Chalky
Jan17-09, 06:19 AM
On Jan 16, 10:42*am, Uncle Al <Uncle...@hate.spam.net> wrote:
> Chalky wrote:
[Moderator's note: Trimmed full quoting]
> > But, the salient principle here IS the equivalence principle, and, in
> > practice, rockets are small enough for the principle to hold true, to
> > within current limits of observational evidence. Correct me if I am
> > wrong, but afaik, tidal forces are only detectable on the scale of
> > orbiting space stations where
> > 1) Dimensions are larger
> > 2) Achievable durations are longer
> > 3) What is observed in practice *is the combined effect of a non
> > uniform centrifugal force (which is demonstrable on a scale of
> > centimetres in laboratory centrifuges), re-enforced by the tidal
> > gravity of the Earth.
>
> [snip]
>
> Tidal forces are detectable over less than a meter diameter. *Eotvos
> balance rotors are no larger than your fist.
I always thought the Eotvos experiment demonstrated the rotation of
the Earth, not the tidal nature of mass induced gravity. Am I wrong?
(I have already pointed out that tidal centrifugal forces are
demonstrable on such scales)
===========Moderator's note ============================================
Actually there are two Eotvos experiments, namely the famous one on the
(weak) equivalence princle which is one important basis of General Theory
of Relativity. See, e.g., Wikipedia as a first overview:
http://en.wikipedia.org/wiki/Eötvös_experiment
As I learnt also from Wikipedia,
http://en.wikipedia.org/wiki/Loránd_Eötvös
he also conducted research on the tidal force on Earth.
> Chalky wrote:
[Moderator's note: Trimmed full quoting]
> > But, the salient principle here IS the equivalence principle, and, in
> > practice, rockets are small enough for the principle to hold true, to
> > within current limits of observational evidence. Correct me if I am
> > wrong, but afaik, tidal forces are only detectable on the scale of
> > orbiting space stations where
> > 1) Dimensions are larger
> > 2) Achievable durations are longer
> > 3) What is observed in practice *is the combined effect of a non
> > uniform centrifugal force (which is demonstrable on a scale of
> > centimetres in laboratory centrifuges), re-enforced by the tidal
> > gravity of the Earth.
>
> [snip]
>
> Tidal forces are detectable over less than a meter diameter. *Eotvos
> balance rotors are no larger than your fist.
I always thought the Eotvos experiment demonstrated the rotation of
the Earth, not the tidal nature of mass induced gravity. Am I wrong?
(I have already pointed out that tidal centrifugal forces are
demonstrable on such scales)
===========Moderator's note ============================================
Actually there are two Eotvos experiments, namely the famous one on the
(weak) equivalence princle which is one important basis of General Theory
of Relativity. See, e.g., Wikipedia as a first overview:
http://en.wikipedia.org/wiki/Eötvös_experiment
As I learnt also from Wikipedia,
http://en.wikipedia.org/wiki/Loránd_Eötvös
he also conducted research on the tidal force on Earth.