Wrong. 'Binary system' is characteristically of you completely undefined but the default assumption is typical compact ~ stellar mass binaries - in principle any combination of WD, NS, or BH. The LIGO and similar wavelength ranges of interest are then on a far smaller scale than interstellar distances, or even typical stellar dimensions. Everything would nicely smooth out to effectively zero net effect over such scales - and that assumes there really could be such TT waves. Vastly rarer SMBH binaries might fit with your assertion, but the Parks team whose 11-year survey came up empty, had a clue or two in choosing pulsar timing as the only sufficiently sensitive asronomical indicator of any such very low frequency GW's: http://www.atnf.csiro.au/research/pulsar/ppta/ See above. May I assume that bit is directed at the likes of Saulson and not myself? Regardless, basically that bit is claiming that GR's version of GW's is dead wrong. Do you acknowledge that? Yes or no?. If you do, how about furnishing the mathematical form of a GW that fits your idea of 'relativity', or at least point to the published literature where such is shown in explicit detail. Otherwise you are engaging in sheer assertion. My own reasons for rejecting GR's version of GW's are almost certainly very different to your own. And, as oft stated, I'm not about to divulge what they are, for 'proprietary reasons'. I assume you have no such inhibition about detailing your reasons. So you disagree with Saulson's explanation - which is btw standard fare within the GW community. Please be more precise - where exactly does the logic in that article fail? Which equations are wrong and why? No waffle, no hand-wavy assertions; provide a detailed explanation. See my first response above. Strangely, I have no argument with that banal observation.
The implication being that Saulson is knowingly contradicting his own analysis that ends with non-null results. No - obviously not. IF GR's TT waves could exist, his analysis which takes into account differential effects, would more-or-less make sense. And I see from a recent 'I like', vacuous tautological statements impress you. Why am I not surprised.Please Register or Log in to view the hidden image!
Those "differential effects" are exactly the ones that allow us to verify the other predictions of relativity, but they are also the ones that confirm the basic premise that is the motivation for relativity. As far as relativity is concerned, no local experiment (a sealed spacecraft in free fall) will ever be able to: measure a relative velocity with respect to an aether wind measure ANYTHING that warps spacetime locally, and this would include a passing gravity wave The "sealed spacecraft with no windows" is necessary to remove Samuelson's "differential effects". We already know that we are traveling at relativistic speeds with respect to galaxies at cosmological distances from us. We know exactly what that means relativistically. This idea is fine, but in order to do it, you need a stable and reliable clock at the distant location which you can compare your local one to. THAT'S WHAT "DIFFERENTIAL" MEANS; IT IS SIMPLY A "COMPARISON". We compare the red shifts of that distant galaxy to non red shifted spectra of local elements heated to incandescence. That is a reliable clock only if you are certain you know the shift is because those galaxies are moving predominantly away from you and are not just spinning really fast, are really massive, or are moving fast in some other direction. The binary pair in the Hulse-Taylor analysis is so far, the only one of those we are able to analyze in enough detail to confirm predictions of General Relativity and calculate the power of a gravity wave. We still don't have a local means for determining if that wave actually propagated in our direction or any other. If we ever do, I'm pretty certain the test setup to find it will not resemble either an interferometer (orbiting or fixed) of a practical size or a resonant bar that is smaller than a planet or a large moon. Anyone, including Dr. Samuelson, who believes that an experiment performed inside of a sealed spacecraft in free fall can be done to determine local curvature of spacetime is basically saying that he is more brilliant than Einstein. We don't tolerate anyone saying that on these forums, so how does he get away with saying, he can build a local interferometer setup to detect gravity waves? I don't care how many subtle multidimensional tensor dynamics squiggles he writes on his Promethium board. I don't care to follow his twisted logic he uses to justify his fat paycheck. If he thinks he will be able to do what he says with the technology he plans to do it with, he is simply the next liar who believes he is more brilliant than the man who explained exactly why an experiment like that with anything other than a null result is impossible. A null result is not verification of gravity waves, or an aether wind. You don't even need Samuelson's tortured General Relativity analysis to make this prediction. Special Relativity works just fine to determine whether or not you will be able to locally detect gravity waves in a sealed spacecraft in free fall. You can't. It doesn't matter where you put your interferometer within this solar system. It will still be in free fall, AND it will still be local, AND the only thing it will be measuring will also be a null.
I get the impression from #83 you accept that GR's GW's do exist but cannot in principle be detected using LIGO-style interferometers or resonant-bar setups with dimensions not an integer (or half-integer) multiple of GW wavelength. Is that about right?
There - see - you can give a nice clear succinct answer!Please Register or Log in to view the hidden image! A couple of suggestions to chew over slowly: 1: No-one and I mean no-one, thinks that a truly local setup could in principle detect a passing GW. That would restrict everything to first-order effects which by equivalence principle always null out. But neither a LIGO interferometer or bar detector are truly local. They may be small wrt assumed GW wavelength, but are still extended systems. Hence in principle can sample gradients (or spatial anisotropies in GR's GW's) of a wave. 2: There is a general situation applying to any wave source - be it acoustic, EM, or assumed gravitational. If it can be generated - it must also be able to be detected by a receiver, typically but not necessarily of the same or similar geometry to that of the source. Principle of reciprocity. [I will add to that, the principle of resonant absorption. Receiver may be very much smaller than wavelength, but high effective X-section is at the expense of a narrow bandwidth.]
Very nice explanation. Thank you. The assumption is that whenever someone designs an airplane, they have a reasonable expectation that it will fly. Put that same airplane on a treadmill, start booking passengers, and it gives me pause to consider WTF, and please pardon my French. That's all.
Dan, I empathize with the LIGO is like Michelson Morley sentiment. But as regards this: There may be a way to work out that you're in free fall rather than floating out there in space. Measuring the fine-structure constant via the Quantum Hall effect might do it. Einstein said you cannot transform away a real gravitational field. He used the phrase "special form" instead of real. See section 20 of Relativity: the Special and General Theory where Einstein said this: “We might also think that, regardless of the kind of gravitational field which may be present, we could always choose another reference-body such that no gravitational field exists with reference to it. This is by no means true for all gravitational fields, but only for those of quite special form. It is, for instance, impossible to choose a body of reference such that, as judged from it, the gravitational field of the earth (in its entirety) vanishes”.
The gedanken experiment with the closed spaceship in free fall, as you might expect, also neglects tidal forces, but everyone understands this. For all we know, the binaries in the Hulse-Taylor system with the huge loss of energy presumed to be in the form of propagating gravity waves, could also simply be losing the energy in the form of internal "tides" or tidal distortions of its mass somehow, but if that were the case, this would break the rules about information other than gravity escaping the EH, wouldn't it? That's an interesting sidebar all by itself. Can GWs get through the EH of a BH? What if by whatever means, the inside of a supermassive black hole contained the same decaying binary system analyzed by Hulse-Taylor? Could the gravity waves generated by that system ever escape? If this is too far off the topic of the thread, we could start another one about it if anyone wishes to discuss it. At least there is no argument, that case is easily and by far the most interesting GW analysis to date.
The idea is that the fine-structure constant varies with gravitational potential. See this. Unfortunately this sort of thing is described as a test of general relativity, and shouldn't be. I'm not impressed by things like the information paradox or "the rules about information escaping the event horizon". Information is just pattern, it isn't something fundamental at all. It isn't like energy. I would urge you to set that sort of stuff to one side. Can gravitational waves get trhough the event horizon? No. Because gravitational waves are akin to light waves, and they can't escape. I know people talk about Hawking radiation, but there's no actual evidence for it, and the given explanation for it ignores gravitational time dilation, and demands particles popping into existence like magic, and negative energy particles. If you know of any negative-energy particles, you ought to call the guys in Stockholm.
I'm cutting Kip Thorne a permanent break on this one since tetra quarks and pentaquarks were discovered just two years after the discovery of the Higgs boson. He predicted the existence of "exotic" matter. Close enough. Whether these are "negative energy" or not is debatable, but they are by all means "exotic" in every sense of the word.
The point to note Dan, is that Hawking radiation has been around for 50 years and there's no supporting evidence whatsoever. Nor is there any evidence of any negative-energy particles. Nor will there ever be, because energy is a scalar, like length. I can cut a chunk off your pencil and make it shorter. I can keep doing this until its length is 0cm, and there's no pencil left. But I can't make it shorter than that. In similar vein I can take energy away from a mass until there's nothing left, but then I can't take any more energy away. Mass is a measure of energy content, and there is no negative mass. Hawking radiation is a fairy tale that relies on nonsense like this I'm afraid, and on ignorance and gullibility. Ditto for Kip Thorne and his time machines. I'm not cutting him any slack at all, because he peddled Interstellar as serious science when it contained huge dollops of woo. I'm sorry, but there's only one word for that, and it is charlatan.
How about your TOE??? Is that also a fairy tale??? Is that why you now refuse to speak on it? As an unqualified ameteur and lay person, your comments on this matter as well as Thorne are ignorance personified.
It's not my TOE, it's Einstein's. He worked on it for years, but couldn't get it to work. I'm not some my-theory guy, I said that in Relativity+. Where I refer to Einstein, the guy you dismiss. And as for being an unqualified amateur, note that Einstein had his miracle year before he got his PhD. As for Thorne and ignorance, next time you see a time machine, be sure to tell everybody.
What Einstein was working on and never concluded was a "Unified Field" theory. Yes you most 100% certainly did claim you had a TOE, and no amount of dodging and weaving will absolve you of that claim. Of course you are, and you have proven that time and time again. I have never dismissed the great man, and just as certainly, I have never taken him out of context, or misinterpreted what he said. You are not an Einstein...Donald Duck, possibly. Now you are being childishly silly. No one said Thorne had a time machine....He and all reputable physicists just agree that time travel is allowed for by GR, and in fact GR gives solutions.
Time travel from the present to the future, but at different rates everywhere, is allowed and governed by relativity. Time travel from the present to the past inside of a rotating toroidal black hole is sheer fantasy that could never be tested or compared to any theory that only works for certain outside of it, or for relative speeds slower than light in a vacuum. It is possible to fantasize about all sorts of inconsistent things, with any equation, but don't pretend that it is science or reality just because it's math. Even math has limits. Those limits are what bind math to reality. Without them, 2+2=5, and charlatans calculate their own paychecks, which is really the only math that interests them. But I don't really understand the fuss about it. Does anyone have a testable theory of quantum entanglement yet? I don't see a requirement for any 'unified' field theory. Multiple fields seem to be the rule in nature. Even relativity, the closest thing we have to a ToE, ALWAYS REQUIRES a minimum of two observers to tell the whole story. Why should this symmetry not also extend to quantum fields? That would explain the speed of entanglement to be the same as "at rest, everywhere at once", the instant of "now" without which, the speed of light cannot be invariant anywhere, and also the explicit origin of time that explains its arrow. A different field moving and limited to c, also "everywhere and in every direction at once" would be the other quantum field. No Hilbert spaces or multiverses are required, because there is only time and energy (bound and unbound) in play in this universe. To make "space", simply rotate your meter sticks in some other direction and propagate some bound or unbound energy in the new direction. It's an illusion. Relativistic space is the only space that exists. Euclidean space died in 1905, yet somehow, it persists in math, and not just geometry and calculus. The "topology" of a pancake just isn't all that interesting. Quantum fields are not Euclidean either. Better yet, unlike time travel within black holes, or string theory, these ideas are FALSIFIABLE, the hallmark of a real science, according to Popper. Entanglement is either faster than light, or possibly simply at rest. That's a fact. Someone needs to explain that, because relativity doesn't. Farsight, you have some other ideas on the topic of this thread worth vetting?
If you don't I will ask the same question about GW. The fuss is about one of the Fs. Simple, GR is about distortion of spcetime around matter/energy or curvatue of the spacetime and GW is ripples in the curvature of the spacetime..not space. This all is mathematical model, geometry, mathematics, not the real thingie. What we see around us is the space, whether empty or full of H/He or of DM or vacuum or matter but not spacetime. We can see the Gravity Waves (not Gravitational Waves) every moment, we just have to go near a sea side. But we will never see GW the way it is proposed in GR, because there is no real stuff called Spacetime....
It isn't time travel. I've spoken about this previously, see for example this post: the stasis box is science fiction, but don’t forget, we can freeze embryos now. In the future maybe we’ll be able to freeze an adult. Then you could “travel” to the future by stepping into a glorified freezer. But you aren’t really travelling to the future. You aren’t moving. Instead everything else is. Agreed. I would add that it's a fantasy because there is no motion in spacetime. We don't move along a worldline, so you can't move around a CTC. There's a bit about this in A World without Time where Palle Yourgrau says Wheeler conflated a circle with a cycle: Please Register or Log in to view the hidden image! I disagree. See Einstein talking about fields in 1929. He says a field is a state of space, and that it can "scarcely be imagined that empty space has conditions or states of two essentially different kinds". There are not two states of space where a photon is. A photon has a non-zero "active gravitational mass" so in a way it's a gravitational wave as well as an electromagnetic wave. I think that's important. It didn't die in 1905. In 1920 Einstein described a gravitational field as inhomogeneous space. Not curved space. And on the largest scale space is flat. Euclidean. Whenever I look at the evidence for entanglement, I see smoke and mirrors. I can never seem to find anything that demonstrates anything that I can actually see. And apparently no information is being sent from A to B. See for example this report. There's nothing convincing, and when you follow the link to the paper all you get is this: After separating the signal and idler photons by 300 km of fiber, we observed high-visibility two-photon interference fringes without subtracting accidental coincidences. And a graph. I'll have a read through it.
This idea about entanglement is changing, and not just in China. Better yet, it's something we can test with real world scientific experiments, something that has been lacking in physics for the last 40 years. No energy is bulk transported from A to B. Pause to reflect; why would there be a limitation, once energy is "bound", on the spatial extent of entanglement? If an electron is restricted to a certain physical size due to entanglement, why couldn't that size be entangled on a much larger scale? Since we don't understand what entanglement is, there isn't any good reason, an electron could not behave in a manner that entangled it with a partner electron on the other side of the known universe, is there? There is energy involved in entanglement states alright, but when that energy is bound, distance doesn't matter in terms of changing entanglement states, nor does time or space really have any meaning for energy that is bound. This is why the speed of light is not a limit to the speed of quantum entanglement. There's no shame in not understanding. The idea even "spooked" Einstein. It took a lot to do that to the greatest scientist who ever lived. Happy Halloween.
