Mach?

Faster than light travel in Poul Anderson's The Star Fox and Fire Time is based on the theory of a man called Mach and is described here and here but I think that this must be a different Mach from the one mentioned by James Blish in The Star Dwellers:

the twentieth-century British astronomer, Milne, transformed the Lorenz-Fitzgerald expression of Einsteinian relativity from a natural law into a teaching convenience;

Adolph Haertel, by applying "Mach's axiom" or "the cosmological assumption," showed that the light-barrier disappeared if the whole mass of the universe was taken into account;

engineers inserted various values for M into Haertel's equations until they found one that worked.

This does not sound as if it should work but does sound like another of Anderson's various rationales for FTL. See here.