Actually it is not completely new what I am going to write now, for I have written about it before: the relation between time and distance (see my blog dated August 18, 2008). However, it is already more than five years ago that I did, and I think that I have something new to add. At least, it is new to me.
Time has always been an intriguing phenomenon for many people, and so it has be for me, too. What is time? Does it really exist as such? Henri Bergson discovered that all words referring to time are borrowed from spatial language. Hannah Arendt went one step further and said: “[W]e can measure time only by measuring spatial distances.” (The life of the mind, Two p. 13) This is also my experience. When I am running in the wood behind my house or when I am making a bike tour, I estimate the time elapsed not by an independent kind of judgement or feeling, but I look where I am and I estimate the distance I have run or cycled and by doing so I guess the time that has gone by since I left home. It’s impossible to tell how much time have passed without using distance as a measure. All other ways to measure time work basically in the same way, for instance when I look at the sun and guess how much its position has changed since I left. (I can use my watch, too, of course, but more about this at the end.)
When I am training on my bike trainer at home I have the same kind of experience. Already after a few minutes of cycling I have lost any feeling for time. There are several solutions for this problem. I can put a clock in front of me, but then I have the problem that soon my workout becomes boring. This doesn’t happen when I am cycling outdoors on the road or when I am running outdoors. Then I become tired in the end but never bored. So, I watch TV and I make workout schedules. This getting bored on a bike trainer is an instance of a general phenomenon: Your feeling for time becomes lost when you have no other points of reference. An extreme case in point is a prisoner in a cell: If he lacks a daily rhythm and cannot make one for himself, he loses any sense of time.
It is often said that space and time are basic points of reference in nature. Also in physics, time is considered as one of the fundamental quantities, next to, for instance, length (distance), mass and charge. But is it correct? Experiences and phenomena of the kind just discussed have made that I have doubts about the fundamentalness of time in nature and so also in physics. For how do we formally measure time? Since time immemorial two ways have been used. One is the return of the seasons, which is nothing else but the rotation of the earth around the sun. Therefore later the succession of seasons has actually been replaced by using the length of one turn of the earth around the sun as a way to measure the length of a year. The other way of measuring time is taking one turn of the earth around its own axe as a reference. So we get the length of a day (and derivatively the length of an hour, minute and second). But in each case in fact the measure of time is nothing else but the distance covered by a certain piece of mass, and a basic unit of time is nothing else but the period a certain piece of mass uses to return to the same place. This doesn’t look very fundamental. Also the way time is measured in physics today is actually nothing but the relocation of something else (see note). It is not taken as it is, like distance, which is, as said, generally used for determining a unity of time. The upshot is, there is no such a thing as the fundamentality of time. Time can only be conceived in a derived way. If that is true, the idea of time is practical but not necessary.
And a watch? It is merely a handy device that translates distance into time.
Note. For the insiders: A second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.