Monday, April 21, 2014

A Myth at the Heart of Physics?

LHC: Two photon event @ ATLAS
Scientific theories are only as useful as their explanatory and predictive power. Thomas Khun in his "Structure of Scientific Revolutions" said widely accepted theories such as evolution by natural selection and the standard model of physics, are paradigms. Theories become paradigms of scientific thought through repeated testing of their predictions about the nature of reality. Repeated positive confirmations of a theory's fit with observation and experimentation increase its acceptability among scientists to the point the theory becomes reality. When a paradigm is an unreliable predictor of empirical results, new theories are developed to replace it. This is what happened to "luminiferous ether" when Einstein produced his theory of special relativity in 1905. Philosopher Karl Popper rejected logical positivism altogether by saying in his work "The Logic of Scientific Discovery",no amount of positive experimental confirmation can make a theory true. Only when a theory can be shown to be false is it scientific. Then, when it is shown to be false it should be discarded in the selection of theories more generally applicable to reality. Theories that cannot be definitively falsified are what he termed "research programs" or even myths. Because evolution by natural selection cannot be definitively falsified, he classified it as metaphysics. He also refused to assign scientific status to psychoanalysis and Marxist economics because the theories are not falsifiable. Popper's logical asymmetry between verification and falsifiablity lies at the base of his philosophy of critical rationalism.

To use Popperian terms, there may be myth at the heart of particle physics. Physicists use the Standard Model to describe the cosmos. In US Person's day that model consisted basically of the atom composed of its subatomic parts, the proton, neutron, electron, and the forces of gravity, electromagnetism and nuclear forces. Further research and development of quantum mechanics at the beginning of the 20th century greatly expanded the number of particles required to explain what scientists were seeing in their equations. For example the proton became composed of three quarks and gluons. Now there is veritable zoo of particles out there including ones that are only virtual. Today scientists say that matter is fundamentally made up of fermions held together by bosons. What the Standard Model does not explain is why the universe is this way. Why are there only three leptons? Why does the electron have the mass it has? Physicists developed another theory, supersymmetry, or SUSY (pronounced "Suzy") as it is nicknamed, to explain these and more unanswered questions. There are other theoretical explanations offered such as string theory, extra dimensions, and multiple universes, but a supersymmetric Standard Model is the physical paradigm. The first realistic version of a supersymetric Standard Model was developed by 1981. It predicted the existence of yet more particles, superpartners of existing particles or "sparticles". The theory implies that every boson should have a fermion superpartner and vice-versa. The hunt began for evidence of supersymmetry. According to the most powerful versions of supersymmetry, sparticles should not be much heavier than a Higgs boson, one of which was measured in 2012 at CERN using the Large Hadron Collider (LHC). The existence of supersymmetry in nature would explain the missing dark matter expected to account for 25% of the 95% unaccounted for matter and energy in the universe.

NOT--experiments at the LHC have so far ruled out the existence of supersymmetry in its most accepted versions. Experimental observations confirmed the decay of a very rare B meson decaying into two muons that confirms the Standard Model prediction but is a blow to supersymmetry adherents. Supersymmetry also predicts a lower mass for the Higgs boson than was recently measured by the LHC at about 120 GeV. Scientists hope to find evidence of supersymmetry at higher energy collisions slated for 2015, but some theoritical physicists appear to be so wedded to supersymmetry theory that they are willing to contort it to conform to experimental results, or put the existence of superpartners beyond experimental confirmation. According to Popper's view, supersymmetry is then no longer a scientific theory that accurately describes the universe, but enters the realm of myth.

1 proton→26 particles @ Fermilab circa 1960's
What physicists know now is that the cosmos is finely tuned: the Higgs boson wobbles on the quantum edge of stablility in a metastable state, meaning the weirdness of quantum effects could push the Higgs boson into a lower energy state, taking the known universe with it because according to the paradigm the Higgs boson is what gives elementary particles in this universe mass. Supersymmetry explains why this does not happen and without it physicists are at a loss to explain why not since there is nothing in quantum theory to prevent such a shift in energy state. According to Genesis, God thought, "Let there be light." Physicists call this beginning the "Big Bang". Because photons exist (light) humans can observe and conjecture about this universe. What "initial conditions" existed before photons began perhaps only God can know, but there also is found the beginning of man's belief.