jh@MIT-CHARON.ARPA (07/24/85)
From: jh@MIT-CHARON.ARPA
***physics warning***
The point was recently made here that the idea of mass was redefined
by physicists to agree with the new (in 1905) evidence from experiments.
This is true (When evidence is found that a physical model doesn't fit the
universe, scientists tend to change the model, because that's easier than
changing the universe!). The idea of a changing mass was abhorrent to many,
however, so there have been other ways found to make the model fit the
evidence. Taylor and Wheeler, in their wonderful text _Spacetime_Physics_
(you only need trig and the most basic Newtonian Physics) modified the idea of
velocity instead. You use a parameter:
-1
x=tanh (v/c), v/c=tanh(x).
As long as you have a calculator to do the hyperbolic functions for
you, all of the calculations are easy (parameters add, while velocities
don't under either system), factors like (1/sqrt(1-(v/c)**2)) get absorbed into
the hyperbolics (time dilations are a cosh function, etc.).
***end physics warning***
Enough on the physics. This idea is much easier to swallow and
understand than any that I have yet seen, and if any of the budding and/or
budded authors who read this are looking for an easy intro into why FTL
Can't Be Done (i.e. what are the reasonable loopholes vs. what will make people
like me tear apart your explanation and ignore your fiction (:-))), Taylor and
Wheeler's _Spacetime_Physics_ is about as easy as it gets. It has a sense of
humor, and doesn't treat you like a professor. It's from W.H.Freeman & Co,
San Fransisco (1966).
--jh--