Holy Principles of Physics

· physics, theory of relativity

To name an ad hoc assumption in physics a PRINCIPLE is a way to give something possiby without substance a very heavy weight. Einstein was the master of this form of science by founding his special and general theory of relativity on:

Einstein formulated in 1905 his working method as follows:

  • the same laws of electrodynamics and optics will be valid for all frames of reference for which the equations of mechanics hold good. We will raise this conjecture (the purport of which will hereafter be called the “Principle of Relativity”) to the status of a postulate, and also introduce another postulate, which is only apparently irreconcilable with the former, namely, that light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body.

Cosmology is supposedly being based on Einstein’s equations
of general relativity, which are 10 coupled non-linear partial differential equations supposedly describing the large space-time structure of the Universe, supposedly being derived from the above Principles.

Einstein’s equations have the concise formulation

R_{\mu \nu} - {1 \over 2}g_{\mu \nu}\,R + g_{\mu \nu} \Lambda = {8 \pi G \over c^4} T_{\mu \nu}

which however is so cryptic that very few physicists claim to understand it, although all physicist pay lip service to idea that these must certainly be God’s equations of the Universe, even if they are way too difficult to solve for humans.

Here \Lambda is Einstein’s Cosmological Constant, the introduction of which Einstein viewed as his biggest mistake.

But there is a way to handle the difficult Einstein equations and that is to combine them with yet another principle:

that is the Universe is the same everywhere and in every direction. With this Principle Einstein’s equations reduce to the very simple FLRW equations which can easily be solved analytically and be shown to  allow Hubble’s Law of a Universe expanding at a constant rate, named Hubble’s constant H, in the only case \Lambda =0 accepted by Einstein.

The 2011 Nobel Prize in Physics is awarded for the discovery that Hubble’s constant does not appear to be constant, which requires the FLRW equations to have \Lambda >0.

Observations and Principles thus conflict and put physics into dead lock: Principles are Principles and must be upheld while Observations are Observations which cannot be denied.

But if we replace Principle by Ad Hoc Assumption, then the conflict disappears because there is no reason to insist on an Ad Hoc Assumption.

The question remains if the Nobel Prize was given to the great achievement of showing that a Principle was wrong, or to the triviality of realizing that an Ad Hoc Assumption is noting but an ad hoc assumption?

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