World Science Scholars

### 20.6 Coordinates for Time

Discussion
• Would the clock synchronization procedure have worked if we had fired baseballs from the origin toward the other clocks in the grid as opposed to sending out a flash of light? Argue one way or the other. (We will come back to this question in a subsequent Office Hour question.)

• Well If the base ball is moving with constant velocity, then we can use this method else it will be a tedious calculation

• If the base balls move at a know constant speed and direction, it works.

• If you think of the baseballs as big photons there seems no reasons why this wouldnt work. You need a lot of them though.

• Yes, but light is more practical

• As long as we maintain constant velocity baseballs should work fine.

• As long as no one is moving, then a baseball should work fine. Only if motion is involved that light will be different because its velocity is not subject to the law of addition of velocities.

• Yes, infact anything moving with constant velocity works here, Nothing special about light.

• Agreed!

• Light has special place, as it’s the only true constant. Baseball wouldn’t do it.

• O

• Ok

• Since the frame is jnertial, a baseball shot from the origin towards the other clocks will continue in a straight line and with the same speed, as would light. Although the speed of the baseballs must be the same, and should be known beforehand.

• with speed know by everybody and constant speed seems to be feasible to syncronize

• All the previous answers sum it up well. The baseballs must travel a constant known velocity and must move past each clock. Then yes, baseballs or any such object works. These assumptions are difficult to pull off. Light is more practical.

• yes

• yes

• Of course if it is moving with constant motion

• No. Light is emitted equally in all directions and on the macroscopic scale is continuous. Baseballs are discrete objects and can’t be fired simultaneously in all directions, which is necessary in order to synchronize all clocks.

• Like it hints in the question, check out 21.6 Office Hours where Brian verifies the answer is ‘yes’.

• Sure, the velocity doesn’t matter as long as you know whatit is.

• Yes, i belivie it would work as long as the baseball doesn’t face any external force and provided we know the velocity at which the ball is projected.

• no i think massive object cant move at speed of light

• Yes if there is no acceleration in the balls’ motion

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