erraticwisdom

I got a bit giddy when we got to the “Space and Time” portion of my Metaphysics class. Most of my semester was spent deciphering bizarre accounts of matter (where two theories’ definitions could differ by just a single word), and I was more than ready for a change. I like the topic of Time in particular because I really have no idea what it is, and metaphysical analysis seems a bit more accessible than a purely physical approach.

Time is typically associated with change, and a famous puzzle related to this concept is Shoemaker’s “freeze world” scenario. Shoemaker’s scenario, first proposed in “Time Without Change”, describes a discrete possible world consisting of three zones: A, B and C. Under normal conditions, the inhabitants of each zone are able to observe and communicate with each other. However, a mysterious phenomenon occurs occasionally whereby all change in a zone ceases, meaning no motion, growth or decay occurs. During these “local freezes”, inhabitants of the other unfrozen zones can observe that all activity has, indeed, stopped (while their zones remain active). Individuals in the frozen zone do not immediately detect the freeze, as their activities will simply resume as if no freeze had occurred. Frozen observers focused on one of the other zones would notice large, instantaneous changes as they become acquainted with the post-freeze world. In Shoemaker’s example, these local freezes are found to occur cyclically (every three years in Zone A, every four in Zone B, and every five in Zone C) and last for one year each time. The cycles are in phase, so every sixty years, the frozen periods of each zone align to create a “total freeze” where absolutely no change occurs in the entire world. The term of this total freeze would be undetectable to the world’s inhabitants who had previously referenced other zones’ clocks or their own perception of other zones’ change to recognize the freeze. This scenario establishes the idea that one in sixty years will be what Shoemaker calls a “changeless interval”.

The importance of these total freezes is that they dissociate the passage of time from the occurrence of events in the world (that our normal conception of time requires). However, there are a few inconsistencies in Shoemaker’s scenario that prevent it from convincingly proving its conclusion. For anyone interested, I discuss some of the more theoretical problems in this paper I submitted in the course. I’ll explain some quick ones here.

The first is a physical problem with the scenario. As far as we can understand, motion and change are critical to the very persistence of matter. The constant movement and vibration of atoms and subatomic particles are required to maintain the tenuous structural and electrical integrity of these entities. Take the phenomenon of absolute zero, for example, the temperature (0K, -273°C) at which molecular motion mostly ceases. Reaching absolute zero is theoretically impossible, an asymptotic limit not unlike the speed of light. Even approaching absolute zero causes wild variations in a substance’s properties including quantum effects like superconductivity. The impossibility of reaching absolute zero therefore raises serious doubts on the feasibility of Shoemaker’s scenario.

Another critique of Shoemaker is theoretical in nature and involves the ideas of time and change in the “freeze world” scenario. The terms are not well defined, and the lack of clarity ultimately leaves Shoemaker begging the question. What exactly does it mean for time to pass in frozen zones, what do these “changeless intervals” refer to? In the scenario, time can be observed to pass when one or two zones are frozen because of the remaining reference zone(s). When the frozen zones thaw, they can consult clocks or observers in the unfrozen zone to learn that their zone had indeed been in a freeze. However, in a total freeze, no such reference exists, and to say that the zones continue frozen for one year is to gratuitously assume the conclusion that changeless time is possible. During the single local freezes, the passage of time is still relative to changes occurring in the unfrozen zone(s). To inhabitants of the frozen zone, the one year freeze passes instantaneously and would have gone unnoticed were it not for observers in the unfrozen zones. However, during the total freeze, all changes in the world cease, and without the reference of changes in unfrozen zones, the intervening period does pass instantaneously and inhabitants of the world would never know. Shoemaker’s scenario is therefore reducible to the total freeze (there is still time and change during single local freezes), and the conclusion that there is a one-year changeless interval is not adequately supported.

These problems mostly disprove the scenario for me. What do you think, is changeless time possible?