Physics Is Culturally Neutral

Lubos Motl should know better than to make the ad hominem argument that a physics concept is discredited just because a Nobel Prize winning physicist who also became a Nazi at some point in his life toyed with the idea.

In this case he is attacking the loop quantum gravity approach to quantum gravity (he prefers the approach to quantum gravity based upon gravitons in 10-11 dimensional string theory), because the physicist who invented the cathode ray tube (which was at the heart of all video screens for half a century) toyed with a somewhat similar aether theory.

Loop quantum gravity (LQG) is a really a class of theories of quantum gravity that argues that, as in general relativity, gravity involves a background independent deformation of space-time, rather than a force mediated by a boson in the special relativistic space-time background of quantum-mechanics. Thus, in loop quantum gravity, there is quantization of space-time at the Planck scale, rather than quantization of a force acting between particles.

It is certainly fair game to criticize potential flaws in one of the two major approaches to quantum gravity, which is one of the great unsolved problems of physics, and eventually he does address some of his concerns on that score.

But, it is not fair game to field as an argument against LQG the politics of an admittedly technically accomplished physicist who explored a distant predecessor of the idea, any more than it is to denounce half a century of television screens as "Nazi Science". This is the kind of criticism that confuses people who don't know better while not informing or persuading anyone who does know better. It is particularly unseemly coming from someone whose own distasteful politics and poor social skills appear to have cost him a position in the physics department at Harvard, despite his clearly solid command of the discipline of physics itself, however, opinionated he might be in that regard towards rival approaches in his discipline.

Motl's offhand accusations of plagiarism directed at an academic rival (which having read many of the academic rival's papers, I can confidently tell you is hog wash), and his failure to engage in the real issues by offering up straw man versions of LQG, are likewise unworthy of a serious and sincere academic.