Interview with FI Cooperstock (contd.)

0:00 I mentioned this in, I think in both my paper, in Foundations and also in this book, that to me, people have been focusing so much on the similarities between E and M and gravity. And I think you have to kind of think about the differences. There are tremendous differences. and to me the most glaring difference when I think about it in the grand scheme of things is that all particles and fields exist in space-time but gravity is space-time gravity is really different and then you have this non-linearity of gravity this is the linearity of Maxwell theory and then you have the tensorial nature of the energy momentum tensor for the electromagnetic field. It's a tensor. Tensor. Whereas, what do you have with gravity? Pseudotensor. Pseudotensor. Where you can make it this, and you can make it that, and you can annihilate it here, and you can break it back here. And then you look at a plane wave, and you've got... I never knew this until fairly, quite recently, within the last few years, that with a plane wave, you could just get rid of it entirely. about that paper, I would have been worried about this problem a long time ago. This goes back to the 70s. I mean, you don't have that with E and M. You don't have an energy momentum tensor that you can get rid of. That electromagnetic wave, you've got it, you've got it, and that's it. It's a tensor. Whereas here, you know, the counterpart, the perfect counterpart, plain electromagnetic wave, plain gravity wave, one of them, you know all about it, you know about its energy characteristics you know what the basics of it are yet with a plane gravity wave it's a whole different story you can actually get rid of it not at a point everyone knows you can always get rid of energy at a point but then you can't get rid of it somewhere else no, you can get rid of it everywhere here you've got curvature you've got a real Riemann tensor you have real curvature, no question about it Yet, from this point of view, it's not carrying any energy whatsoever. And then I've got this Geon thing to back me up now. Oh, I've had some real battle with that Geon thing.

2:30 Oh, boy. Oh, boy. Is that with real Hartle themselves? Yeah, well, with Hartle and some referees. Oh, of course. not with this foundations of physics not foundations of modern physics letters no problem whatsoever with that depends on the person you happen to hit some of them are perfectly open to the idea but others oh my god I think a lot of it is this American relativity fraternity you know that anything that came from Wheeler is the word of God and I really shouldn't be saying this on tape Some of these remarks, I hope, are... Well, I will certainly be happy even if I take something in office to clear it with you beforehand and then I'm ready to quote you or anything. Yeah, yeah, don't... I won't presume that you want everything. It's the Word of God and you just can't challenge it, which is not healthy for science. Not that I've got anything against Wheeler, but you shouldn't have this attitude Like Singh used to say, Einstein is not God, you know. You can challenge Einstein, too. Anyone should be open for challenge, you know. That's what makes science live, you know. But I get the feeling that there's this protectiveness in the American relativity community. My God. I had to go further afield to get it published. Actually, this question of, well, not the relationship so much, but the analogy between electromagnetism and gravitational, it's interesting going back to the papers over the years, people have been discussing about gravitational radiation, and you do find that some people say, well, look, there's this clear analogy with the electromagnetic case, and indeed some people value huge stress on that. There are similarities, and I was lulled by them for years. I was the firmest believer in these things for years. And I can understand the resistance that people have to this new localization thing of mine, because if someone else had come out with it,

5:00 I would have been very resistant to it, because what it does is it calls into question so much of what you've done. You know, I mean, including myself, so much of what I had done in the past, it calls into question. All of these energy calculations, these energy flux calculations, if this new stuff is correct, all of that is out the window. Now, the people that more stuff might just very well be just fine and dandy. I both commit myself either way on that. that's a different approach and it could very well be that all of this is going on in terms of how a system will spin down but won't be exciting oscillators out asymptotically so I can understand the resistance of people you don't want many hours and years of your work to be just flushed down down the river one fell swoop and I guess it was interesting you said that gravity because the other way of looking at it is that gravity is different it's a field theory of course but it's a field theory that assigns a particular type of importance to to the field of the fact that the fabric of the space time itself that's a particular property that's right, the others are part of it whereas it is it You know, it's a unique role, isn't it? It's interesting. It's funny, you know, you look at other particle physics people. Don't look at gravity that way. They look upon it as just another field, like Weinberg. Weinberg's book. He sees it as just another field, and it just fits in. Some little quirks, little quirks, different, but basically it's just a spin-two field instead of a spin-one field, like the photon or spin-zero field. It's a spin-two field, that's it, that's it. And everything just goes through, no problem. That's what I find is interesting, all right, that you do find that certain. I agree, that particle physicists tend to look at it like, okay, well, it's just another field, that's it. That's right, that's right. And it's interesting, I've seen some interesting quotes, I think Penrose is one, where people who've been doing relativity

7:30 complain about particle physicists coming in, you know, for instance, starting to do with cosmology and they got interested in cosmology and so on, and complaining that the particle physicists really didn't have this appreciation of what the relatives were doing and the sort of problems. Certainly in terms of the older arguments about gravitational reaction, whether it carried energy, Feynman who was certainly quite convinced from his own calculations that it did, was quite caustic way back when about people who had deaths. Oh, really? He was caustic about it? Well, he was, to begin with, he... He can be caustic about anything. That's right, he seems to have been... To begin with, he... Interestingly enough, he wasn't as caustic maybe as he can be, but to begin with, he got up when people were bringing this up he responded with this thought experiment that he had and then I think subsequently rubbing on a bar that's right that's right yeah well you know Miss Antonio Wheeler give Bondi credit for that but I dug out I was a bit of a historian in that I dug out that Feynman was from what I could see the originator of that that's true yes I agree I was surprised oh you found out about that from me know that previously. Well, I'd come across when I looked up the Chapel Hill conference. Oh, you looked it up? That's where I found it. I was surprised to find that Bondi was there. I don't think that was very nice that someone didn't intervene and let Feynman take the credit for it. So I make an explicit point of it in my papers. I noticed that. So after that, I read your friend. I thought, ah, so there's somebody who calls it the Feynman. I thought that was interesting, because I had come across this, and I asked, I sort of tried to ask Bondi about it, but he didn't remember anything about the conference that was, you know, he didn't remember anything about Feynman, and it's true, not only, it's one of those things that, now, Feynman mentioned it at the conference, and Bondi was there, and Weber and Wheeler were there, and Weber and Wheeler wrote a paper, again, later in the same year, in response to, you mean the cylindrical gravitational waves thing? in response to Ria Rothen's and they put forward

10:00 again the same argument and again they didn't mention Feynman so it was hard to tell but certainly Feynman was one of the greatest geniuses of all time it was a privilege really to have him here I don't think he was right about that then again he wasn't looking at the whole picture he was not a gravity a gravity expert at all. Sure. I was just like a little sideline of his. So, you're right. He saw these things from the particle physics point of view. So, yes, as I said, I remember he seems to have been constant enough about it. And it's... There seems to be... I'm wondering what you think about it. I mean, I'm not sure if I get the impression reading some of the things that be a certain amount of push and pull that way because after all relativity was always kind of outsider community in a way of especially going back to the 50s and earlier. I was interested in talking to people like Bondi and people who remember that period, how they were saying when they went to the Berne conference in 1955, they were delighted to find that there were other people kids and spirits they thought they were alone in the world It's interesting that to consider whether this question, whether it was sort of, some people felt that it was better on the whole to emphasize the similarity between gravitational gravity and the other fields. And that and that, you know, one reason for resistance to the idea that gravitational radiation doesn't carry energy is that after all that emphasizes while all rudiments are certainly aware of the fact that within relativity gravity has this special function if that's going to have these dramatic physical consequences What special function, I'm sorry? I mean, that gravity defines the background In other words, that the field, the gravitational field has a particular, I don't know if it's ontological, but anyway, a particular function or quality that's not true of the other fields.

12:30 There's a particular role. And if that's going to have these very dramatic consequences, like, for instance, that gravitational waves don't transport energy compared to electromagnetic wave, that then that's certainly not going to be accepted by physicists from outside. That's right, that's right, that's right. There'll be a real resistance to it. It's a really a different, it's a different... You know, actually, as we're speaking here, I'm reminded of a conversation I had with Sink. And I was a real believer at that stage in gravitational radiation and the connection, the energy connection. And I was, at that stage, I was a lover of the pseudotensor, you know, when I came to Dublin. And I remember seeing hate at the pseudotensor with passion, and he gave me a real hard time about it. And I remember he also, you know, in private conversation, he told me he just wasn't sure about whether energy is really the right concept for general relativity. That when you get into general relativity, you know, we shouldn't... There's a good chance that energy is not the thing that should be generalized as it's been, you know, through the history of physics, you know, going from one field to the other. I'm just reminded about that as we're talking here. That's interesting. I thought he was just, you know, I was not with it at the time now I appreciate that remark more now that I'm sitting here talking to you I guess these are influences lingering in the back of my mind slowly, quietly doing their work I hadn't thought about that for a long time just as we're talking here bringing out memories this is one of the reasons I would love to talk to And Pirani did say that, because if you look at the conference that we looked at where Feynman brings up the thing, you notice that Feynman says, well, if he relies on, he mentions Pirani's work earlier in the conference, or at least he does it and does it expanded. I don't know if you've seen that. There's an expanded addendum on Feynman's remarks on the thought experiment.

15:00 Where? It was published separately from the main. In the Chapel Hill conference? That's right. in the actual proceedings there's just a brief note about his thought experiment let me just see what I have here let me just show you what I have I have this is what I have I didn't even know where I got it from this is what I have is this it? we've got a lot of discussions here I should sit down and read from this. It's quite interesting. Okay, and here is where he... Is this what you're talking about? Yes, but then there was a... So there's an addendum Oh, I see. And that's not in here. I don't know what these are. It was given, I think, distributed to some of the participants. Could you send me a copy of that? Could you make a note of that? To remember to send me a copy of that? I'll send you a copy of that. Okay, I'd appreciate that. I only came across it like the fortune decrease it's a long story but essentially one of the participants sent it on to us because it doesn't appear with the regular thing and so in those expanded remarks Feynman mentioned specifically that he's relying on Pirani's presentation earlier in the day where Pirani said well let's look at the Ramanic tensor which is a tensor and we can look at the equation of gtc-deviation and Pirani was influenced here to kind of take this geometrical approach by Singh and so it did play a role at the time that Singh had said well in an indirect way because as you said Singh really wasn't interested in the relation drama himself at least in gravity it did play a role at the time in that coming from Singh through Pirani people said well okay this energy is a problem let's try and look at the at the ring on tensor and the geometrical quality of the thing so that was one of the reasons I would like to

17:30 It's just going to be saying that it can possibly happen. But from my point of view, all of that stuff was just looking at how the particles move in the field of a gravity wave. But to absorb energy, you have to have like a medium, an elastic medium as an absorber. I mean, the gravity wave comes through, the particles move around if they're just free, and then the gravity wave goes away, and there isn't any kind of a heating process going on, right? It's just those bodies moving around, wave gone and then those bodies I don't know whether they're still moving around or not it's a little bit dubious about before and after I don't know if people have analyzed that question but certainly what people always had in mind and Feynman had as well was the rubbing rubbing on a stick and then you've got real heating and you've taken energy out of the wave to really know that you've taken energy out of the wave, you've got heat produced and that's energy wasn't there before now it's there You put a thermometer in the stick, and you've got to heat it up. And what people have never worried about is, what does the gravity wave do to the stick that is moving around? And from my point of view, the stick is also kind of oscillating back and forth with the particles, and so there isn't any rubbing going on. That's interesting. So the stick moves just as much as the particle? That's right, that's right. So there's no rubbing going on. It's not as if you sit there and you kind of rub a stick and you give energy from your body to the stick and you heat the stick up. You have a transfer of energy. So it's interesting. Do the internal forces in the stick play any role? Well, this is the point. That's the whole point of that electromagnetic oscillator, to make a model of the internal forces of this elastic medium. with an elastic medium. That's something people ignored until I got at it from a field theory point of view to really see what's going on. It affects the fields, but it also affects the coulomb attraction, and the net effect is the bodies move together, move the same way as if there wasn't this medium in there. Yeah, that's what you say.

20:00 that's really old word coming back this is I'm kind of amused to hear you tell me about Rosen with this half advanced half retarded that he came back to that years later that's on paper, I must see and I must see this business about him saying getting rid of the pseudotensor I must see that I want to write him about that too the first thing I have to ask is Wallace because of course you'll see he's going to come pretty soon I guess but I would really appreciate not only for you to send me this thing on this Chapel Hill thing but also what Rosen what's Rosen's reference on that do you have a reference written down I might just have that paper and not be aware of it. I've got two big filing cabinets full of reprints there. And the stack there that I don't have time to file anymore. I don't have any paper to do with me, so I may not have that reference. This is a very good thesis topic you're doing. I realize that there's a tremendous amount of scope. You can go even beyond the radiation problem and just into various byways. No one's ever done this kind of thing before, I don't think. It's an interesting thesis idea. It is, very interesting, yeah. I'm delighted with it. It's turned out very well. It's really very interesting. Well, if you come up with it, let me know. But if not, please send me either a reference or even better, a copy of it. I have a copy as well. I appreciate that. With the final thing. Yeah, it's very interesting. Yeah, I was very interested, as I say, in your argument on the, on the, on the, on the thought experiment. Sure, sure. It's unfortunate that, because I remember reading it at the time and, and, and, and thinking of loads of questions that, well, I don't know if you would ever like to be able to ask, and now, of course, it's been so long since I read it first, that I, that I, that I'm sure I had some that I couldn't, that I couldn't think of thought now. because I was wondering if, in general, I remember it hinged around not being sure but was the impact of that so that if, the lessons seem to be therefore that if two bodies

22:30 which were not, well, say two neutral bodies that were not electrically or electromagnetically interacting at all, would have the wave pass and they would move. Yeah, sure, sure, sure. And the lessons of the calculation seemed to be that it would seem that if the two bodies then had some kind of electromagnetic interaction, like the plates or like the pieces of the stick. Well, which an elastic medium is ultimately electromagnetic in origin anyway, you know. That's right. So, and if the wave came by, they would move, and it would be the same as if they moved. They would follow the Geod6. Which is kind of remarkable. Yeah, that was surprising to me. I think. Come in.