Brittany A. Gentry

The role of a time parameter is vital to physics, yet time is often taken for granted. Newtonian physics assumes an idealized time variable that is unmeasurable. In this paper, we answer calls for clearer accounts of the emergence of Newtonian time from timeless mechanical systems (Smolin 2013). We consider a three-particle system in the timeless formalism of Jacobi. Time is abstracted from paths in configuration space in accord with Mach’s prin-ciple of universal inertial reference frames. This paper makes three contributions to the conversation around time. First, our physical demonstration of how Newtonian time is con-structed completes Mach’s arguments about clocks and time in classical, non-relativistic systems. Second, this paper discusses the integration of these ideas regarding time into quantum mechanics. Finally, we answer the question, ‘what do clocks measure?’ using these simple physical systems and use that answer as a foundation for engagement with current metaphysical debates about time.

Presentists argue that only the present is real. In this paper, I ask what duration the present has on a presentist’s account. While several answers are available, each of them requires the adoption of a measure and, with that adoption, additional work must be done to define the present. Whether presentists conclude that a reductionist account of duration is acceptable, that duration is not an applicable concept for their notion of the present, that the present has a duration of zero, or that that the present has a duration, a more robust account of the present is required. I suggest that some of the most difficult questions about duration can be avoided at the cost of no longer viewing presentism as a theory about time, but rather as a theory about existence. In the conclusion, I suggest an interpretation of presentism that allows it to endorse the view that time is nothing more than the measure of change.

Is there reasonable distrust of reputable scientific authority? This paper considers the role of experience in the epistemic process of trusting authority and argues that distrust based on experience mirrors rational processes of belief formation and so produces rational, though sometimes wrong, beliefs. Part one establishes the importance of experience in the basic process of developing trust in authority and in formal epistemologies. Part two considers four ways in which people experience scientific authorities: (1) expertise, (2) distinguishing between individual and group identity, (3) shared identities, and (4) transparency. Given the role of experience in trust formation, the paper concludes that in some cases where non-scientific communities have negative experiences of scientific authority and distrust a reputable scientific authority, those communities have, prima facie, a rational distrust and are likely to distrust.