  We speculate on some novel consequences possibly associated with a change of
elementary particle constants with time. These concern the question as to
whether particles reaching the earth from distant parts of the universe reflect
their properties at their point of origin and so can be different from local
particles. Assuming that such particles would be present in very high energy
cosmic rays, we estimate their density on the earth by two different methods,
finding on this hypothesis a density of roughly $10^{-28}-10^{-29}$. Various
possibilities for detection are discussed, including the formation of unusual
nuclear isotopes.
