In another variation on this theme, subjectivists in the mid-twentieth century were fond of declaring that "everything is relative." In support of this assertion, they sought to invoke the authority of Albert Einstein. Einstein's theory of relativity revised the theories of Newton and adapted them to a wider context of knowledge, including recent discoveries in optics (e. g., Michelson's and Morley's famous 1881 experiment). His Special Theory of Relativity (1905) was based on two premises:

1. There is no favored frame of reference (i. e., "ether") for making physical measurements. The laws of physics, in other words, are independent of one's frame of reference.
2. The speed of light is invariant and independent of the observer's perspective.

Some of the conclusions derived mathematically from these premises seemed counter-intuitive, at least to humans whose intuition is not grounded in experiences involving velocities approaching that of light. Nevertheless, Einstein's theory offers no refuge to the philosophical or moral relativist. Indeed, the latter's position might have been more compatible with quite opposite premises:

1. The laws of physics depend on your point of view.
2. The speed of light is whatever the observer feels that it should be.

Of course, this viewpoint, unlike that of Einstein, cannot be related to observations of an absolute reality.