Einstein’s 1905 Speed/velocity of Light errors

Einstein’s 1905 Speed/velocity of Light errors
by Roger J. Anderton (Copyright: R.J.Anderton 2009)


Einstein made too many mistakes that it’s difficult to deal with them all; this paper is just dealing with some of the errors he made with lightspeed in his 1905 paper on Special relativity.

Hans Ohanian [1] seems to be an Einstein apologist – he admits that Einstein made lots of mistakes, but tries to justify it as despite the mistakes in his derivations; Einstein still comes up with the correct answers. Ohanian might think that, but anyone else reading the numerous mistakes made by Einstein just find themselves swamped under a mountain of those mistakes, making the conclusions definitely ambiguous if not wrong. So Ohanian is trying to just excuse the inexcusable.

Anyway, Ohanian is an Einstein supporter and it is rare to have anyone admit from the Einstein supporter group that Einstein made mistakes. So, there might be progress in that group that all do not believe Einstein perfect, and some attempt might now be made to correct those mistakes.

If we look at the lightspeed issue in Einstein’s 1905 paper on Special relativity: „On the Electrodynamics of moving bodies,“ a good thing to note is there has been a translation problem from Einstein’s original German into English. The German language does not differentiate between the English words „speed“ and „velocity“. (Others have noticed this, so I cannot take credit for discovering it.

In Einstein’s German original paper [2] he has the word „Geschwindigkeit“ this can translate into English as „speed“ or „velocity“.

There is a difference between „speed“ and „velocity“. Velocity is magnitude and direction, while speed is just magnitude.

Thus when Einstein talks of velocity of light being constant does it mean that both magnitude and direction are constant (?) Upon reading many Einstein’s relativity papers, it seems he must mean „speed“ not „velocity“, because he deals with light changing direction when he talks of light velocity as constant; so that is the first issue – when Einstein gets translated into English as „light velocity is constant“ he must be meaning „lightspeed is constant“. That does add to the confusion in dealing with Einstein, especially when he makes transition from Special relativity to General relativity. Einstein can be excused that this is a problem with the translation from German into English. But surely as he became aware of the English language more(after giving lectures to English speakers), he must have become aware of this problem with the word „Geschwindigkeit“. He did not however seek to clarify that issue; he did not seek to clarify lots of areas where his writings are confused; he just left them as a mess; and that is inexcusable except to Einstein apologist who will seek to excuse Einstein of anything.

Collecting all the statements that Einstein makes regarding light velocity (bearing in mind he must mean speed) in the English version [3] of his 1905 paper:

statement1: „We will raise this conjecture (the purport of which will hereafter be called the “Principle of Relativity“) to the status of a postulate, and also introduce another postulate, which is only apparently irreconcilable with the former, namely, that light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body. These two postulates suffice for the attainment of a simple and consistent theory of the electrodynamics of moving bodies based on Maxwell’s theory for stationary bodies.“

statement 2: „In agreement with experience we further assume the quantity

                        2AB/(t‘A – tA)  =  c,

to be a universal constant–the velocity of light in empty space.“

statement 3: „The following reflexions are based on the principle of relativity and on the principle of the constancy of the velocity of light. These two principles we define as follows:–

1. The laws by which the states of physical systems undergo change are not affected, whether these changes of state be referred to the one or the other of two systems of co-ordinates in uniform translatory motion.

2. Any ray of light moves in the “stationary“ system of co-ordinates with the determined velocity c, whether the ray be emitted by a stationary or by a moving body. Hence

                        velocity  = (light path)/(time interval)

where time interval is to be taken in the sense of the definition in § 1, „

me: Statements 1-3 since okay if we bear in mind that velocity should really mean speed, then Einstein is saying the speed of light is constant c in these 3 statements. Things start to go wrong with the next statement: 


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