Re: Equivalence Principle Question

funk420 <funk420@xxxxxxxxx> wrote in news:1188569758.788176.109140@
57g2000hsv.googlegroups.com:

Part one

Two observers are in two perfectly opaque laboratories, let's call
them boxcars with a length l and width w.

One boxcar floats in the middle of perfectly dark and flat
intergalactic space with zero mass density.

The other is in orbit about a large mass (M), also with no mass or
energy density nearby other than the central mass (assume it isn't
radiating).

What's the best way for an unfortunate observer in one of these boxes
to tell whether he is in orbit or not? No peeking out of the box!

Part two

Did Gravity Probe B give an example of such a measurement?



In one of Larry Niven's SF stories, someone follows a cometary orbit around
a neutron star (that was the name of the short story).

If he had not recognized the danger he was in as he approached the unseen
neutron star and managed to keep himself stable near the center of gravity
of the spacecraft, the tidal forces would have compacted him in the fore or
aft of the ship.

(the 'general products hull' was made of a special force field that was NOT
torn apart by the forces) but all the equipment inside the ship was
compacted by the tides.

'Tidal forces' result from the fact that objects inside the ship that are
further from the center of gravity of the system are traveling too fast to
remain in the orbit that the center of gravity of the ship follows and want
to escape outward, while objects closer to the point being orbited are
traveling too slow to remain in orbit and want to fall into the large
central mass.

Given sufficient time, any array of stationary objects 'floating in the
air' in the orbiting ship will drift apart, whereas in the isolated ship,
they will remain 'stationary' or drift toward the center of gravity of the
ship.







--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+spr@xxxxxxxxxxxxxxxxxxxx remove ch100-5 to avoid spam trap
.

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