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#661 Immaterial Agents and Time Dilation

December 22, 2019

Dear Dr. Craig,

Up until recently, I've been a reductive materialist, but I've been so inspired by your work that I've changed my mind. The following question is one that I’m still struggling with however. Before I ask my question, know that my knowledge of special relativity mostly comes from personal interests. I'm by no means an expert in the topic so my understanding may be flawed or incorrect.

My question is essentially: how can we understand time dilation of immaterial things? Considering Einstein's special theory of relativity and specifically the example of the photon clock, we know that if an observer X, holding a photon clock, is moving past observer Y, the frame of reference X experiences time dilation with respect to Y. Observer Y sees the clock ticks in X slow in proportion to X's speed past Y. This is due to the length of clock ticks differing in each frame of reference while the speed of the photon remains constant. Now, for observer X watching his clock, my interpretation is that he experiences normal clock ticks rather than slow ones. If this is accurate, perception and consciousness of observer X is also subject to time dilation.

A materialist would say this makes sense because the observer is solely comprised of material organs consisting of atomic structures alone and atomic structures are essentially photon clocks. Physical neural structures and electrical impulses of the brain are also physical clocks. In other words, those physical structures in the "mind" experience time dilation in the same manner as the physical photon clock. For that reason, the photon clock and observer X's physical "mind" dilate in tandem resulting in observer X experiencing normal ticks.

If we reject materialism, how can we understand time dilation of the immaterial self?



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Dr. craig’s response


What a thoughtful question, Aaron!

For those who lack Aaron’s scientific background, let me explain briefly that according to Einstein’s Special Theory of Relativity a clock in uniform motion runs slowly compared to another clock taken to be at rest. The example of the light clock illustrates this truth. Imagine the clock keeps time by sending a light beam back and forth between the top and bottom of the clock. In a clock at rest the beam is perfectly perpendicular and traverses the shortest distance between top and bottom. But imagine a similar clock in rapid motion going past you. The light beams of that clock will not be moving perpendicularly relative to you: they must travel in a sort of zig-zag pattern if the clock is to function. Since the distances traversed by the light beam in the moving clock are not the shortest, it will take more time for the beam to reach the other side of the clock. Hence, the clock will run slow relative to the observer taken to be at rest. But, as Aaron notes, the person who is traveling along with the clock sees the clock functioning as though it were at rest—indeed, for him, the clock is at rest and so unaffected in its timekeeping. It is the other guy’s clock which is in relative motion and so running slow!

Does time dilation present a challenge to the substance dualist who takes the soul or mind to be distinct from the brain? I don’t see why. The substance dualist doesn’t think of the soul as the proverbial “ghost in the machine” but rather as intimately connected with the brain to function together in thought. Just as a person whose brain has been impaired through drugs or injury will be unable to think normally, so a person whose biological clock has been slowed down will think more slowly relative to an observer taken to be at rest. One’s neural processes in the brain will be slowed and so also one’s thinking. The problem posed by time dilation is really no more difficult than the fact that I feel pain when a brick is dropped on my foot.

For more on humans as psycho-somatic unions, see my colleague J.P. Moreland’s chapters on philosophy of mind in the second edition of our Philosophical Foundations for a Christian Worldview.

- William Lane Craig