1. Determinism is true as far as science can tell. By determinism I mean human actions and thoughts are not above natural laws. Given sufficient knowledge of a person's past, he future is as predictable as the future the positions of planet earth.*

2. Free will is a relation between one's action and his desire, and is thus independent of determinism. If one's action is the outcome of his own desires, then he is free. In other words, [whether you will be free or not in the future is as determined as in the past][1]

3. Physics is not governed by mathematics. Mathematics is the art of saying the same thing in different ways. When a mathematical model contradicts a scientific observation, we revise the mathematical model; we do not punish the physical world for defying the law.

*If I'm not mistaken, Bertrand Russell's view is slightly different from materialism. The difference is similar to that of agnosticism from atheism.

  [1]: http://philosophy.stackexchange.com/a/9329/5116