But things do resist being accelerated, and I’ve read that some still are exploring a Machian explanation for this; though any such explanation would not use the “fixed stars” to define an intertial reference frame in the conventional sense (and hence would not be quite the same as Mach’s or Berkeley’s original definition of the principle), but would still incorporate some aspect of the holism that is intrinsic to the principle. I only understand this enough to say that things somehow always “know” they are being accelerated. How do they “know”? I’m told this is still a mystery, but maybe can be explained if everything in the universe is somehow in communication with everything else, instantaneously. Everything always “knows” where everything else is. Hence I wondered if part of what you were alluding to had to do with connections that look space-like, but aren’t, even outside of EPR phenomena. That’s what I meant by “expanded” entanglement, though that wasn’t a very good way of putting it, I see.
It doesn’t seem to be the case that you were talking about any such thing, though, so my questions aren’t really very well posed.
Easy: They know because they’re feeling a net force. Something is pushing or pulling or whatevering on them.
And if you ask why it is that objects resist acceleration, I’ll just turn the question on its head: Why would it not be the case that objects resist acceleration?
Mathochist, your explanation may be more ontologically satisfying, but I’m not sure how much descriptive utility it has. Just from saying that there exists one photon field, one can’t conclude anything about the sorts of information one could transmit through that photon field. And, of course, one has to deal with the possibility of unlike particles being entangled, as, for instance, an electron entangled with a photon. You’d end up with a single unified field for all particles, which certainly sounds nifty, but we’re out of our depth trying to discuss it.
Frankly, as a non-physicist it’s always seemed very easy to just think of them as solutions to differential equations. Actually calculating the solutions to that massively coupled collection of highly nonlinear differential equations is a problem for the physicists or, at worst, the analysts.
I don’t think so. The whole notion of Mach’s principle has been argued back and forth–I don’t think you can say that General Relativity invalidates it at all. At best, we’re just not sure whether it holds or not.
But there’s still a question of relative motion here. Relative to what? If I remember correctly, Mach’s principle would dictate that in a universe with only two bodies, there could be no sense of motion, and hence no forces. If Mach’s principle really held, if I were in a universe where there’s only, say, me and a ball, and I threw that ball, I wouldn’t feel anything; and the ball wouldn’t either, because there’s no way to define which is moving in relation to the other. GR says uh-uh, you feel a force (you have to, if the equivalence principle is to hold). But why? There seems to be built in somehow, if not a concept of absolute space (a la Newton), or space defined as relationships between objects (a la Berkeley, and then Mach), a concept of absolute acceleration. Is this correct?
That doesn’t follow from the equivalence principle–in your hypothetical case, gravity itself would be extremely weak as well. So, there is still no way to decide, one way or the other.
If you only have two objects, then it would be next to impossible to tell which one was moving. That’s the whole point of relativity, sure, the force on one is going to equal the force on the other. But which one is rotating? If each point of view is valid, then neither will have a perceptible centrifugal bulge, no matter how fast one of them rotates. If they don’t, then that means that inertia is weak. And if inertia is weak, by the equivalence principle, so is gravity.
This is where I get baffled. I’m too dumb for something here, or I’ve really misunderstood. The equivalence principle tells us inertial mass and gravitational mass look/are the same. Relativity tells us the motion of an object can only be defined in relation to other another object, not to any fixed frame of reference (a very Machian idea). With only two objects, it seems impossible to define at least some kinds of relative motion. Hence there’s maybe no meaning to inertial mass (acceleration requires motion relative to something, which in this case is hard to define). But we get gravity from warped spaces, so I’ve read. If I plunked a big test mass into empty space, and plunked a tiny test mass next to it in empty space, the tiny test mass ought to “feel” the big test mass, and move toward it. But if I can’t define, as you described, something like centripetal force (because I can’t define at least that kind of relative motion in a two-body system), then one of the conceptual bases for GR, the equivalence principle, seems to go out the window. Or does it? Gravity gets weaker?
Einstein had three “design goals” when he attacked general relativity: general covariance, Mach’s principle, and the equivalence principle. It looks like Mach’s has not been proved or disproved, and I think he more or less abandoned it later.
The Mach effect may well be M/R related, and so could reach out to the edge of the Universe–far away objects could be just as important as nearby ones. Just what does cause inertia? If it is an exchange of particles, gravitrons, then every massive particle seems to participate in it.
Aah, physicists only have to solve equations in idealized cases. It is engineers that have to solve the messy real world situations.
Coming up with the equations is generally quite hard. There is a reason GR and QED took a while to birth. The equations for this theory of a single field would be much different from any quantum current theory. Quantum fields all propagate. Some uber theory in which some interactions (Bell type) resemble actions at a distance (or, perhaps more accurately, all is one theories?), and yet the particular disturbances that we see as photons propagate, would seem distinctly different, in a mathematical sense.
It is possible to set-up an EPR-type experiment with two scientists measuring the state of one of pair of entangled particles each, where each scientist believes that they were the one to measure their particle first and therefore were the one to collapse the wavefunction determining the state of the other scientist’s particle!
Here’s my attempt to answer (correct me please, physicists, if I’m wrong!):
Their answers will always agree, so I guess it doesn’t matter who was “first”. Say two guys synchronize their watches and then one of them dashes away at 99% the speed of light, measuring his particle only a minute later, while the other observer also waits only a minute, and then measures his. If I’m watching my friend speed away at 99% the speed of light through a telescope, I might think it takes him a long time to measure his particle, but when I see him get his result, it will agree perfectly with mine. And visa-versa through his telescope. I will tell him my measurement determined the state of the particle, and he will tell me the same thing. But as this is a non-local phenomenon, we needn’t agree on when the measurement took place (in terms of proper time vs. relative time), only on the final result. To have it be otherwise would break conservation laws (like conservation of angular momentum)!
It’s not the ‘when’ as the two scientits have different time coordinates, it’s the order that the two measuremnts are observed by both scientits that creates the apparent paradox. The two scientists will both agree on the results of the measurements and the two measurement events will have a spacelike seperation (the seperation does not have to be spacelike but if it is the two scientist will always agree on theorder of the two events) which would prevent any actual paradoxes.
Well, an apparent paradox caused by relative motion is the only one I can come up with to create a situation where two scientists would not agree somehow who observed the particle first. I’m aware that there’s no real paradox. Thinking about this has been kind of interesting though, because it doesn’t appear to me that it’s possible to say either person measured the particle “first” in any absolute sense. It just drives home to me, conceptually, how weird the non-locality of the phenomenon is. It’s just interesting to think that this undetermined-until-observed thing can somehow always be correlated between causally isolated frames of reference, and thinking about all the different scenerios in which this might be true is kind of wild. I suppose to one used to dealing with these things, it wouldn’t be all that remarkable.
If the seperation is timelike or null then it doesn’t demonstrate non-locality and both events will be in each other’s absolute past or future, so in an EPR-type experiment it is always possible to pick a reference frames where the measurement events have different orders, so this is precisely why non-locality is so strange.
i’d like to ask you folks how does the multiverse fit into this all. and i mean the hugh everett type. you know like that the photon doesn’t interfere with itself but with it’s numerous twins in parallel universes.
i don’t really remember how all that went but i know it’s the only explanation of the quantum stuff anyone has told me that actually made some sense to me.
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