On Tuesday, August 26, 2025 at 8:36:42 AM UTC-6 John Clark wrote:
On Tue, Aug 26, 2025 at 3:52 AM Alan Grayson <[email protected]> wrote: *>> A photon is a point particle that has a wave LENGTH. In the early days of Quantum Mechanics they called something that has both particle and wave properties a "wavicle" but for some reason the term never caught on, I think that's a pity because "wave" and "particle" are just words and thanks to Quantum Mechanics we now know that some things don't fit in with either of those words. If that seems strange and confusing it's only because it is strange and confusing. * *Nevertheless it remains true that a photon is a point particle that has a wave LENGTH, and if you know the wave LENGTH of that wavicle then you can calculate its energy, and the longer the LENGTH the less energy it has. And if space is expanding then everything that has LENGTH will expand with it unless there is a force available to counteract it; and in the case of the photon, unlike our local group of galaxies, there is not. * *> Clearly, you're seduced by a word, and that word is "length".* *If "expanding space" doesn't mean that lengths expand then then what the hell does it mean? * *> And, as I've repeatedly stated, the "wave" of a photon is an ENSEMBLE property, and simply not detectable for single events.* *That is simply not true. Individual photons can and have been polarized and that is a wave property. If you pick a direction at random and call that "up" and rotate a polarizing filter to the up direction, and if a** previously unmeasured photon makes it through that filter, then there is a 100% chance the photon will make it through a second filter** that is also in the up direction, but if you rotate the filter by 90° then there is a 0% probability the photon will make it through the third filter. And in all of this we're dealing with one single photon. * *And Newton discovered about 350 years ago that different colors have different wavelengths. In 1905 Einstein explained how the recently discovered "photoelectric effect" works by showing for the first time that light is made of photons and that the energy in a single photon is inversely proportional to its wavelength (E = hc/λ), it's why Einstein got the Nobel prize, it was not for relativity. Red light has a longer wavelength than blue light and it has been experimentally confirmed many many times that a single red photon has less energy than a single blue photon in exactly the way that Einstein predicted. * *I think your confusion over this is because although individual photons definitely exhibit wave characteristics, in addition to that Quantum Mechanics is also able to give us predictions that, because they are statistical, can only be verified by repeating an experiment many times. For example if the polarizing filter in the above example is rotated by just 45° not 90° then there is a 50% chance the photon will make it through the filter, the general formula for the probability of transmission is cos²(ø) where ø is the difference between the angles of the two filters. Because that probability is not 0% or 100% the validity of the prediction can only be made statistically after several trials, but that doesn't change the fact that single photons have been experimentally verified to have both wave and particle properties. * *> I corrected your error on this issue a few posts previously, with no response from you.* *No offense but that's because you make so many errors in a typical post that if I tried to correct every one of them I'd get carpal tunnel syndrome. * *> The idea of photons increasing or decreasing their energies due to red or blue shifting likely pre-dated GR,* *I**t did. Einstein discovered that red photons had less energy than blue photons in 1905, and Einstein discovered General Relativity 10 years later in 1915. But that there was such a thing** as a "cosmological redshift" wasn't discovered until 1929 by Hubble. * *>> As I already mentioned in a previous post, Einstein finished General Relativity in 1915 and he knew his theory's equations said the universe must be expanding, * *> Are you sure?* *Yes.* *> How could he know that in 1915,* *Because that's what his equations of General Relativity unequivocally told him. * *How is that possible if Eddington proved that GR implied the universe could expand or contract? AG* *That could've been a triumphant prediction but at the time Einstein thought it was a flaw, a flaw that he thought he could fix by adding a cosmological constant that would make the universe static. Einstein was wrong in thinking that the prediction of an expanding universe was a flaw in his theory, and he was also wrong in thinking that tacking on a cosmological constant would make a static universe. After 1929 Einstein knew he was wrong and so abandoned the entire cosmological constant idea. * *> if it wasn't until 1930 that Eddington proved that a static universe was unstable, and could be expanding or contracting? AG* *Eddington proved that with or without a cosmological constant General Relativity predicted a universe that was not static. * *>>> But entropy for a closed system can never decrease -- that's the correct statement of the 2nd law.* *>> I know I'm being pedantic but it's actually "entropy for a closed system can *almost* never decrease".* *> I don't claim to be an expert in thermodynamics, but I did take a course in that very subject, and I recall quite clearly that your revision of the 2nd law is false.* *You're certainly correct in saying that you're not an expert in thermodynamics because what you say in the above is 100% wrong. The second law of thermodynamics is a statistical law and therefore can only provide probabilities not certainties, * *Classical Thermodynamics is NOT a statistical theory, and the 2nd Law is NOT a statistical law. Maybe you're thinking of Statistical Mechanics. AG* *although the probabilities of some things are so low we can say the probability is zero with very little chance of being proven wrong. Even if somebody didn't know any quantum or classical physics they could derive the second law by just using logic and the fact that there are more ways to be disordered than ordered. To exactly state the first law of thermodynamics, the one about conservation of energy, you'd need to write a lot and use the word "however" many times and put in lots and lots of footnotes about exceptions and additional explanations. But even a thousand years from now nothing like that will be needed for the second law for the same reason that no footnotes will ever be needed for the fact that 2+2=4. * *>> The second law of thermodynamics alone is sufficient to explain why the state of the universe called "tomorrow" will have a higher entropy than the state of the universe called "today", but to explain why the state of the universe called "yesterday" had a lower entropy than the state of the universe called "today" you need more than the second law, you also need an axiom that says the universe started out in a state of very low entropy. * *> It seems obvious that entropy does not decrease from yesterday to today.* *Everybody agrees that yesterday entropy was lower than it is today, but the paradox is how can that be if entropy... * *> **can remain constant or increase* *Increase with respect to what? * *Increase with respect to time.* *But time is the very thing we're trying to figure out! * *The thing called "tomorrow" is a different state than "today", and there are many more ways for a thing to be disordered than ordered, so it's easy to see that the probability is overwhelming that tomorrow will be more disordered than today. But the trouble is you can say the exact same thing about the thing called "yesterday".* *> so I don't see any problem here. What exactly is the problem you allege?* *It was pointed out by Loschmidt as early as 1876 that it is logically impossible to deduce an irreversible process from nothing but time-symmetric laws. Classical physics was the only sort of laws that Loschmidt knew about in 1876 but the introduction of Relativity and Quantum Mechanics did not change that situation, Loschmidt's logic is as rocksolid today as it was then. The thing that you have forgotten that Loschmidt had not is that the state of a system is not determined exclusively by the laws of physics, it also depends on initial conditions. * *Loschmidt's paradox <https://en.wikipedia.org/wiki/Loschmidt%27s_paradox> * *John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* mak -- 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/0bc67890-dc57-4601-bd9d-b1c6e703be06n%40googlegroups.com.
