There was a time when I understood the theory of relativity. It was many years ago but I passed an exam about it so I must have had some idea. By relativity I mean the concept in mathematical physics, introduced and developed by Einstein a century ago, and since tested, adjusted, extended, employed for a surprising variety of purposes, and, of course, much abused by those who think that, because they recognise the word relativity, they understand what it all means.
Special relativity, introduced by Einstein in a paper in 1905, describes measurement in inertial frames of reference. (It was this limitation which led to its being termed ‘special’). It considers the consequences arising from the postulate that there is no privileged reference frame, no absolute state of rest, and that the speed of light is the same for all inertial observers. The consequences include a number that are highly counter-intuitive, but which have subsequently been shown to be correct, in that they are observed to describe physical reality. The predictions derive from the mathematics he developed to construct the model. This mathematics is not especially difficult to understand; what is difficult is to show to what extent it accurately describes the universe, and to devise ways to test its predictions. Not to mention getting your head around what it actually means is happening out there.
General relativity is the extension of this theory to general frames of reference, and is, physically, essentially a geometric theory of gravitation. Mathematically it develops models to describe general co-ordinate transformations, using what used to be called affine geometry back in my day.
There are far better places than this blog to find out about relativity, but the point here it that it is mathematical physics; it is not philosophy. In order to understand what it has to say about the world you have to understand at least the physics, and the basics of the mathematics. It tells us nothing about human relations, morality or our perception of events in our lives. It does not mean that ‘everything is relative’. It means that certain things which most people have never thought about, and which have no relevance to their lives, are not absolute. Many mysteries remain, and they are staggering and compelling, and the truth, and the search for more truth, is much more interesting than the foolish misinterpretation of a word used to name it.
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