I think the existence of the quantum world guarantees that true randomness exists in the universe. The Casimir effect is one evidence of the random quantum world, where particles flit randomly in and out of existence, governed only by conservation laws regarding charge and spin and so forth.
That quantum randomness can have a macro impact is obvious - it was the whole point of Schrdinger's cat, and its existence is responsible for a great deal of human activity, most obviously quantum research and papers, and a great many Internet pages. Quantum effects have practical applications, such as tunnel diodes, and so does quantum randomness, such as generating secure cryptographic keys.
I do believe we live in a clockwork universe, but only down to the quantum level where elements of reality begin to become truly random. Quantum effects can affect dice, photons, anything.
What does this mean for determinism? I think it means that what we think and do is largely but not completely deterministic, and that any sense of control we have is an illusion.
--Percy
Edited by Percy, : Grammar.