Online research in philosophy

Einstein's argument on the relativity of simultaneity itself is the first result of the special theory of relativity. This argument is reflected in the structure and functioning of the physical world. The arbitrary nature of the decision regarding the particular inertial reference frame from which the argument on the relativity of simultaneity begins is discussed. It is this arbitrary, or freely made, decision that is the basis for the significance of the argument of the relativity of simultaneity itself on the structure and functioning of the physical world. The same concrete circumstances in the physical world can support either direction in the argument on the relativity of simultaneity, as well as other results, in the special theory (i.e., with either of two inertial reference frames in uniform translational motion relative to one another considered "stationary" while the other inertial reference frame is considered "moving"). There are different sets of results in the physical world associated with the choice in direction that is made, for example as concerns the temporal durations of occurrences or the spatial lengths of existents in these inertial reference frames. Experiments testing the equations derived in the special theory that relate the temporal durations of occurrences or the spatial lengths of physical existents in inertial reference frames in uniform motion relative to one another generally have not tested predictions with both of the two inertial reference frames considered, in separate scenarios, the "stationary" reference frame. It is proposed that empirical tests in two directions be developed and conducted. If empirical results from such tests support the predictions of the special theory, these empirical results would support the thesis that there is a cognitive factor in Einstein's argument on the relativity of simultaneity that affects results derived in the special theory concerning the physical world. One such test is proposed.

It will be shown that, in comparison with the pre-relativistic Galileo-invariant conceptions, special relativity tells us nothing new about the geometry of spacetime. It simply calls something else "spacetime", and this something else has different properties. All statements of special relativity about those features of reality that correspond to the original meaning of the terms "space" and "time" are identical with the corresponding traditional pre-relativistic statements. It will be also argued that special relativity and Lorentz theory are completely identical in both senses, as theories about spacetime and as theories about the behavior of moving physical objects.

High-level study discusses Newtonian principles and 19th-century views on electrodynamics and the aether, covers Einstein’s electrodynamics of moving bodies, Minkowski geometry and other topics. A rich exposition of the elements of the Special and General Theory of Relativity.

It is routinely assumed that Einstein discovered the relativity of simultaneity by thinking about how clocks can be synchronized by light signals, much in accord with the analysis he gave in his 1905 special relativity paper. Yet that is just supposition. We have no real evidence that it actually happened this way. In later recollections, Einstein stressed the importance of several thought experiments in the thinking that led up to the final theory. They include his chasing a light beam thought experiment and his magnet and conductor thought experiment. They do not include thought experiments on clocks and their synchronization. My goal here is to show that other pathways to the relativity of simultaneity are quite plausible. In several places Einstein stressed the importance in his discovery of special relativity of stellar aberration and Fizeau's measurement of the speed of light in moving water. The results can be seen as direct observational expressions of the relativity of simultaneity, if one knows how to read them. I will suggest that, thanks to his knowledge of Lorentz's 1895 Versuch, Einstein did know how to read them, and that it is quite possible that these observations first led Einstein to the relativity of simultaneity.

Are speical relativity and probabilism compatible? Dieks argues that they are. But the possible universe he specifies, designed to exemplify both probabilism and special relativity, either incorporates a universal "now" (and is thus incompatible with special relativity), or amounts to a many world universe (which I have discussed, and rejected as too ad hoc to be taken seriously), or fails to have any one definite overall Minkowskian-type space-time structure (and thus differs drastically from special relativity as ordinarily understood). Probabilism and special relativity appear to be incompatible after all. What is at issue is not whether "the flow of time" can be reconciled with special relativity, but rather whether explicitly probabilistic versions of quantum theory should be rejected because of incompatibility with special relativity.

It is widely believed that the principal difference between Einstein's special relativity and its contemporary rival Lorentz-type theories was that while the Lorentz-type theories were also capable of “explaining away” the null result of the Michelson-Morley experiment and other experimental findings by means of the distortions of moving measuring-rods and moving clocks, special relativity revealed more fundamental new facts about the geometry of space-time behind these phenomena. I shall argue that special relativity tells us nothing new about the geometry of space-time, in comparison with the pre-relativistic Galileo-invariant conceptions; it simply calls something else "space-time", and this something else has different properties. All statements of special relativity about those features of reality that correspond to the original meaning of the terms "space" and "time" are identical with the corresponding traditional pre-relativistic statements. It will be also argued that special relativity and Lorentz theory are completely identical in both senses, as theories about space-time and as theories about the behavior of moving physical objects.

Modern readers turning to Einstein’s famous 1905 paper on special relativity may not find what they expect. Its title, “On the electrodynamics of moving bodies,” gives no inkling that it will develop an account of space and time that will topple Newton’s system. Even its first paragraph just calls to mind an elementary experimental result due to Faraday concerning the interaction of a magnet and conductor. Only then does Einstein get down to the business of space and time and lay out a new theory in which rapidly moving rods shrink and clocks slow and the speed of light becomes an impassable barrier. This special theory of relativity has a central place in modern physics. As the first of the modern theories, it provides the foundation for particle physics and for Einstein’s general theory of relativity; and it is the last point of agreement between them. It has also received considerable attention outside physics. It is the first port of call for philosophers and other thinkers, seeking to understand what Einstein did and why it changed everything. It is often also their last port. The theory is arresting enough to demand serious reflection and, unlike quantum theory and general relativity, its essential content can be grasped fully by someone merely with a command of simple algebra. It contains Einstein’s analysis of simultaneity, probably the most celebrated conceptual analysis of the century.

According to the moving spotlight theory of time, the property of being present moves from earlier times to later times, like a spotlight shone on spacetime by God. In more detail, the theory has three components. First, it is a version of eternalism: all times, past present and future, exist. (Here I use “exist” in its tenseless sense.) Second, it is a version of the A-theory of time: there are nonrelative facts about which times are past, which time is present, and which times are future. That is, it is not just that the year 1066 is past relative to 2007. The year 1066 is also past full-stop, not relative to any other time. (The A-theory is opposed to the B-theory of time, which says that facts about which times are past are relative to other times.) And third, on this view the passage of time is a real phenomenon. Which moment is present keeps changing. As I will sometimes put it, the NOW moves from the past toward the future.1 And this does not mean that relative to different times, different times are present. Even the B-theory can say that 1999 is present relative to 1999 but is not present relative to 2007. No, according to the moving spotlight theory, the claim that which moment is present keeps changing is supposed to be true, even from a perspective outside time.

In this paper I distinguish interpretations of the question ``How fast does time pass?’’ that are important for the debate over the reality of objective becoming from interpretations that are not. Then I discuss how one theory that incorporates objective becoming—the moving spotlight theory of time—answers this question. It turns out that there are several ways to formulate the moving spotlight theory of time. One formulation says that time passes but it makes no sense to ask how fast; another formulation says that time passes at one second per supersecond; and a third says that time passes at one second per second. I defend the intelligibility of this final version of the theory.