Deutsch claims that some of the problems of the dynamical laws approach come from the fact that, given a set of initial conditions, this approach can tell you what will happen in a particular situation, but it is often difficult to capture notions of what is in principle possible or impossible. He gives the example of describing why a particular perpetual motion machine will not work. The dynamical laws approach would tell us that the machine won’t work because the torque on one of the axels isn’t large enough, but any physicist would just tell you that it is impossible to build a perpetual motion machine and be done with it.
Of course not. Macrsoscopic PM machines are impossible because of macroscopic laws, ie. the laws of thermodynamics, and any physicist would say so. (Microscopic PMs aren’t impossible … Atoms are PM machines, unless protons decay).
And entropy is a dynamic law, in the sense that it’s dependant on an initial condition. A lower entropy state will decay into a higher one, but a high entropy state has nowhere to go..Entropy can only explain the arrow of time on the assumption that universe started in a low entropy state.
Of course not. Macrsoscopic PM machines are impossible because of macroscopic laws, ie. the laws of thermodynamics, and any physicist would say so. (Microscopic PMs aren’t impossible … Atoms are PM machines, unless protons decay).
And entropy is a dynamic law, in the sense that it’s dependant on an initial condition. A lower entropy state will decay into a higher one, but a high entropy state has nowhere to go..Entropy can only explain the arrow of time on the assumption that universe started in a low entropy state.