Sunday, December 6, 2020

Multiversality

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Recorded: 2020/06/25 Released: 2020/12/06

Jim and Randy discuss rationales for the existence of a multiverse, guided by quantum mechanics, string theory, and the anthropic principle.
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Notes:

1. The papers we read for this program:



2. Related Episodes of Physics Frontiers:


3. Randy mentioned Sabine Hossenfelder's video on String Theory.

4. Jim mentioned Ian Hacking's The Emergence of Probablity.

5. Please visit and comment on our subreddit, and if you can help us keep this going by contributing to our Patreon, we'd be grateful.

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Transcript (Rough Draft)
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Sunday, October 18, 2020

The ANITA Experiment

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Recorded: 2020/06/04 Released: 2020/10/18

Randy tells Jim about charged black holes, which exhibit an interesting reduction in their gravitational attraction. They discuss the Reissner-Nordstrom metric and an alternative theory.
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Notes:

1. The papers we read for this program:
  • Anchordoqui, L.A., V. Barger, J.G. LEaned, D. Marfatia, and T.J> Weiler "Upgoing ANITA Events as Evidence of the CPT Symmetric Universe" Letters in High Energy Physics 1, ? (2018). [arXiv
  • Gorham, P.W., et al., "Characteristics of Four Upward-Pointing Cosmic-Ray-Like Events Observed with ANITA." Phys. Rev.< Lett. 071101 , (2016). [arXiv]
  • ICECUBE COLLABORATION (over 250 "authors"), "A Search for ICECUDE Direction of ANITA Neutrino Candidates." ApJ 892, 53 (2020). [arXiv]
  • Safa, I., A. Pizzuto, F. Halzen, R. Hussain, A. Kheirandish, and J. Vandenboucke, "Observing EeV Neutrinos through Earth: GZK and teh Anomalous ANITA events." Journal of Cosmology and Astroparticle Physics 2020, ? (2020). [arXiv]
  • Romero-Wolf, A., et al., "A Comprehensive Analysis of Anomalous ANITA Evens Disfavors Diffuse Tau-Neutrino Flux Origin." Phys. Rev. D 99, 063011 (2019) [arXiv]



2. Related Episodes of Physics Frontiers:


3. ""The Saga of Atomspheric Neutrinos" by J.G. Learned at teh University of Hawaii. A perspective on the history of neutrino physics that Randy sent me and I mentioned in the podcast.

4. Please visit and comment on our subreddit, and if you can help us keep this going by contributing to our Patreon, we'd be grateful.

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Sunday, August 16, 2020

Electromagnetic Gravitational Repulsion

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Recorded: 2020/05/21 Released: 2020/08/16

Randy tells Jim about charged black holes, which exhibit an interesting reduction in their gravitational attraction. They discuss the Reissner-Nordstrom metric and an alternative theory.
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Notes:

1. The papers we read for this program:
  • Lo, CK "Comments on 'Unification of Gravity and Electromagnetism by Mohammed A. El-Lakany' and Einstein's Unification" Journal of Physical Science and Application 7, 28 (2017).
  • Graves, J.C. and D.R. Brill, "Gravitational Bounce." Phys. Rev. 120, 1507 (1960).
  • Carter, B., "Complete Analytic Extension of the Symmetry Axis of Kerr's Solution of Einstein's Equations." Phys. Rev. 141, 1242 (1966). The next reference is so short, familiarity with this one is important.
  • Carter, B., "The Complete Analytic Extension of the Reissner-Nordstrom Metric in the Special Case e2 = m2." Phys. Lett. 21, 423 (1966).
  • de la Cruz, V. and W. Israel, "Gravitational Bounce." Il Nuovo Cimento 51, 6444 (1967).



2. Related Episodes of Physics Frontiers:


3. The Nature of Space and Time [Amazon], a debate between Stephen Hawking and Roger Penrose about relativity and cosmology. A very accessible, and recommended, discussion. As I mentioned to Randy, it's a good place to get acquainted with Penrose diagrams.

4. Gravitation [Amazon} by Misner, Thorne, and Wheeler. Contains all the information about gravity that you always wanted to know.

5. David Waite's general relativity on-line textbook and YouTube Channel.

6. Please visit and comment on our subreddit, and if you can help us keep this going by contributing to our Patreon, we'd be grateful.

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Transcript (Rough Draft)
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Tuesday, July 7, 2020

Sterile Neutrinos

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Recorded: 2020/04/24 Released: 2020/07/07

Jim and Randy explore dark matter proposals based on sterile neutrios. Even more difficult to detect than the three active neutrinos of the standard model
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Notes:

1. The papers we read for this program:



2. Related Episodes of Physics Frontiers:


3. Please visit and comment on our subreddit, and if you can help us keep this going by contributing to our Patreon, we'd be grateful.

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Transcript (Rough Draft)
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07:26:11 Oh, and welcome to physics frontiers Episode Number 52 sterile neutrinos Show Notes for this episode can be found at frontiers dot physics@n.com slash 52 shows include the papers that we discussed in this program as well as links to related physics frontiers 07:26:30 episodes. And now Jim and Randy. 07:26:33 Okay. How's it going, Randy what's going on. Jim, it's good to hear from you too. Today we're going to talk about sterile neutrinos sterile neutrinos what is a sterile nutrient already. 07:26:43 Alright so, we all know that the neutrinos are incredibly weird because back in 98 they discovered that the neutrinos coming from the sun were oscillating, so they're changing from one form of neutrino to another form of neutrino to another form of neutrino 07:26:58 on their way to the earth, which is just bewildering. 07:27:02 So now, of particle physicists and cosmologists are looking at the idea that there may be another type of neutrino, that's different than this, the three that we know about the electron neutrino the tower, the new on neutrino in the town neutrino, then 07:27:17 there may be a kind of a neutrino which only interacts with other neutrinos through the week force, and with gravity, but not with anything else, or rather through mixing it's through mixing right yeah it's see it's through mixing it's not through the 07:27:35 week horse. So the whole point of the several neutrino is that it does not interact with the weak force. And that's why you can't see it, but it does have an impact on like the ratios that they're seeing in. 07:27:45 What is it short baseline neutrino detection experiments. Well yeah for the first paper I think he was talking about that a lot and they showed up in the other two but the whole idea was for these reactor experiments and these disappearance and appears 07:28:01 experiments, you have a short baseline that's a short distance between oscillations you remember what the distance was down. 07:28:08 I know that it was pretty short like on the meter scale, I think. Yeah, so it was on the meter scale not on the 20,000 kilometer scale like the regular oscillations. 07:28:18 And so they were looking at those things and they said we have to have these really massive neutrinos. 07:28:33 You don't have to have but one way to explain that is, is that you have these massive neutrinos that are sort of in the neutrino mix. yeah so they what they they honestly into that form on rare occasion, that's the idea so that's why they. 07:28:39 That's how they're explaining away like the five or 6% discrepancies are seeing in those experiments. Yeah, it has to be very rare, or that is because the oscillation frequencies related to the difference of the square of the mass, you know these normal 07:28:54 neutrinos are less than 170 million electron volts. If you add up the normal neutrinos their mass is less than 170. million electron volts. 07:29:06 And this other guy has to be somewhere around one electron but at least for the kinds of the talking about in the first two papers. 07:29:15 In the third paper they get really really massive, but I mean as a comparison and electron has a mass of about one half of the mega crumbles about 500 to electron volts. 07:29:28 So these guys are like 3 million times 30 million times something like that. That's massive. 07:29:35 And then, with all of the different constraints, the heaviness of the normal neutrinos and the active neutrinos he called active because it interacts with the weak force. 07:29:44 The heaviest of those could be 70 million electron rules. 07:29:48 That's the maximum NASA could have because that 170 million lead from volts is a maximum size or a maximum limit for the sum of the three it could get down to as low as about 59.5 million electron volts. 07:30:04 Wasn't that first paper the first article that they talk about a sterile neutrino with a massive like 1.7. 07:30:11 electron volts. It was like a range between like point six 1.7 electron volts, I think, Well yeah, they've got two different experiments. The appearance and disappearance experiments and those should have about 0.6 electron volts squared, and the reactor 07:30:25 experiments should have a mass difference between the smallest neutrino the lightest neutrino and the neutrino of 1.7 electron volts squared. 07:30:37 And me take the square roots for both of those things it gets closer to one electron bolt for the mass and that latest between know probably doesn't matter very much at all because the latest nutrients at maximum could be 50 million electron volts or 07:30:51 one 20th of an electron balls in this. 07:30:55 Okay. All I did was I took all the information that they gave me and I found the limits for each one of the neutrinos in the latest one has a range from zero to 50. 07:31:06 million electron volts, or actually a little bit lower around 49.5 million miles, and then you know the other ones have the other ranges as well. And those are all inferred right that based on the probability of them shifting from one form or the other, 07:31:20 right. Yeah, and I think they do that by looking at the Z, with the width of the energy line for the Z Bowser. 07:31:30 Yeah, because neutrinos interact with a Z bows on the W bows on, and they'll definitely also interact with leptons like the electron right neutrinos yeah yeah the regular old neutrinos show up in electron decays, and that's how the weak force was first 07:31:48 postulated, and the neutrino was first postulated was because there was a little bit of a problem with the energies, with the old reactor experiments with the old model chamber experiments. 07:31:59 They postulated that something was going on with neutral particle. Yeah, I'm going to skip the history Cohen Shut up. 07:32:06 Well, let me ask you this because this is this is a question that was didn't see answered in those papers because I, I should have done some deeper digging but is there a difference between the electron neutrino that the Mulan neutrino and the town neutrino, 07:32:21 other than their rest mass. 07:32:23 Like, do they have a difference in their properties or anything. Yeah, I mean they don't have charges. Yeah, and anything else so they're just neutrinos that show off with interactions involving like the new on in the towel on as well. 07:32:38 It's just a towel particle I don't know if the only difference between them is the rest mass. 07:32:43 Then, isn't it more like there's like one type of neutrino there that's changing its maths. Well that's what the oscillation say, yeah, that's what I'm saying is that though the oscillations suggest that the nutrient all three flavors and neutrinos are 07:32:57 just a neutrino in three different states, well I mean that might be one way to look at I don't think that's the way they think about it. My feeling is the oscillation is just weird because what happens with the isolation is, you have the three real nutrients, 07:33:10 which are new one new two to three. 07:33:21 And then you have the three neutrinos we actually see which are the electron neutrino them you know and the tower neutrino, the real ones are the ones that satisfy all the fun symmetries of, you know, the standard model and stuff like that and the ones 07:33:28 that we see are some linear combination of those things so it's a superposition of those three different things and that's sort of what all that mixing angle is about. 07:33:38 And that's where all that talk about coherence and incoherence came in right yeah in that paper. He was saying let's give the name of the paper and the author to because we usually do that so people can follow you know completely forgot to tell everybody 07:34:01 we read something, a bunch of stuff like a few articles in the popular press plus some papers that were published basically what's happening is, if the mass difference is much smaller than your uncertainty in the square of the mass, then plane ways are 07:34:10 okay you basically end up with a very long wavelength. And if you have that very long wavelength, you can just assume that it's a plane way, but it's the uncertainties on the same order of your mass difference, and it's about that one to do electron volts, 07:34:25 volts, squared areas where the uncertainties, no longer have this thing that looks like a plane way then you have to wait packets because couldn't because your neutrinos more localized, and then if you have something that's really really massive, and 07:34:40 that'll show up in the cosmology stuff and means your material is going to be very localized and you aren't going to see any oscillations. Another question that came up was looking at this was it seemed like they were suggesting that the oscillations 07:34:53 aren't just like a random statistical thing as much as it seemed like they're saying that, that the neutrinos were interacting with either Wz bows ons or some other particle between the Sun and the Earth and ordered oscillate or those oscillations being 07:35:07 driven by an interaction, or is that purely a probabilistic function, my understanding from this is that it's probably list because they call it qualify probabilistic in it which made it seem like it was just the probabilities are just falling out of 07:35:20 like Ambien interactions maybe that's what I was thinking. Anyway, is not really any space that nutrient is can travel through where they're not going to have some level of interactions right. 07:35:30 Otherwise, like how could it neutrino go from like a smaller mass to a larger mass, if they didn't somehow get that energy from some kind of interaction right the uncertainty principle may be sufficient for that, but that means that we might be talking 07:35:43 about the interaction with the vacuum expectation value of the energy and the ambient space maybe like quantum field fluctuations. Because Isn't that how the uncertainty principle works and other models where they basically borrows energy from the vacuum 07:35:57 and then gives it back. 07:35:59 Alright, so I thought it was I thought was more particle based like it was like they were encountering, you know bosons or something in space. 07:36:06 I don't think that can be true. Well, maybe it's true maybe that's why they isolate but I mean they're saying that, even though these guys don't interact with the wh zero zones. 07:36:20 Please still. 07:36:22 Okay, I was just talking about normal ones, you can still stay with the other ones so they can so absolutely right. 07:36:29 with the wnz bosoms, then it can be caused by good week field, but they all have mass right so they all have to be interacting with the Higgs field right and that has a specific vacuum expectation value right so maybe that mass oscillation has something 07:36:59 to do with this interaction with the Higgs field. 07:37:02 Honestly, they spend a lot of time talking about the Higgs field in here but I wasn't always sure exactly what was going on. Yeah, it's a tricky subject the neutrinos are so unbelievably weird, and then to throw on top of this possibility of sterile neutrinos. 07:37:16 It's like, Holy smokes, because this is a whole other whole other ballgame. I mean, at least with most of quantum physics, you have discrete particles that remain discrete particles. 07:37:28 I guess corks do some kind of oscillations to generally just look at it as an idea like we don't look at the world right. 07:37:35 Yeah, the world was wave freaky or than we normally think, but at least normally like electrons, stay the same you know you think, you know, certain particles decay like a new ones that come into the atmosphere. 07:37:48 I mean, they all have a, an identity and when they decay that became very specific ways. 07:37:54 You know only only it was the, I guess the neutrinos and corks The only ones I can think of off the top my hand to do this weird oscillation thing where they changed from like one basically flavor to another right. 07:38:04 We should talk more about the sterile neutrinos so the accelerator experiments are the reactor experiments, I should say are indicating that there could be the presence of these several neutrinos with a rest massive somewhere around one electron volts. 07:38:23 In that, you know, mass square term, but cosmological either looking at sterile neutrinos with a much larger mass, like 3.5 kilo electron volts right well they're seeing a line at 3.5 cooler from volts per saying that the neutrino has to have 7.1. 07:38:38 electron volts, as its mass to see that line during the decay. Oh, okay. So, so the neutrino decays. So what happens is the circle neutrino isolates back into an active neutrino. 07:38:52 And that actually neutrino is excited so it. It's Wz particle I don't remember which one, and that z particle then splits off into two more neutrinos. 07:39:07 That's the signature that they're looking at in that 3.5 kilo electron volts line. 07:39:09 Now, I guess that's the explanation for the line so the line came person the explanation came later. But that's how they're interpreting that one. So they're seeing the photons with that much energy is that right the 3.5 kilo electron volts photons. 07:39:22 I don't think of the measurement of the neutrinos so eventually was have turned into photons. 07:39:26 Okay, so that's what they're thinking might be a dark matter candidate right that's what they think is a dark matter candidate, although it's really really heavy. 07:39:33 Yeah that is way heavier than the reactor experiments are indicating. 07:39:39 But on the other hand, cosmological Lee, like you know you see cosmic rays with tons of energy to right, it's way higher than anything we produce in a reactor, so I wonder I wonder if there's some mechanism cosmological that could explain the presence 07:39:52 of those high energy neutrinos, like maybe, I don't know black holes or something couldn't create a really high energy neutrino, I don't know. 07:40:11 I thought that was only like a hot, hot Dark Matter candidate. If they had the really low like one electron volts, rest mass but that it could emulate the findings are seeing, which is, which is like a cold dark matter of thing, if they were much more 07:40:35 because then they'd have what less kinetic energy right. I think that's why they call them warm. So at some point in one of these papers. I think it was the one we're talking about, which is no other role of sterile neutrinos in particle physics, yeah 07:40:41 the roles of certain fields in particle physics, which is a review article by Satan que con who's in Korea. Yeah, yeah. So I think that's the reason why they made the distinction between hot and warm, right, because nobody likes hot dark matter anymore. 07:40:59 Yeah, that's can work because it wouldn't clump right though, if it was hot, it wouldn't clump around the galaxies like we're seeing is that right. I think that's one of the reasons I mean there were a lot of reasons why. 07:41:09 It couldn't be about dark matter was explained galaxies, stability, and so I mean that would have been one of the first things that go into the theory so maybe after a while, people decided didn't work but probably there were a lot of other reasons that 07:41:23 went into that. 07:41:24 Well, I just think I mean if they were hot, and they you know they were real moving fast enough then they would have an enough kinetic energy they have escape velocity right so they want to gather in a nice cloud around galaxies right they just fly out 07:41:37 out all over the place in space like photons, possibly but I mean, at the time that people decided to, you know, neutrinos probably weren't the thing they were so, hoping that they were going to be with the Masada particles or something and he completely 07:41:50 Nast listen wander around and travel with the speed of light and all those other fun things you get to do when you have no mess. So I remember when Dark Matter first came out, the first. 07:42:02 No, you know. Well, I guess when it was being popularized in the press in the 90s. It seemed like our best explanation that point probably was something like a neutrino because it has to be something like virtually no interactions, other than gravity 07:42:13 And there has to be an awful lot of it. So this kind of brings that that idea back to life because even though your regular active neutrinos can't fit the bill, the sterile neutrinos might do it. 07:42:23 I don't think it ever really disappeared since the first idea about several neutrinos showed up I mean this persona neutrinos showed up in like 1968 or something like that. 07:42:32 Oh I thought that the like our first real indication that these babies existed was after that experiment that ran from like 1990 1995. We're at like Los Alamos National Lab. 07:42:43 Well I think that's the first time people thought they really need them. Oh, I see your theorized before that think there was a guy in Russia in 1968. 07:42:53 Yeah, I'm not going to try to pronounce his name. 07:42:54 First theorized them, and I think he was actually known for other things as well. 07:43:02 But there was no need for them, and it's one of these things where you're saying, basically, here's this thing that you'll never see as really important. 07:43:11 So, that's a great theory but you know we probably want to look for something that is a little more testable then later on they find out there's some deficiencies. 07:43:20 Once you find out there the deficiencies then you start worrying about things like that. Yeah, you're missing something right. 07:43:27 So there's also this weird, thumb. They call it tension, which is a nice word for it. tension between the appearance and disappearance arguments for the sterile neutrino. 07:43:40 So apparently they've got strong appearance, indications, but they have like counter disappearance evidence. So yeah, I mean the first paper actually seemed to be pretty good with both of them. 07:43:53 The first paper being sterile neutrino a short introduction, what I'm thinking about is the first paper is the one that basically started off people looking at several neutrinos is a really strong candidate, at least in this particular cycle, which was 07:44:07 are there several neutrinos at the electron volts scale. I cop. I'll Tony and Shrek. And that was in 2011, the other one that you're talking about this sterile neutrino a short introduction by now Marv from 2019. 07:44:24 And that's just going over the things that people sort of know extended some time in between there, or maybe just a personal judgment but sometime in the years, it seems like there was a falling out with the disappearance data because cop seemed to be 07:44:39 It seems like there was a falling out with the disappearance data because cop seemed to be pretty happy with using the disappear status to try to fit his three plus one, three plus two and one plus three plus form theories about the sterile nutrients. 07:44:52 And basically, he was using that disappearance stated help and try to get stuff, but there was an issue in the, in the 2019 paper. So those disappeared stated don't really seem to fit everything else, so we should talk about that. 07:45:04 Right. I mean there is another thing there that we didn't mention which is, if there's one sister all neutrino, why aren't there more several neutrinos. 07:45:13 And in fact, when this cop was looking at the data. This guy's from Fermilab. He didn't think that having just one certain neutrino get the right and he wanted to. 07:45:24 Yes, so he thought he needed to to actually fit the data that he had from the LSND and the mini boon experiments. 07:45:34 Although the later papers, seem to think that both of these experiments were not correct in some way. 07:45:42 And we shouldn't think about them booth very heart. Yeah, Dimitri nama does seem to be kind of bearish on the subject, based on that disappearance data. 07:45:52 Well, but he still looks at several things. Well, basically, you know, we have the two different ideas here like appearance data says that if you have a decay new on, it's going to pay into an electron, or positron plus a electron neutrino plus neutrino 07:46:11 an anti immune neutrino right now anytime you neutrino. Then there's an excess there's more electron neutrinos and you expect, and that's what it maybe my appearance and disappearance they're looking at the reactors. 07:46:23 And, you know, somebody updated the theory, and all of a sudden, there were fewer on the order of six to 12% fewer neutrinos than you expected in reactors and in calibration sources and stuff like that. 07:46:38 So those are the anomalies that tell you that you probably need this has the logical data doesn't really tell you you probably need this, but instead you're trying to use this to explain the cosmological data right but there it has more logical data seems 07:46:52 to be not neutral but fairly aggressively against anything that anybody thinks up to explain it, at least as far as I can tell, because in this paper Lee I think you're right i mean this paper on sterile neutrino short introduction my novel paper. 07:47:07 He's seems to be pointing at Big Bang nuclear synthesis and the inflationary rate of the universe. 07:47:14 How that how the existence of sterile neutrinos would alter those models significantly. Right. 07:47:26 I think he said that the universe would expand faster during the inflationary epoch, and it would alter the nucleus at this is so that when we might get different readings on like a hydrogen isotopes and so forth or helium isotopes, can't remember which, 07:47:36 I can't remember what, but then in, and so that sounded really compelling like okay yeah if it's just going to change the, the entire Big Bang cosmology and give us wrong estimates of the prevalence of isotopes in the early universe then, this can't be 07:47:48 right. But then, reading in the role of sterile neutrinos in particle physics paper. 07:47:55 It seems like he was saying that because the sterile neutrino isn't going to interact via that weak force, and because of its, what was it its mass maybe he said that who actually want to be detectable they want to create a detectable influence on the 07:48:10 abundances of early isotopes. So they seem to be having two different viewpoints they're like that papers seem to indicate that the sterile the trainers are still allowable within the cosmological data, right. 07:48:24 So it's a very controversial area, no doubt. When I look at these papers, there were a lot of them that came out, you know, last week, even when this gets put up online, they'll still be a lot of makeup put out last week, so people doing a lot of work 07:48:38 in the area and trying to explain things with the several neutrinos, and maybe if I things that were not so ancient like these two and 2019 papers. 07:48:51 2019 is ancient now, you never know 07:48:56 everything could have changed. Right. But it's hard to tell because, you know, if you look at the press, everything is brand new and never been done before and all that other stuff so it's hard to actually use them as a guide to what's going on. 07:49:07 Instead, you have to sit around and read a bunch of 50 page papers, see if there's actually anything new one. Yeah, somebody thought there was something know at least enough new to publish. 07:49:18 Like I was saying, you know, we've got these different experiments with these different things. I think it is estimates of the parameter matrix element. 07:49:29 So, these things mix, right, you can talk about as an angle but really it's mathematically represented as a matrix that looks like rotation matrix is a unitary matrix it acts like a rotation matrix. 07:49:41 So, you have you, remembering something. According to a street grid, and then you wanted to switch it over to north, south, east, west sort of thing you'd have a matrix similar to that, you could use this to rotate the components. 07:49:56 And that's how they get the masses, right, because that works. 07:50:00 You have a mass, if they weren't rotated rotation. These are real rotation what it is is it basically gives you the superposition state of the neutrinos. 07:50:09 And so that's going to tell you well if you have an electron. 07:50:14 Then you have so much new ones so much new to so much new three. 07:50:20 Right. And if you have a new one, you have a different number for each one of those. So each one of the three neutrinos that we see is a different superposition a different linear combination of different combination of the three standard model neutrinos, 07:50:37 does anybody offer any explanation on. I'm confused because how can this sterile neutrino oscillate with with active neutrinos like how do you lose the weak force interaction. 07:50:49 And another way that's true but I think that's just part of the quantum mechanics, you know the oscillations are sort of part of the quantum mechanics, I think that part of the interactions, so you're just saying that, instead of having three different 07:51:02 standard model neutrinos you have the three center mountain credos, plus a sterile neutrino, or two, or seven or however many decide you need to make this work. 07:51:12 You just had an oscillation of more things. 07:51:14 So when you're trying to detect the neutrinos This is why the disappearance data is so compelling is you'd expect to be able to detect a certain probability from any reactor or the sun or whatever, but you're seeing a gap, like you're not getting the 07:51:41 that you expected. So it looks like you're missing something right to the tune of a few percent, you have postulate these sterile neutrinos it's really fascinating for the different experiments that mixing has to be smaller and smaller from different things, right. 07:51:43 right. So, for the reactor deficit disorder of the absolute value of the matrix element for the mixing between an electron and the poor country no has to be 0.1 for our friend now mouth, said the for cosmological stuff. 07:51:58 it sounds to me for all the cosmological stuff that e4 element has to be very very small, which means that it just doesn't happen, right. So, to explain this stuff in the early universe, basically, you know the Big Bang nuclear synthesis stuff, three 07:52:14 combination epic yeah and the cosmic microwave background and all that other stuff. If you try to explain those things, then that mixing element has to be very very small, basically, to the point where it almost never happens that the neutrinos will turn 07:52:29 into the several neutrino for a while. So that's a little bit weird for two different regimes actually put multiple regimes, either the largest in the smallest of the different regimes for them. 07:52:41 Yeah, he was saying that the cosmological arguments disfavor additional external neutrinos with math is larger than like point three electrons. 07:52:50 That's right. So those would be the order of these other neutrinos, and that also means that they be oscillating a lot with them, so you know it's starting to get to a point where it doesn't look like it's a completely coherent idea, but like I said there 07:53:04 are a lot of people working on it maybe there's a way to put it all together. Yeah, this is such a challenging area because they were running those experiments at Los Alamos National Lab for like five years and they got like 90 detections of neutrinos 07:53:18 over that period. We're used to thinking about you know the billions of inner of collisions they have per second or whatever the Large Hadron Collider. 07:53:26 So yeah, we're working with limited data, and it's such a nascent field of exploration, that there's all kinds of experiments and errors in there that we might not be able to see right, possibly I think you do a pretty good job of things. 07:53:39 Yeah. Is it got all these cross sections and everything worked out but still, the data is so limited right like it's so hard to get detections if you could get a few billion detections and you'll be a lot easier to analyze this statistically and get higher 07:53:51 confidence, but I did notice that they're talking about like three sigma confidence level that there's another neutrino right and this makes at least, but then they said that the combine the data from one experiment and a completely different experiment. 07:54:05 And I don't know if that's legitimate Can you do that can you combine data, then they said that it was like a six sigma confidence level for the existence of another type of neutrino. 07:54:15 And then, that kind of sets you back on your heels you're like shit four five is the standard right yeah I think that was the whole point of what top was doing right. 07:54:22 Yeah, That's right. On the other hand, he knows it's warm so great. And then when you look at sort of the ranges were these things could actually be. 07:54:32 They're pretty small. Right. I mean, they're pretty small and they're not really finding things there so it's a little bit worrying, to think about it that way. 07:54:41 And again, the data are not all consistent where would be so you look at this kind of experimented so it's okay with that it doesn't work at all, so they have very specific ranges, but as far as I know they hadn't really found anything there, and sometimes 07:54:56 some of these lines where they say the things have been cross off still kind of close to it so I mean possibly there's something there but, but it is and look really compelling, although I mean obviously they think it is maybe just want to be the first 07:55:19 one to predict it, just in case. 07:55:13 I don't know I mean that those discrepancies I mean, like you said, I mean, when you've got discrepancies on the order of like, you know, five to 12 or 13% or whatever. 07:55:22 That's pretty significant. I mean, even though we are working with limited numbers of detections they've been doing it for a long time. Right. And they do have a good handle on how often those interactions happen with the particles and their chamber and 07:55:34 they can detect that and they know what these are top quantum physicists figuring out these experiments, that's still a very significant finding think there's something going on there that they can explain. 07:55:44 I mean, the big significance about this is not so much the explanation not in the explanations interesting, but I don't really understand why there wouldn't be something else plus the line with the that pretty much says, There's no more neutrino except 07:55:59 PDSA well then it doesn't interact with anything. So neutrino that doesn't interact with the WMZ particles, but the discrepancies. Look, important enough to be one of these things we think it's one of the one of these places where the standard model is 07:56:13 going to break down right I guess that's why the pressing into it because that's our first exciting light for new standard model of physics right beyond standard model of physics. 07:56:22 Yeah, there aren't very many places where it looks like there are problems with the standard model. I didn't talk about it 17 a couple episodes ago there's this and there's like, there's one other thing that I have to say though I did lose a lot of my 07:56:33 excitement about the X 17 findings when I did some further reading and found out that apparently that same lab has been predicting this kind of particle on multiple occasions before over a period of like 10 or 20 years, and they were you know they're 07:56:45 wrong. On the other hand, the several neutrinos acts 17. You know what they're seeing is saying that there's something wrong with the standard model, the ideas that they have might not be the right ideas, but what they're seeing is probably significant. 07:57:03 Yeah, and that's that's more than we've gotten from the freakin multibillion dollar Large Hadron Collider which only really confirmed the Higgs boson and everything else. 07:57:12 Yeah, a lot of places we just see confirmations and that's nice, it's useful, but it's just confirming what seems to have been true already. Yeah, pretty well trodden since what the 70s or 60s. 07:57:25 You know the standard models complex enough, but I mean the places where it breaks down is where there's going to be new fundamental physics for the people who do that, because otherwise we're going to get really bored, does that to make a modification 07:57:38 of the Standard Model when they found neutrino oscillations. I don't know how much they had to change it. I think what happened is they sort of changed what they meant by an electron neutrino right to be this mix of the center of all neutrinos. 07:57:53 Okay, so it's pretty minor modification that in order to accommodate that. Because I don't remember they were surprised by it so it wasn't predicted by the standard bottle. 07:58:02 No, no, maybe not, but they were able to cobble it in, I guess, seems to be good enough. That's it kind of exciting thing because if they had to modify the Standard Model A little bit once for neutrinos maybe they have to do it again. 07:58:12 I mean if there's actually anything to this. 07:58:15 Yeah, well, was there anything else in these papers you wanted to touch on Jim, I think that's everything I'm mean for the last one, the rules paper I only read at once and so that pretty quick so see no I don't see anything except for notes telling me 07:58:31 to look up other things, see what the hell we were talking about, I have to say that I was really impressed when I was reading about how this all came about right how this Sterling Trina idea started or emerged in the like the disappearance data and all 07:58:45 that, and family lab like built like a special detector neutrino detector in order to test those results with equipment tailor made for that exploration. 07:58:57 And that was the mini boom, and now they're working on the micro Boone right so it's cool that they're building like customized detectors to explore these questions. 07:59:06 I'm more excited about these kind of like tailor made experiments to answers, certain, you know, empirically driven questions that come up that I am about this like building a bigger Collider, you know some places that can't build a bigger collider right 07:59:19 like in the middle of Chicago. Sure, and they're not cheap either you can't go building a, you know, increasing order of magnitude collision energies, you know, every year. 07:59:31 It's a really expensive way to go, but these are cool because they're, they're less expensive, and they're and they're looking to answer a specific question which came up, you know. 07:59:39 Okay. So, apparently, I do have a note here that says that me right handed neutrinos right so interact with the left handed neutrinos, and the Higgs particle via the collar interactions so it seems something about the form of the interactions, basically 07:59:54 saying that somehow there, they are pulling the energy out of the vacuum exploitation value of the Higgs field. Okay so, so the active and the sterile neutrinos, which are the left handed and right handed neutrinos. 08:00:07 They do interact, but it's mediated by this Higgs field. Well, I'm not sure, the way I, the way I wrote it down, it sounds like the both interact with a blue collar type interaction, but it doesn't say exactly what all pressroom. 08:00:23 Okay, That's the way I read down in my notes. The Ocala potential that that's that plays a big, big role in the strong force Right, yeah. So when you get to get your name on one of these equations, Jim. 08:00:41 I think it's a little late if I was going to do that I would have done it that way you Cal was he was some you know upstart like MIT grad or something. 08:00:45 On 25 I'm going to revolutionize physics with this equation, I don't know, let's see, he was born in 1907, so probably not right he was like our age. Now he's probably is like 40 or something right oh geez, he was in the 30s. 08:01:01 So yeah, he was in his 20s. 08:01:05 So yes, you have to remember that next life. 08:01:11 So you got to give up all the good stuff when you're like a teenager and in the young adult in order to make your breakthrough and then you can like as party. 08:01:19 I should have put that put that backwards in my life. 08:01:23 Yeah, I don't think it works that way I think if you miss out on your 20s you never get them back. 08:01:30 Unless you move to New Orleans. 08:01:36 Yeah, I guess I've seen a couple guys in New Orleans try that. Burning Man to you'll see some of that. 08:01:40 That's another reason to stay with it. Yep, got it all hanging out baby. 08:01:46 All right, Jim, thank you so much for going over all this with me. So it's a really intriguing thing I mean there's definitely something something he's explaining here we just stare on the train was might be the way to go, or maybe there's something even 08:01:56 weirder going on with neutrinos that we don't know yet. There must be something weird going on with neutrinos, well there's something weird happening right because they can't explain away those discrepancies right. 08:02:06 Doesn't matter how big a hole you dig under South Dakota, you still can't find enough of them to figure out what the hell is going on, or Antarctica, like you've seen the ice cube right. 08:02:15 I've never been there No, I mean, I've seen photos right they made this gigantic neutrino detector under the ice, you know, it's crazy. That's a good place for not going to get very many visitors. 08:02:27 I'd love to see it but there's just no freakin way I want to go into the freaking it's archaic yeah that's another thing you miss. 08:02:33 I did have a friend who decided to go down, down there oh yeah but 08:02:40 yeah I don't, I don't remember I just remember he decided I'm gonna take six months out of my life and live in an article, Jesus, I don't know why I decided that, but then I never saw it again so 08:02:52 you know if you made it back. 08:02:54 Well, I don't even know if he made it there. Okay. Was there an intro definitely is the ARPANET back then or something. Oh, man, that was a long time. 08:03:02 It was probably 94 so with the people I was hanging out with. 08:03:06 Oh, right. Well, that is a wrap. All right, Jim, we have a great week. Oh, you want to do this in a week. Yeah, absolutely. We know we got the pandemic vacation going on so let's make use of it remain sterile disinfect your groceries in the, you know, 08:03:21 we'll make it till next week and we'll do another one that's a horrible thing to say to them. 08:03:30 I'll talk to you later right duel friend gave 08:03:32 You have just listened to episode number 52 of physics frontiers sterile neutrinos Show Notes for this episode can be found at frontiers physics FM com slash 50 to show notes include the papers we read for this program as well as related episodes of physics 08:03:50 frontiers. thank you very much for listening, and good night. ------------------------------------------------------------
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Tuesday, June 9, 2020

Gravitational Wave Astronomy

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Recorded: 2020/03/19 Released: 2020/06/09

Randy and Jim about the perspectival nature of quanta, the Unruh effect, which says that for highly accelerated systems, additional particles and temperature will be seen.
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Notes:

1. The papers we read for this program:



2. Related Episodes of Physics Frontiers:


3. Books discussed on this podcast:
  • Shutz, B., Gravity from the Ground Up (2015). A well-written elementary text on astronomy. It has a very interesting format where the mathematics is eliminated from the main text, but it includes boxes that do simple calculations mixed in the main text. It includes many topics in genreal relativity including gravitational waves. [Amazon]
  • Shutz, B. A First Course in General Relativity, 2nd Ed (2009). I guess I have the first edition from 1985, but it's the second copy of the book I owned because when I was a grad student ca. 2000, I gave my copy to an undergraduate (who was really interested in GR and said the book was, at the time, out of print). It is more detailed than the book from my undergraduate special topics course, but it is more-or-less standard for the time, with at least as much discussion of tensor analysis as relativisitic physics. [Amazon]


4. Please visit and comment on our subreddit, and if you can help us keep this going by contributing to our Patreon, we'd be grateful.

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Transcript (Rough Draft; Added 2020/07/02)
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10:16:18 So Randy what's going on. Good to hear from you, Jim today we're going to talk about a really exciting topic that I just absolutely love and is truly a new frontier in physics and astronomy. 10:16:28 New Frontier a physics and astronomy, what are we talking about today. Gravitational Wave astronomy. This is the field of research, which has been theoretically and all kind of observational II developing for decades but now with our first direct detection 10:16:48 of gravitational waves at the Lego facilities were up and running. So we're in a new frontier, where we can learn things that we could never have learned before, and we can probe into regions of space and time that we could never have gotten data if direct 10:16:59 data from before. And, you know, I was thinking about this when Sabine Haas and Felder, did a YouTube video where she was talking about how she doesn't really think that building a bigger particle collider than the LSC is really such a great idea. 10:17:15 And she said, where we can really learn things that are new and help physics progress is in the realm of astronomy by studying dark energy and dark matter and this gravitational wave astronomy is exactly the kind of tool that we need in order to, I think, 10:17:29 get the observational data and move Theoretical Physics for it because the universe is kind of perplexing us at these scales. And I think we're going to learn a lot more by looking outward than we are, by looking at a particle collisions right now. 10:17:43 Well yeah, there's a lot of things that you can learn about this what particular things were you thinking that we could learn. Well, one of the first things that started to come out in the popular press when they detect the gravitational waves from the 10:17:54 collisions of black holes and so forth. And they've had a lot of protections I didn't realize like it's been it's been rapidly advancing over the last year or two. 10:18:02 They had maybe a dozen detections from advanced language Virgo, I think, in 2015 2017. 10:18:13 And then, in this past year, why goes come back online. 10:18:18 And they had around 65 or 70. In the past year. That's right. I put a there's a, you can look on, there's a Wikipedia list of gravitational wave observations and it's just goes on and on and you're like oh my God, if you're really busy the last year, 10:18:32 in so holy smokes, I mean this is so March when we done this and they came online last April, and so it's around six a month or so. Yeah, so this is a burgeoning area of research this making huge progress already. 10:18:58 that emerged when they detected the first gravitational wave collision like gravitational waves from a collision of astronomical bodies, they were talking about how you can actually based on analyzing the signal, like if you have a high enough resolution 10:19:02 with your detector, then you can sort of tease out what's going on inside the event horizon of a black hole as it's merging with another massive body right. 10:19:13 So we can start learning things about the dynamics within the event horizon for the first time. 10:19:19 Because gravitational waves see it can tell you about what's happening inside with a and how the masses are exactly colliding with each other when in the coming years when they start getting the Lisa, the space antenna online, then we'll be able to probe 10:19:34 the low frequency gravitational wave realm, and we can even start getting data from you even way way earlier than that. They're saying that we could get data about what was happening with the big bang it moments like with within 10 to the minus 24th second. 10:19:50 So this is a great advancement. That's throwing open doors that most of us have never even considered to be possible, like we could actually model the evolution of the era of cosmic inflation, for example, you know maybe theoretically will eventually 10:20:05 come up with an equation that shows us why this accelerating expansion happens in the first place. I think those are some of the goals and the long term, right, and this seems like a great way to get there. 10:20:16 Right. And this seems like a great way to get there. So a lot of things can be happening with the gravitational waves, and they were forced to take it only about five years ago. 10:20:23 I guess we should say like usual, we're looking at a particular paper that was written much earlier than that, right in. 10:20:32 Like 1999 2000 timeframe, which is gravitational wave astronomy by Bernard shirts, who's written a couple of books on gravitation one on general relativity that, as well as one on just gravitation in general I think called gravity from the ground up, 10:20:47 which is a lot more accessible because obviously the guy in the field. 10:20:51 So he wrote this review paper in 1999 telling us what he thought we could expect. 10:20:56 And he was looking into the future. He was like, he looked into the past and gave us a little summary of the kind of gravitational radiation theory that has already been sort of understood with binary stars and so forth. 10:21:07 But then he also looked step by step into as our gravitational wave detectors start detecting the first signals and then the next generation that refines them and so forth and so on. 10:21:18 So he was looking into the future and now we're in that future and it's, it's wonderful because he had a really clear view of what we could expect and what we're going to be doing and we're doing a lot of that stuff right now. 10:21:29 Actually, about two years ago. He put together a collection. I don't know what the collection is, I just found the article online gravitational wave astronomy delivering on the promises, where he talks about basically seven of those first dozen or so 10:21:43 events. 10:21:44 So when they measured that he went through and he talked about what they'd actually learned. He's done a little bit more on that. What I thought was really interesting was, there's another paper with the same name by William pressing Kip Thorne from 1972. 10:21:59 Wow. And the reason why they were doing it then is there was a guy named whoever that I think in Chicago, and he had a bar type interferometer, and he was claiming to have seen some kind of event, some sort of gravitational wave of them. 10:22:15 And so they went through all the physics in that, in 1972, you know, talking about different kinds of possible detectors and different kinds of possible events, which is more or less the same thing that just it was very interesting to find that, actually 10:22:31 there was another one in the 1980s that I didn't look at, I didn't recognize the name of the guy who did it. Since this other one was my clipboard and Kip Thorne is one of the guys who got the Nobel Prize, when they discover the gravitational waves because 10:22:44 was one of the three people important in life ago, I decided to pick that up and give it a look to, how does it compare because I found this paper to be pretty surprisingly well written and comprehensible. 10:22:58 I think he did it I think shoots did a great job of summarizing the field. I mean it's like a 29 pages, including the references. So it's not a very long paper but but he did cover a lot of territory in the broad strokes of what we're talking about, and 10:23:14 anybody can find this paper just go to Google Scholar and look up shuts gravitational wave astronomy and you'll find it on the archive for free. 10:23:22 I guess first they'll find it on the show notes, as we always put these in the show notes. Let me see if I can guess what the URL will be should be frontiers physics FM com slash 51 shows up there if you want to look at the papers we put all the papers 10:23:47 the papers that we talked about as far as how they compare, I mean the reasonably similar they talked about the same physics a Kip Gordon one is a little bit longer, has a little more math and it doesn't have a lot of really exceptional math. 10:23:52 So it's something you can actually read, it's something you can read and just skip the equations if the equations bother you, and it should be okay, which is the same really pursuits ships does have a few equations in there but they're not really equations 10:24:04 that will hurt your brain. Yes, pages or derivations it's just like here's, here's the formula that we use for estimating something, I mean they talk about more or less the same things. 10:24:14 You know a lot of this stuff was a lot more theoretical in 1972. 10:24:18 I mean, they did have those bar detectors in place at the time and I mean there are a couple of places in Italy, where they do have our detectors as well, but the interpreter detectors are the big thing but both of them talk about both of those kinds 10:24:32 I don't think that I don't think at that time they were thinking about something like Lisa, where you put three different satellites in the same orbit as the Earth around the Sun, you know making a giant equilateral triangle and bouncing light off of 10:24:47 them to try to figure out stuff about gravitational waves. Wait, you saying that the Lisa experiment will have like three different satellites that like a triangle elated at the Earth's orbit around the sun so it'll basically be like an Earth orbit size 10:25:04 detector. That's what I have here in my notes expected, 2034, five ESA, I wasn't sure if it was three satellites were going to be in, in the orbit around the Earth or in the Earth's orbit around the sun, and I was kind of intrigued because you can build 10:25:17 this thing as big as a whole is the whole solar system if you want it to you know you could go way out to like Pluto. Yeah, they said it was the same as your sort of it. 10:25:26 The equilateral triangle that you give a much better signal to noise ratio, and you'll be able to see into the much lower frequency of gravitational waves where you can look into, like, you know, before the surface of last scattering I think that's right 10:25:44 300,000, years after the Big Bang, you will be able to see beyond that veil I think instead certain information right yeah they can look into that they can see mottos if mottos exist at all these other things that you could possibly see right so he's 10:26:00 are things to take at least so far I can only look at three kinds of events, basically, right. 10:26:09 Mergers actually they're all mergers right they're black hole black hole mergers which is the most common one neutron star neutron star mergers and by holding on servers, and those are basically what they can see it because those are all high frequency 10:26:21 events right yeah because those are all greater than 107. So yeah, they can make and see those. 10:26:28 You can't see like a man made source or anything like that. So it is interesting that in that first set of data, they only saw one event with the neutron star neutron star merger. 10:26:38 He was able to see the gamma ray signal optically about two seconds after they got the gravitational signal. 10:26:46 So, that is really interesting that actually puts a limit on the speed of gravity, somebody else who went ahead and did all the math on that. 10:26:57 That was Neil Cornish I think he's in Montana. Soon there she has these huge air about this right now this is the first time we've been able to constrain the speed of gravity and the speed of gravity has to be in between, like half the speed of light, 10:27:12 and 1.5 times the speed of light. 10:27:24 It's pretty big airport. Maybe, maybe it's a little bit smaller, maybe it's point five five, the speed of light and 1.43 times the speed of light. Right. Although we have a pretty good idea that the speed of gravity has to be the speed of light because 10:27:28 Although we have a pretty good idea that the speed of gravity has to be the speed of light because at least in in general relativity. If the speed of gravity is different from that, then you know the solar system ended up being unstable. 10:27:39 That would be bad. But, you know, one of the things we're looking at is if the speed of gravity and the speed of light are different than general relativity is wrong. 10:27:46 So we have to look at one of these modified gravity models, but he was saying that with the two detectors and maybe even with the third detector, you need another 20 of these neutron star neutron star events. 10:27:58 And in that past year they're more than five and not all of them seem to have gotten all the data they need to do this, increase that by a factor of 20 it down to their 20% instead of hundred percent or 50% or whatever it is, but I mean of course it for 10:28:13 seeing the gamma ray bursts, get radically and then more and we're seeing the gravitational waves arrive within so in such a short span of time of each other that pretty much just as direct because direct proof that there, you know, within you know a 10:28:28 fraction of the speed of light. Well, they don't actually know the direction that things are coming from. You have to have a perfect model of the merger of those two things to figure out when the first show up. 10:28:40 Remember, the gravity, or shows up a couple of seconds before the gamma ray burst. 10:28:45 And it takes a little bit longer for, you know, the optical burst, maybe as much as an hour longer for the optical there's so I mean it takes a long time for all these different things to show up. 10:28:56 So, which happens when and how much different, they should be all depends on your model for that collapse. But it's it makes sense though that the collapse of the gravitational collapse will proceed in a mission of light right because there are processes 10:29:14 have to take place for the energy to be released in the form of light right. You've got to have reactions and all that kind of stuff happening so it's like changing its its its its state. 10:29:27 So, doesn't it take it you know doesn't, isn't it reasonable to think there'd be a little bit of lag before we saw the light burst, oh yeah that's reasonable should it be only one should only be two seconds. 10:29:38 Yeah. 10:29:39 And on the event I guess right. So you have to have better models for that and actually probably need to have a good idea about the position, and the actual distance. 10:29:49 So, that event was supposed to be 14 mega parsecs, you know, plus or minus 825 million light years away, excuse me, you know, 125 million years ago, plus or minus 12 million years, it's still a pretty narrow range probably no matter what your model. 10:30:07 But still, you need to have a good idea about what's going on there, you have to have a good idea about the children are exactly the thing is coming from in the sky. 10:30:14 One thing he said though was, if you had the other two detectors come online. 10:30:19 One is in Japan, Cobra, which is actually online about a month ago as we talked about, she came online 25 February, that's in. He flew Japan and the other one is Lego India, which will come online in 2024 because they wanted to have a similar detector, 10:30:38 as far away as possible. First they tried to do it in Australia, right, you Perth is a perfect place for example, because there's nothing per thousand miles around Perth, basically, Western Australia is what would happen if there was no boss status in 10:30:55 Nevada. Right. But, you know, Western Australia is a great place for. 10:31:00 So you can put it in Perth or maybe put an adult I knew we're going to try to put it in PR. Are you saying that it's it's great place because there's a low noise in terms of like industrial things happening and all that stuff. 10:31:10 I'm just guessing that, that's the reason why they put it there. 10:31:13 But I'd expect so I mean you don't want it to be, you know, you want to put them in New York City. 10:31:19 Although I guess when they were wanting to build it and build my goal originally I wanted to build one in Los Angeles and one in Boston. Right, keeping hope close the universities and, you know, all the fun places you want to go, Well, I mean, the people 10:31:32 who wrote the grant were at Caltech and MIT. 10:31:36 Right. 10:31:37 They want to be able to walk out of there. Walk out of their office and go down to the gravitational lab, what oh yeah I mean it might not be you know right there I might be here in the country somewhere but at least they want to be able to go there without 10:31:50 having to buy a plane ticket. 10:31:52 I mean, You know, spend one day a week there and then, you know, spend a couple of days a week there and then a couple of days on campus or, you know, something like that, rather than have it be, you know, as far away as possible from both both places. 10:32:08 it's still stay in the US. 10:32:10 So you still wouldn't want to put one of these on Hollywood Boulevard. 10:32:14 You probably wouldn't want to have one of these. 10:32:18 Crap, I forgot the name of one street I knew in Boston. 10:32:22 I guess it's been too long. 10:32:23 Yeah, because every muscle car with with a great stereo system goes by, you're gonna get a little vibration in your detectors right. 10:32:45 I always feel bad for the guys out here in Louisiana they have the Lego facility and Livingston Louisiana which is in the middle of frickin nowhere. And I keep thinking, like, like the super genius eggheads out there in the middle of Louisiana countryside 10:33:01 with all the locals they must seem like aliens out there. I think it's a perfect place. 10:33:04 That's politics right you got big money he divides both summer. 10:33:09 So yeah, couldn't get one in Australia so they, they're putting one somewhere in India, which is similarly not near anything, it's in, it's in the middle of a triangle between Mumbai, Hyderabad and indoor, I tried to look it up it didn't look like there's 10:33:24 was anything that I could conceivably recognized, but when that comes back up and you have those five detectors, according to whatever I was reading. 10:33:37 It sounds like they be able to, with only a few detections get that down to 1% for the air or the speed of gravity sweet well I mean beyond that, I mean I guess it's just do the more detectives you have, the more you can clarify the signal right so you 10:33:50 can get more tease more information out of each event you detect I think right, you get a lot of different information, they'll be coming to defame goals might be easier to notice. 10:34:01 Yeah. And then, the more angles and the better you can you can figure out the polarization so you know exactly the orientation of the system with respect to your observatory and all that stuff yeah I guess that's another thing is that with the five detectors 10:34:12 you can constrain the polarization so right now they don't really know what's going on with the polarization they just kind of guess, and you know we want to think that we have this cross polarization. 10:34:20 The suit cross polarization because it's a quadruple radiation. And what do you call those two different forms of polarization. I when I'm reading the paper it looks like a plus sign and cross product kind of sign. 10:34:33 Well what are those called verbally Do you know, I just called them crossing plus okay fair enough. Let's see, but with five detectors you'd be able to tell it was a vector polarization or a scalar polarization or even a longitudinal polarization. 10:34:48 So this is supposed to be transverse wait so there shouldn't be any longitudinal polarization general relativity, you find any three of those things that's a violation of general relativity. 10:34:57 So, and they also apparently test cosmic censorship right which is a postulate by Penrose, I think, was it Penrose or was it Hawking who isolated them. 10:35:10 I can't recall what it was the cosmic censorship hypothesis again. It says that no naked singularities exist in the universe, so that means, or anything hilarity there has to be an event horizon. 10:35:18 Well, except in this paper he mentioned that the Big Bang itself is the only naked security singularity we can ever expect to see. Yeah, but if you improve your detectors. 10:35:29 Man, I'm not sure which one you have to do probably you have to have the Lisa to do this, if there is a naked singularity then you could see it, or possibly to pay their models or right yeah i mean if there's any place where we're going to learn new physics 10:35:40 it's in these extreme regions that have been totally invisible to us until now. I mean, it's kind of interesting that they're just so many of these black holes out there, and until the 1990s people didn't really think there would be any at all. 10:35:53 I think that's one of the things that I wrote down is one of the hypotheses in here yet. If we have a lot of these small black holes, these black holes that are, what they call stellar mass black holes and only 10 times the NASA V or something like that 10:36:07 30 times, if they're all over the place than they should be very frequently to check it. It seems like that's interesting. 10:36:15 times, if they're all over the place, then they should be very frequently to check it. It seems like that's interesting. Actually I guess it says says here in my notes that I was wrong with the matches the matches should have been seen by the first generation detectors and the first generation detectors didn't see anything. 10:36:25 anything. Yeah, we're not having much luck detecting really any kind of particle to explain the dark matter effect or the dark energy effect and that just really seems to be pointing in the direction of, we need a better understanding of gravitation, you know like, 10:36:40 seems like somewhere along the line general relativity is going to have to have a supplementary equation to modify it along the way I don't know, but it just seems like particles aren't the way we're going to understand this getting this kind of data 10:36:52 from astrophysical events seems like the most fertile soil to dig for new physics, you know, but I think that is one of the things that they think is that it is possible that with Lisa, you might be able to see such high energy events that you could see 10:37:06 the low energy effects of quantum gravity actually start seeing the deviations from general relativity, wow that's exciting. 10:37:15 But I mean, people have been looking for deviations from general relativity for a long time, and I mean we've looked at this stuff by will, and it looks like every single parameter they look at every single thing that they can think of that might change 10:37:29 gravity a little bit once they find a way to test it, it looks like it's general relativity all the way. so I mean, but those are all like individual events right like specific star systems and specific types of collisions and all that kind of stuff. 10:37:42 It seems like that all works great with general relativity, but at the larger scale the cosmological scale, we're looking at gravitational effects that we don't have a freaking explanation for some of these effects might just being, you know how the different 10:37:55 measurements made because I mean it just seems like if you have two different ways to measure the Hubble constantly they both give you different answers, one of your measurements is probably wrong or your physics is completely off right which is what 10:38:07 people want. But on the other hand, whenever they try to do anything then fix that. It doesn't really work, it always has some other issue with. 10:38:17 That's true. We definitely haven't found the right answer yet, but I think we're going to find answers it's some it's in this area, you know, because there's all kinds of new data out there in this realm that we've never even had a chance to look at before. 10:38:29 But we know when we keep building bigger colliders like spin offs and also Felder was saying. It's the with the Elysee just really confirmed the Standard Model, it didn't give us anything new. 10:38:39 You know we haven't seen any new particles at all, she was saying that you'd need some extravagantly more powerful particle collider in order to start probing like plank energies, before you we expect to see anything new in particle physics right. 10:38:53 But this is something that's like within reach. Now, gravitational wave observatories, you know, so we'll have good as we can get, you know, given that later on we'll make technological improvements will have these sort of the infrastructure up for, you 10:39:08 know, having terrestrial measurements that are going to be almost as good as we can get as far as the size of the detectors are concerned because once we get the one in India, and now we've got the one in Japan. 10:39:20 We've got almost the entire globe cover, you just send me something in Australia, and in space, we did you say the least, it goes online and 14 more years. 10:39:30 Well that's what they say. On the other hand, I think I was, you know, I was looking at some of these papers in here and they were always off by about 10 or 15 years by when things were going to happen. 10:39:42 So, but I mean that's when the ESA is thinking of getting the song, so NASA dropped out of that one. So that's all Europe. Ah, we're getting trailed and particle physics and now gravitational physics to Jesus, but we're still number one and incarceration 10:40:02 rate so that's a good thing. 10:40:02 Well, I mean, right now, we're right on top of the gravitational physics but yeah I mean Lisa will improve significantly over what we've got. Yeah. 10:40:13 You know, assuming it actually goes, it is a different region, but they should be able to take the same things as, like, Oh, you know you were also assuming that there will Sylvia European Union, by 2034, or United States for that matter. 10:40:27 We are in the midst of the Apocalypse, 10:40:31 all bets are off, man. 10:40:34 One of the things that he said in this paper that caught my attention was that what do you say here quasars X ray binaries supernova and gamma ray bursts. 10:40:49 Use relativistic gravity to convert mass into energy with efficiencies 10 times or more greater than nuclear reactions can achieve. I mean, that's fascinating. 10:40:56 So, it's converting mass into gravitational radiation energy right 10 times more efficient than a nuclear reactions. So I think fusion reactions are like, 1000 times more efficient than fishing. 10:41:08 And so this is at least 10 times more efficient than that, I guess. I think that was all talking about the reasons why we already know, in 1999, the gravitational radiation so important. 10:41:20 Yeah, because they model all kinds of things that quadruple path. Right. Yeah, so we can already see through our observations, things that required gravitational radiation to be halfway through whatever they were the cataclysmic variables binary neutron 10:41:36 star systems and young neutron stars. And so that's what the all those things were saying is that you know you need something more efficient than nuclear reactions to make these neutron stars lose the enormous amount of mass they had to be losing during 10:41:51 those events right carries your momentum out of the system as they're driving together and the Novi. I think the people who do work call it movie, but they don't actually say that they say sneeze supernova events sneeze, in this paper was he using like 10:42:09 the pyramid for eyes post Newtonian equations to model some of these effects. These didn't look like the fully nonlinear tensor field equations that you sometimes see, I mean he was using the quadruple approximation and gravitational waves using critical 10:42:25 contributions are so small, even when you have a reasonably high. 10:42:29 and enterprise post Newtonian system is a way to put parameters in there that will categorize all the different theories gravity, so that you can compare experiments and see which categories of gravitational theory are still viable given the experiments 10:42:58 and the observations that we've seen. Oh okay I was getting that mixed up with the like the linear approximation of gravity that we saw with like Robert forward. 10:43:07 Well this is approximate is at some level, they're just going down to the quadrupled term and that expansion is ignoring the optimal terms and all those other ones that, like, go on forever. 10:43:17 Yeah, you're just looking at the lowest order term that actually produces the gravitational radiation he has since it's small, right i mean if you look in Lego, the vibe changing the length of that path that the protons bouncing about in that giant Michelson 10:43:34 interferometer is about one 10th the size of a proton right and arm length, I think I didn't, I should have looked this up. I think it's four kilometers, and the change in that length is smaller than approach. 10:43:51 Super time. That's the size of the gravitational wave. Great. So if that's the size of the quadruple radiation, and how small theatrical radiation. Great. 10:44:03 Right. orders of magnitude smaller than that I guess I'm. 10:44:14 Wait here is just looking at the Lego on Wikipedia and it's saying here that you're right it was before kilometer mirror spacing of less than, 10,000, the charge diameter of a proton. 10:44:17 They can detect less than 10,000th of the charge diameter a proton. Now I guess the charge diameter is probably much larger than the actual radius. SAS as charged diameter I wish they would have put that in terms of an actual you know radius like this. 10:44:34 I guess it's like a square radius or something that they usually use for the proton but it's like a fairy fairy specific finite number. Yeah, so you generally think of the nucleus of an atom is about one centimeter. 10:44:46 It's up to God, it's amazing. And I keep making upgrades, they got like an extra order of magnitude I think back in 2014 or 2015 when they made their first detections and then they've made that gets additional upgrades since it's like optics on the science 10:44:59 of optics This is making leaps and bounds forward. Yeah, one of the things they do for that. That's still a pretty small arm. So what they do is they bounce the light in there it's at that regrow and for barometer on top of a Michaelson interferometer. 10:45:12 So they bounce the light back and forth like 100 times to make it larger effective arm length. 10:45:19 So the effective are like for that light as it bounces back and forth is more like 400 kilometers, or something like that. Cool. Yeah, I think that paper that we talked about it to be talking about that paper about detecting a gravitational field in the 10:45:35 lab where you had like a pair of Helmholtz coils, and then you had an interferometer, and they're talking about bouncing the light back and forth between that region of warp space time for like months. 10:45:49 So, you know, I guess you can amplify the sensitivity of your detectors but I mean, I'm not I blows my mind to think that you could keep like specific photons bouncing back and forth between mirrors so that much time. 10:46:01 But I guess maybe that's within reach. Alright, so let's see what else was in this paper that we really enjoy finding here. 10:46:08 He did give a list of different regions that we could start looking into a lot of it's just free not the fine art of astronomy getting a better understanding of certain types of neutron stars and. 10:46:20 x ray binaries and all that stuff. Well, I mean, we can look at some of the titles, same here was the other one relic gravitational waves from cosmic strings updated constraints and opportunities for detection. 10:46:35 for example, so that I think was the one where she was talking about the second, the Big Bang seen another one in here. It is it is ships again, or shoots shoots again. 10:46:49 And he says that you should be able to see the week scalar component of gravity that comes in unified field theories, if it exists. You know the scalar tensor gravity is not highly likely based on that parameter eyes post Newtonian framework, but gravity 10:47:06 is a part of, I guess, you should have a week scale of opponents somewhere, at least according to this a apparently didn't have a reference for me. I don't have a reference to that because that's looks like something you'd want to read. 10:47:17 So those are a couple of things that have to do with to string theory unified field theories in general, lots of talk about noise. Yeah, that's where the Weber bar really looked like a long reach to me because he was saying that the for the amount of 10:47:32 length of change in a Weber bar to be near from a gravitational wave that you could expect. It was on the same, the same order of magnitude as the is the quantum noise was like well Holy crap, how do you tease a signal out of that. 10:47:45 Yeah, but, I mean, we never thought he'd seen something until he died, you know whoever was also doing this at room temperature which is almost insane. 10:47:54 Kelvin temperatures, so that's a little bit better but from the zero point fluctuations zero point vibrations are supposed to be so large that you shouldn't be able to see anything unless he was saying, you use squeezing to move the noise into the conjugate 10:48:19 variable. And that sounds really tricky with a giant bar, or whatever it is that they're using. Yeah, I've seen, talk about those squeezed light states but not I've never seen anybody talking about squeezed like squeezing and whole bar. 10:48:34 You don't have to squeeze the bar you just have to squeeze the photos or the phone on, excuse me, so far nones in the bar. 10:48:42 I'm sure, I'm sure I'm not sure. 10:48:44 No no yeah I think you're right I remember we were talking about the phone ons and the bar, and that's still. 10:48:51 That would be done. I guess nobody's figured it out because it hasn't been built yet and figured out how to do that in those Italian detectors. I think we covered all the highlights of this paper so far. 10:49:02 I look forward to seeing more more papers, analyze like these 50 or 60, different signals that they've gotten so far and see what they're learning. I'd love to see what the resolutions looking like of the signal. 10:49:15 Because apparently the clearer you can model that gravitational waves signal, the more you can figure out about what's going on in invisible realms optically, you know, I just want to see if I put any notes in my gift on paper to see any strange predictions 10:49:29 he may have made or something like that. No, I didn't make any notes, I made some notes but didn't make any notes that said, you know, by 1980, we should be surfing on the gravitational waves or anything. 10:49:41 You know, I wonder if you're saying that there was a two second delay between the gravitational waves arriving and the light that we could see the gamma ray burst. 10:49:50 Boy, you know, I wonder if that would be enough time to set up some kind of like automated astronomical system so that you could rotate your telescope to that point in the sky. 10:50:05 Once this gravitational wave signal arrives so that you could make sure that you could get all of the optical data that you wanted from that event. I mean, apparently, they weren't able to get the data on one because place where you could see it optically 10:50:15 would have to look through the sun or something like that. So, that doesn't work through crap. 10:50:23 Yeah, hopefully, too hot and the gravitational waves just waltz through the sun but yeah electromagnetic waves seem to have a problem. 10:50:32 You know one of the things that I hadn't occurred to me until I decided this paper was they're saying the gravitational waves get gravitationally lens. 10:50:46 But what more can we learn with the gravitational lensing of gravity waves that would be really interesting to think about. I mean I looked at some of the data, unfortunately, you know I just wonder how they're even with as much information out of that. 10:50:52 It doesn't look like it's the cleanest signal, of course they're going to make it better and better and better. So, but still sometimes on these things. 10:50:59 It's amazing that they can claim, they've seen something, but on the other hand if you see something 1.7 seconds for something so that somebody else can actually start pointing things that other places, then you have probably it's, but it's amazing that 10:51:13 with the account some that thing that you know they're modeling was as useful as it was, yeah I wonder if these events will happen like behind a galactic nucleus or something so that we can start seeing the first detection of gravitational lensing of 10:51:29 gravitational radiation. I guess that's probably improbable for, you know, one of these events to happen directly behind a source of extremely high gravity, but it'll happen eventually. 10:51:39 Right. Well I would say that it's highly likely that there are these events happening, a place where you have a large social gravity right you have these supermassive black hole sitting in the middle of galaxies right. 10:52:46 Find a galactic nucleus. 10:52:48 I mean the galactic nucleus just. You shouldn't be able to data on one because place where we could see it optically would have to look through the sun or something like that so that doesn't work through crap. 10:53:03 Hopefully, to hawks and the gravitational waves just waltz through the sun but yeah electromagnetic waves seem to have a problem. 10:53:10 You know one of the things that I hadn't occurred to me until I saw this paper was they're saying the gravitational waves get gravitationally lens. We know the gravitational lensing of light and we've learned tons of stuff using that. 10:53:19 But what more can we learn with the gravitational lensing of gravity waves that would be really interesting to think about. I mean I've looked at some of the data, unfortunately, I just wonder how they're able to tease much information out of that, it 10:53:30 doesn't look like it's the cleanest signal. Now of course they're going to make it better and better. So let's sell, sometimes on these things. It's amazing that they can claim, they've seen something, but on the other hand if you see something cool point 10:53:42 know with the account some that thing, you know they're modeling was as useful as it was, yeah I wonder if these events will happen like behind a galactic nucleus or something so that we can start seeing the first detection of gravitational lensing of 10:54:07 gravitational radiation. I guess that's probably improbable for one of these events to happen directly behind a source of extremely high gravity, but it'll happen eventually. 10:54:17 Right. Well I would say that it's highly likely that there are these events happening, a place where you have a large source of gravity right you have these supermassive black hole sitting in the middle of galaxies right. 10:54:30 Probably it's it's likely that that'll happen but you have to have some kind of knowledge of where things supposed to be in the first place. Right, yeah. 10:54:39 Yeah, it's the see the shift you'd have to know where it was, if you're looking at continuous events in season right if you see a star and then it gets close to Jupiter and then you measured this little shift. 10:54:49 It's simple, but if you have these discrete events, and they're these black holes, they're sitting out in the middle of nowhere, and you can't see until they actually hit each other, then how can you tell whether or not they blend. 10:55:06 Now maybe you can maybe hand by a you know redshift or something like that. polarization change maybe right now some of the events that you should be able to see with Lisa are continuous events. 10:55:13 Yeah, like orbits and stuff, you know, rather than to black holes merging can black holes, spinning around each other, that's supposed to be maximally asymmetric event, it's continuous, if you can actually see something over here by a galactic center 10:55:27 in the sky, then you just watch it and see what happens. So he said that's, that's an ESA pro project right lol Lisa thing. Yeah, I think, NASA dropped out in 2010 2011. 10:55:40 I think that's good push it back needed got a better idea. Come on, to be honest, if you're just thinking about it, you probably want to have a second detector. 10:55:48 Yeah, and probably have it in a different corporate as well but you definitely want to have it in their orbit, that's not this in the same plane is here. 10:55:57 So be nice to have another one that late 90 degrees cover both and all axes. Now we're talking. Okay, well, no yes he was right to grant and see what happens. 10:56:08 See, see the congressman in the United States has this physics thing really been proven. Come on. 10:56:17 All just God's will, if they have to come to a meeting every year in New Orleans in February, they'll be happy. Well, they won't be happy right now. 10:56:34 Sounds good you. You have a great time, Randy thanks for talking. Thank you, Jim, it's always good to hear from you. All right. Bye now. Bye. 10:56:37 You have just listened to physics frontiers Episode Number 51 gravitational wave astronomy. Show Notes for this episode can be found at frontiers physics FM com slash 51 show notes include the papers we read for this podcast, as well as links to related 10:56:57 to episodes and suggested reading.
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