From: glird on
/On May 7, 2:35 am, Peter Riedt <rie...(a)yahoo.co.uk> wrote:
> Expansion = contraction
>
> Lorentz contraction formula L1=L*sqrt(1-(c/v)^2)
snip

Lorentz's formula was
x' = beta*el*x,
in which beta^2 = c^2/(c^2-v^2), so
beta = sqrt[c^2/(c^2- v^2)].
Evidently Peter thought that c^2/(c^2-v^2) reduces to
1-(c/v)^2; thus that by letting L1 replace x' and L replace x,and
setting el = 1 as L did,
beta*el*x -> L1 = L*sqrt(1-(c/v)^2).
However, c^2/(c^2-v^2) DOESN'T reduce to 1-(c/v)^2.
If you don't believe me, Peter, try it yourself. For simplicity, let c
= 1 unit/sec and v be a fraction of c; i.e. v = .6c or .8c. Example
for v = .6c:
sqrt[c^2/(c^2-v^2)] -> sqrt[1/(1-.36)] = 1.25, and
sqrt(1-(c/v)^2) -> sqrt[1-(1/.6)^2] = sqrt(-1.777) = "Error".

Regards,
glird