- #1

Freixas

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*c*in every direction or

*c/2*in one direction and instantaneously in the other. Nature does not provide us with a way of determining the one-way speed.

I can follow some of the basic reasoning as to why trying to measure the one-way speed of light requires knowing the one-way speed of light. But let's say I have an observer in a spaceship that we consider to be at rest. There is another ship circling this one at a constant distance of 299,792,458 meters (1 light second).

*By definition*, we begin with the two ship's clocks synchronized with respect to the rest observer. It's not important that we do this—it just makes the numbers in my example easier to state.

We will also assume that the speed of light is

*2c*in one direction and instantaneously in the other. Let's say that when the experiment begins, the orientation of the two ships is such that the light from the moving ship is traveling toward the rest observer in the direction where it travels at

*c/2*and where the clocks read 0. The light reaches the rest observer at rest time 2 seconds.

The moving ship moves slowly around the circle. At some point, it is located where the light will reach the rest observer instantaneously. At this point, the rest observer notes that the traveling ship's time equals the rest time.

Because the moving ship is moving relative to the rest observer, we could expect some slowing of the moving clock from the rest observer's view. I'm suggesting that the ship move slowly enough that this slowing is minimal. It would seem that the rest observer would see a trend of the observed clock slowing down and speeding up. If the speed were

*c*in every direction, the rest observer would always see the moving clock lag his own by 1 second (plus a small, but slowly increasing delay from the motion).

I'm sure I'm making a big mistake and that the experts here will clear it up. Thanks!

Originally, this started out from thinking about viewing the night sky. If the one-way speed of light were slower one way than the other, then one direction would show a younger universe than the other, and I started wondering if this would be detectable.