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essentialsaltes -> RE: Earth Basics (3/11/2008 7:55:33 PM)
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quote:
ORIGINAL: HighPlainsDrifter Well theoretically, it's probably at least possible that the earth is the only thing in the universe that's not moving at all, and everything else might actually be in motion, right? I'd have to wonder if physics could definitively prove otherwise. It depends how many laws of physics you're willing to break. For instance, the nearest stars (other than the sun) are several light years away. If they go around the earth every day, then they travel many light years per day, faster than the speed of light. This is considered a no-no in physics. A more interesting situation comes up with respect to the Coriolis force. At the risk of confusing everybody (including myself), the Coriolis force is a fictitious force. It doesn't really exist, it just appears to precisely because we 'pretend' that the earth is fixed when we do our freshman physics calculations. If you fire a cannon due north, you expect the cannon ball to land due north of you. It doesn't, because the earth *isn't* fixed, but rotating. Similarly, if you drop a mass from a tall height (in a vacuum), it doesn't land directly beneath its starting point. It's deflected slightly east and south, due to the Coriolis force (in the northern hemisphere). So... since the earth rotates, there appears to be a Coriolis force. But we understand that it's really just an artifact of assuming a fixed earth for ease in calculation. If the earth didn't rotate, no Coriolis 'force' should appear. But we really do measure those deflections. They're real. As are hurricanes (which always rotate the same way in the Northern Hemisphere due to the Coriolis 'force'). So if the earth were really fixed, that would mean that the Coriolis force was actually real! But it's not gravity or electricity or any of the known forces. It would have to be a new mystery force that always coincidentally acted in such a way that the earth appeared to be rotating once a day. The fixed earther's mystery force is kind of like the young earther's mystery force that makes radioactive nuclei decay at a changing rate that always coincidentally acts in such a way that the earth appears to be 4.5 billion years old.
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