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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.

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.

Funny, I in fact do not remember that! That's not the experiment I described.

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?

It looks like you want me to emulate the sun orbiting the earth rather then the earth spinning. Very telling! If you really believed that it didn't matter, you wouldn't feel the need to modify my experiment to more closely simulate the sun orbiting the earth!

However, you say that the spray will go off center - and you're wrong about that. The spray was aimed at the center, and each droplet is moving towards the center, and it'll hit the center. However, if the water jet is rotating around the center, then the path of the stream will curve and the angle at which the water hits the center will be lagged from the actual position of the stream.

I think I'll kindly do the experiment with the "sun" stationary and the "earth" rotating, thank you!

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.

The difference it makes is that if the sun is orbiting, then the light will travel in a spiral, and will strike the earth at 2.1 degrees behind the the actual position of the sun. If the sun is not orbiting, then the light will travel in a straight path, and will strike the earth at the same angle as the sun is.

Your transit at the sun doesn't demonstrate anything at all except that the sun's angle changes with time.

Thanks,

-Jesse

What difference does it make whether the sun rotates around the earth or the earth spins?

For one, if the Sun was revolving around the Earth every 24 hours, it would have to do so at 11,000 km/s in a circular orbit. Among the differences -- not the least of which is that this is dynamically impossible -- the speed of the Sun would be 11/300ths of the speed of light, and the corresponding relativistic contraction of the Sun would be 1.8 minutes of arc, which would be easily seen.

And the Earth can't just be sitting there spinning. It has to be orbiting the Sun. Regardless, you can deduce obvious differences with respect to the motion of the Sun against the constellations. But I bet the rest of the universe is not allowed in this pointless atheist exercise.