more

Any physical theory is always provisional,in the sense that it is only a hypothesis.As philospher of science Kal popper has emphasisd a good theory is characterised by the fact that it makes a number of predictions that couldin principle be disproved or falsified by observation.Each time new experiments are observed to agree with the predictions the theory survives and our confidence in it is increased but if ever a new observations is found to disagree,we have to abandon or modify the theory.In practice,what often happens is that a new theory is devised that is really an extesion of the previous theory.For esample Einstein's general theory of relativity predicaed a slightly different motion form Newton's theory of gravity.