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Re: A Question of Simultaneity



Set up two detectors on a railroad car (spaced along the direction of
travel). Wire the detector outputs into a coincidence counter whose
output blows the train whistle when coincident events occur. All of this
apparatus is on the moving train.
Now add, on the train, an isotropic light source midway between the
detectors. When this light source fires a pulse, the train whistle will
blow.
A second observer standing on the ground sees that the whistle was
triggered by light arrivals which were not simultaneous in the ground
frame, but he realizes that the apparatus is rigged to fire only for light
arrivals which are simultaneous in the TRAIN frame.
Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor
----- Original Message -----
From: "Thomas McCarthy" <tmccarthy@SPS.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Friday, January 25, 2002 1:29 PM
Subject: A Question of Simultaneity


Hello,
If two flashes of light appear simultaneous and consequently trigger
a response, how does the non-silultaneous nature as viewed from another
frame explain the occur of the same response, yet the light is not seen
to impinge upon the trigger at the same time? Thanks.
Tom McCarthy