The actor known for portraying Capt. Benjamin Franklin “Hawkeye” Pierce on the TV show “MASH” and more recent guest shots on NBC’s “30 Rock” is also a visiting professor at New York’s Stony Brook University school of journalism and a founder of the school’s Center for Communicating Science.
The center is sponsoring an international contest for scientists asking them to explain in terms a sixth-grader could understand: “What is time?”
This is the followup to last years so-called “flame challenge”, in which he solicited explanations about what a flame is. But there’s a problem: in asking “what is a flame?” the real question is about what is going on in the process of combustion — it’s an analysis of a physical process, and people were asked to explain that. The winner did an excellent job, though Feynman’s pretty good, too.
However, asking “What is time?” is a different beast. I’m guessing they won’t be satisfied with the stock answers of “time is what is measured by a clock” or “time is what keeps everything from happening at once”. However, unlike fire, time isn’t a process that can be broken down into simpler parts, at least as far as we currently know — it’s much more fundamental than that. (It might be an emergent phenomenon, but we haven’t sussed that out to the point where anyone can offer anything as a reasonable answer.) Which puts the question squarely in the realm of philosophy — metaphysics — rather than science.
As I see it, the problem is similar to this: Take a word and try and define it, using only words that are already defined. You can’t. For each word you use in a definition, you need to define that word, and in each definition, you need to define all those words. You end up with circular definitions, so you have to rely on a collection of words that we simply accept because we inherently know what they mean or we give examples rather than a definition. (This is vaguely reminiscent of Gödel’s Incompleteness Theorem — that within a mathematical theory there will be certain arithmetic truths which cannot be proven. Perhaps there is a formal analogue for languages, which would be beyond my experience.) We have some concepts in physics which are fundamental, and it limits what we can do, explanation-wise. We can describe how time behaves and how we can measure it, and use it as a basis of explaining other things, but not what time is.
There is another answer, though it’s still consistent with the thread’s title. Time is a bookkeeping convenience, like other concepts we have (such as momentum and energy). We notice that it has a certain predictable behavior and that it’s useful, so we exploit those properties. In this case, that events happen in a certain order. It matters, for instance, if a piano drops out of the sky and onto a location where you have been standing, if you are there (or somewhere else) when the piano hits. You can be where the piano hit, you can be at home, you can be at the store, you can be at work or school, but all of those are not simultaneously true — there is some orthogonal coordinate that can keep those separate and helps us keep track of what’s going on. Meaning that time helps us solve kinematics problems and other problems in physics.
This is not an argument that time is illusory — it’s real, as far as I’m concerned, but it’s conceptual rather than physical. Which puts it in the same category as momentum and energy and even length. Funny thing, though, is people generally don’t as the same kind of deep question, “What is length?” They can see it, rather than have some other perception, and that seems to be enough, just like the foundational words that make up a language that can’t truly be defined.
Maybe I’m wrong. Perhaps someone out there will rise to the challenge and really be able to explain what time is. But if they can’t, I won’t be disappointed.