Does Relativistic Motion Affect Time Perception on Moving Trains and Platforms?

[JVNY]

It seems to me that what's really going on here is bad pedagogy: trying to teach concepts like relativity of simultaneity while still attempting to preserve ordinary intuitions about concepts like "now". This leads to either an inconsistent interpretation--sometimes talking as if "now" is real and sometimes talking as if it's just a convention--or issues like the ones you raise, where it seems like single events happen "now" twice for an observer that changes his state of motion.

I think that it is an issue of pedagogy. The citations do not give the answer, but the complete question posted on another site implies the answer. The complete question is here, http://www.physast.uga.edu/files/phys4102_fertig/HW%20Chapter%2015.pdf , and includes the following about the brother's age "right now" before and after the frame jump:

If the traveling twin is asked the question, "How old is your brother right now, and which of you is younger?", what is the correct reply (i) just before she makes the jump, (ii) just after she makes the jump? (Nothing dramatic happens to her brother during the split second between (i) and (ii) of course -- what does change radically is his sister's notion of what "right now" means.)​

The Dolby and Gull article points out similar issues at page 1257, using "Barbara" as the traveler:

Bohm goes on to say that ‘‘after the acceleration at E an event such as N is ascribed a smaller time coordinate than it had before!’’ . . .

Also, if Barbara’s hypersurfaces of simultaneity at a certain time depend so sensitively on her instantaneous velocity as these diagrams suggest, then she would be forced to conclude that the distant planets swept backwards and forwards in time whenever she went dancing!​

So Dolby and Gull draw the hypersurfaces of simultaneity using the radar method instead.

 

[phyti]

This drawing reduces the example to Greens perception of Reds motion.
The left part is essentially the same as drawn by George in post 5 using radar methods.
The transfer for each from the platform to the train occurs at t=0 instead of 60.
The original red path is retained (black dashed) for comparison of before and
after positions (magenta) of clock ticks.
The right part is refined to replace the instantaneous changes with
continuous paths for 40 time units, thus rounding all the corners.
When compared the all inertial version is a good first approximation.

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