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[Phys-L] FW: Terrell Effect



I sent this privately, rather than to the list as intended.

Sort of the inverse of a common list-serve faux paus.


________________________
Joel Rauber
Department of Physics - SDSU

Joel.Rauber@sdstate.edu
605-688-4293


-----Original Message-----
From: Rauber, Joel
Sent: Tuesday, January 17, 2006 9:34 AM
To: 'Rick Tarara'
Subject: Terrell Effect

The question of what one "sees" when traveling relativistically has some
interesting history. If we take the viewpoint that what one sees is
what a piece of photographic film records (or a CCD) then the answer is
different than if we consider what a frame of reference "observes".

(A) The photographic film records a locus of events of photon strikes
that occur simultaneously at the location of the film, in the
photographer's frame of reference, PFR. Of importance, is that the
origination events of those photon's (whether they are actual creation
of the photon, or the event of last reflection of the photon before
striking the photographic plate) are not simultaneous in the PFR. The
photographic film essentially records the location of points on objects
at different times, since the travel time from those points to the
photographic plate are different depending on where the objects were
located. (in more fancy terminology, I'd say that the location in space
that the film records for objects is such that the objects must lie on
the past light-cone of the film; ignoring the spatial extent of the film
for the moment)

(B) What the PFR "observes" is the location of all objects that are
simultaneous in the PFR. This is usually taken to be the time of
exposure of the event, or the time when one looks out the window.

These two statements are not identical. This was not fully appreciated
until the late 50's when Terrell pointed out that what a photographic
plate or eyeball observes is (A) rather than (B).

See below, and better yet, cited references therein

James Terrell, "The Terrell Effect,"
Am. J. Phys. 57 9-10 (1989)

________________________
Joel Rauber
Department of Physics - SDSU

Joel.Rauber@sdstate.edu
605-688-4293



| -----Original Message-----
| From: Rick Tarara [mailto:rtarara@saintmarys.edu]
| Sent: Tuesday, January 17, 2006 9:08 AM
| To: Rauber, Joel
| Subject: Re: The view from the Enterprise.
|
|
|
| >
| > Are you interested in Terrell effect aspects of the problem?
| >
| > Joel R.
|
| If I knew what that was, I might be! ;-)
|
| I'm being lazy here and trying to use the expertise of the list to get

| something I'm sure I could find with enough searching. Besides doing
| these updates, I am involved with a major project of getting all my
| software and web pages translated into Spanish (and Catalan), and
| thrown in there classes have started back up.
|
| Anyway, if you have any insights, please share them--probably with the

| whole list since we need something to get away from BC's paranoid
| political ramblings. ;-)
|
| Rick
|
|
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