Relativity FAQ

in article , Nathan Jones at
ics wrote on 12/7/03 3:19 PM:

Dear reader,
I have noticed that more than a few of you are having trouble understanding
Einsteins special relativity and general relativity principles. I am going
to be writing another FAQ this one specifically on the Einstein absurdities
and paradox's. Post your queries now and I will consider them for you and if
they are meritable they will be included in the FAQ to be released in a few
weeks or so.

Nathan Jones Physicst.


I have come up with an easy way to explain distance shortening in uniformly
moving systems. It is based upon work by Richard Feynman that actually got
into a NOVA episode. He readilly explained the twin paradox.

Essentially, he made a clock out of a Fabry-Perot interferometer--a laser
resonator if you prefer. A pulse of light bounces back and forth between the
mirrors. It is clear that the light path, and consequently the period, is
increased in the moving system over that of the stationary twin (your)
system.

___ ___ ___
\ / \ / \
\ / \ / \ /
\ / \ / \ /
\ / \ / \ /
--- --- ---

It should be clear that it takes longer to get things done in the moving
system. Straightforward geometric calculations will give the relativisticly
correct period for the moving clock as well as for the age of the moving
twin. Note that the moving twin will age at the same rate independent of the
direction of motion.

These conclusions depend upon the fundamental postulates of special
relativity. The laws of physics are the same in any uniformly moving system.
This includes the speed of light. The conclusions you draw are then correct
no matter how unlikely you may think the are. (Paraphrased from Sherlock
Holmes.)

In some way things are experimentally easier now then when Einstein worked
on this problem. Information exchanged between systems on lengths and
measures can no be described in atomic terms. These include periods of
cesium oscillations for and wavelengths light for distance. Distortions from
doppler shifts and the like no longer have to be compensated.

Bill