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, we explore more of the ejecta diversity. There is a much wider range of morphologies, particularly when smaller diameter craters or craters formed in the Northern Plains are considered.

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.

We consider the types of information available to the planetary geomorphologist to investigate craters on Mars. This information primarily takes the form of images, as well as topographic and compositional data, collected from Mars orbit by a variety of spacecraft. We then review aspects of the chronology of Mars, from the earliest geologic epoch (the Noachian) until the most recent (the Amazonian), and how the rocks formed during these time periods are distributed across the planet. We discuss that what can be observed on Mars today is not the way in which the planet has appeared throughout its history.

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.

Here we delve more deeply into differences in the ejecta and show some of the rare features and characteristics associated with the freshest examples of craters. When trying to understand the flow processes displayed by the ejecta, these features no doubt provide additional details on the emplacement process as well as illustrate the potential variability across the planet as a function of geographic location.