Dylan

I do not believe there is an ultimate frame of reference. All frames of reference are equally valid, but there will always be a simplest frame of reference for any physics problem. Eric mentioned an ultimate frame of reference based on the center of the expanding universe. this would be a (theoretically) completely stationary point. This does not make it the ultimate frame of reference, Why would this centered, stationary frame of reference be anymore valid in an experiment taking place on earth than any other much simpler frame of reference?