Vinaire's Blog

Reference: Disturbance Theory

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From Wikipedia,

“Historically, the transformations were the result of attempts by Lorentz and others to explain how the speed of light was observed to be independent of the reference frame.”

The null results from Michelson-Morley’s experiment in 1887 led to the belief that the speed of light is the same in all inertial frames. For example, light is observed to have the same speed, c = 3 x 10⁸, meters/second, relative to the earth and also to the sun, even when earth is moving at a speed 3 x 10⁴ meters/second relative to the sun.

It is possible to show theoretically that the earth has a speed relative to space, which is the reference frame of no inertia. However, this speed is so small that no experiment so far has been able to measure it directly. See Michelson-Morley’s Null Result.

But the actual problem lies in combining the speeds that belong to particles, such as, light particles and the earth, which have a difference in inertia of many orders of magnitude. The vector algebra works only with particles or bodies that have inertia of similar orders of magnitude.

Lorentz transformation was an effort to resolve this anomaly, where velocities could not be simply added or subtracted per vector algebra. The following links provide the derivation of Lorentz transformation.

Reference from Khan Academy

Reference from Yale University

The derivation of Lorentz transformation is based on the following assumptions.

Assumption #1: The speed of light is the same in all inertial systems.

Based on Michelson-Morley’s experiment, the speed of light of 3 x 10⁸ meters/second was not affected by the velocity of the earth, which is 3 x 10⁴ meters/second relative to the sun. This velocity of the earth is 1/10,000 of the speed of light. The “v/c ratios” of most material bodies in the universe are of the same order. Therefore, this assumption is good for a “v/c ratio” of 1/10,000 or less.

Lorentz transformations may not be valid for “v/c ratios” that are much greater than 1/10,000 and close to 1, as found at the sub-atomic level.

Assumption #2: The gamma “fudge” factor is the same for observers in different inertial systems.

In this cosmos, each body is drifting in space under a balance of forces. These forces depend on the inertia of the body. Therefore, the inertial systems are not exactly alike, and we cannot assume the gamma factor to be the same for them.

However, this assumption is good as long as the difference in inertia among these systems is much less compared to their difference in inertia with light.

Lorentz transformations may not be valid for motion of particles with inertia much less than the inertia of earth and closer to the inertia of light, as is the case with sub-atomic particles.

Lorentz transformations are at the heart of special relativity. Therefore, these limitations apply to special relativity as well.

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