Re: Isn't time a misnomer for event time?

Hello Frank,

This is a pretty technical question, so let me just give a
quick introduction for others who may read this. 

In everyday life (and `pre-relativity') physics, we assume that two 
observers who see two events will measure the same time interval,
(delta t), between the events. The two observers will also 
measure that the two events occur the same distance, (delta x),
apart. Einstein's theory of special relativity, however, says
that the two observers moving at different speeds will NOT 
measure the same values of (delta t) and (delta x) between two
events. The thing that is constant for both observers is the
"proper time" -- symbolized (delta s) or (delta tau), where:
(delta s)^2 = (delta x)^2 - (c * delta t)^2
["^2" means "squared", and c is the speed of light]

If we solve for (delta t) we get
(delta t) = (1/c)*sqrt[(delta x)^2 - (delta s)^2] 
so if [(delta x)^2 - (delta s)^2] is less than 0 
[ie |delta x| < |delta s|], then (delta t)
is the square root of a negative number and
that the time interval is imaginary. This would be bad,
but it turns out not to be a problem: the only observers
who would observe |delta x| < |delta s| are those
moving faster than the speed of light, which special relativity
already says is not allowed. 

You are right that it's the proper time s (I think this is what you're
calling event time) that's important, not the clock time t. The 
proper time is the only thing that's measured to be the same by all
observers. In everyday life, however, we are usually moving so slowly
[compared to the speed of light] that the effects of special
relativity aren't important, so we can assume (delta t) and (delta x)
to be the same for two observers.

I hope this clears things up. There are a lot of books on special
relativity, so if one gets you confused, try another one, or come
back and ask us more questions.

Pauline