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The water won't hit the center and if you spin the MGR fast enough neither will the light.

But the water and light are aiming right at the center! Anyway, you're on. I've run water jets on my mill's rotating bit, and trust me, it hits the center regardless of spin speed. I don't even have to have the water pulsing, do I? I mean, if pulses don't hit the center, then a steady stream won't hit the center either, will it?

Lets say that you have a sundial and for illustration lets say that the sun is a little over 7 AU away so that it takes the light an hour to get here. When the Sun dial indicates that it is noon with regular light, where would the Sun dial indicate the direction of the Sun if light was instantaneous? One o'clock right? So where is the sun in actuality, at the noon position as you claim or at the one o'clock position that I claim?

Ahh, I like it, A gravitational sundial. Perfect.

In answer to your question above, If the sun orbited the earth at the rate of 24 hours per orbit, then yes, I agree, the optical sundial would read one hour behind the gravity sundial. (Oh I love that idea. Gravity sundial. I might built one. would that be possible?) But the fact is that the sun doesn't orbit the earth, but rather the earth rotates at the rate of 1 turn per 24 hours.

But give me a weekend or two to do the water on the merry go around experiment and then maybe we'll know more.

By the way, what is the difference between the earth rotating at the rate of 180Deg/8.5Min and a merry go around doing the exact same thing? How come one would lag the suns optical position 180 degrees from its gravitational position and not the other?

Thanks,

-Jesse

But the water and light are aiming right at the center! Anyway, you're on. I've run water jets on my mill's rotating bit, and trust me, it hits the center regardless of spin speed. I don't even have to have the water pulsing, do I? I mean, if pulses don't hit the center, then a steady stream won't hit the center either, will it?

Remember, your water source is a barrel on the outside edge of the MGR going round in circles, not you standing off to the side with a hose spraying it on the center of the MGR. Set up your buckets on the MGR so that the stream is hitting the center when it isn't moving. As you start rotating, the spray will go off center. Can you predict which direction the stream will go, before you do your experiment?

In answer to your question above, If the sun orbited the earth at the rate of 24 hours per orbit, then yes, I agree, the optical sundial would read one hour behind the gravity sundial. (Oh I love that idea. Gravity sundial. I might built one. would that be possible?) But the fact is that the sun doesn't orbit the earth, but rather the earth rotates at the rate of 1 turn per 24 hours.

What difference does it make whether the sun rotates around the earth or the earth spins? The sun appears to revolve around the earth from our perspective. The apparent position of the sun is not the actual position of the sun. The sundial experiment holds true regardless of whether the earth is spinning or the Sun orbits the earth.

Can you think of any way that using a sundial you could determine whether the earth was spinning or the sun was orbiting the earth?

Here is another experiment you can try at home, with the proper eye protection of course : ) Go out at dawn and point a transit right at the edge of the Sun at the instant the first light appears at the horizon (it should be the same point). Now wait 8.3 minutes and measure the distance from the edge of the Sun to the horizon. That is the difference between the Suns apparent position and its true position.