John,
On Sun, Mar 2, 2014 at 3:51 PM, John Berry <[email protected]> wrote: > From a discussion in another group, I can say that the view of SR would be > that what is simultaneous in the train frame would not be viewed as > simultaneous in the track frame. > > This would only be true if the sprayers were triggered by signals sent from a particular railroad tie in the track's frame of reference. For example, consider that two signals are sent -- one to the back and one to the front of the train -- when the middle of the train crosses that particular railroad tie. Since the signals travel an equal distance, the sprayers are activated simultaneously in the train's frame of reference. Of course, from the track's frame of reference the signals do not activate the sprayers simultaneously because of relativistic effects. However, in my though experiment, the sprayers are activated by two synchronous programmed clocks on board on the train instead of by signals sent from the track's frame of reference into the train's frame of reference so the relativistic argument against simultaneity cannot be applied. > But the rotary argument is hard to fault. If a disk has a circumference > of 100 units of length, and with length contraction is now 99 units of > length to the rotating frame, but it now sees a 100 unit measure in the > stationary frame to be only 99. > > So something that should fit around it in the stationary frame can't fit > around it in the disk frame. > > No issues with simultaneity, and if you look at the disk from an on-top > view you can simultaneously see every length unit marked must be contracted > at once. Actually there is an issue as now the radius is not contracted so > this view should not even be possible. > > This is why I avoid applying SR to rotating reference frames, although I did a google search and found this author claims it can be applied http://math.ucr.edu/home/baez/physics/Relativity/SR/acceleration.html > It is entirely contradictory to rotate something under SR, SR must insist > on time dilation and length contraction to be seen from both frames for > light to be seen as C, except if it happens then a non-solvable paradox > occurs with both time dilation and length contraction that would not occur > with linear models where distance causes issues of communication delay, > growing communication delay (Doppler) and as the paradoxical time > accumulates in the twin paradox so does the degree to which > non-simultaneity can account for it. > > But once all of those issues are removed with rotation or possibly > vibration, none of those issues can account for he paradox, it is like > handing the twins a set of instantaneous walkie talkies in the classic twin > paradox. > > John > > > harry
