Wednesday, October 14, 2009

time present and time past are both perhaps present


Yeah, but.... If "clocks exist" means — as I think it does — "we measure time," then we've gained immeasurably from those who first learned the trick. I can't imagine civilization evolving without clocks existing in this sense and, even with its attendant evils and discontents, civilization is better than the alternatives of which we know. To take one tiny example of clockism that leaps to mind, consider the "clock" that lies at the heart of every computer.

All the same, "time doesn't exist" is a nicely provocative conceit and there's ample warrant in philosophy and science for making that statement. Thus from a philosophic position, a man named John Ellis McTaggart could defend an assertion that "Time is unreal, and that all statements which involve its reality are erroneous."* And from a scientific one Einstein could write: "For those of us who believe in physics, this separation between past, present and future is only an illusion."**

McTaggart is not the only philosopher to assert that, despite appearances, time, or some aspect of time, is unreal. The argument is related to the radical idealist one that nothing exists outside the thought in my mind. It's akin the the theological position that since nothing exists that is not in the mind of God, God's mind is the only reality. I'm too pragmatic to take this seriously tho it's interesting to play with the idea.

Similarly, and more concretely, there is a considerable literature in which scientists discuss the unreality of time. When condensed into laymen's language these hypotheses are both fascinating and unnerving.

Supposing that we accept that time exists, if for no other reason than that otherwise we'd go batty, we still have difficulties explaining what it we mean by the term. Definitions are slippery.

For example, one of the problems both philosophers and scientists contend with is the paradox that our version of time goes forward but not backward; you can't really imagine Merlin living his life backwards from death to birth. As the author of an article in the Stanford Encyclopedia of Philosophy succinctly puts the matter, we perceive that "causation is asymmetric; later events cannot affect earlier ones, as a matter of mind-independent fact, and this is why we do not perceive the future, only the past." However, perception is the only evidence for this uni-directional movement. Philosophers have no compelling rationale for what's called temporal asymetry beyond asserting that this is the way things are. Meanwhile physicists have shown that this apriori statement is not true for all aspects of time: with regard to things very small (quantum mechanics) and very large (relativity) there is no temporal asymetry: time can be demonstrated to flow both forward and back.***

There's another way in which time is difficult to grasp. A group of experiments on the brain reveal that by the we become conscious of making a decision, we have in fact already made it. What we perceive to be happening in one time frame is actually happening in another. As the author of one study of this phenomenon puts it: "Our brains are shaping our decisions long before we become consciously aware of them... Patterns of activity in certain parts of our brain can predict the outcome of a decision seconds before we're even aware that we're making one."****

The first study of this nature was conducted by Benjamin Libet who found that a time lag of only about half a second, but others have shown that the delay between decision and conscious decision-making can be as long as ten seconds.

When I started this piece I thought I would proceed at this point to outline Henri Bergson's concept of duration, but think now that I'll leave that for another time.


Some further reading:



*The Unreality of Time, by John Ellis McTaggart; published in Mind: A Quarterly Review of Psychology and Philosophy (17 (1908): 456-473).

**Quoted in: The Collider, the Particle and a Theory About Fate, by Dennis Overbye, New York Times, published: October 12, 2009. }

***The new theories that are killing time, an article in The Telegraph (UK)

**** Unconscious brain activity shapes our decisions


{I couldn't find images that convey the way we perceive time to flow; this tries; source:}


{Henri Bergson; source: wikipedia}

No comments: