Hoping for some input on the following: In the development of what is now known as classical physics, there was a tacit assumption that the universe was governed by laws, which we did not know, but attempted to understand. In modern physics, most notably with Relativity and Quantum Mechanics, it seems that this philosophy changed. Instead of assuming that the universe acted in a certain way, regardless of how we observed it, we began treating the universe as acting in a way consistant with how it is measured. To more aptly illustrate my point consider the following: Werner Heisenberg proposed that we could not measure both the position and momentum of a particle simoultaneously. Classically speaking, one might say, a particle has a definite position and momentum at a given moment, but any attempt to measure one will skew the measurement of the other. Modern Physics, specifically Quantum Mechanics, seems to insist that the particle does NOT have a definite position and momentum at a given moment. Instead, the view became that a particle is actually a "likelihood of positions and momentums." In an attempt to simplify my point, I will abuse the language a bit and say: Classical View: Modern View: I don't mean to suggest that either view is invalid. Certainly, physics is a pragmatic science, so we should expect that both of the above statements should hold true. But, if I am correct, it does seem to represent a philisophical difference in regards to the approach. Am I mistaking something about the interpretation of modern physics, or overlooking something in the development of classical physics? In any case, input is appreciated.