Time is what clocks are used to measure. Information about time tells the durations of events and when they occur and which events happen before which others, so time plays a very significant role in the universe’s structure, including the structure of our personal lives. But carefully describing time’s properties has led to many unresolved issues, both philosophical and scientific.

In his book, The Structure of Time, William H. Newton-Smith claims that we cannot decide whether the structure of time is continuous or merely dense. I discuss here the extent to which he is correct. I argue that he fails to provide strong enough arguments to defend his claim, but I then suggest how he might overcome this issue. I also argue that we must reconsider the consequences that he draws from his “undecidability result”.

In Minkowski spacetime, because of the relativity of simultaneity to the inertial frame chosen, there is no unique world-at-an-instant. Thus the classical view that there is a unique set of events existing now in a three dimensional space cannot be sustained. The two solutions most often advanced are that the four-dimensional structure of events and processes is alone real, and that becoming present is not an objective part of reality; and that present existence is not an absolute notion, but is (...) relative to inertial frame; the world-at-an-instant is a three dimensional, but relative, reality. According to a third view, advanced by Robb, Capek and Stein, what is present at a given spacetime point is, strictly speaking, constituted by that point alone. I argue here against the first of these views that the four-dimensional universe cannot be said to exist now, already, or indeed at any time at all; so that talk of its existence or reality as if that precludes the existence or reality of the present is a non sequitur. The second view assumes that in relativistic physics time lapse is measured by the time co-ordinate function; against this I maintain that it is in fact measured by the proper time, as I argue by reference to the Twin Paradox. The third view, although formally correct, is tarnished by its unrealistic assumption of point-events. This makes it susceptible to paradox, and also sets it at variance with our normal intuitions of the present. I argue that a defensible concept of the present is nonetheless obtainable when account is taken of the non-instantaneity of events, including that of conscious awareness, as that region of spacetime comprised between the forward lightcone of the beginning of a small interval of proper time t and the backward lightcone of the end of that interval. This gives a serviceable notion of what is present to a given event of short duration, as well as saving our intuition of the “reality” or robustness of present events. (shrink)

This brief review of Mario Bunge’s research on physics begins with an analysis of his masterpiece Foundations of Physics, and then it discusses his other contributions to the philosophy of physics. Following that is a summary of his more recent reactions to scientific discoveries in physics and a discussion of his position about non-locality in quantum mechanics, as well as his changing opinions on the nature of spacetime. The paper ends with a brief assessment of Bunge’s legacy concerning the foundations (...) of physics. (shrink)

It is widely believed that relationism cannot make room for the possibility of intervals of time during which no changes occur. Benovsky has recently challenged this belief, arguing that relationists can account for the possibility of changeless time in much the same way as substantivalists do, thereby concluding that the two views are interchangeable for all theoretical purposes. This paper intends to defend the meaningfulness of the traditional dispute between substantivalists and relationists, by contending that the particular form of relationism (...) on which Benovsky has based his criticism is in fact alien to that debate. (shrink)