11:36:03 And, you know, please feel free to bring up any points in relation to any of the Ford talks we had today so. So, I wanted to lead off and I hope that people can hear me.
11:36:14 Yeah, we can hear you. Okay, good.
11:36:17 So, you know, it just keeps bring up a really good point, which is that then we have this sort of hierarchy of awesomeness.
11:36:24 And I just think, if nothing else if we learn about these quantum gravity discussions that.
11:36:31 First, there's the sort of fundamental question is, is there a quantum communication channel to gravity I say that's the fundamental on the easiest one because it's the one we think we can test in the near future.
11:36:44 And everyone expects the answer is yes.
11:36:47 So great so that's an experimental as task now like theory wise we're done.
11:36:52 You know, just have you do the experiment do the experiment.
11:36:55 Then there's this sort of next order question which is, what does the rabbit on as a quantum object exist.
11:37:04 And we can argue from a field theory perspective about what you guys need to include.
11:37:09 We can also argue for example that you know going to your idea that hey, I have a mass is a local displacement of the linear ization expansion of the metric.
11:37:20 It is a local displacement of the linear eyes expansion of the metric. I can think of that if I knew about gravity.
11:37:32 In terms of a cat state of a displacement of gravity tons quarter of like if you take the mattress example of space time right you put an imprint here or an imprint there.
11:37:35 But one of the big challenges in this second step, which is this sort of, is there a quantum object we can call the gravitas of the representation of Lawrence group that it's been to that we think of as the gravitas.
11:37:48 I think one of the big challenges there is that that's not observable directly.
11:37:54 Yes, right. So, you know, to think about trying to measure, are you in this cat state.
11:38:00 You have to actually be able to somehow break the interaction of course these time is so stiff.
11:38:08 So. So what it does is this fall upon us, right and this is I think what you're trying to do cause upon us to include the measurement apparatus and our whole story as well, which is kind of what the spins are doing, because if there's some spontaneous
11:38:22 wave function collapse.
11:38:23 And this is the point maybe Arkady will appreciate.
11:38:27 It's a disaster for what was a sort of displacement of the vacuum, so irrelevant you can't see it, to suddenly it's here or there, and all these fluctuations left behind.
11:38:38 So I just received
11:38:42 an SEO so I never see Higgs directly.
11:38:45 So I didn't mean it. So the point is, I don't know if they're spontaneous collapse theories.
11:38:52 Then one of your predictions will be there will be these huge emissions of gravity.
11:38:56 When you observe an object a massive object in one place versus another.
11:39:00 And so I just want to say like, we don't yet know how to probe.
11:39:04 This quantum gravity on space, but I kind of I hope is that a helpful way to think about like first order.
11:39:13 Is there even quantum communication to gravity yes no second order. is there an object that we can call the gravitas that behaves according to quantum mechanics.
11:39:21 And then third order. You know what is the sort of in self interacting theory that we get them. Yeah, I think that's the here I'd like to look at and I'm very curious to your thoughts and comments on that.
11:39:31 No, I could easily, but but this is me. I was trying to say is that your first step, which you are mentioned, has nothing to do with existence or very.
11:39:47 No, I mean,
11:39:47 I completely agree the gravity is convenience, but not necessary. No no no it's a it's a will show up not in seven seconds and lesson is a big job, but as a next step but like when you can see them emission.
11:40:00 For example, of course you will get good sleep.
11:40:05 So, so I don't know whether I can I can I can clarify a little bit. I mean, on the pumps point of view and and I mostly agree with what Jacob has saved, and saved so maybe, maybe my response is also towards Arkady mainly.
11:40:23 But what I would like to stress is that, you know, we are doing the experiment when the masters are moving on religion is typically that's fine. Okay.
11:40:45 up local PBS still assuming that you know physics is fundamentally local interactions. Right. And if you take physics is fundamentally local, or at least local over the scale of separation of directors.
11:40:52 Right. So if you assume that then you definitely need a mediator and it is here we're Jacobs point of communication comes in so communication becomes a necessity because just because of the locality of physics.
11:41:03 So, you cannot think of Newtonian direction as an action at a distance, okay, even if the masses are non relativistic you can't think if you accept reality which you cannot think of it as a action at a distance right so there has
11:41:19 been there has to be a mediator, that's the only assumption that means there's a communication.
11:41:23 Right. And then, as well as ego is emphasizing this will find out what is the communication channel.
11:41:30 Right.
11:41:31 And, of course, one interpretation of this mediator, it is the standard one, you know, low energy effective filter in quantum theory is for children.
11:41:40 Right.
11:41:41 But this does not be God depend on whether you believe in virtual very tense or not but you should believe that there's a communication, right, because nothing can happen faster than speed of light.
11:41:52 That's an assumption that's not what you're proving in the experiment. Nothing can happen faster than light is an assumption we are bringing in from, you know, locality of quantum field theory is very high you tested.
11:42:03 Go faster than light.
11:42:04 So something must have gone from one must be another, and we know a classical Asian going from one place to another, cannot see it in general, you're sending bits.
11:42:19 You're not sending cubits, I mean even except massive electromagnetic wave, which is not what this is optional, but whatever is going right, it has to be something has to be the first week want, but it doesn't.
11:42:26 That's not appears when you can see the non logistics system, so what you're talking about. It's a DVD collection.
11:42:35 So to check that not it's not delay a uniquely juicy, music, and then of course you you need to do a collections of his say exchange by transfers. I mean, you know, physical, you later me, in a sense, it comes together but, But, but that most of the discussion
11:42:55 was about TV success. Yeah, yeah, so so what I'm telling I'm perfectly believing in non relativistic of the masses right so say take a little mystic charges a charge sitting here, just sitting there, right.
11:43:07 But that would you say the interaction between them is faster than light noses.
11:43:15 When you can see them. Right, right.
11:43:18 Okay, okay. So we are not testing relativity here that we are assuming relativity.
11:43:25 If we combine our experimental results, along with relativity that nothing can go faster than right, then we can show this but within our experiment, it becomes very hard to test religion, just because of the time scale is this is this is just a gestation
11:43:42 of GLAMAZON what tells you this confirms is because, good gravity waves is, is, is some way of confirmation of this.
11:43:52 Right, right. Yeah. But yeah, so, so, of course, and then in the first part of an open stock, so there was this this other thing the bound state of gravity doesn't matter.
11:44:04 Okay. That dear Actually, we are talking of is optional parameters which are interacting.
11:44:11 Yeah, it's like standing we have residence in that collection of mass and grab it is like a cabbage, like a quandary so so the mass more very binary the gravity and so that is that is that is actually a little bit separate from the second part, No, no,
11:44:27 I won't be Tony and failure is not miss blame it on its own system of my surprise, my master particle Mars and, and they are not sourcing those things we're not talking about, those are the external ambient vacuum of the gravitational field, with which
11:44:57 they are interacting so these are these are still have that internal discussion, like for example time delay. Example forces like that, but it's still not about the grave with them as a particle, it's about, you know, changing say image of the systems
11:45:05 as I flew
11:45:10 Igor and then, Jake. Yeah.
11:45:16 Yeah, thanks. Also thanks for the last two talks were really kind of a nice, a, just a quick comment here on this discussion now I, you know, I think it's a very clarifying point of view but regardless, that goes for Jake said everything that's exactly
11:45:29 the point that different assumes or what's rather says, when the students just precondition that there is some mediating degrees of freedom. Then, such an experiment can show that they have to be quantum.
11:45:42 But that's a pre assumption you don't show with kind of as a separate gravity, maybe another way to put it, that every experiment that wants to probe quantum gravity have to see across the pond.
11:45:52 And I think that's maybe a mindset, which sometimes comes from fear theory. I think that's what this quantum information mindset, maybe breaks a little bit it ask different questions, signatures of quantum mechanics are not just simply signatures only
11:46:05 of gravity, it could be other signatures quantities. And I think that's what Jake was saying terms of classical versus quantum communication channel. But I actually wanted to ask a quick question to answer, probably for me.
11:46:18 And, namely you suggested this benchmark of how many gravitas they are in this coherent state effectively. And I think, on the one hand I like it because it's about okay how big is your kind of state that you created the gravitational field and how different
11:46:31 is it because it's superposition. But on the other hand, what I don't like about the measurement to suggest is you seem to suggest it depends on the mass.
11:46:45 And that's strange to me, in the sense that if you were if I were to be able to make the moon or or whatever a much larger object in a big civil position, it would just be better.
11:46:50 It creates even bigger space time, so I don't see that benchmark why it would prefer specifically like massive around the time.
11:47:06 It makes it harder and harder to extract quantum properties for a massive system, take an example of a black hole, the black hole, if you want to extract any quantum, you know, here it becomes much harder.
11:47:13 The only way I can extract it to Hawking radiation. And so very very you're setting. I mean, in the context of your setting, if I create a black hole in a superposition bigger than it's granted uncertainty, then I'm done, like you think your proposal
11:47:27 kicks in.
11:47:28 So in fact if you're back when you can't say it's maybe harder to make it, but if you can do it, then it's much better system.
11:47:34 But if it's very massive creating a superposition becomes very very hard.
11:47:40 Sure.
11:47:41 She is you have to create a superposition and what I'm giving it criteria that if the mass of the system becomes bigger than the tennis to minus five grams.
11:47:48 Even experimental it's very very hard.
11:47:52 You create the superposition. So one has to come up with the procedure, how to create the superposition. Sure, but I don't think this benchmark captures How hard is experimenting I don't think thats related that with the grog its own content.
11:48:03 So I'm not sure if that flip actually captured by.
11:48:07 So what I'm saying is it becomes harder and harder. If you want you can of course create it by some mechanism which I don't know, maybe you require some violation of say maybe creating some wormhole or something where you can create extract i mean you
11:48:20 know create superposition. But just within the normal physics in becomes very very hot.
11:48:28 So, just to briefly follow up on that point.
11:48:32 Another way to think about this number of gravity is actually not in terms of g m squared.
11:48:37 But in terms of GQ squared Ricky was the mass quadruple.
11:48:46 And I know that that's like to look at it, but I'm just saying my own know I wish, when I teach this is actually to put it in terms of, well first and then go to the gym square, I just want to mention that for, you know, to give some, some contacts there.
11:48:57 I will say another point which I think it may be our cutting may not appreciate, we can write down.
11:49:05 Theories of gravity that are not quantum.
11:49:10 They don't communicate quantum information, but they do have gravitational waves.
11:49:15 Okay.
11:49:28 So, the existence of gravitational wave doesn't tell you about quantum gravity, it just tells you that there are low frequency expectations of the effective field during via classical response. Just to be clear, okay, animation, then, Ted.
11:49:32 Thanks. Thanks for the discussion.
11:49:37 As I understand it, the whole sort of debate or discussion that our bodies have to raised, I think, is because we are trying to combine two inherently incompatible things in the low energy to limit the gravitational interaction is Newtonian.
11:49:55 It is therefore instantaneous.
11:49:57 On top of that we bring in the fact that mediators, do not move faster than light that is now a special relativistic imposition, which Newtonian gravity does not allow right because the Newtonian gravity action at a distance everything happen instantaneously.
11:50:14 So I think it's the combination of these two.
11:50:19 I don't know if I want it to be dramatic I would say mutually incompatible in positions that I think is leading to all the confusion that we are seeing.
11:50:29 I just wanted to
11:50:31 let it anyways thanks for yeah so I think you see that we are we are job, all that we are assuming is the quantum mechanics and especially relativity.
11:50:42 And so if I buy these two items, what do you want assuming is Newtonian gravity and special relativity, which are mutually income.
11:50:51 I'm not buying I'm deriving the Newtonian potential.
11:50:56 Yeah, but my in my want to limit your action is instantaneous.
11:51:00 No, it's not action is instant instantaneous you Tony and actually.
11:51:06 No, it is not.
11:51:14 Maybe I can, I can see some new so if you take the low energy of masses limit of General.
11:51:15 Right. That will not be an instantaneous state on any interaction.
11:51:19 One can start with that he will still have the form of interaction, but we be like a teacher function, you know after the Litecoin it believes that yeah so of course quantum mechanics, has nothing to I mean quantum quantum has nothing to do with creativity.
11:51:33 Creativity but but we do use the ratings to quality. So in some sense, rather than starting from Newtonian we can say we are starting from when the masses have low energy, but movement version of general relativity.
11:51:51 Okay, um, so I think it's Ted's turn now.
11:51:57 And then john.
11:52:00 Yeah, I had a question or different angle, this is for Igor, about the idea of the quantum twin effect.
11:52:12 Would you be able to implement this in a very different experimental setup using safe fiber optical fibers, carrying circular polarized light and coherently splitting photon into an upper and a lower branch of fiber and recombining so that would be the
11:52:33 spatial degree of freedom, but also the rotation of the polarization direction, acting as the internal clock.
11:52:44 It's just a masking would have set up like that be able to implement the effect that you're interested in.
11:52:52 Thanks a lot for the question. It's a very good question. So of course the photons are good to work with photons and tantric is a freedom, they have to travel, not on now curves.
11:53:03 So they have to experience the proper time, which is wouldn't be No, I mean, you know, in a fiber it's moving less than the speed of light.
11:53:10 Exactly, exactly. So I think if you do it in a medium, such that they actually are, you know, having fine at proper time, when you sit on a photon, and then compete, then you would have also polarization type of.
11:53:24 Well, you have to have polarization that evolves in time.
11:53:27 Yeah, so anything that the dynamics kind of entrepreneurs Asian rotation within depends on it. You're exactly right.
11:53:35 I think the numbers for that are not so good but it's possible, that's I guess what I'm wondering about is the numbers game It sounds like a much simpler sort of experiment if the numbers work exactly so you do photonic experiments that have Matt away.
11:53:48 And just to mention I it's a long ago, and as a PhD student I looked a little bit at that with some experimental.
11:53:55 I don't remember the numbers they weren't very good, but it's worth revisiting, but we pivoted the time to something else, namely increase space.
11:54:04 I mentioned before, the free space you can, you can use the Shapiro delay for the same effect.
11:54:09 And so if you have like a big free space interferometer let's say between a satellite and earth, and you just shoot up a single photon, you know, like a Johnny palm has for example and you put it into proposition.
11:54:19 And then that will experience to differentiate period.
11:54:36 face if the people seen our comic fountains. That's interesting alternative.
11:54:53 basically a particular parameter of square kilometre square 10 kilometers something of that sort, and then you'll see a fish.
11:55:06 Okay, so I think john you can ask a question.
11:55:11 Yes, it's going back to the witness test of.
11:55:24 Let me put it this way I think grab it onto the very confusing way of phrasing things, and I think I can understand why why I call he doesn't like that way of phrasing. I would say it's just a question about whether the macroscopic gravitational field can be in a quantum superposition
11:55:31 itself.
11:55:32 Right. So, but let me ask some more experimentally related questions, which is, you have to make sure that there is no sources of D coherence and there's no which way information also you know in this thing.
11:55:47 So I want to know for instance things like after if I mentioned I do laser splitting mentioned I do you know I split you know some central master a bunch of admins by doing the usual large momentum transfer splitting.
11:56:02 I want to know what the effective accelerations are, and how quickly that that instant of splitting the way packet is happening, right, because I want to know.
11:56:11 After all, we all know if we have two masters on these two different trajectories. We are going to have an outgoing set of gravitational waves from that thing.
11:56:21 And now you need to know the wavelength of those gravitational waves and how well they can possibly localize the two different masters and do different positions right, otherwise we start losing coherence information, so no one is discussed this as far
11:56:31 as I can see because somebody answered this thing about I mean how could How could it control. What about all the other sources that are here and so actually hope to realize it's an experiment john I think we discussed this in one of our papers.
11:56:46 So, I mean, again from the QFT perspective what will happen is that if I just construct a vertex.
11:56:53 I mean, I've got two masses. And my superposition is like a massive system, then this vertex will not admit any Grammy time, per se. So all that we need.
11:57:03 I mean, so we need to stay some kind of like two level system, like, going from like, I mean hydrogen atom if I go from.
11:57:17 I'm confused. If I spatially split split a mass, I spatially split its way function. There's some event you have to put it through some, some gradient you know it's made me feel great and electrical gradient, you have to imply laser polls.
11:57:25 So, that event will cause a relative acceleration between effectively between to the branches. I mean, you know, was it initially your particle is just going on, you know, a constant velocity trajectory and now it's not, it's for short was not so it doesn't
11:57:38 make gravitate towards during that time.
11:57:51 So, yeah, I've actually just me a large number gravity been submitted and you can calculate the leading older using classical thing, but there will be graded on so the question is, is, is it, is it possible for those Gravity Forms.
11:58:03 In some cases to be enough. The either Decaux here, or you you have which way information. No it doesn't really, it doesn't get an equal is very very surprised by the garbage lead.
11:58:32 is very geeky couple the one hour squared of G suppression. That saves the world. I'm actually not blind eyes I'm just confused by that, do you do you do agree that let's let's just make the assumption Gravity Forms exist, good assumption.
11:58:45 Right. And do you agree that there are some gravitas submitted during the splitting a specific event. Yeah, okay.
11:58:54 I think they just do not give them each party information.
11:59:02 Well, this is a crucial issue right about this and so I haven't seen any of you guys
11:59:07 futuristic issue so if we are hugely to be very very clear.
11:59:15 If you want to create a graph of time. You want to have this extra mission rate is from acceleration at the moment where it happens. Yes, stronger effect is the mission of photons, of course, yes, from the same effect is all, you know, locally charge
11:59:29 matter even though, neutral electrically in March skills.
11:59:32 though, neutral electrically in March skills. So, let's look for example what happens in an admin for imager.
11:59:37 So in an atom interferometer when you make it which which path moment where you hit the bottom of the pulse of light.
11:59:43 You use this coherent state of light, in order to hide the actual number of photons from the atom, and the consequence of that is that there's very little back action so the atom, there's no information admitted into the far field.
11:59:56 So you get this very good split.
11:59:58 and the correction is from electrodynamics, which is the spontaneous remission of extra photons basically so the equivalent effect in Gravity is spontaneous mission to grab tons from the instantaneous acceleration.
12:00:12 And if we know the electrons and Emma correction is a part in 1000 at order alpha.
12:00:17 We know that I agree, I agree all these connections directions. Yeah, I understand you know of course it's there but it tends to the minus 45.
12:00:28 But you can do. You can do a formal calculation also you can do and one can show that whether or not. And this is something which we actually performing similar calculation for gravity is a good question is excellent question is definitely very good.
12:00:43 The question is definitely very good. But the part of the answer is already there in Weinberg's book, as well as in Scotland, there was a very nice book, where he discusses the quantum field theory of gravity primitive level.
12:00:55 And the idea is very similar that you go from say hydrogen atom if you go from excited states to downstate how much garbage on would you image. So this is very similar kind of computation.
12:01:04 Well yes I mean I've done this. It's just a question about whether there are other sources of coherence. Right. you're not taking account count off and doing these experiments and clearly there are, I'm going to click right at some level course there
12:01:17 sources the coherence right you have to very carefully screened against whether there's a fundamental limitation from just the protons and you're claiming no there's no, there's no limitation just from the better the better the worst enemies actually
12:01:32 this, you know, classical sources like snakes littering or birds chirping or butterfly passing by, they can create a huge phase, which can be phase of our quantum system.
12:01:43 And for that reason we really have to go for the, you know, dropped our kind of experiment like where you can nullify the local acceleration. And that is one of the hardest one.
12:01:53 And this is also a problem for like to experiment as well. That's why they have gone underground to get rid of the seismic noises and things like that and they require very sophisticated way of canceling the noise and all.
12:02:05 Okay. Hey, I think we have to wrap up at this point I thank you everyone for the discussion and I want to thank all the speakers and the participants who made this into a wonderful conference.
12:02:19 So thank you to all the speakers and participants.
12:02:23 Doug Is there anything you want to say, No, I think you said it all, thanks everybody for coming and discussing and presenting.
12:02:34 All right, so thank you very much for a wonderful workshop.
12:02:39 Yeah, thanks a lot for organizing this very topical workshop so it was very good and thanks to our tardy for asking all these very interesting questions is probably a signal of my superior Genesis on this occasion, but I still plan to make a point I'm
12:02:57 sorry to continue this is it.
12:03:02 First of all, wrote instantaneous direction is no specific of a narrative is it exists, before he succeeded as well. So, but it's mixed up with this exchange by real particles.
12:03:14 And then what john was discussing.
12:03:17 Yeah, and also you can mention is that of course you.
12:03:23 There is a difference between say in the little guy with on some, you know, go with and waves, but it's similar to like emission of light.
12:03:33 If your atomic admission you're saying that you're missing a meeting quadrants. Okay, yeah, Alyssa light in the sky helium can be made on this and it is a classical away.
12:03:45 Right, so, so, so then we can see this guy Helios in, in, in western light but not coherence in a mission of, you know, some, when you hover, you know some independent items immediate right so solid for gravity you of course you will have similar situation
12:04:02 right so so gravitational wave is.
12:04:06 I mean like a let laser light.
12:04:08 If it's like championship.
12:04:11 But, but, in this sense, it's not checking off individually.
12:04:30 I agree with this but, but, but I think that it would be really difficult to avoid this. I mean, if you are trying to construct a digital picture, which combined balls.
12:04:32 So, when it was says that it was amazing gravitation will result good.
12:04:32 I get.
12:04:34 It's only in the sense that you have this kind of like champions way right but it doesn't feel by itself was a good with them exist or not.
12:04:44 Okay, sorry. I'm sorry.
12:04:48 Was it the conveniences but they'd like, Okay, Well let me add, if I were king.
12:04:53 I would assign a half dozen of you or eight of you all the people have been talking in the last half hour to get together and write a joint paper on what what you agree on but more importantly, what's the open questions are and what the issues are probably
12:05:09 you should be so awesome.
12:05:12 I think it's a wonderful idea that if someone wants to do it, it would be very good because it will give us some state of, you know, art, and where we take it from here.
12:05:24 Doc Are you suggesting proceedings of this workshop
12:05:29 will, everything is recorded, of course.
12:05:33 But this would be a step further beyond to proceed. This would be some kind of outcome review paper.
12:05:40 Maybe not as majestic is a full review paper, but a statement of issues, but also the full transcripts, you can just print them out.
12:05:50 Yeah, but it's all in Google gibberish. You know, I am
12:06:04 well Josephine Sir, I think we're done, Josephine or Anna Maria, do you have any last thoughts on on Maria left.
12:06:13 because I think she had some other commitment.