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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.
1. The papers we read for this program:
- Shutz, B., "Gravitational Wave Astronomy." Class. Quantum Gravity 16, A131 (1999). [arXiv]
- Shutz, B., "Gravitational Wave Astronomy: Delivering on the Promises." Phil. Trans. R. Soc. A 376, 20170279 (2018).[arXiv]
2. Related Episodes of Physics Frontiers:
- Physics Frontiers 31: The Parameterized Post-Newtonian Framework.
- Physics Frontiers 10: Requirements for Alternative Gravity Theories.
- Physics Frontiers 6: General Relativity for the Experimentalist.
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)
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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