Yes but this 4th grader wants this highly educated poster to NOW say what is the physical cause for claiming the resting clock physically dilates according to the view of the traveling twin. ...
FOR WHAT MUST BE THE 30TH TIME:
THERE IS NO PHYSICAL CHANGE IN EITHER FRAME* (or any of the thousands of other different frames, all of which DESCRIBE events in frame A as having
different time dilation and length contractions. - That is not possible if there is ONE real physical change in frame A.)
For example: How does frame A clock have physically changed tick rate so that frame B describes it as half the tick rate of frame B clocks and frame C describes the tick rate of frame A's clocks as being 1/3 of the tick rate of frame C's clocks?
I hope you can think of more than two frames at one time, but that does seems to be beyond your mental capacity. Try harder; you need to think about at least three frames at the same time. (A’s “physical change” for B is NOT possibly the same as for C; but B & C can each DESCRIBE an
unchanged cesium clocks tick rate differently.)
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* Hence no need to postulate a physical change for something that does not happen and even forces one to postulate the THEORY changes as theories, such as quantum theory can CALCULATE THE ENERGY LEVELS OF ATOMS, etc.
For example, Cesium is used in many atomic clocks. It has energy levels given by Quantum Theory for it 55 electrons. The energy differences between these levels determines the frequencies of cesium radiation. The cesium clock simply counts a specified number of cycles of radiation from one of these energy level transitions to define a second in all frames. Thus, the only way a second defined in frame A could change is if there is a change in the atomic energy level structure, which for cesium happens to be:
Shells 1,2,3 4 are completely filled & n = 5 is almost, but the highest angular momentum sub state of the n=5 shell (called "f" in standard spectroscopic notation) is still un occupied. High angular momentum states of the more complex atoms are with higher energy levels than some of the zero angular momentum sub states (called "s") of lesser principle quantum number n. For example in cesium's case the 6s state fills before both the 4f and 5d electronic sub states.
The outer most shell of cesium is none-the-less that single "6s" (zero angular momentum) electron, much like hydrogen* but because with zero momentum it penetrates all the way down to the nucleus, it is still well bound for an n= 6 electron. (1st Ionization Potential: 3.89 Volts; 2nd Ionization Potential: 25.1 Volts) This is also why it fills before the and 4f & 5d electrons do as you move up thru the periodic table of the elements.
SUMMARY: For your "physical change in moving frame A" to be correct you must destroy almost all the known quantum mechanics and chemistry facts. I.e. Re-arrange the electronic structure of atoms so that their radiation has lower frequencies and counting a fixed number of cycles of it by an atomic clock then takes longer.
Your idea that cesium clock defined second is different just because the frame is moving wrt to your historic CFR or some absolute frame is NONSENSE that is impossible to accept by anyone with college entry level understanding of electronic structure as a sequential filling of QUANTIZED energy levels as one move up thru the periodic table of elements if they also understand how an atomic clocks work. (I.e. that they counts a fixed number of radiation cycle made by transitions between these QUANTIZED energy levels to advance a second.)
Before trying to correct SR and 100,000 physics Ph.D.s and 100 years of confirming experiments, you should at least learn something about atomic clocks and how quantum mechanics THEORY sets the structure of atomic energy levels.
Again: atomic THEORY does NOT change with speed.
There is no physical change** to explain.
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*Cesium is quasi hydrogen like with one outer most electron - I.e. in the first column of the periodic table. Part of the series: H, Li, Na, K, Rb,
Cs, Fa
**Not in any frame, including the "resting frame" (the choice of which is arbitary for SR considerations) I.e. physicist observers in B will tend to take their frame B as "resting" and my frame A as "moving," but I will do the reverse. - Take my frame A as "resting" and their frame B as "moving." Neither needs any historical information to do correct SR physics, nor is there any way the cesium atoms could even be told of it if it did exist.
PS I happen to know a little known, but interesting, and possible very economically important, property of cesium:
When cesium is briefly on a hot tungsten surface (a surface with a relatively large work function) it "evaporates off" as and ion! (Leaves its 6s electron behind to become a conduction state electron of the solid.)
I worked at LASL two summers while in graduate school. In one of them we were very seriously looking into the feasibility of making a "thermal battery." (I helped one permanent employee build a high temperature vacuum furnace with a hot tube of tungsten (Possibly the world's biggest incandescent light bulb, but inside a steel vacuum tank so no light was seen.) Idea was that the thermal energy of a nuclear reactor could be converted directly with no moving parts into electricity -I do not know what happen to the idea but AFAIK is not being actively explored now (at least not in the US).