----- Original Message ----- 
From: "Richard Baker" <[EMAIL PROTECTED]>
To: "Killer Bs Discussion" <[EMAIL PROTECTED]>
Sent: Friday, September 12, 2003 4:32 PM
Subject: Relativity, FTL and causality


> A while ago, Rob was puzzled by FTL leading to causality violations in
> special relativity. I've just posted an article to my weblog that tries
> to make this clear:
>
> http://www.theculture.org/rich/sharpblue/archives/000089.html
>

I liked your website Rich, but I have a quibble.  You say:

"The laws of physics look the same to all observers."

I'd argue that it would be better to say

"The laws of physics look the same to all observers in inertial reference
frames."  The clearest example of the laws of physics being different in an
accelerating reference frame is trying to write laws of physics for a
rotating coordinate system. One would not obtain the same set of equations
of motion that one would obtain in a non-rotating reference system.  This
contrasts with linear velocity, where one cannot determine absolutely who
is moving and who is still. With respect to angular rotation; one can tell
who is spinning and who is still.

I'm not insinuating that you don't know this, of course. My quibble is that
your statement is open to misinterpretation.

Dan M.

 This is the "Principle of Relativity" that lets us perform calculations
relative to any inertial frame we like and be assured that we will get the
same values for all physically meaningful quantities. This postulate holds
in classical mechanics too.


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