In a 2002 paper, I offered a novel way of thinking about the compatibility of free will with determinism, one that depended on appealing to the typical understanding of time of the philosopher of physics as simply one of the four dimensions of the Block Universe, albeit an especially interesting and important one. I argued that rejecting the everyday notion of “passage of time,” and of the explanatory privilege that we usually give to past → future determination as opposed to future → past determination, allowed one to articulate a novel way of defending free action in a Block world subject to deterministic laws. The problem is, most of the time these days I no longer believe in the Block and do believe in the passage of time! But I still believe that human action is (often) free, and that physics poses no genuine threat to our freedom. In this paper I will explore how the core idea behind “Freedom from the Inside Out” can be modified to be compatible with a metaphysical picture in which time passes, and explanation is not fully time-symmetric.

Working inside the control-theoretic framework for understanding thermodynamics, I develop a systematic way to characterize thermodynamic theories via their compatibility with various notions of coarse-graining, which can be thought of as parametrizing an agent’s degree of control of a system’s degrees of freedom, and explore the features of those theories. Phenomenological thermodynamics is reconstructed via the ‘equilibration’ coarse-graining where a system is coarse-grained to a canonical distribution; finer-grained forms of thermodynamics differ from phenomenological thermodynamics only in that some states of a system possess a free energy that can be extracted by reversibly transforming the system (as close as possible) to a canonical distribution. Exceeding the limits of phenomenological thermodynamics thus requires both finer-grained control of a system and finer-grained information about its state. I consider the status of the second law in this framework, and distinguish two versions: the principle that entropy does not decrease, and the Kelvin/Clausius statements about the impossibility of transforming heat to work, or moving heat from a cold body to a hotter body, in a cyclic process. The former should be understood as relative to a coarse-graining, and can be violated given finer control than that coarse-graining permits; the latter is absolute and binds any thermodynamic theory compatible with the laws of physics, even the entirely reversible limit where no coarse-graining is appealed to at all. I illustrate these points via a discussion of Maxwell’s demon.

There is a long-cherished hope, which has its origins in the work of Boltzmann, that all that we are going to need to do in order to account for all the of the differences there are between the past and the future is to add to the fundamental time-reversal-symmetric dynamical laws, and to the standard statistical-mechanical probability-measure over the space of possible fundamental physical states, a simple postulate – a so-called “past hypothesis” – about the initial microstate of the universe as a whole. And there are various widespread and perennial sorts of puzzlement about how a hope like that can even seriously be entertained – puzzlements (that is) about how it is that the macrocondition of the universe 15 billion years ago, all by itself, can even imaginably be up to the job of explaining so much about the feel, today and on Earth, of the passing of time. I want to try to alleviate those puzzlements here. I will begin with a number of very general observations – and then, by way of illustration, I will present a new and detailed analysis of how it is that a simple pendulum clock invariably arranges to turn its hands clockwise in the temporal direction that points away from the Big Bang.

We conduct a case study analysis of a proposal for the emergence of time based upon the approximate derivation of three grades of temporal structure within an explicit quantum cosmological model which obeys a Wheeler–DeWitt type equation without an extrinsic time parameter. Our main focus will be issues regarding the consistency of the approximations and derivations in question. Our conclusion is that the model provides a self-consistent account of the emergence of chronordinal, chronometric, and chronodirected structure. Residual concerns relate to explanatory rather than consistency considerations.

In this chapter, I endorse phenomenal conservatism as an epistemic theory of justification and I defend that we are justified in believing that the direction of time is primitive because it seems to us to be primitive, unless there were defeaters for having such a belief. This is what I call the “Argument From Appearances.” I then analyse one of the most powerful arguments against this argument, the “Time-Reversal Argument,” and claim that it relies on supplementary premises that can be challenged. Therefore, it is rendered harmless and does not qualify as a solid defeater against the Argument from Appearances.

The “Consequence Argument” has spawned an enormous literature in response. The most notable of these responses is David Lewis’ which is based on his account of counterfactuals. My reason for adding to this literature is that I show that while Lewis’ diagnosis of the argument is on the right track, the account of counterfactuals he relies on to rebut the argument is defective and, consequently, he rejects the wrong premise of the argument. I will develop a response that is in some ways similar to Lewis’ but relies on a different and better account of counterfactuals based on statistical mechanics. My account of counterfactuals is based on an approach that goes back to Boltzmann and has more recently been developed by David Albert in his book, Time and Chance. This account, which is called “the Mentaculus,” provides a framework for explaining and connecting the various so-called arrows of time, including those of thermodynamics, causation, knowledge, and influence. It is the last of these arrows that is key to my response to the Consequence Argument. If my response is effective, then it will turn out that physics (together with some philosophy), rather than conflicting with freedom, is able to rescue it, at least, from the Consequence Argument. Digging more deeply I will argue that metaphysical views about the nature of time and laws underlie the arguments for the incompatibility of free will and determinism and more generally for the difficulty in seeing how there can be free will in a world in which the motions of material bodies conform to fundamental laws of physics. I will conclude by showing why this is so and how the Mentaculus response to the consequence argument involves relacing these metaphysical views with an alternative account of laws and time more in tune with Humean metaphysics.

In a series of papers published during the last decades, with Mario Castagnino we developed a global and nonentropic approach to the arrow of time that follows John Earman’s “time direction heresy,” according to which the problem of the arrow of time can be addressed in terms of the geometry of space-time, independently of entropic arguments and without appealing to non–time-reversal invariance. The aim of this chapter is to present a review of the global and nonentropic approach to the arrow of time, and to consider some aspects that were not discussed in detail in those original works. In particular, it will be analyzed to what extent the arrow of time can still be defined if the conditions of time-orientability, cosmic time, and time-asymmetry are not satisfied. The role of time-reversal invariance in the present approach will also be discussed. Finally, certain issues about contingency, fundamentality, reducibility, and objectivity will be considered.

The need to implement time reversal via complex conjugation in quantum theory has always been a bit of a puzzle. Why should i go to –i under temporal reflection when it has no spatiotemporal dimensions? I’ll provide a new insight into this question by showing how the little-appreciated “quantum-looking” classical Schrödinger equation of Schiller and Rosen faces the exact same problem. Since we know how to escape this problem classically, this observation teaches us one way to solve the problem quantum mechanically too. Big picture: if I’m right, the puzzle over quantum time reversal is connected to the interpretation of quantum theory.

Chapter 1, “The Road to Quarks,” traces the period from 1896, with Henri Becquerel’s accidental discovery of radioactivity, to 1935 with Hideki Yukawa’s theory of the nuclear force.

Discoveries of radioactivity by Becquerel; the nucleus by Hans Geiger and Ernest Marsden, as interpreted by Ernest Rutherford; the range of the nuclear force by Rutherford and James Chadwick; and the discovery of the neutron by Chadwick, are briefly described. Concepts from quantum mechanics and quantum field theory necessary to explain Heisenberg’s unsuccessful attempt to understand the nuclear force, and Yukawa’s successful theory of pion exchange, are explained. These include Heisenberg’s uncertainty principle, quantum fluctuations of quantum fields, and virtual particles as the carriers of force.