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Thread: Measuring Velocity of an Inertial Frame in Free Space

  1. #1 Measuring Velocity of an Inertial Frame in Free Space 
    Forum Freshman geistkiesel's Avatar
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    Oct 2009
    Determine the velocity of an inertial frame using only three recorded time-of-flight events wert motion of a single light pulse.

    The question then is, does this measurement of velocity constitute a prohibited condition anticipated by any postulate[1] of SRT?

    “It is impossible to measure or detect unaccelerated translatory motion in free space”?

    From the schematic of the system in Figure 1 measuring the velocity of the inertial frame A is clearly a very simple system. The A frame velocity is determined by a measurement of the distance a pulse of light travels in specific recorded time events. There are only three of these events: 1. the time the pulse was emitted from the A frame at t0, 2. the time the pulse arrived back at the A frame after reflection from the inertial frame transponder, Tp at t1, and 3. The arrival back at the A frames of the light pulse re-emitted at t1.

    The total light path has been segmented into two parts, (d1 + d2) and (d3 + d4). Remember the direction of the light pulse is unimportant, it is the total light path traveled that is measured.

    The distance difference, (d1 + d2) - (d3 + d4) is the distance the frame traveled during the total time-of-flight traveled by the light pulse that is (d1 + d2) and (d3 + d4).

    Picture the frame moving in the direction of the pulse moving away until the distance (d1 + d2) was traveled (project a straight line without the reflection). Attaching the final pulse trajectory to the end of the (d1 + d2) and heading toward the oncoming A frame, the collision of the pulse and the A frame determines the total distance traveled by the pulse and t2 duly notes this event.

    The definition of velocity is,

    V = [Xn+1 − Xn]/[ tn+1 − tn] (1)

    The data base of experimental data is contained in the three time events, t0, t1, and t2. Expressing the dn in time and speed parameters with unit speed of light c = 1, then ,
    (d1 + d2) - (d3 + d4) = [(t1 − t0) − (t2 − t1)] = Va(t2 − t0) or,
    VA(t2 − t0) = 2t1 − (t2 + t0) hence,

    VA = [2t1 − (t2 + t0)]/(t2 − t0) (2)

    There is no referenced inertial frame to which the A frame VA is measured, or needs to be measured from; there is no “absolute velocity reference frame, implied or expressed, where Vf = 0”. Remember, the VA was not determined by a stop watch and meter stick. The VA is a calculated term using the known speed of light, the time-of-flight of the pulse trajectory segments, and the definition of velocity. Can the origin of the light pulse be located and returned to? Yes, but there should be a valid reason for such a future activity – sentimental reasons ought not to be consider a valid reason. If the VA becomes suspect, measure the velocity again.

    V = (Xn+1 – Xn)/(tn+1 – tn). (1)

    I found this postulate in [1] Chapter 11, Relativistic Flight Mechanics, “The Handbook of Astronautical Engineering”, 1st Edition, Ed. H. H. Koelle, fwd. W. von Braun, McGraw (1961)

    Mother Nature include time in her creation so everything wouldn't happen all at once. Anon
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