What is the present? How long does it last? Does it even exist?
It seems to me that what we call the present is just the borderline between the past and the future and what we think of as the present is really the information
out our brain has processed in the past few hundredths of a second, so is really the recent past. Fifty years ago the best time pieces could only divide a second into hundreds. Now we can divide a second into billionths. Every time an atomic clock “ticks”, it is now in the past and the next one is in the future.
So the present is really not measuring time so much as measuring thought. The present is what is in our mind now (unless we are reminiscing about the past or speculating about the future).
In ancient Rome, the god Janus represented gates, doors, borders and the Present. He is depicted as having two faces, one looking back at the past and one looking forward to the future, with essentially nothing between. A perfect depiction of Now!