On Monday, June 23, 2025 at 7:23:48 AM UTC-6 John Clark wrote:
On Mon, Jun 23, 2025 at 1:13 AM Alan Grayson <[email protected]> wrote: *>> Accurate measurements are absolutely necessary if you want to detect ANYTHING! If your measurements are lousy then you will not be able to detect tidal forces, and if you can't detect tidal forces then you can't tell the difference between being stationary on the surface of a planet and accelerating in a rocket through empty intergalactic space. * *> In a recent post, here's where you claimed accurate measurements were irrelevant to detecting tidal forces:* *>> "The sensitivity of the instrument is not the issue, no matter how sensitive it is if you pick a small enough region of space it will not be able to tell the difference"* *And my remark in the above is 100% consistent with my other remark that "**Accurate measurements are absolutely necessary if you want to detect ANYTHING!"* *>> "There is a limit on the precision that any real instrument can have because it will always produce an error, let's call it Ω, that is greater than zero. So no matter how small Ω is, I can always produce a finite region of space in which your instrument cannot detect a difference between gravitational mass and inertial mass. And regardless of how large a volume of space you're interested in, provided it's not infinite, I can produce a large but finite sphere of matter that produces a gravitational field that your instrument cannot distinguish from acceleration." * *And my remark in the above is 100% consistent with my other remark that "**Accurate measurements are absolutely necessary if you want to detect ANYTHING!* *> So, in this scenario, the experiment can be done so that tidal forces will not be detected* *Obviously it can be done! It's ridiculously easy to perform lousy experiments that have huge error bars, but such experiments can tell you nothing. More precise experiments are more difficult but they have the potential to tell you that something is not true. Extremely precise measurements have been made but none of them show that the equivalence principle is false. * I am not contemplating lousy measurements. If I have great measurements and detect tidal forces, therefore denying the EP, I can easily change the design of the experiment, so tidal forces will not be detected. Thus, affirming the EP. So, what we have here is nothing less than a contrivance to prove what we want to prove; namely, that the EP remains intact. AG *> and one can conclude the EP holds.* *This is physics not mathematics, no experiment can prove that something is correct, but you can prove that something is incorrect. And so far at least the Equivalence Principle has never been proven to be incorrect. * * > But this is obviously contrived, and depends on NOT having no definite idea what "local" means. AG * *The operational definition of "local" means that no matter how sensitive your tidal force measuring device is, I can pick a volume of space that is so small that your device cannot detect that tidal force. If your device is infinitely sensitive (such a device would be unphysical, but never mind) then "local" would be a point which has zero volume. * Sure, you can always design the experiment to get the result you want. Is this what you call "physics"? AG *>>The reason all objects fall at the same rate under the influence of gravity is because gravitational mass and inertial mass are equivalent. And that is the Equivalence Principle. * *> I'm not sure how this conclusion is reached. AG* *If you double the gravitational mass of an object falling to the Earth then you double the force it feels from gravity, but if they are equivalent then you have also doubled the inertial mass, so it takes twice as much force to produce the same acceleration. Therefore the rate of acceleration an object has as it falls to the ground is the same regardless of what the mass of that object is. * *>> You said you're not interested in what Physics professors at major universities who have spent their entire careers studying General Relativity have to say on the subject of General Relativity. Why is that? * *>I never made that claim. You're putting words in mouth!* *No I am not! I can provide a quotation, words actually coming out of your mouth, or at least your keyboard: * *"I have no idea what Wheeler's colleagues think about this issue, nor does it really matter."* *> University professors are usually too busy to deal with issues I raise,* *Don't be ridiculous! All the questions you have raised are ones that you'd expect from a high school student being exposed to relativity for the first time, and all your objections have all been answered to the physics community's satisfaction more than a century ago.* When I was a graduate student, I had no problem with Relativity. I accepted it without reservation. Now that I am more mature in my thinking, I see there are several unresolved issues. I am not averse to discussing these issues with knowledgeable persons, but most, like you, prefer character assassination, rather than trying to see where I am coming from. AG * You're fighting a war that ended a long time ago. You're like Shoichi Yokoi, a Japanese soldier who didn't know World War II was over and so hit in the jungle on the island of Guam until 1972. If you want controversy you'll find plenty of it in Quantum Mechanics but not in relativity, and certainly not in Special Relativity. * *>> 20 years before Einstein was born Maxwell used his electromagnetic equations to calculate the speed of light, and it agreed perfectly with the experimental determination of the speed of light. however those equations did NOT say what that speed was relative to, they just said that was the speed of light. At the time many thought that was a major flaw in Maxwell's idea, but Einstein thought it was Maxwell's greatest triumph. **If you believed what Maxwell's equations are telling you and the speed of light really is the same for all observers, then Einstein proved in 1905 that the logical consequence is time dilation and length contraction; if they did NOT occur then there would be a true logical paradox.* *> While I agree that for the velocity of light to be frame invariant, from a logical pov we get time dilation and length contraction. That's the conclusion of an observer in the rest frame observing a moving clock. But the observer in the frame of the clock, does not measure these phenomena. So what I find baffling, as the muon case shows, is how apparent* *If things were otherwise it would be far worse than baffling. * Things as they are, remain baffling. You just can't admit that you can't answer my questions. For example, how can an observer see a moving clock ticking slower than an observer in the moving frame, which is at rest with the clock in his frame? That is, how can an apparent observation become real, as in the muon case? You can't bury the question by saying that's how Relativity works. AG . *If the speed of light was constant for all observers but time dilation and length contraction were only apparent and not real then you have a full-fledged logical contradiction on your hands, one that existed not in the abstract world of mathematics or formal logic, but one in the actual physical world. We know for a fact that our physical world is mind-bendingly odd, but odd is not the same as paradoxical. * *>>> I reiterate my opinion that Einstein's equation just tells us how to calculate unknowns of interest, but doesn't offer any physical model of exactly how,* *>> You could say exactly the same thing about Newton's equation F=ma, in fact you could say the same thing about ANY equation in physics. * *> Yes, I can say that, and I do, but in the case of classical E&M, it was known before QM that electrons occupy the outer regions of atoms,* *That is incorrect. Quantum Mechanics started with Max Planck in 1900, Rutherford didn't discover that electrons were "orbiting" the nucleus of the atom unAAtil 1911. * And in 1911 QM was not in its final form. That would take another 15+ years. Classical E&M gives us more than a clue whey we can't walk through walls. AG *And classical electrodynamics could NOT explain how it could be possible that a negatively charged electron could orbit a positively charged nucleus because an orbiting object is experiencing acceleration do to the fact it is constantly changing directions, and classical electrodynamics says that an accelerating charged object, such as an electron, will emit electromagnetic radiation, lose energy, fall to a lower orbit, and spiral into the nucleus in 10^-11 seconds. * Does QM explain why atoms in motion don't radiate energy? The protons in the nucleus would presumably do that if they accelerate. With someone like you, who indulges in character assassination, I have to be extremely rigorous. Otherwise, I will incur your de-facto wrath. AG *Obviously that doesn't happen. So what classical electrodynamics says is not relevant when you're talking about something as small as an atom. As I explained in my previous post, the true reason I can't pass my hand through my desk is because of quantum mechanics, more particularly because of the Pauli Exclusion Principle.* *John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* wsa *When you touch a marble with your finger, why is a force applied to the marble? To really get to the bottom of that question you need more than classical physics, you need Quantum Mechanics. It's not because of electromagnetism which can be attractive or repulsive or zero if there is no electrical charge, and atoms have no electrical charge, and both your finger and the marble are made of atoms. * *The real reason is because atoms have electrons in their outer layer, and electrons are fermions (that is to say they have half-integer spin) and so must obey the Pauli Exclusion Principle which says that two fermions cannot be in the same quantum state. * How does Pauli's Exclusion Principle prevent radiation loss due to acceleration? AG *On the other hand bosons such as photons (that have integer spin) do NOT need to obey the Pauli Exclusion Principle, in fact in some circumstances they prefer to be at the same quantum state. In 1917 Einstein used that fact to discover the principle of Stimulated Emission, which is the operating principle behind the LASER, which is an acronym that stands for Light Amplification through Stimulated Emission of Radiation.* *But why is the Pauli Exclusion Principle true? Because Quantum Mechanics demands that it be true. What demands that Quantum Mechanics be true? I don't know. * *> when you're sitting on your butt, but time, the 4th dimension, continues to advance. Also, when I used the condition "at rest", I meant at rest on the Earth, or any other frame one might choose. AG* *On a space-time diagram you are always moving at a constant speed, the speed of light. When you're sitting on your butt all your speed is in the time dimension, but when you get up and start walking a small part of your speed is in a spatial dimension, so your speed in the time dimension decreases slightly. And that is called time dilation. * -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/everything-list/1ef0c278-f3de-4007-86f5-8ab3b39f170dn%40googlegroups.com.
