How long is the present moment?

The only moment that you can truly experience is the present, or NOW. You can't live in the past, you can only remember it, and you can do it only NOW. You can't live in the future, you can only plan for it, and you can do so only NOW. The present, or NOW, is the amount of time that can use information accumulated in the past or plan for the future.

Practically, the only time in which you can truly actively do something is NOW. Philosophically, it is often said that it is truly important to enjoy NOW, and make the most out of it, experience the present, grasp the moment. The poet and philosopher Horace expressed this concept in a Latin poem with the phrase “Carpe Diem”, or seize the day.

This is all good, and I do agree with that statement; entire books have been dedicated to this subject. A popular one is “The power of now”.

One question that I have been dwelling with is: “how long is the perceivable NOW”? If you think of time in mathematical terms, NOW is an infinitesimal length of time. It is similar to a mathematical point, which is more of a concept than a physical and humanly perceivable reality. A mathematical point doesn’t have a physical size and doesn’t have a physical shape. It’s simply a concept, with no physical counterpart. It is a simplification. An ideal.

Think about a visible line. A physically visible line is composed by an infinite number of theoretical mathematical points. Similarly you can think of a perceivable length of time as composed by an infinite number of theoretical and infinitesimal points in time, or NOW moments.

I wondered how long is a "more useful NOW”, that is, I wonder how long is the smallest stretch of time that one can truly dwell in.

Going back to the analogy with a line, my question is similar to asking: how long is the shortest visible line? How big is the smallest visible detail of a picture? How far apart must two visible lines be to be perceives as two separate lines? What is the smallest pixel of a hypothetical display, to be able to represent the smallest perceivable detail of an image?

Concentrating on the question about the pixel, I am assuming that there is a certain critical size of pixel. If you made pixels any smaller than that critical size, the human eye wouldn’t be able to perceive any additional detail. This would make any pixel size smaller than the critical size simply not useful for better representation of an image as perceivable by the human eye. That critical size exists, and has been measured, and it depends on the distance from the eye to the observed image. That critical size is accurately (and absolutely) expressed as an angle; for purpose of discussion, and to give you a simpler example to grasp, if you are looking at a monitor from 20 inches distance, the critical size of a pixel is 1/530” (Source:

Going back to the concept of time, here is some interesting research information about human perception of time:

How long does the ‘present moment’ last? In the case of humans, it has been found that sound pulses separated by more than 3 seconds can no longer be grouped into pairs because they fall outside the span of attention. This represents the maximum interval of time that is simultaneously present for subjective evaluation – a kind of attention span bridging past and future events.
How finely can we divide our little 3-second lives? The shortest perceivable time division – sensory psychologists call it the fusion threshold – is between 2 and 30 milliseconds (ms) depending on sensory modality. Two sounds seem to fuse into one acoustic sensation if they are separated by less than 2 to 5 milliseconds. Two successive touches merge if they occur within about 10 milliseconds of one another, while flashes of light blur together if they are separated by less than about 20 to 30 milliseconds. [Source: Nick Herbert, Elemental Mind, Dutton, 1993].
The conclusion is that the critical length of perceivable time is represented by the fusion threshold, that is between 2 and 30 ms. The span of time that you truly live in the present moment is about 3 seconds, and is somewhat of the bridge between present and future. More phylosophically one could say that we slide through life on a 3 seconds surfboard, which carry us across all moments of our lifetime. Your existence is all concentrated in these 3 seconds; anything else is either a memory or a plan.

Something to think about…