|Victor J Stenger
emeritus professor of physics and astronomy University of Hawaii
The greatest innovation in elementary particle physics happened in the twentieth century with the discovery that the laws of physics are not restrictions on the behaviour of matter but restrictions on the behaviour of physicists. When physicists construct a mathematical model of nature, that model cannot depend on the point of view of the observer. Otherwise it would not represent an objective reality.
In 1915, Emmy Noether proved that the great conservation laws of energy, linear momentum, and angular momentum must exist in any theory that does not depend on a special moment in time, position in space, and direction in space. Einstein’s theories of relativity were shown to follow from the absence of any special direction in space-time.
This principle of point-of-view invariance was then further generalised to include the abstract space used to describe quantum state vectors and called gauge invariance. When applied equally to all points in space and time, global gauge invariance leads to the conservation and quantisation of electric charge as well as most of the structure of both classical and quantum physics. When allowed to vary with space and time, local gauge invariance leads to the electromagnetic force and the zero mass of the photon. When coupled with a random process known as spontaneous symmetry breaking, gauge theory forms the foundation of the highly successful standard model of particles and fields, which for over 30 years has been consistent with all observational data.
Prof Victor J Stenger is emeritus professor of physics and astronomy University of Hawaii and adjunct professor of philosophy University of Colorado. His latest books include The Comprehensible Cosmos: Where Do the Laws of Physics Come From? (buy this book from Amazon(UK)) and God: The Failed Hypothesis: How Science Shows that God Does Not Exist (buy this book from Amazon(UK)).