Posted by Steve on March 31, 19101 at 15:18:27:

In Reply to: Is quantum gravity only fiction? posted by Craig Busse on January 17, 19101 at 18:21:14:

Hi there!

I'm by no means an expert on physics, but I dabble a bit on occasion. However, I think I may be able to at least shed some light on a few misconceptions that may help focus any future research you may do on this question.
I guess the first thing I should point out is that although it's firmly rooted in our vocabulary, 'centrifugal force' is actually a misnomer. Despite the name of the device known as a 'centrefuge', originally the force was named 'centripital force'. (Unfortunately I'm not versed in etymology so I couldn't tell you what caused the difference). In any case, centripital force is the name we've given to a situation that we view as an outside observer. Let me set up a situation for you...
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You place a large shallow bowl on a table and spin the bowl (we'll ume air resistance and the friction with the table surface are negligable, and the bowl can spin indefinitely). Then you pour water in the bowl. You'll notice that the water moves toward the edge of the bowl and thins out in the center. This is what we generally think of as centripital force. However, let's say you were in a very tiny room, and were placed in the bowl while it was spinning. Let's also ume this room had no windows and you had no way to measure the outside environment. This room would then be forced to the side of the bowl. Because you can't reference the outside environment, the only thing you can ume is that you are in the presence of a gravitational field. AND you would in fact be right, according to general relativity. So because of this, we can say that on a basic level the centripital force is a form of gravity, only viewed in the third person. All it becomes is relativistic accelerated motion. And 'gravity', or the perception of it, is produced by accelerated motion.
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Now that we've seen that centripital force is really just accelerated motion, and that accelerated motion is directly linked with gravity, you question of 'is gravity a fictional force' can now be addressed.

However, I see that I've already managed to write quite a lengthly post, so I'll leave it to you to find the details. But relativity, quantum theory, and string theory all say that gravity is not fictional. The problem is that our inability to find an explination of gravity is what keeps relativity from combining with Quantum mechanics. However, there seems to be quite a bit of promise for a theory of gravity located in String Thoery. And for that I recommend a great book by Brian Greene, "The Elegant Universe".

Well I believe that about does it... until we meet again, have a very pleasant day!

Steve

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