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From: ellis@flairvax.UUCP (Michael Ellis)
Newsgroups: net.physics
Subject: Re: Query - re. Speed of Light
Message-ID: <256@flairvax.UUCP>
Date: Wed, 12-Oct-83 05:57:29 EDT
Article-I.D.: flairvax.256
Posted: Wed Oct 12 05:57:29 1983
Date-Received: Thu, 13-Oct-83 09:51:07 EDT
Organization: Fairchild AI Lab, Palo Alto, CA
Lines: 50

Hope this doesn't become tedious to advanced physics people, but I'd
really like to know how things appear from a C-velocity reference
frame. From my previous article...

>... you can never `do anything' at C -- you are `frozen' as long as you
>continue to travel this speed.  Therefore, you cannot turn on your
>headlights while traveling at C.

{nb. we're discussing hypothetical zero rest mass people, clocks, headlights}

to which, unless I misunderstood, Greg Hennessy replied:

>(in an inertial frame traveling at C..) A person can do anything he wishes,
>including turning on the headlights.

Now wait a second. To my understanding, any positive time interval in a
C-velocity reference frame corresponds to an infinite amount of time in ALL
sub-C reference frames. To the extent that an infinite amount of time in
the `universe' has meaning at all, Greg Hennessy's remarks seem correct.

Seems to me, if you were in a C-velocity frame:

o If a positive amount of time passed (as measured your clock), the first
  thing you'd encounter would be, uh, maybe the end of the universe.  This
  would occur instantaneously. I won't even try to speculate where or when
  you would be if you and your clock kept going after that...

o If precisely zero units of time passed (again, by your clock), but your
  velocity were subsequently (according to someone else's clock) slowed to
  less than C, you could have traveled to ANYWHERE in the universe.

It is in this sense that I meant you can't `do anything' (except move in a
`frozen' state) in a C-velocity reference frame.

Comments, flames welcome. I'd really like to know if this is correct. And
does experimental physics show that time does not pass for photons? It
always struck me as strange that they were something, yet had no mass.

-michael

-ps to Darth Wombat:
    I wasn't trying to pick at your response as much as I was trying to
    determine how things `appear' to a photon. Sorry.

-pps Whether this article is correct or not, we still haven't determined
     what things `look like' from a C-velocity frame. I heard somewhere
     as your velocity increases toward C, the visual area in the direction
     of motion `appears to expand'; does this imply that at C the point at
     your direction of motion expands to fill your entire visual field?