From: moon@mozart.llnl.gov (Steven Moon)
Newsgroups: sci.space
Subject: Re: What is the speed of light measured from?
Date: 1 Sep 92 21:52:52 GMT
Organization: Lawrence Livermore National Laboratory

In article <1SEP199204185362@reg.triumf.ca>, vincent@reg.triumf.ca (pete) writes:
|> In article <1992Aug31.173411.13396@cbfsb.cb.att.com>, 
|> wa2ise@cbnewsb.cb.att.com (robert.f.casey) writes...
|> >Makes you wonder how the "particle" of light "knows" how fast or slow to
|> >speed up by to be travelling at the -speed o' light- at or near the
|> >local frame of reference.  Does it "feel" the local gravity, or something?
|> > 
|> 
|> What you have to understand is that c is not just a velocity.
|> The way this universe is constructed, it's like a point that
|> time and space both pivot on. You could say that c is infinitely

I don't see your point.  If you consider c = infinity you are then 
just dealing with Galelian transformations.  If you are considering the
point of view of a photon, this is a philosophical question.

|> fast, for anything travelling at it, it's just that the geometry
|> - in fact the _logic_  - of the universe requires that it not
|> be seen as infinitely fast by other observers. For instance,

The logic (as you call it) of the Universe says (as far as SR) that
physical laws are the same in all reference frames as well as the speed of light.

|> if you board some wonderful rocket, which can sustain constant
|> acceleration ( in your frame of reference ) and commence 
|> accelerating, it will seem to you that you just keep getting
|> faster and faster, and you pass c without incident. The only

This is not true.  In order to measure the velocity of your 'wonderful' rocket
you must make some measurements.  You take you watch and meter stick and measure
some object at rest w.r.t. the inertial frame you started in (say the Universe)
So measure the position of some Star at two different times.  You will not 
come up with some velocity > c.

|> catch is that in the rest of the universe you travel through,
|> time seems to be going by faster and faster relative to yourself,
|> such that to observers in other frames, your velocity never
|> quite reaches c. They also see your time slowing down, so they
|> can understand why you might think yourself going faster than
|> c ( for simplicity I've left out all the interesting details
|> of how times can be compared between reference frames).

I would suggest brushing up on your SR.  A.P.French's book is, in my 
opinion, one  of the best.  Some wonderful light reading would include 'Mr.
Tompkins in Paperback.'  The first story is about a place where the speed of light
is quite small and SR effects can be observed with a bike.
 
|>     Now for light, and anything else travelling at c, duration
|> of time has slowed to 0 as seen from any other reference frame,
|> so this can be seen as equivalent to travelling infinitely
|> fast. This sort of solves the problem that led Einstein to
|> relativity in the first place - how, if one were in the frame of 
|> reference travelling with light, and observed the (now stationary)
|> electromagnetic fields which comprise it, one would see 
|> the EM fields vary in amplitude periodically
|> in space, which according to Maxwell's equations shouldn't
|> be possible without electric charges at the local maxima.
|> The solution is that in relativity, this frame of reference
|> is not well defined, and it occupies no time, so it's
|> never really there to contradict Maxwell. Thus light always
|> knows how fast to go: as fast as possible.
|>     The moral of the story is that the world is not at all
|> as it seems, and nothing like our naive Aristotelian/Newtonian
|> intuitions.

I, honestly don't know how to respond to this.  Study special relativity.
Getting all your information second hand from popularized books and TV shows
is quite dangerous.  

|> ========================================================================
|> Wait until time is fully dilated                          Pete Vincent
|> before releasing tangent bundle...

.Steve
Newsgroups: sci.space