Comments about "Postulates of special relativity" in Wikipedia

This document contains comments about the article Postulates of special relativity in Wikipedia

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In the last paragraph I explain my own opinion.

Contents

• 1. Postulates of special relativity
• 2. Alternative derivations of special relativity
• 3. Insufficiency of the two standard postulates
• 4. The 1905 system as "null theory"
• 5. Alternative relativistic models
• 6. Mathematical formulation of the postulates
• 7. See also

Reflection

• Reflection 1 -
• Reflection 2 -
• Reflection 3 -

Introduction

The article starts with the following sentence.

Albert Einstein derived the theory of special relativity in 1905, from principle now called the postulates of special relativity.

Okay.

Einstein's formulation is said to only require two postulates, though his derivation implies a few more assumptions.

Okay.

The idea that special relativity depended only on two postulates, both of which seemed to follow from the theory and experiment of the day, was one of the most compelling arguments for the correctness of the theory (Einstein 1912: "This theory is correct to the extent to which the two principles upon which it is based are correct. Since these seem to be correct to a great extent, ...")

A theory is an explanation

1. Postulates of special relativity

1. First postulate (principle of relativity)

The laws of physics take the same form in all inertial frames of reference.

There are certain problems with this postulate.

1. First of all the postulate is not clear.
   Which laws of physics are meant? What have laws of physics to do with an inertial frames of reference?
2. What is the reason behind this postulate?

2. Second postulate (invariance of c)

As measured in any inertial frame of reference, light is always propagated in empty space with a definite velocity c that is independent of the state of motion of the emitting body. Or: the speed of light in free space has the same value c in all inertial frames of reference.

The question is why this postulate?
The reality is that it is very difficult to measure the speed of light in one direction in an umambigous matter. To claim that the speed of radiation is constant makes the whole issue simple.

The two-postulate basis for special relativity is the one historically used by Einstein, and it is sometimes the starting point today.

This sentence is not clear.

As Einstein himself later acknowledged, the derivation of the Lorentz transformation tacitly makes use of some additional assumptions, including spatial homogeneity, isotropy, and memorylessness

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