11:30:42 We can in a minute. Go over to our more general discussion, but I just, yeah.
11:30:58 RKDHO Central the talk and just to follow the point are in what sense. The difference between classical quantum.
11:31:03 Because if you haven't considered this is, like, non atheistic potential for example, and it's quantum mechanics because knowledge is potential, you know, all I can say is that it is linear like gravity what I mean.
11:31:18 So, in this sense, not.
11:31:22 I mean the difference between classical quantum is it says, it seems. I mean, kind of, not not not clear to me I mean what what what, because if it's just quantum mechanics of this non military is what is, what is the difference.
11:31:44 I can only answer in an intuitive way and I'll admit that this is not fully satisfying. But if I have an object that is either here or here, and then the question is which direction does the gravitational force, pull.
11:32:01 If we were talking about the cool lump potential, then the gravity, then the electric static force would have a 50% chance of pulling that way, and a 50% chance of pulling the other way and measuring the electrostatic force would collapse the super position
11:32:23 and people don't know where the object is. If gravity shares this feature, then I would call it quantum and this narrow sense I'm not claiming I can detect gravitate towards or anything like that.
11:32:38 I'm just claiming that the experiment would show that gravity can be in such a super position. But my understanding is that because the gravitational metric 10s are in general relativity, can't be in a superposition. But you do see a couple of the Einstein
11:33:00 But for to the metal. And so the experiment, both do nothing more nothing less to decide, then to decide between these two cases, okay I follow what you're saying but I will say that to me, I would not see the difference between state court case and this
11:33:15 one because it was the labels that it was just like one page potential. To me it sounds the same, not much the same. I mean, you medically but I mean in terms of invitation so that's why I'm asking me you know is that is it.
11:33:32 Okay, I'm sorry, is it maybe it's not maybe myself.
11:33:42 But, but it seems to me that in the onset because I do not see so well formulated, you know, kind of, because it seems to me that might be.
11:33:44 It's not that.
11:33:59 Let's let me open up the floor to this question I was wondering what it was going to come out. I'm glad it came up now.
11:34:06 So, in fact, it seems to be the gravitational physicists are not have not come to a consensus on them. There, there are some gravitational theorists with very speculative ideas, there's no coherence at all or something.
11:34:22 Then on the other end of the spectrum, there are people who say, well, you're not really measuring anything it's just a longitudinal something your other something or other.
11:34:30 And so some serious, including Ted JP Jacobson, and Bob Wald who are very widely respected have thought about this carefully, a TED Are you on the call Can you address the question of what is classical versus quantum gravity in such an experiment mean
11:34:46 that if I may say something. No please go ahead. I caught up on this point, a lot and part of the reason I think with Andy we started this whole procedure.
11:34:58 So, to answer his question. So, let's play a very simple game marketing, I give you a coin. And let's imagine that coin is quantum.
11:35:07 Okay. And I keep a coin I'm sitting in growing in. And I imagine that my point is quantum.
11:35:13 I request you to toss the coin billion times, and I do the same, I toss the coin billion times.
11:35:20 And let's say we don't have any other interaction. There's just a purely let's say classical interaction, classical scattering like playing football and nothing more than that, you would if you would do this experiment you will get 5050 50% up 50% down.
11:35:36 And I would also get 50% up, and I will get 50% down.
11:35:41 However, if there is an interaction between you and me if I set up, which is quantum in nature, then this will not be 5050.
11:35:49 It will be maybe 5149, or whatever.
11:35:52 So what it tells you that I'm able to, you know, influence your experiment and you can influence my experiment.
11:35:59 And this can happen, provided you have set up some kind of quantum communication between you and me.
11:36:07 And think of this exactly this this way. If gravity is purely classical, then it will never entangle the two systems.
11:36:15 And if the gravity is quantum, although it's a column potential, although say exactly like the same potential what Newton told us. Yes, 400 years ago, but the fact that if the gravity on is quantum the optional interaction.
11:36:30 Can entangle the two masses. So that's a different difference which you have perhaps. But what about the magnetic force, let's say is that it is charged particle I mean what that would mean that, then you think it's also would be a way to check it this
11:36:45 way exactly what exactly you can you can exact right but but in case of our of my day here some you.
11:36:54 You have no doubt that it is scared of classical quantum at the same time, it is existence, this interaction right and. Okay. And I will say that that's a p label to me quantum it this way, loops are important in a bit of activity where loops are not
11:37:12 contributing. Then, you know, classical fealty or quantum.
11:37:18 I mean, okay it's.
11:37:22 So I'm trying to make a point about, say, kind of loop collections. We also see the label.
11:37:28 The label is equivalent to classical theory. So what you're what you're saying. it looks like a three levels. That's why I, I, I don't, I do not see, you know, kind of differentiation between classical quantum at this level.
11:37:45 Yeah, I mean, in from vomit perspective I agree that there is no loop diagram because anything with loop will be very very suppressed. You will never ever be able to detect it.
11:37:53 But the fact that this entanglement feature is there in any sketching process you can take even more sketching sketching. These are all children processes, okay but but at this level, it just means this way.
11:38:11 Give it a shot.
11:38:13 there is no difference between looks and magnetic along.
11:38:24 So it's classical and quantum is the same set at the same time, mean kinda small empty to to put a console related. Okay, what, what would you scattering or pass catching, would you consider them a classical scattering or quantum sketching a dealer well
11:38:31 I do not see the difference.
11:38:34 You know the answer is the same but the processes of course there is optional. You know you buy the
11:38:41 show. There's no sort of shell is on physical it's just about technical way how we calculate this. Absolutely, absolutely.
11:38:49 Better This is that in the classical if it were classical sketching, you would never see this entanglement So what it means is that there is no Spin Spin correlation there will be no healthy correlation.
11:39:01 No, no, it's a three level you can have scattered an accountant for Walker relations.
11:39:08 And they do, what is it, they'd call to call it classical quantum. I mean, in this sense it's quantum in you know the label like that, it's not exactly classical but but these would be not an interpretation, it would be like a medical degree.
11:39:25 Let me say this, let me say this a little bit differently. If you do an experiment where gravity should entangle, but yet no matter how hard you try, you get no entanglement.
11:39:36 This is an indictment of linear rise theory of quantum gravity. Yeah, okay. That's what we really mean, yeah, yeah.
11:39:47 It's not saying it's saying that something's wrong because it's not entangling and it should.
11:39:55 That's what we're talking about. Yeah, I think that's exactly right. I'm experimenters on the call when the theorists you're arguing this vociferous Lee.
11:39:59 All the more reason to do an experiment right.
11:40:03 Yeah, let's see last.
11:40:12 My, my definition of quantum gravity is if you, if you don't have to quantifies the gravitational field. Yeah, it's not quantum gravity. That's my definition I, it's clear people have different definitions, but that's my definition.
11:40:19 And, and, also, I think the statement about loops versus trees is a little bit confusing, because I mean recently people have been calculating scattering amplitude in classical gravity, by using loop techniques and there's nothing wrong with it.
11:40:33 If you exchange multiple classical effects of a field it looks like a loop diagram, but it's, it can still be classical.
11:40:46 But they look quantization in in your eyes case, a quantization it's of course is there right so so you can say that, you can quantifies small population.
11:40:57 I mean, there and the easiest way, but ok but this would be, there is no boundary between existence between classical QCVM quantization of legal immunity is a quick summation, what I mean, there is no, no, I mean, of course it, I agree with you.
11:41:17 I mean, there is no not, I mean, of course it, I agree with you. But, but my might be a good thing to touch on when patients when people are talking about classical go if they argue that there is not made to quantifies.
11:41:27 This small place and the lake and make this an interest to me sounds strange, but I also thought that the quantum effects of gravity have already been seen anatomy interferometry or a neutron tree before that.
11:41:40 This is the phase accumulation, that goes from taking different pads is produced by an expert that gravitational field than that, it's already, but that doesn't that doesn't show the quantum superposition principle for the gravitational field itself that's
11:41:55 that's the crucial thing.
11:41:57 That's the effect of a classical background field on the shoulder cat state or some other system and atomic system. It doesn't show the same position field for the additional fields the crucial issue is does the, the macro you know the macroscopic gravitational
11:42:10 field satisfy a superposition principle or not.
11:42:19 Does that mean that it's quite it can. It's a crucial stepping stone to you having to have it, it's necessary. Okay, but it's not to show that you needed a full quantum description.
11:42:33 No, but I certainly say it's a necessary part of it. Yeah, there are several stepping stones and they're all important experimentally, they're all important experimental benchmarks, I think, I think, Monday one example I can give because I've been thinking
11:42:43 about these problems a long time I suppose if experimental is can ever create very thin long strings.
11:42:51 And the beautiful aspect about strings in three plus one dimension is that it doesn't gravitate, so I mean at the tree limb and say exactly to answer to this point.
11:43:01 So suppose if I can construct superposition have two strings.
11:43:06 Then there will be a one new computation.
11:43:09 Besides the which are tardies would love to see this kind of experiment, one day, but the problem is that is the press base but at GE square and the effect become so timing, that maybe we even with 50 years technology, it would be very very hard to do,
11:43:24 but maybe let's say 100 years if one can do that. That will be really really wonderful experiment.
11:43:29 Because you are really seeing one loop effect in the superposition, as well as entanglement.
11:43:40 Yeah, good. Okay, Dave.
11:43:49 Dave you're still muted you there.
11:43:52 Sorry about that. Can you hear me now. Yeah.
11:43:55 Yeah. So thanks for both of those talks this morning, I've actually got a question for Peter about this idea of using asteroids for detecting low frequency gravitational waves.
11:44:07 I've been thinking about the role of clocks in those measurements. So if I understand properly the clocks are located on these asteroids and they're sending out very regularly timed pulses, and you're measuring the arrival time of those pulses, relative
11:44:24 to the local clock. and what that gives you is a distance measurement between the asteroids. So, if I understand that correctly, it seems like if you instead have a third asteroid.
11:44:40 You have some source of pulses there and you send it out simultaneously to other sources you have a retro reflector. and then you measure the arrival time coming back.
11:44:51 It's much more similar to the Lisa concept, and it would reduce the requirements on the atomic clock, almost trivial requirements. At that point, yeah definitely exactly it's the usual sort of trade off that we have even in the middle of hurts band sort
11:45:10 of just, you know, just like the the nice atomic clock paper was pointing out okay you know this atomic clocks give a different way to pick up let's say that same sensitivity curve that Lisa picks up with the atomic clocks indeed you would, in principle,
11:45:26 only need a single baseline, whereas, you need to baselines are a triangle.
11:45:34 If you're not using an atomic clock. Exactly. That's right. But, but exactly as you say you can either use the multiple baselines like Lego and Lisa do or you can just use really good clocks and then a single baseline.
11:45:45 That's right and you definitely have that choice here to
11:45:49 the, so So in principle yes and that's also definitely like an interesting mission architecture to keep in mind.
11:45:59 It does worry me more I mean I ok I guess I suppose it's also probably a question to you how hard you think it will ultimately be to make a space qualified clock at this 10th of minus 18 level.
11:46:10 The reason I say that is running this triangle with uncontrolled proof so Lisa, of course, has, you know, very carefully chosen the orbits of their satellites.
11:46:23 Right, so the relative motion between the proof masses is minimized. Whereas you can't do that with asteroids you have this huge relative motion.
11:46:33 And to me, that makes it sound like so they have you know tight specs on the relative, the, you know, differential arm length change between their different arms, right, you can't do any of that I mean I'm like you know these things are got some eccentricity
11:46:47 that our life will be changing by you know point one au or something.
11:46:53 So that's what led me to be let us begin by thinking about atomic clocks but but yeah In principle, that's not a, let's say, this is where we started because we're mainly focusing on how good the proof masses so I think Yeah, considering all options is
11:47:06 still very interesting, for sure.
11:47:10 Yeah, I don't know exactly where the best trade off lies I mean I think if you can avoid having to get a 10 to the minus 19 level clock in space then it's worth thinking about.
11:47:23 And, you know, delivering retro reflectors to a bunch of asteroids and, you know, using numbers and in that way to get rid of some of these systematic effects like what you're talking about.
11:47:36 Seems like an attractive option to me.
11:47:40 So it's an interesting thing to think about, for sure. Yeah, no, definitely no absolutely that's absolutely that's very interesting comment for sure.
11:47:49 Yeah you know you need you need the link on every aspect, so you need the transmitter you need the receiver and transmitter and every ass are near and on or near every asteroid, but yeah absolutely it's it's possible that ends up being the way to go.
11:48:02 Oh, why, why, could you not just do retro reflectors on every asteroid. Um, well okay depends what baseline you're going for but we think we really do want a pretty long baseline, and then you really need the power source you know you lose too much.
11:48:20 Your, your shot and it will become very small, if you just have a retro flag to sit Same, same way LISA does even have a much smaller baseline.
11:48:27 The, I mean I didn't really go over it at all but the link noise curves I showed just assumed.
11:48:33 That's the link noise for one way, not for across and reflecting back. That would be much much worse.
11:48:40 Okay. But, you know, that may be fine I mean you missed it however what you're saying I think is still very interesting I mean like I said that's is the, the other sort of mission architecture and very much worth keeping in mind.
11:48:49 There's no real reason you can't have a satellite just hovering near or on an asteroid.
11:48:57 Thanks. Yeah. The new film had his hand up for several minutes now.
11:49:03 So, I mean, I think the dream thing would be to send these clocks, to the Kuiper Belt.
11:49:11 If we can if NASA is willing to do that that would be fantastic because you know as.
11:49:17 Of course this is just my dream that you're stripping pass to the empty space. And that might be a way to even see if there is a neighbouring black hole, sitting there.
11:49:28 And I'm between me observers will perhaps never be able to detect it.
11:49:32 But in such a clock who would be able to detect it actually would see if there is any small, you know, gradient gravity gradient noise if it picks up.
11:49:49 So I think this program of clock is fantastic if we if we can build something like this. Yeah, absolutely. And in fact, you also win for gravitational waves and everything by going farther out in the solar system would be would be very interesting, I
11:49:56 agree. I don't know how to cost that but you know I'm not a not a not a net satellite engineer obviously but but yeah, for sure. Yeah.
11:50:06 I endure Tim picked up a normal accelerations for a while.
11:50:11 That was like full DC so I don't think you have to worry about that if you're not going to go into the full DC mode.
11:50:21 But yeah, they had to track all the outer bodies but there are a lot less outer bodies and there are in the asteroid belt. So, i, right.
11:50:38 Yeah, yeah, you know, and yes not being a DC is is crucial.
11:50:43 Yeah. Any other questions for to morning speakers in the latest morning session any other topics to raise.
11:50:53 Um, I just exchange exchange email with Ted. He said he had to leave for a committee meeting.
11:50:59 You know we're all professors and scientists, we have to go to committee meetings, and he left it exactly the wrong moment.
11:51:07 I'll certainly twist his arm to make some comments.
11:51:10 Tomorrow, both on his own behalf and he's also read Bob was paper carefully, which speak to this classical versus quantum debate.
11:51:21 The economic comment just on this topic for a second, I think, Lance I'm not sure Lance you asked the question to Peter about nano graph. And that guy align my understanding is that people have claimed that Daya once it runs long enough and that's the
11:51:36 crucial time can be can be much more sensitive in that, in that frequency range to things like cosmic strings or some background stochastic thing, and then the nano graph, but I think it requires a minimum running time or something like five to 10 years.
11:51:52 Right.
11:51:54 because it's extremely low frequencies. and yeah.
11:52:00 But have they presented any results on shorter frequencies yet it sounded like that was a proposals proposed sensitivity.
11:52:08 I don't know it's a very good question, please you know there's a huge amount of data coming out of God, right, lots of different other groups also processing it for us and maybe it's all public, you can do with the public data, or you need to be great.
11:52:21 I don't know.
11:52:28 Okay anything more.
11:52:35 So maybe this is a big question to bring up this late in the session but I was really curious Peter about the ideas using kept ions to detect military charged particles, I think it was I wonder, can you give me a high level overview of the head.
11:52:54 Yeah, actually, I'm happy to Yeah, I can give you the one minute version, maybe, and then also I'm happy to follow up with you and or anyone else I was actually a shame that I went too slow I wanted to talk about that too.
11:53:03 I'm excited about it.
11:53:05 The basic idea is the following that, so we were talking about millet charged particles and what I can show you in more detail but you just have to believe me for right now is that you know there's been a lot of interest in middle charged particles recently,
11:53:18 and a lot of interesting parameter space where I think actually Lancer someone's explaining this earlier, you know if you got a loop factor that was suppressing your kinetic mixing things like that.
11:53:27 Let's say I've got charges you know 10 miles 100 minus two down and maybe 10 minus four or five.
11:53:32 Those are actually, you know all the much smaller than the charge of electron large enough that they do a lot of scattering in the earth.
11:53:40 So, if they're out there, if they exist when they hit the Earth, they don't really make it too deep underground detectors, making it very hard to look for them in any of our traditional Dark Matter experiments.
11:53:52 So I'm glossing over a lot of subtleties here but that's the basic idea.
11:53:56 And then in fact actually incense some one really big problem is that the thermal lies in the earth.
11:54:01 So they become 300 Kelvin, which is about 30 million EV and kinetic energy, which is way below the threshold of any of the dark metal detectors we build as you may know, right so particle physics you know we usually in particle physics right we're making
11:54:16 a low threshold detector that might mean maybe we get all the way down to. electron volts threshold energy deposition for a dark matter detector. And that would be great, that lets you look for like dark matter.
11:54:26 But you know, but not 30 million EV, which is what you need to see something thermal eyes to room temperature which is an interesting scale anyway and no charges provide an example.
11:54:35 Um, what, what we got excited about though is that you do have a ton of these things I mean they get stuck in the earth, there's a lot of them around.
11:54:43 If there's even a few out there, they pile up in here because they're they're realizing, they're they're getting stuck.
11:54:48 So it's a funny population you're looking for a huge number of pretty low energy things we sort of in short story is, it looks like ion traps are really ideal for this they're really optimal right they have.
11:54:58 You can see really low energy kicks to them they're in that sense there are fantastic particle physics detector, with a really low threshold.
11:55:07 They don't have a lot of target mass right compared to, tons Xenon it's something you have a few ions in your trap, but that's okay. These are particles of high charges a very high scattering cross sections so and and large number density.
11:55:20 So, and large number density. So actually, the, the ion trap may be an awesome fence really optimal dark energy detector for this kind of particle with low energy deposition but a very high cross section.
11:55:31 So that was the.
11:55:33 Maybe the one minute summary, but but I actually would love to talk to anybody who's interested in ions or anything more.
11:55:39 So, yeah, that sounds like something would be really interesting to look into in a little bit more depth. There are several experiments in our group that you know could do measurements in that direction.
11:55:53 Perfect. That'd be great. Well yeah, maybe I'll follow up with you and anyone else who's interested yeah just just ping me send me an email or something.
11:56:01 Yeah, I'm Flaminia has her hand up, please go ahead.
11:56:06 Yeah. So, thanks a lot so I just wanted to give a comment on this result by Bob well that that was mentioned because I've actually worked on that as well.
11:56:23 it. But yeah, maybe I can, I can tell you briefly what the content of that of the theories, please.
11:56:29 I'm an author of the paper. Also, so maybe I can draw
11:56:30 So basically it's an experiment where you have important permission language, you have two parties that isn't Bob.
11:56:40 And, and each of them has a particle So here you have a particle Ellis, that has an observer Alice that has a massive particle that produces a gravitational field so it's the source of the gravitational field, and the setup that you use here is linear
11:56:53 as gravity.
11:56:54 So, it's a, what has been discussed in this discussion session before.
11:57:01 And initially Bob holds his particle in a chop. So, it doesn't feel the gravitational interaction, and you open the superposition in Alice, long before the experiment starts.
11:57:15 So that basically the Newtonian field is not an approximation. So it is exact, two, three to the gravitational interaction, just with the Newtonian field.
11:57:24 And then at some point, Bob can decide whether to release it struck struck or not.
11:57:31 And if Bob is a trap. Then the particle of Alice in the particle of Bob and the gravitational field, become entangled whether if Bob does not really strong, the state from inseparable.
11:57:46 So now imagine that you'd want to describe everything, but just with classical gravity So, but, you know, but you still keep the fact that you have any interaction.
11:57:57 So basically, unless the key point the crucial point of the discussion is that, unless you can see the vacuum fluctuation of the gravitational field, and the emission of gravitational registration superposition.
11:58:10 And remember that, using the Newtonian view was not an approximation, in this in this result, then you end up with faster than light signaling. So basically, Alice can know whether Bob release the truck or not, before like Chrissy time.
11:58:25 So, this.
11:58:30 So the fact is that you only use the Newtonian in here, and you didn't need any regard that potential or anything because this tuition will start to click Alice.
11:58:37 Alice doesn't move the mouse before, so it's it's not, it's really not procrastination. So it seems that you're forced to introduce some quantum features of the traditional field and you cannot simply explain.
11:58:50 So either you have to give up, no Faster, faster than light signaling principal or you need to introduce some quantum features of the additional fields in the description of this thought experiment.
11:59:02 So the thing is that, of course, the crucial point here is that is the reality, so the, you need to assume the gravity immediately entanglement. Once you do that, then it is not a problem to treat it with the Newtonian field and you are forced to introduce
11:59:18 these quantum features of gravity.
11:59:20 So maybe an enormous just contribution discussion
11:59:26 that clarifies things greatly for me anyway thank you very much. Thank you were reading way late but so discussion has been worth it.
11:59:35 We're running way late but the discussion has been worth it. Well, you know, people can go to lunch anytime they want to let's keep talking here a little bit of a newcomer.
11:59:45 Yeah.
11:59:46 Thanks for coming as it's good that you explained it, but one thing which I was a bit cautious about as us speaking that suppose even if you take a matter of interferometer.
11:59:58 It doesn't release that many gravity fans, even though it's a trap it's actually you can think about it as a kind of like, you know, black to black holes oscillating around each other, but the number of gravitate towards the onshore gravitate towards
12:00:13 em is so tiny that almost negligible action.
12:00:17 So it's not the onshore aspects which is important, is just the, the official fluctuation that's important here.
12:00:26 Well, but in any case, even if the number of gravitas is very small, then you will always find that there is a threshold. So, which depends on the distance and then the energies.
12:00:37 So it's really a delicate balance between all the different physical quantities that are at stake here, which makes it possible to have faster than let's signaling and of course if you will have, if you have less gravity and emission than you will also
12:00:55 have less gravitational interaction and don't, it all depends on the distance between Allison Bob and how big your superposition is the pharmacy your possibilities.
12:01:03 So there are different physical quantities that make that combined perfectly. So that's basically you then you have no paradox, if you, so you have no faster than let's signaling.
12:01:15 If you take into account this, these two elements recommending fluctuations and the mission of repetition radiation.
12:01:21 And, yeah.
12:01:31 Igor did you want to follow this up. Yes sure if I may.
12:01:32 Yes, I was following discussion passively was putting my kids to bed. Finally, managed.
12:01:38 So I just wanted to mention one I think issue which hasn't been said but I think you can greatly clarify the issue between classical and quantum cheer.
12:01:54 Namely, it all falls around the notion that we work in the Newtonian limit.
12:01:55 So the Newtonian limit we just have the courage to potential. We have a perfect theory without any quantization just a potential entity tangles our systems.
12:02:04 So from that perspective is purely classical think the statement to say that such a source test masses can probe quantum gravity relies on one initial assumption, and I don't think this has been stated here explicitly but this is always included in all
12:02:20 these formulations, namely the assumption is that gravity is described as a local field theory.
12:02:29 And this does not work for a classical local few theory. If it has to entangle system.
12:02:34 But, so then if it's a local theory has to be context, in order to entangle the systems.
12:02:40 So there is a classical description which is perfectly valid will just Newtonian instantaneous actually the distance. That would be fine to be sufficient but if you assume it has to be a local theory that has to be contest.
12:02:53 So I think it's in this sense that these experiments can probe, some type of quantum nature of gravity under deception assumption.
12:03:01 Yeah.
12:03:03 So something. Yeah, please. I mean, yes i i agree with that point actually I mean, at least I think both papers both new permanent but also by you know like a federal and others who in a letter, who worked on this.
12:03:15 Well, aside, you know, explicitly you precisely can't have a non local interaction right that's going on in some sense, otherwise you don't the theorems for the classical channel content tangle, you know to quantum systems actually breaks down.
12:03:33 But can I say something, I think it's a little bit confusing I think this is the thing that worried or cardi that always Racing's in terms of virtual Gravity Forms we know we can always find me like all filter calculations, where you never use the phrase
12:03:45 virtual particles right that's not the way it is, it's a it's a sort of gauge and description dependent way, you can always really do things with everything on shell.
12:03:57 And so, I think it's useful sometimes to rephrase those statements in what was going on in terms of on show grab it sounds.
12:04:07 It's still missing some things interaction, even miss quantization. Yes, so. So then the question is, with the experiment is sensitive to, you know, kind of.
12:04:17 But he said that to say that when they are quantization like a local field see, you know, kind of in a nice clarity.
12:04:32 Samson beyond instantaneous interaction. If he's not sensitive then it doesn't matter right because it doesn't save instantaneous interaction.
12:04:38 As a Newtonian imitator.
12:04:41 And then I need to find this experimental signature of nonlocality as a one which john mentioned that it should be something which is beyond this is the direction right, the signal, you know difference between say, I don't know if the magnetic case and
12:04:42 I.
12:04:59 this one, right.
12:05:01 and I do not see.
12:05:04 This was pronounced is because entanglement by itself would be, you know, like you say, not like Like you said, you know, would be like a normal is something you said that action, you will respond to.
12:05:15 So we need to do to go with this no signature.
12:05:19 Well I think I think it's one of the issues that really pushing on but this is the second or third stage experiments, you'd want to do it such you can actually see the causal nature of the entanglement building up.
12:05:28 Right. I mean, that's the crucial thing but that is super hard to do right because you need very sure john is a very interesting marriage, I love it what you are, what both of you are raising the issue is very interested in physical one can do it.
12:05:40 Awesome. So imagine, and you can just exactly the look at locality of the quantum field theory, suppose you create the says to strangle our competitors.
12:05:57 Because right now the clocks are very good. They can reach up to the position of one part intended to 18. So, if you drop the other one.
12:06:05 Inside the Litecoin within this procession of tennis to minus 18 second, you can even test, the Litecoin structure of the essential field theory, and that's something beautiful thing which no one can in principle, one can do it, of course, in reality,
12:06:19 it would be very very hard, but yes, I didn't think you agreed in principle, but I think in practices is, you can't do the gravitational entanglement of things in that, in that cause of why you would want to do that in the end.
12:06:31 Yes, you would want to do that. Yeah, yeah. No, but I mean, if he is no negativity system, then all this kind of nonlocality if it would be surprised by know I mean by this parameter right so so it would be.
12:06:47 I mean, so you made something where. So, so in this way you, you are sensitive to, to find it, where you have a velocity of life, right, you should be sensitive.
12:07:01 Yeah, I think we better bring this to a close and just a minute or two on NMS you have your hand up please go ahead and please get quite quick yeah thanks I think to crystallize what sort of going on what you really need is a loophole free belt test of
12:07:18 entanglement generated by gravity, right, that is really what we are talking about here and that I think would be the unambiguous signature quantum effects of gravity has not even been done with the nuclear forces because you would have to do your experiment
12:07:34 on a timescale of I don't know 10 to the minus, such a large number.
12:07:41 So, I mean, yeah, it may happen someday, but I think that is that that would be the ultimate loophole free and ambiguous. Yes, Yes, quantum aspect of gravity.
12:07:52 I disagree with that if I may say there's a confusion. Namely, if gravity induces entanglement between other systems, whether you have a belt test of these other systems or not, will not resolve the issue that's raised by a party.
12:08:07 Of course the ultimate test is no belt test off gravitational you use of freedom themselves, that's of course a different story but that nobody has to the cloud experience.
12:08:16 So I don't think what you're seeing with address the issue of race by our cardi. I think our car these issues just goes down to the fact that if he, you know, we know how to get the Newtonian limit have any fear theory, and then the Newtonian limit.
12:08:32 You know, we have a classical interpretation, and that just, you know, it's a potential in Schrodinger equation and we cannot tell much about where these hidden degrees of freedom will come from.
12:08:44 So I do think there's this edition assumption when needs to assume.
12:08:49 With that, you know, there's some degrees of freedom, which are themselves some kind of local gigs of freedom that induce this this interaction.
12:08:58 No idea. Tell us about that. Yeah, I was probably sloppy in stating that yeah so I think the degrees of freedom in which your violate your bell inequalities Yes, is, is an important consideration yeah so if you, for instance, sort of, yeah so if you sort
12:09:17 of did the kind of experiment that people have talked about which is entangled things that are super positions of masses and doing spin readouts. I think if you did a battle violation of the spin degrees of freedom that would probably not constitute a
12:09:34 proof for the battle violation of gravity, I think, Is that what you're saying right you're right i think it would be the same objections that card is raised.
12:09:46 No, I agree. I I was sloppy in my statement yeah so you would have to do the bell violation on sort of some sort of center of mass position degree of freedom of object I don't even know what that would be.
12:10:00 But this is what the whole proposal is, this is what the spin entanglement witness for quantum gravity is, it is the equivalent to a belt and equality test, not honestly it's not a better test right because because to do a better state you have to be
12:10:09 sort of separated by a distance within which the light cannot communicate information right. That is precisely the reason why sort of the loophole free belt tests are done with the sort of huge experiments that have kilometers apart right.
12:10:31 Let's see, I'm going to use my chairs prerogative to cut this off. We have plenty of time to talk tomorrow, and I'll get to Florida Flaminia for one last comment.
12:10:41 Thanks. No, I just wanted to actually bring forth cigarettes point. And to say that I think I also think that the real challenge is to show that the, the masses local interact to the gravitational field, which would amount to sing that the gravitational
12:10:56 field is immediate or, and without doing that, I think, one cannot conclude.
12:11:04 The main point of what you're saying here, which is that gravity is the mediator of entanglement. And so, went to distinguish the nature of the gravitational field.
12:11:12 So that's, that's one of the main issues in this at least experiment that I don't know how that could be, that would be achieved.
12:11:24 Yeah, good well I'm going to applaud all four of the speakers today.
12:11:31 Holger Peter, Jason and Jamie and all the discussions to this has been a great discussion will have plenty more time tomorrow there will be more talks tomorrow on on these various subjects.
12:11:41 So thanks for all for coming. See you at ATM California tomorrow.