Our universe is a state machine built of elementary particles; strong electric currents in the human neural network cause the illusion of free will.
Physical interactions among any number of elementary particles are governed by physical laws. First-order change is the change of the state which is governed by the physical laws. Second-order change is the change of the state which breaks the physical laws, so it is impossible in real world. The first-order change is computed out (first-order computation) based on physical laws. Conscious experience and the feeling of free will, are the results of the first-order computation; they have no impact to the first-order computation. When a control system automatically plans for what it shall do, (as a workaround to deal with the unpredictability of what itself will actually do,) it unintentionally maps the real world and its model illogically, and the way it works is defined to be the first-person perspective. Mixing up the real world and its model conceptually, and using the illogically mapped model unintentionally, jointly lead to the illusion of free will.