13 - What produces the flow of time and why in a single direction only?

Summary

Contemporary science has uncovered the relation between time and physical processes, making it possible to ‘grope’ for the first links of the time chain in the past and to project its properties to the distant future.

But what does modern science say about why time flows at all, and why only from the past to the future? I should immediately say that experts still lack an exhaustive, clear and generally accepted answer to this question. Nevertheless, a great deal has been achieved in this field, too, and we will have a quick look at some fragments of the achievement of the science of time.

In the post-Newtonian era, physicists have always emphasized a surprising property of the laws of nature: they do not in any way single out the direction of time flow from the past to the future.

We easily recognize this fact by looking at the simplest problems in mechanics. For example, let a ball roll along a surface, hit a wall at a certain angle, rebound and continue rolling. Now we can, in our minds, reverse the direction of time and imagine the ball rolling in the opposite direction, going through all the points of its trajectory in the opposite order. It is as if we had filmed the experiment and then projected the film beginning with the last frame. All laws of mechanics describe the motion of the ball equally well both in the forward and the reversed directions of time flow.