From: Eugene Leitl (eugene.leitl@lrz.uni-muenchen.de)
Date: Mon Dec 20 1999 - 18:47:17 MST
Eliezer S. Yudkowsky writes:
> The Foucault pendulum experiment could probably serve to demonstrate
> that the Earth rotates. Given that the Earth rotates once every 24
Iterestingly enough, you have to calculate Coriolis impact in
long-range artillery.
Btw, g value (9.81 m/s^2 in most civilized places) varies over Earth
surface. It's smallest at the equator. Of course it is also modulated
by mass anomalies...
> hours, as the pendulum will demonstrate, it's easy to see that the Sun
> is probably staying in the same place. As for the Earth itself going
How do you _know_ it's staying in the same place? It's just a lamp,
mounted upon a crystal sphere. Angel-powered(tm).
> around the Sun, that probably takes the computation of planetary
> motions; at best it could be demonstrated more immediately by the
> incredibly tiny changes in the apparent positions of stars depending on
> which side of the Sun we're on.
<smacks forehead>Parallaxis, of course!</smacks forehead>
> But in my opinion, the most compelling demonstration that Earth must
> orbit the Sun is dropping an apple, computing Newton's laws, and thus
> demonstrating that if not for the orbital velocity we'd drop into the
> Sun. Of course, pre-Newton there was no Principle of Mediocrity...
This assumes you know that the Sun is big.
> Now for a different stumper I got hit with (once; after that I looked it
> up). How do we *know* the Earth is 4.5 billion years old?
Radioisotope dating?
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