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May14-09, 04:52 AM
P: 24
Wrong. Any acceleration of the earth reduces it's pull on the ball. Thought experiment needed;
Take a binary system of 2 planets, one 20% more mass than the other. Your'e standing on the big one. In your reference frame the small one is falling towards you at velocity v.
Now jet over and land on the small one. Standing there in its reference frame the big one is falling at exactly the same velocity v.

No matter what the 'share' of mass between them the total acceleration is the same, (only the distance changes that - 2nd law).

So both balls would hit at the same time whatever. That's equivalence!

Except for Godels incompleteness theorem etc. There are loads of other tiny factors, there IS an ether so relative atmospheric drag comes into it, your spaceship taking off and landing, the relative pull of the sun whichever its closest to, etc. Thats why Mr Planck invented plancks, and we have Quantas, supposedly if it's smaller than that it's undetectable (thanks Turtle) and we can ignore it. (though one day we'll find we need it!) Not using Quantas is fine, BA fly to Aus anyway.