Terrence asked:

What is the smallest point in time if such a thing exist? Or Is time infinitely divisible dose time have a frame (an instant or event that is truly distinct) or is all of time continuous? or is time an illusion that is just a property of matter and only exists with the realm of this existence?

Karan asked:

What is ‘real time’ or time according to philosophy? Is it a dimension or is it a continuous ‘fabric’ of the universe with all events ordered in it without any classification as ‘past’, ‘present’ or the ‘future’? Or is the relative concept of time the only reality?

Answer by Jürgen Lawrenz

If you put the various prejudices about the objective existence of time aside the answer is very simple.

Time is what living creatures experience as the periodicity of natural phenomena.

We do not experience time as itself. Time for us is the impression conveyed by cyclic events like the daily sunrise and sunset, the way we articulate our days into activities, then also the lunar and solar cycles and the seasons.

Accordingly the smallest possible increment of time depends on the perceptions of which any creature is capable. The time experience of a fly will accordingly differ from that of a human being. For example there are one-day flies who cram the experience of a lifetime into one day. Therefore the sensation that they might have of one second would be a very much longer sensation than for you.

But you may now object that we human sense time as a continuum. It is not a problematic difference when you allow for the fact that human perceptions are more subtle than those of flies. But to illustrate this, let me point out to you that an old-fashioned movie on a strip of film holds a long series of stills. Plainly there is no time in each of the stills. But when the projector moves the film at the rate of 24 frames per second, you receive the impression of ‘time flowing’ because of the smooth motions of the scenes. Behind this technique is the simple realisation that a human eye working in consort with the mind connects these frames. The smoothness is a sort of ‘illusion’, because you already know that the motion depicted by the film is a cheat. But the point is that real life experience is not much different. Our nerves are living fibres; they cannot take up a continuous impingement of the radiant energy of light. Each takes up a certain quantity and then needs a rest period. So they work as a team, overlapping their sensations, and then leave it to the mind to stitch these impressions together.

Strictly speaking, therefore, the answer to your first question is: The shortest point in time for us humans is the gap between the frames of a film. I’m sure it has been measured, probably in terms of milliseconds. But whatever the number happens to be (which doesn’t tell you much anyway), this interval is the shortest that is meaningful to human beings. But a different, smaller number would apply to fleas. Indeed science works with an altogether different spectrum of times – physics in increments too small for any human to conceive of them, and astronomy with increments too large.

But the point in each of these examples is that time does not exist independently. Time for you, for flies, for physicists and for astronomers is in each case the intelligible uptake of the motion of objects and processes. We simply select from among them a handful to serve us as a standard. A day is an idealised stretch of time between two sunrises. You know this varies every day, yet we measure our hours, minutes and seconds by this phantom length. Similarly a second is standardised arbitrarily physicists who have determined on our behalf that 900 billion vibrations of a caesium atom is equivalent to one second. But this is a simple circular argument, as you will surely perceive.

In a word: There is no shortest point in time, the question has no object. Every answer must ineluctably refer to some object or process in motion that is being observed. Those observation facilitate an arbitrary incrementation of ‘time’. Accordingly every answer to such a question is necessarily also arbitrary.