Mitcher

Yes, in the thread about entanglement and non-locality. The one here or so it seems isn'it ?

Jumping in the wagon here but what about the hypothese that two events would be spacelike in the 4D continuum but also much closer to each other in an oblique, 5th dimension in which those two non-local events would be local ? As long as physical information is not allowed to transit tru it. A Nobel prize for an experiment they did 50 years ago while still at Berkeley ? woaw.

To be able to describe our physical world one need a vocabulary, that is a few selected letters we will use to build more complicated sentences. Today they constitute the international system of base units, its elements are time, distance, mass, current, etc... They have been arbitrarily selected, other elements could have been chosen, for instance momentum, velocity, entropy, curvature... From your exemples of a stopped clock being right twice a day or the Newgrange one you don't seem to realize that the clocks would in fact be the rotation movement of the Earth for the first one and the revolution of the Earth around the Sun for the second one. In fact you absolutely do not seem to pay attention to what I'am saying, I do not know why nor where you are heading with your persistent questions about details.

That's what I meant. The atoms are not moving but electrons are changing to an excited energy state so there can be no change without a move(ment). My point is that ALL clocks must have something moving or changing or desintegrating in order to operate and fulfill their role of measuring time intervals, and I'am curious to see if you will be able to point out a clock truly not moving at all. For a reminder the starting point was that movements are, maybe, more fundamental elements than space and time which seem to be postulated and axiomatic rather than rigorously defined. They can be described but not independantly, all we know about them is that they are... relative so of course even the definition for continuum is altogether vague. I agree. The Sun's culmination is a periodic event, the ticking of any clock is also a periodic event and those events are then compared. But how a periodic event can take place without some periodic motion or change or active process that determine this event ?

The simplest and oldest clocks were the Moon, the Sun, an hourglass.. Their movements are used as benchmark and supposed to be proportional to time intervals, so you obviously need something to move to achieve a measurement of a time duration, In fact I do not understand why you question this as it seems so obvious. I also understand that you can merely consider time as a simple parameter t and that it's enough to do physics without having to worry about what it is on the physical plane but if one considers that every piece of matter is carried away as if in some sort of timely path with velocity c it helps to adequately illustrate Relativity. Light can be used as a clock.

As I said the coin analogy was not mine, i forgot who spoke of it first here but from what i understood it was only to clarify that nothing non-local would be at play when measuring two (anti)correlated particles apart from each others. It was not to modelize the wavefunction or anything, it was to explain that nothing magic happens when measuring one part of two opposite parts : one know immediately what it is even before measuring it. If i got that wrong then i suppose it means that non-locality is a QM feature after all ? A sure sign something is seriously flawed in the model but that's truly personal. When one says that a photon is a particle and a wave at the same time it's an analogy one can comprehend, at least intuitively. I see no problemo with this.

To measure intervals of time you do need a working clock, IOW a moving clock, IOW you need movement, a constant, cyclic one. I do not think i'am saying anything esoteric here. If you input a badly defined time into your model you will get a badly defined time in the output, so to know if time is a fundamental element of reality or if it is illusory as an emerging structure from more fundamental strata is... fundamental i guess.

I find it extremely informative and interesting but I'am missing the point, what interest do we have in knowing if it's a dollar or an euro ? It could just be a medal with green/blue faces since we are only interested in knowing if the polarization of the photon or the electron is up or down. It was not me here who choosed this coin analogy but it was usefull in understanding that there is nothing causal in instantly determining the other face of the coin once we measured the first one. Now you got me confused i must say.

Let's do a thought experiment à la Einstein and imagine that you would be emitted from a laser on Earth and absorbed on the Moon 1.3 second later. But for you it would seem that the trip was instantaneous, and that's not meaningless. Then how the lenght of an arc comes in play here ? Why not a line, like the sinus of pi/2 to describe both the time and space parts in equal magnitude ? Then cos of pi/2 = 0 for the geodesic.

Apparently i expressed myself badly, sorry, i didn't mean that some sort of kinetic is requested in order for clock to work but in order to measure an interval of time, it is a subtle difference. I have no idea how a motionless anything, be it atom or particle, could possibly measure time. A caesium atomic clock counts the number of its cycles for instance, and an electronic transition cannot be completely at standstill in my understanding. Then i do not understand your view that investigating the nature of time could be unscientific, to me it's quite the opposite. For instance i did read some research where it was investigated if time could not be of a quantized nature. If so, it could not have no consequences on our understanding of physics.

I have re-read all this discussion with extreme interest and it seems that pretty much everything has been possibly said about non-locality, sometimes even a few times. There are obviously some competent and very patient people here taking the time to explain carrefully and i certainly do not intend to start it all again, however if the explanation for decoherence and a supposed non-locality is something as trivial as the analogy with the coin, the question that comes to mind is why did Einstein and followers up to this day had to use complicated notions as action at a distance, collapse of an unphysical wave function etc.. This is what puzzles me now and because I understood completely every objections made by Bangstrom here, given that I had exactly the same prejudices resulting from all my previous readings. Is it because those QM pionneers had not competely understood those phenomena ? Even today there seem to be quite a few opposed QM schools, local realism being just one of them. Is that part of the situation ?

In photon's frame, which i understand is not a valid reference frame, however one writes ds = 0 = simultaneous.

Ah come on, I'am not here for the sheer pleasure of arguing. What question do you mean, is it "Motion isn’t absolute, so what motion is required?" ? I thought I had honnestly answered. In my simple understanding any constant motion is needed in order to measure a slice of time, a clock has motions all inside it. I basically mean the covariant Lorentz equation for space-time coordinates valid in all inertial reference frames, the only distance in space-time all observers agree on.

Well, it has everything to do with above discussion. Basically how do we operationnaly measure time ? What are its observables ? If time is quantized down to some scale instead of flowing-like we might take a different approach. Time is not absolute either, it differs according to the gravitational potential, or to the velocity of the observer, and maybe to its distance in the cosmological sense too.

ok, thank you.