On what does our gaze open? It sends back to us the image of a space that unfolds and that invites us to move freely. Is the time, an invisible reality that has taken over all things? And yet, we have the intuition of its presence: the return of the sun, of the moon, each day, the return of the stars, the seasonality. The regularity of the day has allowed the construction of calendars which, in an amazing way, have predicted the return of cyclical phenomena such as Stonehendge or Pömmelte.

Moreover, in the Middle Ages, the day was separated into 2 halves, day and night, each containing 12 parts, so the duration of an hour changed during the seasons.

Galileo, visiting the Cathedral of Pisa, has the intuition of the isochronism of the swing of the candlestick. He studied the pendulum and demonstrated it on small oscillations. This leads to the development of clocks and, miniaturized, to mechanical watches. Today, watches use natural oscillators such as quartz, atomic clocks being only a sophisticated version of this system, since it is enslaved to the frequency of a radiation emitted by the change of electronic state of an atom, for example cesium 133.

In short, time is measured from motion, and in particular from repeated motion. It is not a direct measure of time. The frequency of light is the result of the operation c /?, ie the speed divided by the wavelength, a distance. The movement is characterized by the speed, it is proper to the movement, when we compare 2 movements, we compare their speed. The physicists have a concept about this, the quantity of movement which is the product of the speed and the mass. This concept is used in the infinitely large, it is the impulse. General relativity uses the energy-impulse tensor. It is also used in the infinitely small, and in particular in quantum physics.

If, following Einstein’s idea, we make the hypothesis that the Universe is in perpetual motion, he compared it to a mollusk which does not stop moving all the parts of its body. In the universe, nothing is still, when we do not move, we go at the speed of the earth, 200-250km/s in the Milky Way. We do not feel it because we are in an inertial reference frame. Moreover, everything around us seems to be motionless, except if we take a microscope like Robert Brown, and we will see the incessant agitation of pollen grains.

So, if we deduce a measure of time from motion, and use this measure to calculate the speed of a movement, there is a kind of return to sender, a useless detour. Time would then be justified by the illusion of the immobility of space, which could thus be separated from time and recombined with it to give the measure of a movement.

And then, do we really know how to manipulate time? When we evoke the instant t, what is it? If we measure t from a Euclidean geometry based on real numbers, we come up against an impossibility. A distance of space, we can always make an approximation of it. If one considers locally that space is immobile, one can take the time to improve one’s measuring apparatus to approach the point x as close as possible. But for time t, once it has crossed the present, it is no longer there. The definition we give to time excludes immobility. In reality, we only manipulate durations, i.e. distances related to a movement, this is the basis of the stroboscopic effect. The measurement of time is fundamentally not of the same nature as that of space, which is direct.

Thus, we suddenly understand Heisenberg’s indeterminacy equation. If we measure space, i.e. distance, to obtain the position x of a particle, we cannot at the same time measure its impulse, i.e. its velocity, since, for the first measurement, we have made space immobile.

On the other hand, we also notice that in the equation of General Relativity, time does not appear explicitly, it expresses in any point of the space-time, the equality between the local characteristics of the geometry and the measurement of the impulse energy. This equation manipulates velocities, time is only a geometrical dimension of space-time. After all, if time did not exist, if it were only a dimension of motion, then space-time would be a space of motion, and one would more easily admit the compression of time or space.

I like the idea that time is only an abstraction, that everything is in constant motion, which causes an irreversible energy degradation, entropy, which also affects light whose constant loss of energy pushes it towards the infrared. In the universe, living beings show an exceptional performance to degrade light, they are infrared light emitters.