©Fernando Caracena 2013
What is Physical Reality?
Physics is in the eye of the beholder. Physics is what we have discovered through experience codified into a set of mathematical relations that constitute the theories of physics. In common speech, the word “theory” is taken to mean unfounded speculation, such as in “conspiracy theory”. In physics, theory means ideas about patterns in the operation of nature that are well verified by observations. These patterns are very consistent and are stated mathematically. A contradiction or two by valid experiments is enough to bring down a theory that is long established and has been held as true. So the truth of physical theories is provisional, being accepted so long as the theory continues to be verified by experiment. Operating in a fixed range of experiment a theory can become well established. The set of physical theories then establish a paradigm, such as classical physics. However, as experimental techniques advance to probe deeper into the mysteries of the universe, new observations (such as in quantum phenomena) have overthrown a whole set of old theories, and so established new paradigms, such as quantum mechanics and relativity.
In the establishment of a new paradigm, the old one is not totally discarded. The old one is recognized as a good approximation of the truth that applies well, within the range of classical experiments. So we recognize that physical theories are all approximations of truth that apply within a well defined domain of experimental evidence, but not necessarily outside that range. Physicists like to think, or at least say, that the next breakthrough in theory will be the theory of everything, the truth once and for all. Nature is kind enough to be understandable by the human mind on a certain level, but it is not totally comprehensible. Its hidden depths, its arcana, must be explored by ever more subtle and elaborate observations. For example, as result of the Heisenberg Uncertainty relations of quantum mechanics, we must use higher energies to probe into the smaller scale structure of matter.
Δx Δpx ≥ ħ/2 , (1a)
Δy Δpy ≥ ħ/2 , (1b)
Δz Δpz ≥ ħ/2 , (1c)
Δt ΔE ≥ ħ/2 , (2)
The newest best platform for probing the scales of matter much smaller than the components of the atomic nucleus (protons and neutrons) is the Large Hadron Collider, which is contained in a large underground tunnel 27 km in circumference that extends across the French-Swiss border near Lake Geneva.
Physical reality remains an elusive, subtle goal that is pursued by ever more energetic and elaborate experiments. Physics will become stagnant and a fixed paradigm only when the human race runs out of resources to be able to support research in physics.
This discussion continues by examining the realities behind the wave-particle duality.