## False assumptions

The basic assumption of general relativity, the standard model of gravity, is not, as you might think, the general principle of relativity. By 1915, Einstein had adopted instead the equivalence principle, that is the equivalence of gravitational mass (that determines how heavy something is) with inertial mass (that determines how hard it is to push it). Many people have questioned this principle, and many very accurate experiments have been carried out to test it, on the Earth and in orbit. No discrepancy has yet been found. But cosmological evidence strongly suggests that the principle does not hold in the universe as a whole.

Mathematical analysis of this problem cannot only suggest whether or not the principle is correct, but can also suggest in what ways it might be incorrect, and therefore guide the choice of experiments to do. In this blog, I present arguments that the principle is incorrect, but that experiments on or near the Earth cannot detect this. On the other hand, spacecraft travelling to or beyond the outer planets of the Solar System should be able to detect it. Moreover, I believe they already have detected it, but that this is not yet recognised.

Turning now to quantum mechanics, on which the theory of sub-atomic particles is built, the foundations date to the 1920s, at which time the basic assumptions were adopted. The basic concept is spin, and the crucial fact is that an electron has spin 1/2, whereas a rotating sphere has spin 1. The mathematical relationship between these two is expressed by saying that if you ignore an overall $\pm$ sign in the symmetry group of spin 1/2, then you get the rotation group of a sphere.

Now we have to distinguish carefully between saying these two symmetry groups are mathematically the same (this is called “isomorphic”), or physically the same (this is called “equal”). Quantum mechanics would not work at all if they were not isomorphic. But the assumption that was made in the 1920s, and has never been questioned since, is that they are physically equal. In this blog I prove that this assumption is wrong: it is inconsistent with the existence of accelerating bodies anywhere in the universe.

Partly this is a confusion between a physical sphere which is physically rotating about a certain axis at a certain speed, and a mathematical sphere that is independent of time and has no preferred axis. But it is also partly a confusion between a spinning sphere that exists in isolation (analogous to a photon), and a spinning sphere that is attached to the rest of the universe via gravitational interactions (analogous to an electron).

Questioning basic assumptions makes people very uncomfortable, and often angry. Physicists are no exception. I have made many enemies. By denying the two basic assumptions I have made myself an outcast. But it is worse: I have refuted them. Both.