I'm not a physicist, so take all of what I write below with a grain of salt. On the other hand, I'm also not an internet video personality, so at least you might not need the entire salten sea.
(December 5th, 2024, 09:28)Cornflakes Wrote: What is time? Or more directly, what definition of time allows for time to be reversible?
My understanding: There's no such definition because "time"
isn't reversible ... any more than "length" or "width" is reversible. In classical
or quantum mechanics, all events/interactions are
in principle "reversible in time" - the way your car is "reversible in length." That is: You can turn the car around so it's parked back-to-front in the same direction in which it was previously front-to-back, and it will still be a functional car. (Actually if you really reverse it in just one dimension, you'll end up with a British car with the driver's side on the right, and I vaguely recollect that if you take it to extremes at the quantum level, you may end up with an anti-matter car, so please don't try testing this with some kind of magic one-dimensional-reversal ray.)
But if you take the case of say a drop from a leaky faucet falling into the sink and splattering, and you run the whole scenario backward as if with a rewind button on a movie, and calculate the momentum and kinetic energy of each of the (various other interacting molecules and) zillion tiny water droplets which (as you watch them backward) happen to be converging on the same spot in your sink, where they smash together into a single big drop, bouncing off the sink together, exactly counteracting one another's lateral kinetic forces with the help of cohesive forces from hydrogen bonds, and consequently rebound up to your faucet, slowed by the force of gravity until they come to a stop right up against the faucet's edge where adhesive and cohesive forces keep them from falling again, you'll find all the numbers add up and the physics works with no problems. It's just that such an event would be so wildly improbable in the universe as we understand and experience it, with every molecule moving exactly right, that we know it would "never" happen that way in the real world. We make our predictions on the basis of this understanding and experience, and they keep turning out to be right - in our continuing understanding and experience. If enough sinks and nearby water droplets keep existing for long enough (don't ask me how many googolplexes of sink-years would be needed; I couldn't even calculate it) eventually some "reverse drips" will actually occur. They're so unbelievably, impossibly rare though (on a macroscopic scale and/or over any significant timeframe at least) that we can ignore them for all practical purposes. (Also for
virtually all
impractical purposes.)
So going back to the first question, "What is time?" a
physics answer might be something like, "A dimension of spacetime in which we consistently observe entropic asymmetry in the same direction." It
does all depend on what we can observe though, because...
Quote: (December 4th, 2024, 16:12)shallow_thought Wrote: Philosphically, all physical theories are empirical.
I would say this is true not just philosophically, but by definition. A "theory" (by colloquial definitions) without empirical support - indeed without an
overwhelming mountain of empirical support - is not a physical (or scientific) Theory (by the scientific definition).
Quote:But this is my big objection to quantum theory. There is a lot of deep thinking that about things that are nonsensical. In my opinion "collapse of the wave function" is garbage theory.
Are you objecting to quantum theory (in which case, see my comments on Heisenberg below) or just to some of the philosophical garbage that's been foisted
onto quantum theory? "Collapse of the wave function" is sometimes used as short-hand, but really it's just part of the Copenhagen Interpretation, which as the name implies is not a scientific theory but an attempt to force quantum mechanics to fit with (
some of) our unsupported preconceptions about the nature of the universe (at the expense of other unsupported assumptions). If you want to call the Copenhagen Interpretation a "garbage theory" (if you mean "theory" in the colloquial sense; it is very much not a scientific Theory, and isn't called one) my only objection would be that many people find it a useful tool for thinking about quantum theory (which is notoriously
extremely difficult) and making new and testable predictions about it - and anything useful isn't garbage.
As short-hand, by the way, as far as I know, "collapse of the wave function" pretty much just means "the point(s) where we can actually start observing events for which we need quantum theory to make accurate predictions." Note that the "we" doing the observing here is important only to us: There are references to e.g. "an intelligent observer" associated with the Copenhagen Interpretation, but that observer is nowhere defined, and my understanding is that that any events that are observ
able even in
principle qualify, whether they are "actually observed" or not, and that this has been demonstrated experimentally. I should add that as far as I know, there is no "hard line" between observable/classical mechanics and quantum mechanics: As effects of quantum phenomena become more and more readily "observable" (i.e. have increasing probabilities, based on quantum mechanics and experiment, of predictable "classical" interactions like triggering macroscopic sensors and the like) the quantum effects "smooth out" so that subsequent results are observed to be more and more in keeping with classical expectations as their prior maybe-observable interactions grow more-reliably observable, showing off a "grey area" between quantum and classical theory. One hypothesis about this is that classical effects are just a consequence of quantum interactions naturally "smoothing out" into predictable patterns this way e.g. as the number of interactions grows large, but we don't have the computing power yet to make enough specific new predictions from this hypothesis to test it adequately. Which is to say, it might still be way off-base! (In collapsing-waveform short-hand, you'd say that in the "grey area,"
some of the quantum waveforms "collapse" by interaction but others still get through as "probability waves." I think.)
Quote:Another example of a garbage theory is the Heisenberg Uncertainty Principle.
Again, there may be garbage philosophy that hand-waves some connection to Heisenberg, but the uncertainty principle itself is in no way garbage. It's one of those things that can be discomfiting or seem intuitively wrong, but if you decide to quit using technology that relies on its accuracy, you can't post about it on the internet anymore because you've just taken your cell phone and computer and ultimately every other piece of modern technology out of bounds.
On the videos in this thread: I didn't actually watch either of them (and won't - some people really like getting information through video media; I ... don't) so my only definite comment on the one you posted most recently would be that any attempt to explain quantum uncertainty to a lay audience in three to four minutes of video is inevitably doomed. I can make a
guess though, that the first three minutes try to make quantum indeterminacy intuitively comprehensible by talking about it as though it were a result of the means of measurement affecting experimental results - the "observer effect" - as many have tried before, all the way back to Heisenberg himself. There are problems with this "explanation," but they're problems with that method of making it seem more intuitively comprehensible, not with quantum indeterminacy itself: Heisenberg uncertainty doesn't describe a limitation of the precision of our observations except insofar as we can only observe what's actually
there. What it in fact describes is exactly a limitation of classical-style (and therefore intuitively sensible-seeming to us humans) descriptions of quantum phenomena. In other words: It's not (just) that we can't precisely measure a particle's position without affecting its velocity; it's that "position" and "velocity" are classical mechanical (and intuitive-to-us-humans) ideas that
don't work anymore when you try to use them with enough precision that you can no longer neglect quantum effects. Of course, since I never watched that video, I can't be sure that's even what's being discussed.
Luckily for me, going back to the
first (lonnnnnng) video in your thread, I find it was produced by someone who also has written text articles, including (at least) one about aether, so maybe now I know what you're
talking about! Sadly, the article is (perhaps-entertaining, depending on if you like that sort of thing) drivel. Its argument for aether is
almost reminiscent of Russell's Teapot, except that this "defense" of aether appears to be written without any grasp of orbital mechanics or the scientific method. Also, while I'm looking back at it, I should point out something else from your first post: Classical mechanics has
not been "solved" long ago ... nor
yet! There are vast ranges of obvious phenomena for which it never provided an adequate description and still doesn't.
Many of these can
now be described quantum mechanically, but our "solutions" are
still not complete!
(Now, in the event that anyone reading this actually knows, I'd love to learn which parts I misunderstood and what I missed!)
). I'm now hoping that it suicides into either my C1 axe or fortified archer in the city.