Dear Ed Keane III:

"Ed Keane III" wrote in message
m...

There was a time when it was not known that there was
a speed of light.

This would be before Galileo, then...

Imagine some of the strange features of
physics if one thought that the Sun we see is the Sun now
instead of an image of the Sun's past. Would it be possible
for something to arrive here before we saw it leave the sun?
Obviously one could not leave somewhere now and get
here before now. Probably one would find the question to
be so ridiculous as to never work out that this would involve
going backwards in time.

It *could* appear to do so.


What if one wanted to cling to this outdated idea even
after learning that it takes time for light to get here from
the Sun? One might consider the speed of light to be
instantaneous and the measured length of time to be a
feature of space-time geometry. What strange ideas
might one come up with then? One might be that going
the speed of light (c) would be the same as getting
somewhere in no time and it would not be possible to
go as fast as, much less faster than, the speed of light.
Would this mean that you lose the ability to accelerate
when one nears c or would attaining c be like trying to
accelerate to an infinite speed? Pre-Special type
Relativity would seem to rule out the first possibility
and the second could lead you to try to adjust all kinds
of things to fit the model.

Part of learning the limits is reaching for them. We have driven particles
very close to c. The ancients, based on written texts, did not get much
over the speed of arrows, bombards, and the like.

David A. Smith