Barring theories of quantum consciousness or some "new physics" suggested in, for example, certain work in systems biology does not mean a simple understanding of physics leaves us with a reductive program in which free will is impossible. Physicalism does not entail reductionism or the impossibility of higher level structures like those of the mind as being causally efficacious:
"there are several reasons for questioning reductionism in the context of classical (nonquantum) dynamics. First, although the reductive program asserts that all higher-level dynamics can in principle be causally explained in terms of physics and chemistry, reductionism does not imply constructionism. This is because there is an immense number of possible emergent entities at each level of both the biological and the cognitive hierarchies, so what actually occurs depends largely on happenstance (Poincare's fortuitous phenomena) that is consistent with but not constrained by the laws of physics and chemistry.
Second, reductionism does not explain how the various types of Aristotelian causality (material, formal, efficient, and final) are to be sorted out. Under nonlinear dynamics, even the threads of efficient cause become interwoven, and downward action of formal causes makes lower-level dynamics depend on higher-level phenomena, at variance with reductive assumptions.
Third, from an operational perspective, the nature of time differs at higher and lower levels the arrow of time being bidirectional under energy conservation and unidirectional under the energy-consuming dynamics of biology. This is problematic for biological reductionism because a system with unidirectional time is asked to be described in terms of bidirectional time.
Fourth, living creatures are open systems, regularly replacing their atomic and molecular constituents. Thus exact knowledge of the speeds and positions of these constituents at one time cannot be used for making higher-level predictions at later times.
In biological and cognitive systems, finally, myriad closed causal loops and networks with positive feedback obscure the relationships between cause and effect, leading both to the emergence of new dynamic entities with unanticipated properties and to chaotic interactions among them."
Scott, A. (2006). Physicalism, Chaos and Reductionism. In The Emerging Physics of Consciousness (pp. 171-191). Springer Berlin.
