Tom Jonard's Relativity's Domain PageThe Relativity theories of Einstein fill out the classical physical picture of the world in which we live. They correct the theories of Newton and Maxwell which preceded them and take our understanding of the universe one step further. In so doing they make some counter-intuitive claims. And sometimes the apparent disagreement between Relativity and the way things seem to be leads people to question whether Relativity is true.
On this website we use a classic thought experiment involving trains, a station and observers on each to develop some of the concepts of SR. But the reader should not hurry down to the train station (if they can find one) with their stopwatches and clip boards to confirm our "experiments". It is only under extreme conditions that the extreme phenomena we discuss and which these theories describe appear. These conditions include travel at near the Speed of Light and intense gravitational fields.
Since these are not the conditions of our everyday life it is no wonder that scientists did not discover all this before Einstein came along. In fact the physical laws discovered by Newton, Maxwell and Einstein's other predecessors work perfectly well to describe and predict all phenomena we usually encounter. They work so well that NASA does not need to resort to the laws of Relativity to calculate spacecraft trajectories to distant planets and achieve credible accuracy. They work perfectly well for everyday life too and we do not need to consider Relativity for any practical purposes.
But this does not mean Relativity is not true or even that it is useless.
It is useful if we wish to understand why space travel at or in excess of the Speed of Light is unlikely in the real world (as opposed to Star Trek). It is useful if we wish to understand what a black hole is and why we believe they exist.
Neither is Relativity beyond our experience. It explains why Muons created when Cosmic Rays hit the top of our atmosphere survive longer than they should -- longer than their laboratory counterparts -- and are detected at the surface of the Earth. (They do so because boosted to near light speed by their parent Cosmic Rays time passes much more slowly for them than it does for us.) You have only to ask the right question and possess the right tools to see Relativity in action for yourself.
The proper domain of Relativity is the forward edge of our understanding of the universe. Because that distant place is not like our everyday experience does not mean that we should doubt the better understanding that it provides (though we might for other reasons do so). Rather we should recognize that while our everyday assumptions about the world are useful for our everyday well-being we are not justified to thoughtlessly extend these to distant realms.
Also it is good to know that while Relativity says that some of science was or is fundamentally "wrong", it does not say that science is wrong in the whole. Actually a better word when describing the state of pre-Einsteinian physics would be "incomplete". All scientific theories ought to be assumed to be incomplete. And we should expect them to be revised or replaced in the long run. Correction and refinement over time is after all the center and power of science. And lack of a dogmatic body of knowledge is not a weakness.
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Created December 28, 2001,
© 2001, Thomas A. Jonard