Jethalal S. Zaveri
Prof. Muni Mahendra Kumar
Newton's Laws of Motion, which, for three centuries, were the basis of physics, do not apply to the subatomic realm (Strictly speaking, Newton's laws remain valid in some experiments involving sub-atomic particles and may be taken as good approximations with description of what is happening.) Probability (and not absolute certainty) is a major characteristic of quantum physics because events of individual subatomic particles cannot be determined precisely/accurately. The concepts of position and momentum (mass x velocity) are intimately bound up with our idea of an entity called a moving particle. Werner Heisenberg, a German physicist, proved that even if we had the best possible measuring devices, time and determination, it is not possible to know both the position and momentum of a subatomic particle (say, an electron) with absolute precision. Both can be known approximately, but the more accurately we know about one, the less accurately we know about the other. For instance, given a beam of electrons, quantum theory can predict the probable distribution of the electrons over a given space at a given time, but cannot predict the course of a solitary electron. The precise mathematical form of the relation between the uncertainties of position and momentum of a particle is known as Heisenberg's Uncertainty Principle. It has undermined the whole idea of a causal universe.
