World Science Scholars

20.6 Coordinates for Time

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    • 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.

      • I agree. So, if we synchronize the clocks only in one direction and know the function of velocity (then we can calculate the time to reach each point), it works. In other cases, not.

      • while I agree that light is a constant that we know, change it to single photons then throw out 1 at a time we can calculate our answer, Now we replace photon with baseball and then we come to the same answer just with speed of proton vs speed of baseball. Ratio’s will remain the same so the answer won’t change.

    • 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

    • If the ball is moving with a constant speed, it is as good as a flash of light. Of course it would take us much longer to synchronize the clocks with a baseball, but since it is hypothetical anyway, it would work.

    • In the case of George and Gracie problem, one firecracker at a distance of 1/3 explodes and one close to him explodes at the same time this event is seen by Gracie at some far distance away so why don’t we consider the case of simultaneity in which it takes some more time for firecracker close to him to reach Gracie?

    • Not quite. Speed of light is the same in all inertial frames of reference, unlike speed of balls.

    • Yes, as long as you know the equation of motion of the baseball.

    • if every observer at each clock knows the time their clock has to start at, exactly, when they detect the baseball, so that every clock shows the same time or are still off then in theory yes. The problem is you cannot guarantee constant velocity. The baseballs would have to be fired in every possible direction simultaneously. There would be no point because you would not be able to translate into a system of observers in motion.

    • the light sent out travels to and across all points.

      A bafeball only has one tra, jectory.

      No, we should noe use baseballs, light is the correct thing to use, only.

    • No we cant do it because the velocity of the baseball cannot be observed same by all frames of reference as light

    • As both photon and (constant velocity) ball are signal carriers inside same reference frame this should work. As v < c the receiving station must wait longer period of time before receiving the message. BR JKi

    • Yes, the clock synchronization procedure would have worked if we had fired baseballs from the origin toward the other clocks in the grid instead of sending out a flash of light. The reason is that in this scenario, both the observers (clocks) are assumed to be stationary, and they are not moving relative to one another.
      In the conventional procedure using light pulses, the observers need to account for the time it takes for light to travel from the source to each clock. However, in this baseball scenario, we can assume that the baseballs travel at a constant and known velocity, which is much slower than the speed of light. Since both observers are stationary, there would be no relativistic effects that would cause time dilation or other issues that could affect the synchronization process.
      The basic idea behind clock synchronization in this scenario is that a baseball is launched from the origin toward each clock. When a baseball reaches a clock, the observer at that clock sets their clock to a predefined time, and when they receive a baseball from the origin, they record the time difference. By doing this for all clocks in the grid, they can determine the time offset between each clock and the origin.
      As long as the observers take into account the time it takes for the baseballs to travel to each clock from the origin, the synchronization should be accurate in this scenario, given the assumption that both observers are stationary relative to each other.

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