguments. From the one I was saying. So the arguments for the non-existence of a regular metric inside of vision B. Were more
Farshid Soltani: dramatical. In the sense that you see from the left side of this region there are 2 sets of inner and outer horizons. That come into Region B, and they don't come out from the left boundary. So this means that in some way these horizons need to end inside this region.
Farshid Soltani: There were some arguments that this could not be possible. using an effective concept of metric.
Farshid Soltani: What I want to say is that it turns out that this is not true, in fact. The effective metric we constructed. For the space-time in the exterior region. B can be
Farshid Soltani: naturally and most importantly, regularly
Farshid Soltani: extended inside of the region. B, and as you can see from this diagram. This is how trapped an anti-tap region behavior. So take, for example, the trapping inner and upper horizon. So, and soon as they enter the P. Region, start to
Farshid Soltani: go towards each other, and they meet the second pointer, thus closing the truck region, which is now a compact regional space time. The same happens to the untapped up region in the future.
Farshid Soltani: and the rest of the B region is really only a non top region which serves as a sort of connection between the non top region in the interior of the backward, where the start bounces and the non dropped exterior asymptot region.
Farshid Soltani: Also, you can see from the diagram on the right how curves of custom radios behave.
Farshid Soltani: Now
Farshid Soltani: here, I'm not saying that this is an effective metric for the Be region. In fact, we have no physical motivation for it, and we are not even sure that there should be an effective metric, as we will say before, this is just a proof of concept for the possible existence of an effective metric inside this region. So there are regular metrics that describe this region. We don't know if there's physical or there should be a metric at all in this region.
Jerzy Lewandowski: A question about a question about the behavior of the are equal, constant surfaces.
Jerzy Lewandowski: so so are they killing horizons in, in, in inside this gray region.
Jerzy Lewandowski: No, no, the keeping symmetry is broken inside this region. So this
Farshid Soltani: they're not now? No?
Jerzy Lewandowski: Oh, I see. So they are like dynamical horizons.
Farshid Soltani: Yes, yes.
Jerzy Lewandowski: Umhm, okay, thank you.
Farshid Soltani: Thank you for the question.
Abhay Vasant Ashtekar: But but time like right?
Farshid Soltani: Yes, this is a true conformer diagram. So the light cone is always 45 degrees. And yeah.
Abhay Vasant Ashtekar: yeah, but I mean, Mike, my point is that it's not only region B, but everything that is causally related to Region B.
Abhay Vasant Ashtekar: We don't really know that the metric is is is going to be classical. So this is just a side remark. I just wanted to say that because the metric is not classically classical in that region, then it would not be classical in A to the future of that region, either. So I think I just wanted to mention that because we are focusing only on Region BI was making a
Abhay Vasant Ashtekar: like, you still want?
Farshid Soltani: Yeah, this is just
Farshid Soltani: what we get out of the effective equations individuals, a, M and and C, and the the metric because stuck for next year. But then this metric needs to be checked. The fields of the quantum region in B needs to be checked, and it needs to have the correct properties to get this based and out of it. There's also the possibility that quantum effects leaked in the future and all the future of the B region. And it's the quantum data is a possibility.
Abhay Vasant Ashtekar: Thank you.
Farshid Soltani: Yes.
Farshid Soltani: So in any case. even if if there is effective metric for each, and B, or it is a deep quantum region.
Farshid Soltani: This PIN from frameworker can describe it. And so let's see how we do it.
Farshid Soltani: The black-to-while metric. In the exterior of the quantum b region. Depends on 4, 3 parameters. The mass, M. Of the collapsing star
Farshid Soltani: erez agmoni the bounce time, capital T, which is related to the proper time. Experienced by a distant observer from the moment in which the black hole is formed to the moment in which the white hole disappears.
Farshid Soltani: and then 2 advanced times. The alpha and the beta that defines location and size. Of the quantum region people.
Farshid Soltani: Interestingly. the 2 parameters, MB. Alpha D. Beta. I lock up parameters. that is a local observer can study them analyzing the local geometry around him.
Farshid Soltani: However, the bounce time T
Farshid Soltani: is a global parameter, so a lot of observer cannot measure it studying the geometry around them. But it can only be studied by decent observer calculating its proper time. From the formation of the black order that the appearance of the black order
Farshid Soltani: this parameter, if you want to think about it is very similar to the radius of a cylinder. If you study the local geometry of the cylinder, you cannot see the radius. But if you study globally, the radius, you know, is a parameter of the geometry.
Farshid Soltani: So
Farshid Soltani: once we have this 4 dimensional geometry, this induces a three-dimensional geometry on the boundary of the P region. And this basically gives the initial state of the trans quantum transition of geometry and the final state.
Farshid Soltani: So this is really a standard transition of geometry calculation. So any tentative theory of quantum gravity that wants to describe the real border should be able to describe this process.
Farshid Soltani: Let's see how the spin from framework does it.
Farshid Soltani: So the state of the right spin for model for continuity is the generalized Eprl Kkl model, and it is defined on the discrete setting. So the continuum limit of spin for models is still another question. So all the calculations are done in the discrete settings. So the first thing we need to do is discretize the boundary geometry of our region.
Farshid Soltani: Erez agmoni there is no unique or really correct way to do it from a practical point of view. What you want to do is to take a discretization which is refined enough to get enough degrees of freedom of the phenomenon. But you also want that discretization which is simple enough for the transition amplitude to be computed and analyzed. So you need a balance between these 2.
Farshid Soltani: In any case, once you define a discretization, you can take its dual picture and get a graph gamma. the one for the specific geometry we got is represented in the picture.
Farshid Soltani: and the notes of the graph are represented as colored sphere. However, the details of this construction are not relevant. I will not comment on them.
Farshid Soltani: The point is, once we have the graph, gamma, we can define the space. Of spin networks. Over this graph. And this will give me the boundary, Hiba space. Of the theory in which the spin compensation, amplitude is defined
Farshid Soltani: erez Agmoni also given the graph and the discrete geometry that we have from the continuous dimensional geometry. We can then define a unique coherent state in the Banda Hub space that describes, peaked on the classical, discrete geometry we found. So this gives initial and finance data for the quantum transition.
Farshid Soltani: Once this is done, we need to get a spin form. That describe the quantum transition of geometry once again. There's no unique way to define the spin form. And it
Farshid Soltani: it comes down once again, just to a balance between refinement. To get an activities of freedom for the phenomenon and simplicity for the corporations to be manageable
Farshid Soltani: once a concrete spin form is defined. We can get the
Farshid Soltani: spin from transition amplitude right here for the phenomenon. Now the transition amplitude
Farshid Soltani: for this specific space timer was explicitly computed in the references at the top of the slide.
Farshid Soltani: Unfortunately, this is a very complicated object, and it was not possible to analyze it right away, but, as you will see in the next slide, the
Farshid Soltani: The.
Farshid Soltani: We were just able to analyze it, the the spin from for the original hug at the valley space timer. So we hope that we can. We can get to these more refined spin forms in the next year. So
Farshid Soltani: before moving on to these results. I wanted to mention. What this transition up to the actual means?
Farshid Soltani: so for the physics of Region B. What we know is that
Farshid Soltani: there might be in theory many different viable options. For what happens in region B, the black to water position is one of them. There might be others so ideally. What we want to study with this transition amplitude is the probability for the black to white organization to be realized instead of the others. This is something we don't have control over. So it's something that we cannot get with this framework.
Farshid Soltani: However, what we can get is we can restrict ourselves. To the subspace! Of black to white hole scenarios! So, as you see, there are 4 free parameters. So the black to Western transition can actually happen
Farshid Soltani: in many different ways. Depending on the values of these parameters. So we can restrict. On this start pace. And ask questions. About which one of this particular completion of parameters is most proper, more problem than the others. So this transition amplitude
Farshid Soltani: allows us to study this space of parameters. So this is a well-defined quantity
Farshid Soltani: and normalizable, and we can ask a lot of questions with it. For example, we can ask
Farshid Soltani: erez agmoni is the transition amplitude suppressed for microscopic values of the mass. M. So the transition to happen only at the end of the evaporation process, or there is a non-vanishing probability, also microscopic masses. So this transition could happen at any time.
Farshid Soltani: Erez agmoni. We can also ask, what is the probability? What is the average pounce time of this model, we can ask all possible questions regarding these parameters.
Farshid Soltani: This question rain did ask, for the speed, from transition, amplitude of the original algebra space timer and results were recently obtained. So I will comment on this.
Farshid Soltani: Hi, can I ask a quick question? Yup, sure.
Deepak Vaid: So how one of the parameters that you have is is is M. That's the mass right? Correct? So so I mean, how exactly is the mass encoded in the definition of this
Deepak Vaid: of the spin-form state.
Farshid Soltani: Yeah, the 4 dimensional geometry depends on the master. So when I get the boundary geometry of the P region, this will also depend on the master. So the value of my transition amplitude depends on the mass of this coherent state right here.
Farshid Soltani: So we get a different answer for different values of the month.
Deepak Vaid: No, I guess I guess what I'm trying to understand is that like I mean.
Deepak Vaid: if if I if I look at individual vertices in the spin form.
Deepak Vaid: or if I just look at the spin form, state independent of the background, geometry. can you assign a sense, a notion of mass to that to that graph state.
Farshid Soltani: No, the concept of mass come from the understate.
Farshid Soltani: There's been from
Farshid Soltani: describe the geometry. I don't have a way to assign a concept of mass there.
Farshid Soltani: It surely must be encoded in some way.
Farshid Soltani: I don't know how to define it from the outset. Yeah.
Deepak Vaid: okay, thank you.
Farshid Soltani: No worries.
Farshid Soltani: Alright. So
Farshid Soltani: erez agmoni the spin form for the quantum region in the space timer was constructed Velenski in 2,016, and this is the spin form they used. As you can see, it's much simpler than what the one I showed in the last slide. So this is why we were able to get
Farshid Soltani: to analyze this transition. Amplitude is also true, however, that
Farshid Soltani: this spin form needs to capture the degrees of freedom, not only of the physics of the B region. But really of the full, complete quantum region that really
Farshid Soltani: erez agmoni. So this means that a lot of degrees of freedom needs to be described by these quite simple spin form with only 2 vertices and no internal faces. So while this is fine. The
Farshid Soltani: erez agmoni that's from numbers we get out of it should just be considered as a rough idea of of what matter is, if we then will be able to analyze also more complex platforms and confirm this results. It would be a strong, a stronger analysis.
Farshid Soltani: So the analysis of this Pinfo model was initiated by Christopher and Ambrosio in 2,018, and the main results that I'm presenting here were already found. However, there were some technical details that were left open, and so these were recently taken care of in Christa. Do the office.
Farshid Soltani: What they find is that the probability for this transition to happen goes as the exponential of the negative ratio of the square, of the mass, of the collapsing, the matter, and the square of the plank mass. So this means that when the mass is macroscopic.
Farshid Soltani: this transition is highly suppressed. In fact, as you can see, the lifetime of the process. Processed exponential. Of the
Farshid Soltani: erez agmoni ratio, of the square mass of the collapsing matter and the spur of the drug master. So this time is a very long time before the transition can happen if we don't consider the hope evaporation process, in fact, much longer.
Farshid Soltani: that they're hoping evaporation time.
Farshid Soltani: and this is great. This is an actual, genuine prediction of the model. The assumption that we're made of neglecting Ok. Evaporation. Turns out to not be correct. And this is given by this prediction here made with the spin from framework.
Farshid Soltani: This results were also recently confirmed numerically by the work of pizza.
Farshid Soltani: So this numerical confirmation was also for this just 2 vertex vertex model, or Yes, okay.
Farshid Soltani: yes. All the results for now are just this simple speaking. which is already a great result of
Farshid Soltani: so, but I hope I convey them in this talk. Is that the the black to Whitehall transition? Is a very natural scenario for the physics at the end of evaporation process of a black hole.
Farshid Soltani: and we were able to construct an effective metric. For the space timer that also takes into account the the quantum geometry of the interior of a black hole.
Farshid Soltani: We've also seen how the spin from formalism is perfectly able to describe. The quantum transition of geometry happening inside the spontane region, and is also able to get out estimates, physical estimates for the 3 parameters of the model.
Farshid Soltani: This is all nicer. However, this should not be seen as the end pointer. This is really just the starting point for more refined analysis
Farshid Soltani: erez agmoni. In fact, just to mention a few of them. We've just seen how the Spin form transition amplitude told us that the most probable scenario for the black to water. Transition is this transition of the horizon happening at the end of the evaporation process. So we should really work to implement better the poking evaporation process in the context of the black to transition.
Farshid Soltani: Our starting point, our first step was done in my team, the soil of La in very 19. But more work need to be done
Farshid Soltani: erez agmoni. Also it is interesting how, in the interior region of a black hole, now we have an inner horizon. So this designer horizons classically, as soon as you are the ingoing and outgoing matter streams up, I bay dynamical objects. So it will be interesting to study how these quantities behave in the context of the
Farshid Soltani: effective quantum geometry and effective equation of motion
Farshid Soltani: erez agmoni. Secondly, we've seen how we got the first result for the spin from calculations, and this is greater. It would be very nice if you would also try to go in the next step and be able to analyze more complex transition amplitudes, and confirm these results.
Farshid Soltani: Furthermore, everything I said applies only to the stakeholder symmetric case. We know that physical black holes rotate. So it will also be good to be able to generalize this model. With the addition of the angular momentum.
Farshid Soltani: Finally, an interesting point is that the transition of geometry in the quantum field region was often compared with a handling phenomenon in non-relativistic quantum mechanics. But there are some very clear similarities between the 2.
Farshid Soltani: It will be interesting to to see to what extent. These 2 scenarios are similar, and to get a clearer picture about this.
Farshid Soltani: With this I conclude. Thank you.
Hal Haggard: thank you, Farsheid. Thank you for your time management.
Carlo Rovelli: Yes.
Hal Haggard: we'll begin with questions. I see that Ding has already raised his hand, ding, feel free to unmute and ask.
Ding Jia: thank you.
Ding Jia: Very nice talk. I like it very much. I have a question about the second bullet point. It's an existential question.
Ding Jia: what does it mean to have an effective metric? And what is it good for? So I have another notion of effective metric which is a start with a quantum path. Integral.
Ding Jia: impose some boundary conditions I solve for the relevant set of points
Ding Jia: this gives me one or multiple effective metrics and know what it is good for, because
Ding Jia: maybe the whole path integral, is hard to evaluate.
Ding Jia: And I used these saddle points as my leading other approximation to the passenger. So for this notion of the effect of metric, I know its meaning. Do I understand correctly that you're using a different notion of effective, effective metric. And if so,
Ding Jia: what's the what's the what's its meaning of life?
Farshid Soltani: Yeah. The meaning is so you can start from the quantum theory of the geometries, or let me go back to.
Farshid Soltani: So, for example, here, from for the interior physics of the style, you can take the classical physics. Then you can go into the quantum theory of this geometry, and then you can define a coherent state on the classical state. Then you can
Farshid Soltani: follow the quantum dynamics of these quantum state. And you can realize that
Farshid Soltani: the the main peak of these coherence data satisfy some effective equations which are the one gives here. So this really quantum coherence data whose coherence remains to all the way to the collapse. And then what happens later, and so I can describe effectively the physics of the peak of these quantum state to these effective equations.
Farshid Soltani: So the true theory is still quantum. But I can get an approximation of what happens. By studying just these physics here.
Ding Jia: in comparison to the other notion of effective metric.
Farshid Soltani: I'm not familiar with the notion you gave the way I see it is that there's a lot of different way to get approximation of the physics of this region. So there might be 2 different approximations that get right different sort of physics. And that's okay. Just get
Farshid Soltani: more pages of different physics that then can put together and see the clear picture.
Ding Jia: Do I understand correctly that for your notion of effective metric
Ding Jia: you require, you know, some time evolution for it to be meaningful.
Farshid Soltani: And
Farshid Soltani: yes, you choose.
Farshid Soltani: You need to choose a sort of
Farshid Soltani: and
Farshid Soltani: time field or time evolution you want to study doesn't need to be.
Farshid Soltani: And in particular, then we can start evolution. That specific
Farshid Soltani: times you've chosen. Yes.
Ding Jia: and the year notion of effective metric.
Ding Jia: You only need to know the initial boundary condition. You don't know. You don't need to know anything about the future boundary condition.
Farshid Soltani: Correct.
Ding Jia: I see that's a very special
Ding Jia: type of effective measure. But I understand it. No, thank you.
Farshid Soltani: Thanks for the question.
Hal Haggard: Yurik.
Jerzy Lewandowski: okay. So my question is about this.
Jerzy Lewandowski: a surface on which the surface.
Jerzy Lewandowski: the surface quantum state is defined, so
Jerzy Lewandowski: there is a ambiguity in fixing the surface. so how S. Sensitive is the result? deformations of this surface.
Farshid Soltani: Yeah, so this really is not a problem of this specific kind of geometry. The problem of what is the pound? I didn't quantum mechanics. So it's the same problem. And
Farshid Soltani: in theory one expect that by choosing different
Farshid Soltani: Panda is you should get the same physics. Out of it.
Farshid Soltani: Erez agmoni! The only way to prove this in our context is to prove, different boundaries for this region. Calculate the transition amplitude, get out results and then compare them, and they should get out to be compatible.
Farshid Soltani: Please. Of course, sir. out of the question right now. But that's the idea. And that's the hope.
Jerzy Lewandowski: Okay, thank you.
Farshid Soltani: Thank you.
Abhay Vasant Ashtekar: Have a question. Yeah, II just couldn't raise my hand somehow. Something went wrong. Yeah, I just a quick, quick question would just do it. I would like to understand better
Abhay Vasant Ashtekar: the relation between your slide 2021 and then 22, basically 2021 seems to be much more elaborate.
Abhay Vasant Ashtekar: With lots of vertices and lots of is that right? That a lot many vertices here?
Farshid Soltani: Yeah, yeah, this is quite a more complex. Here we have 14 vertices 28 notes
Abhay Vasant Ashtekar: So what is known? In that that case.
Abhay Vasant Ashtekar: what is known in that case many notes. And yeah, what what is known yet? Because you just went to the simplified model and told us what is known.
Abhay Vasant Ashtekar: But in this case, you just set up the problem. But I didn't understand what exactly was shown.
Farshid Soltani: Yeah. So we we've shown that we can get a transition ampute out of it, though we have computed a well defined transition amplitude that we have when we're trying to analyze it is, of course, a very complicated object. So we still haven't been able to get any physics out of it. But the hope is to do the same. The same process we need for the most simplified model also for these more complicated transition output.
Abhay Vasant Ashtekar: and there is no
Abhay Vasant Ashtekar: is there any signal at all that the limitations of the simplified model might go away like
Abhay Vasant Ashtekar: what? Sorry for the simplified model, you know, one gets this results which stays at the
Abhay Vasant Ashtekar: you know that the probability is exponentially suppressed and very, very large. Is there any reason to see that with inclusion of board vertices improves that slightly, or which way it goes, or Internet? That is very signature like on that.
Farshid Soltani: this something we're working on. And we want to do, we want to confirm this results.
Abhay Vasant Ashtekar: Okay, thank you.
Farshid Soltani: Thank you.
Hal Haggard: Are there further questions
3453 Deepan Betal: I had a question.
Hal Haggard: Yes, please go ahead.
3453 Deepan Betal: There is a description from the does the description from the black hole to Whitehole transition change? If you are near the if you're near the cosmological bounds.
3453 Deepan Betal: I mean either after the bounce or before the bounce. If if you have primordial black hole or a black hole which is
3453 Deepan Betal: going into the bounce in, the lady knows.
Farshid Soltani: So this is not something I'm worked on them. So I'm not sure but we're actually very interested in these. In our group. Francesco, we are working on, what? The the presence of these kind of reminisce through the bouncing cosmological bouncer to mean both to ecological bounce up, and to this kind of object. And this is still work in progress. But it's a very interesting scenario. Yes.
3453 Deepan Betal: thank you, and add one more question, though. In the, in the bouncy cosmology there has the. There is a stimulated particle creation, or something like that.
3453 Deepan Betal: Is there something similar in the black hole to White Hole transition that we have? So
3453 Deepan Betal: some kind of particle creation other than hopping radiation is happening?
Farshid Soltani: Yeah, I'm sure there is. It is a very highly dynamic zoom field region, and I'm sure that you study, and it's something that should be studied better. After it's not easy to get the calculations done.
Hal Haggard: I'll return to you. Just I'm gonna give Carlo a chance to ask a first question. Carlo, please go ahead.
Farshid Soltani: Commuter. Still.
Western: there are cameras. Okay. Can you hear me?
Hal Haggard: Yes, yes.
Western: Okay. So this is not a question. It's it's an attempt to to throw clarification. I hope it doesn't. I don't. I don't create confusion. For she was so crystal clear and everything.
Western: II want to. Some point of I mentioned. Don't you expect in the future of the transition to still have a quantum quantum? So something quantum with the metric, a a spread in the metric?
Western: A that I would like to try to offer a classic issue about that.
Western: that was yes, but the and this Co. Actually compatible with the fact that in the past of the quantum region there that we don't question marks.
Western: there's a classical metric
Western: in the following sense. There are
Western: 2 ways to think about quantum mechanics. One is to see the wave function. It evolves and just follow the evolution of the wave function.
Western: the other is that and if you think of just any quantum phenomenon, the laboratory
Western: you compute the probability for one or the other of alternative. what? What did the Copenag interpretations call measure measurement outcomes.
Western: or in the many world interpretation is called
Western: declared branches. So the probability of this or that to happen. So imagine you have a
Western: you have an atom that decays you compute the probability for it to decay in some time, for instance.
Western: And then in in in standard, the laboratory quantum mechanics
Western: you treat what happened later. Completely classical. You have a Geiger counter that has clicked at some time. So you say, okay. So from this point on, II forget by quantum theory.
Western: II have a classical solution, or certain Geiger counters as as as click the time specific time. T.
Western: But the the theory tells me that there's a probability distribution about one of the other things happening
Western: so this is another way of think about quantum mechanics instead of thinking forever away function evolving. You think that at some point you you can go back to the classical approximation.
Western: But what remains with you? Different alternatives might have happened. And this is the way quantum mechanics is treated here. So the the the quantum mechanical physics is relevant in the gray region
Western: after that. There's a classical theory. But the predictions about what happened, that classical theory is probabilistic.
Western: So there could be one or the other of different things happening. And in particular there could be one of the other of different, for instance, parameter t the global parameter t that that
Western: that first it introduced 12 different values.
Western: So the intuition that wait a moment there should be something quantum later on. It's not contradicted by this situation here is that the the the probability assigned by this model to to to the global feature of the classical metric outside to the parameters side does not have not a a spread. So that's where the the
Western: the, the, the
Western: th, the later effect of what mechanics come in, which might be relevant for thinking like unitarity in sky, plus or things like that, or to be sorry, plus or like that. So this
Western: I thought this was always the I mean for she started introducing this as a as a realization of the with dashikar bourgeois paradigm. At the beginning you can think at the Black Hole in the standard way which you think at the at, at the quantum phenomena in the laboratory in which you you just say quite to effect, or
Western: for some time after, after I go back to classical theory, of course, remembering that there's probably solution in in in Copenhagen terms is like there was a measurement, or in a in a in many world terms. There was a was a different branches possibilities. So I hope this, you know, helps bring it together different. See that they're compatible.
Abhay Vasant Ashtekar: II kind of agree with you, Carol, but I mean.
Abhay Vasant Ashtekar: you have said before, you know that there's a heiser, Buck Cut, and so on. But you know there is no management that is taking place here. There's no heiser back cut. So what you said just now is that
Abhay Vasant Ashtekar: you know these are just various probabilities. But the problem is that if, in fact.
Abhay Vasant Ashtekar: the situation extremely quantum mechanical. then
Abhay Vasant Ashtekar: it's not. I mean, if, in fact, it turns out
Abhay Vasant Ashtekar: that the proven distribution is sharply peaked. so that at classical geometry is a good approximation.
Abhay Vasant Ashtekar: then I think these pictures have some intuitive meaning.
Abhay Vasant Ashtekar: but if it turns out that in fact, the classical geometry has
Abhay Vasant Ashtekar: really, I mean the the things are fluctuating so widely
Abhay Vasant Ashtekar: that that is just a mistake to say that, you know there is a there's a classical geometry there.
Abhay Vasant Ashtekar: Yeah, it's just it's it's just like.
Abhay Vasant Ashtekar: you know, just like you did. You know a black hole? It's just a mistake to say that. Well, it's almost flat, it's not.
Abhay Vasant Ashtekar: And so th it it all depends on what the the final answer is, if you like, if, in fact, it is quite a mechanical, and the state is widely oscillating and widely wiggling, and so on, so forth.
Abhay Vasant Ashtekar: Then we can still say that. Well, I just said, but I agree with you that that you can still say that
Abhay Vasant Ashtekar: that there is a priority for this to happen, that to happen, etc., etc. But then the classical pictures don't be deemed very much.
Abhay Vasant Ashtekar: and my concern always has been, as you have told you, as we discussed before is really that in this region?
Abhay Vasant Ashtekar: I mean that
Abhay Vasant Ashtekar: if I look at the hawking radiation, don't ignore it. If I look at the hawking radiation.
Abhay Vasant Ashtekar: Then
Abhay Vasant Ashtekar: at at the kind of end point of the
Abhay Vasant Ashtekar: when the black hole has shrunk to a plant boss, or something like that. At that case. At that time the the the radiation is really very ultraviolet. The temperature is extremely high.
Abhay Vasant Ashtekar: and then what comes out to the black hole?
Abhay Vasant Ashtekar: The output to this, this transition surface is really
Abhay Vasant Ashtekar: is is faced out, and that is how we sort of try to make sense of unitarity.
Abhay Vasant Ashtekar: That, that I enough of those more should have very, very stretched out, and the matching of that II think it's very, very hard to make the matching of that using any classic concept
Abhay Vasant Ashtekar: near
Abhay Vasant Ashtekar: the region U alpha u beta on sky plus.
Abhay Vasant Ashtekar: And and I think that that that is my main concern. Basically.
Abhay Vasant Ashtekar: I think this region D is extremely small, but still you all find you beats are very close to each other in some ways, in some sense.
Abhay Vasant Ashtekar: to me. I think
Abhay Vasant Ashtekar: II mean II completely agree that we should do everything we can by saying, Well, let me make this assumption and see what happens. I I'm I on, come same as you about this.
Abhay Vasant Ashtekar: II really feel that
Abhay Vasant Ashtekar: that can somehow, heart of a problem is to understand the true content nature of what is happening in this
Abhay Vasant Ashtekar: u alpha u beta little label of that. So I just wanted to set.
Abhay Vasant Ashtekar: II agree there is no absolute contradiction. But the question is of usefulness, of such a picture
Hal Haggard: any response from Western? If not, can you mute the mic
Hal Haggard: and ding? Why don't you go ahead with your question.
Ding Jia: Thank you. Again, the question about regularity and effective geometry, effective metric.
Ding Jia: Do you insist that
Ding Jia: an an effective metric has to be nancing or regular.
Ding Jia: I ask this question because, for example, previously you were mentioning that in quantum cosmology, you think of a wave function evolving in time.
Ding Jia: and you think of the effective geometry as where the wave function is picked. Now, I don't know any reason in principle to rule out the possibility that of a unitary evolution for the wave function.
Ding Jia: The wave function is picked along a singular bus trajectory.
Ding Jia: So the question is. do you consider this as an open possibility that for your effective geometry you have a a singular geometry.
Farshid Soltani: Mathematically I would say, I agree with you.
Farshid Soltani: my physical point of view. I don't see how to make sense of a single id, so I don't expect the the we would find one in any of these scenarios.
Farshid Soltani: but from a mathematical point of view, I think yes, you're right
Ding Jia: from a physical point of view. If I have a unitary wave function
Ding Jia: will function evolving humanitarian.
Ding Jia: I can just do out in the quantum mechanics. There's no I don't see any apparent
Ding Jia: difficulty in making sense of the physical predictions, because I have a units are evolving wave function
Farshid Soltani: so you wouldn't have any difficulty in
Farshid Soltani: explaining physically what is happening until you reach a single id. But when to reach the single point. How do you explain physically? What is the secret? Id.
Ding Jia: if you're doing quantum mechanics, what you do is do measurements. You assign probabilities to measurement outcompers. Even if the peak of the wave function is singular.
Ding Jia: the probabilities are still meaningful to some. To one they will be all the conditions you want. I don't see any difficulty there.
Farshid Soltani: Okay, I'm not sure it might make sense. So I need to think more about this, I think.
Farshid Soltani: yeah. it's really just a matter of if this singular id means something physically, or is it just?
Farshid Soltani: it happens to be like these and detective jump description is normally about there. And I think he's finding the quantum theory that it might make sense, I guess.
Ding Jia: Okay, thank you.
Hal Haggard: Any additional questions.
Hal Haggard: If not, I had a follow-up question on Abi's question when you were on slides 2021. This is the more refined spin foam model.
Hal Haggard: Ii understand that you're very interested in confirming the results that people have already seen in spin phone models. But I wondered also if you've thought about additional questions that we'll be able to address with this more refined spin phone model. Are there other observables that you might be able to probe?
Farshid Soltani: Yeah, the main.
Farshid Soltani: So basically, this is much more complex, not only to get more degrees of freedom, but also because we are starting a different space timer than the original one. And so now the topology of the quantum region is different, and a discretization of this topology turns out to be much more difficult to find than the original model one. So this
Farshid Soltani: to find a topology which seems tractable with nice symmetries already takes A much more complicated structure. And so from these.
Farshid Soltani: erez agmoni, these are really 2 different model. Your original proposal just 2, 3 parameters, M. And this pounce time. Here we also have these new parameters that define the quantum region. So surely with this new 2 parameters we can probe differently the quantum region, only the horizon. So we can ask questions about how big should this region be? 150?
Farshid Soltani: How is the actual time? Only this transition? So these 2 parameters surely allows us to have much more control over the quantum region and its properties.
Hal Haggard: Thank you. Next last, call for questions.
Hal Haggard: If there are none, let's thank Farshi again. Thank you very much.
Farshid Soltani: Thank you.
Farshid Soltani: Thanks.