How are "down" and "up" defined?

[C K Dexter Haven]

Fear not, Irishman, being corrected by Cecil is like being corrected by God -- good for the soul, and not many mortals are so favoured.

An amended Mailbag item on this topic will be published shortly, and our thanks to all those who contributed thoughts.

[JillGat]

RM Mentock... isn't that the Chandler Wobble guy?

[RM Mentock]

Hi Jill

Just thought I'd bug Dex for awhile, instead.

.

[jab1]

Way to go, Mentock!

I would've said "down" was toward the center of gravity of a planet or star or other heavenly body also. And "up" would be the opposite direction.

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Feel free to correct me at any time. But don't be surprised if I try to correct you.

[RM Mentock]

jab1

Actually, that's something that I should have included in my OP, but I didn't. ZenBeam is the one who pushed on that one: the pull of gravity that you experience is not necessarily towards the center of gravity. That only works in approximation (when you're far away from the mass), or for symmetric spheres.

A good example of this is our solar system. Where is the center of gravity? Somewhere close to the Sun. But we here on earth don't perceive a force towards that center of gravity. We wouldn't even if we were not revolving or rotating.



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rocks