Lorentz Jr

No, the strong form of the principle (at least as interpreted by some people) means more than that. It goes beyond what observers experience and claims that there's nothing "under the hood", i.e. that no mechanism is required for time dilation because it's "just a matter of geometry". Anyway, I don't know how to explain this distinction more clearly, so let's drop the subject. We're repeating ourselves. Same thing. I criticize the metaphysical principle, and you respond by defending the mathematical theory. We're talking past each other. Yes, that's very different from both ordinary human intuition (maps are about space, not time) and the intuition of 19th-century physicists (science is about mechanisms). Most people outside the modern physics establishment would say that simple comparisons of observational data and theoretical predictions only require the ability to read charts and compare numbers and have nothing to do with intuition. Maybe so, although I'm not sure how new theories of any kind at all can be developed without some general principles or opinions to guide the theorists. Anyway, let's forget about the ether for now. I've been reading about emergent spacetime, and that looks like it may be close enough to what I have in mind.

You're confusing the mathematical theory with the metaphysical principle. The theory doesn't need excuses as long as people remember that it's just a theory. An abstract model that doesn't really explain anything and may be subject to further refinement. Curvature for GR, quantum complications for the ToE, etc.. The principle of relativity is a very different animal. It's only one possible interpretation of the theory. It's a platypus, with time for a nose and space for a tail. The extreme form of the principle says there's no reference frame with any special properties at all, which means time and space are somehow "interchangeable" or "made of the same stuff". That's an extraordinary claim, and as such, it requires extraordinary evidence. That's what people keep making excuses for. It's not what I've been demanding, it's what people have been claiming. They claim that SR "explains" things, but it doesn't. It's a shallow, phenomenological model that describes non-gravitational, non-quantum things very nicely, but it doesn't explain a damned thing. It doesn't explain time dilation, it only describes it. Yes, and I'll try to keep my mouth shut about this subject in the future unless someone else brings it up again. It only came up recently because of the "fabric" thing. I'm done with analogies, Markus. Other people may not understand this distinction, but one of the lessons that have been burned into my memory over the last year is that analogies aren't evidence of anything. They're just stories. They don't prove that what the person is saying is true, they only explain what the person is saying. And I understand what you've been saying. If I tell you life is like a bowl of cherries, that may explain how I feel about life, but it doesn't mean I'm right. So, to summarize, this is where we disagree. You can appeal to physical intuition, and you can talk about abstract mathematical models, but it's BS to conflate the two ideas. From an intuitive physical point of view, a "map" with time in it is very different from a map with only spatial dimensions. That's the lie of trying to "explain" time dilation by calling it "just a matter of geometry". Representations are mathematical models, not physical explanations, and the things that people intuitively understand as "maps" are only about space, not time. It's your two cents, and it's also the two cents of almost everyone else in the physics community. So the question is, why do I seem to be the only weirdo who doesn't believe in the principle of relativity but still believes in physics? I feel like I've gone from arguing with anti-establishment trolls on one website to arguing with pro-establishment trolls on another site! That's my two cents. 🙂 Sure, but any relationship requires a mechanism, and any nontrivial one requires a preferred reference frame to account for the traveler's motion.

Fundamental principles vs details of the problem at hand. Got it. 🙂

And I couldn't find anything about them in a quick internet search.

The feeling is mutual, Markus. Spacetime doesn't explain time dilation, it simply builds it into the abstract formalism, misleadingly calls the formalism "geometry", and declares that no mechanistic explanation for TD is necessary because it's already built into the "geometry". That's circular reasoning, and I've finally lost patience with the excuses that people keep making for it.

That's math. I was talking about physics.

Then it's not machinery. Thank you, martillo. When you're observing a turtle and trying to figure out how it behaves, mathematics can describe the behavior for you. To explain the behavior, i.e. to understand the machinery that makes the turtle behave the way it does, you need to examine and describe the next turtle down, the one that supports the turtle you're studying. An explanation for the behavior of one turtle requires a description of the next lower turtle.

No.

Derivations of the Lorentz transformations define localism in terms of a single speed limit that applies to all phenomena in the entire universe. That definition seems unnecessarily restrictive to me. After all, nobody complains that c is greater than the speed of sound. Light is defined at a lower level of abstraction than sound, so it's acceptable for it to be faster. Similarly, that also applies to phenomena at a lower level of abstraction than light. If the geometry of space is Newtonian, and matter and radiation are implemented by some mechanism in an ether, there's no reason that mechanism couldn't propagate at (VERY) superluminal speeds and simulate relativistic "geometry" for light. A more general form of localism only requires that the speed is finite. It would explain things like quantum entanglement and wave-function collapse without any tortured reasoning about fate or consciousness or invisible universes, all of which conflict with Occam's razor.

I'm pretty sure the range of physical conditions that have been observed is still fairly limited. There's plenty of room for disagreement between GR, which allows wormholes and time cycles, and gauge theory gravity, which doesn't.

There's a direct link between the theoretical formalism and the elapsed time. So what? That's the thing we're trying to explain. You said something about "causal efficacy", but things can't cause themselves, so that was nonsense. Your earlier point about detecting the ether's motion is also nonsense, because that's not the same thing as having an effect. It was established way back in Einstein and Lorentz's time that, for whatever reason, time dilation and length contraction are coordinated in such a way that they have the same effect regardless of the ether's velocity. As for proving the ether's existence, I've tried to explain that time dilation is evidence of something that causes time dilation, and an ether is one conceivable explanation but not the only one. So the relativistic argument seems to be that spacetime and real space are equally valid because they're both "models". But real space is simple, intuitive, and easy to explain. One can think of it as a network of little cells (Roger Penrose has called it a "spin network"), so proximity could be implemented as connections between cells, and distance along a path could be the number of cells on the path. And those cells could potentially be related to quantum-mechanical phenomena. What is the equivalent structure for spacetime? What underlying physics could it possibly represent? Why should people accept the apparently ridiculous proposition that a structure combining such obviously different phenomena as duration and extent can be anything more than a mathematical convenience? The final justification for relativity so far seems to be, not that spacetime provides a physical explanation for time dilation, but that theories in general don't have to provide explanations, because they're "just models". Which to me seems like blurring the distinction between science and religion. Maybe this would be a good place to end the thread. I'm not sure I can stand reading these excuses anymore without getting uncivil.

How do you measure the length of the path? In real space it's the number of meter sticks, laid end-to-end along the path, that are required to connect the two endpoints. What is the equivalent operation in Minkowski space?

Except in nonrealist interpretations of quantum mechanics, where Jack and Jill don't actually go up the hill, they just have an increasing probability of being detected there! 😄 You get today's award for worst analogy, swanson. Congratulations. 🙂 So what? I don't have to know how the engine in my car works to know that it's there and it propels the car. So what? We don't have to know things exist to speculate about them. Because we haven't finished with the first step yet. The next step is just Control Theory 101: You can't drive your car without turning the key in the ignition and operating the pedals and the shift lever and the steering wheel. You need to interact with your car in an absolute sense, not just wave your car keys in the air relative to the ignition switch or wiggle your toes near the gas pedal. An ether can affect a moving object, and the object can control the ether through its absolute motion. Not relative motion. Only absolute motion can have a real physical effect. All I'm doing is answering your questions, swanson. If you don't want me to soapbox, please stop provoking arguments with me with your false analogies and pointless comments. As for not arguing in good faith, you still haven't answered my question about your claim that "time moves at a slower pace in some reference frames". All you did was lecture me about derivations, cite generalities, refer to some "straw man" that I "fabricated" without specifying what it was, and ask some irrelevant question about "time" without specifying what you meant by it or what your question had to do with our discussion:

The effect is indistinguishable from the rules of SR. That's all the distinction means. It's not even absolute. It just means the ether's state of motion hasn't been detected yet, and it doesn't have to be detected for the ether to exist. I'm not going to deny that this is a bit of a stretch. An invisible ether sounds like IPUs or monsters under the bed. Although apparently the observed combination of time dilation and length contraction minimizes some relevant action, so maybe that could explain why they're so closely coordinated. The ether is just an attempt to make sense of frame-independent time dilation, because none of the answers from SR make sense to me. Quantum wave functions represent real physical phenomena, and their time evolution is a physical process. LET and SR were developed before QM, so I tack that on as a sort of "neo-LET". I do believe there's such a thing as universal time, and I think it's required in LET for time dilation to be a real effect. As for what time itself ultimately is, as I mentioned earlier, that may be too hard of a question for science to answer. I leave it as a question for the Creator and limit myself to thinking about physical processes.

No. To an observer viewing the glass from directly above, the rim is a circle and there is no ellipse. Observers will agree on the geometry of light rays reaching your eyes and creating elliptical images on your retinas, but that's not the rim of the glass itself or the surface of any liquid inside the glass. It's just your perception.

According to LET, no experiment can detect the ether's state of motion. That doesn't mean it's not there, any more than the fact that you don't know how to open the hood (bonnet) of your car means there's not an engine inside it. The fact that the car moves with no external propulsion implies that it must have an engine, and the fact that the astronaut is younger than his twin when he returns to Earth implies that something slowed down the time evolution of the astronaut's wave function. Air drag. There's a limit to how fast the planes can fly, so, if we assume they all fly at the same speed, which is physically reasonable if they have similar capabilities, then the ones taking less direct routes have to plow through larger quantities of air. That's not a real effect. It's frame-dependent. The age difference in the twin paradox is the same to all observers. 🙂 That's why I don't insist that the ether exists. An alternative explanation is that the entire universe is some kind of simulation. As I said earlier, the speed of light as an absolute speed limit is suggestive of a CPU processing speed. My only requirement is that real physical effects have real physical causes, and changing reference frames to analyze a problem (e.g. when the spaceship turns around) isn't a real physical cause.

I don't think there's anything unusual about my use of the term. A mechanism is something that makes something happen. If someone says something "just happens", or "It's just a matter of geometry", they're denying the existence of a mechanism for whatever phenomenon they're discussing. I summarized it in three sentences, Markus. I don't think I can boil it down any more than that. No, it's not physical. The "path" you're referring to is the path through Minkowski space, and Minkowski space is a mathematical abstraction, not real physical geometry. And there's nothing about the spaceship's real path through 3D space that explains time dilation. You can't prove a negative, Markus. The ether hasn't been detected in the past, but that doesn't mean it can't possibly be detected in the future or that it doesn't exist. It potentially provides a mechanism for time dilation, and no one in the early 21st century can say what other physical consequences it might have. But there is a consequence. The astronaut is younger than the twin who stayed on Earth. That's a real, physical, frame-invariant consequence. It's a consequence of something, and an ether is a reasonable candidate for that something. Boundary conditions and paths through abstract mathematical spaces are not. Nonsense, Markus. You're making excuses. An ether can potentially explain time dilation, and explaining the ether itself can be left for future generations. There's nothing unusual about "kicking the can down the road". All science works that way. The behavior of one turtle is explained in terms of the one holding it up, the behavior of the lower turtle is explained in terms of the next one down, and so on and so on and so on.

Make sure everything is plain text. It sounds like you may have some rich text in there.

Phi (and many others before him) made the positive assertion, "There is no space time fabric". That claim isn't part of GR, and I agree with Einstein's view that some kind of underlying reality is necessary to explain why GR works. "Clocks don't tick more slowly, time moves more slowly." You're just moving the goalposts with semantic gibberish, swanson. If the astronaut is younger than his twin when he returns to Earth, then why did "time move more slowly" on the spaceship? The laws of physics on the ship are exactly the same as on Earth, and yet somehow less "time" elapsed on the ship. You're very creative, swanson. Very persistent and very creative. 😄

No, that's not it. There's nothing wrong with shallow theories if there's no clear evidence for specific mechanisms. The problem is when people deny that any mechanism ("fabric") exists or formulate principles (no preferred frame) that are incompatible with the existence of any mechanism. I don't, and what I question is why you keep knocking down these straw men. I hold people like Phi (and almost everyone else in the mainstream physics community 🙄) accountable for using the idea of "geometry" as a way to suggest that no mechanism is required. They use it as a "magic wand" to create confusion between physical mechanisms and mathematical descriptions. No, that's another straw man. I'm not criticizing the theories, I'm criticizing people who interpret the theories in confusing or unscientific ways. That sounds reasonable. 🙂 Boundary conditions are a mathematical concept, not a physical one. If two systems have different outcomes between the same two points in spacetime, there must have been some physical difference between their environments. Boundary conditions are a mathematical concept, not a physical one. They don't say anything about physical mechanisms. Sure we do. Lorentz's ether interpretation says there's an ether with its own reference frame, and time dilation is caused by motion through that mediuim. Not that there aren't problems with that idea, like why is there no experimental evidence for what the preferred frame is? But at least it's scientifically valid. Trying to "explain" the frame-independent time dilation in the twin paradox through paths and boundary conditions is not. Speaking of "living in a simulation" theories, they do provide another (barely) conceivable explanation for the lack of evidence for a preferred frame, because a simulation can do whatever the simulator is capable of making it do. For instance, c as a universal speed limit smells suspiciously like a CPU processing rate. I don't like to emphasize them, because they seem so nutty, but they're still technically more scientific as physical mechanisms than appeals to boundary conditions and "paths through spacetime". That's not unique to simulation theories. It's a fundamental question about reductionism. What are quarks and leptons made of? What are their constituents made of? Does the tower go down infinitely far, in which case even the smallest actions entail infinite amounts of information processing? Or is there a swamp of nondeterminism underneath it, in which case the universe is ultimately founded on magic? It's one of the questions I've given up on trying to answer, because I'm not sure it's possible to answer it. I take time to be another one of the great unanswerable questions. Chalk it up to God and leave it at that, because the only other alternative is being wrapped up in a straightjacket and living the rest of your life in a rubber room. It's too hard a problem. Time dilation is different though. That's just the behavior of clocks, and why should the behavior of clocks never be affected by anything? There's a certain narcissism in defining something as important as time in terms of whatever gadgets our current technology happens to be capable of producing. If two synchronized clocks disagree after one of them has flown through space for a while, then obviously something happened to alter the ticking rate of at least one of them. You are making vague assertions with no supporting logic or evidence.

Causality. All these things happen with no mechanism to make them happen. GR isn't so bad, because curvature is at least a shallow explanation, I'm not complaining about that. But then people say it's only "geometry", not "fabric". Any serious discussion with amateurs should explain any subtleties they need to understand, instead of playing "Gotcha!" with them by simply denying what they said with only the meaningless "explanation" that "it's just geometry". We've discussed SR before (a mechanism for time dilation in the twin paradox requires a preferred frame, and many physicists subscribe to a "hard" or "strong" interpretation of SR that denies such a frame exists).

You're changing the subject, Markus. I made a complaint about current practices, and you're criticizing it based on past intentions. Still off-topic. No, you think about it, Markus. I've been thinking about it for two or three years now. The laws of physics are exactly the same for all observers, and yet somehow astronauts who fly through space magically age less than people who stay on Earth. All kinds of things happen in the vacuum, with field disturbances and time-varying metrics, and yet somehow this all happens with no "fabric", i.e. implementation, to make it happen. That contradicts and conflicts with the most fundamental principles of science. And yet somehow the outcomes aren't always symmetric.

A lot of politics has happened in that time. Today's physicists use the word "geometry" as a rhetorical bludgeon to shut people up when they complain about the unscientific nature of relativity as a metaphysical principle. "It's just a matter of geometry". Baloney! Geometry is mathematics, and math is description. It doesn't explain anything or rule out things having some kind of substantive implementation. The word "define" is confusing here. Anything can be defined. Definitions are just relationships between ideas and words. The point is that geometry can only describe, and it's scientifically absurd to say that things happen with no implementation. Saying that something can't be a "fabric" because it's a "geometry" is a rhetorical BS tactic, and referring to "magic wands" in the same post is hypocritical.

The same kind of magic wand you physicists wave with the word "geometry". So spacetime has a geometry. So what? Lots of things have geometry. Geometry is just a mathematical description. It doesn't mean fields and gravity waves happen by magic or unicorns or leprechauns. It doesn't mean spacetime isn't implemented by something that an amateur might call a "fabric" or "ether". From Einstein's 1920 address in Leiden: This is only the summary in the last paragraph. There's a fuller discussion earlier in the talk.

When you see a normal object, the object permanently absorbs the colors you don't see. It also absorbs the ones you see, but only temporarily. Electrons near the object's surface get excited by light shining on them, and then they re-emit the light in all directions in colors that correspond to the energy gaps between the electron states. I don't think it's possible for chrome to not be shiny (as long as it's clean). The energy gaps between its electron states are very small, so it reflects all electromagnetic radiation. What do you mean? Are you asking why light emits light? All accelerating electric charges emit electromagnetic radiation, and ordinary objects are illuminated by light sources. Other than being quantized, photons are just waves in the electromagnetic field. They are the glow.