If and when all the laws governing physical phenomena are finally discovered, and all the empirical constants occurring in these laws are finally exp… - George Gamow

It was a bank holiday, and Mr Tompkins, the little clerk of a big city bank, slept late and had a leisurely breakfast. Trying to plan his day, he first thought about going to some afternoon movie and, opening the morning paper, turned to the entertainment page. But none of the films looked attractive to him. He detested all this Hollywood stuff, with infinite romances between popular stars. If only there were at least one film with some real adventure, something unusual and maybe even fantastic about it. But there was none. Unexpectedly, his eye fell on a little notice in the corner of the page. The local university was announcing a series of lectures on the problems of modern physics, and this afternoon's lecture was to be about Einstein's Theory of Relativity. Well, that might be something!

Avanzamos más de prisa o la calle se vuelve más corta: a fin de cuentas, da lo mismo.

Let us now divide the time interval from o to t into a large number of very short time intervals and draw vertical lines as shown in the figure, thus forming a large number of thin tall rectangles.