# The difference b/t free fall and outer space

1. Aug 5, 2004

### HungryChemist

You are in the closed elevator with the apple. You feel weightless. So you want to know whether you're free falling or in the outer space. Place the apple about a meter away from your eyes. If the elevator is in free fall, the apple will move close to you slowly, but if you're in the outer space the apple will be standing still. Because in free fall elevator, the gravitational force acting on the apple, in small scale, is not parallel to the gravitational force acting on you.

2. Aug 6, 2004

### jcsd

Or indeed if you place it 'above' you you wil start to move away from it or simlairly you might notice you start be strecthched a little by tidal forces. This is because usually (infact in all but the most ridculous of situations) graviational fields are not homogenous (though perhap by assuming sherically symmetric graviational fields you (and I) shouldn't make conclusions about gravitational fields in general)

Howvere this is not a problem for the equivalence priniple, as the equivalence principle only really refers to highly localized frames of reference, so the elevator has vanishingly small volume, infact it really is just a geometric point.

3. Aug 6, 2004

I got it!!