The longer I think about free will the closer I come to the conclusion that it is only possible if our universe is not strictly deterministic. Assuming that free will means I can make any choice I want regardless of my own and the worlds physical state. A deterministic universe would not allow you to actually choose, your "choice" would be a logical consequence of the universe's state.

If we turn that around, then having free will as defined before means that there is such a thing as randomness. This randomness may exist in human decision making alone, but it might also be a part of physics although there is not yet an indication that this is the case.

Again; the existence of free will is depending on whether our universe is deterministic or chaotic.