*This article is taken from the journal Les Indispensables de Sciences et Avenir n°209 dated April/June 2022.*

General relativity posits that the curvature that prevails at a point in space-time—think of the deformation of the mattress by the weight of a Petenck ball—is proportional to the density of matter and energy that is there (since by virtue of ) the equation E = mc², matter and energy are two sides of the same thing and *to weigh *So both). So general relativity is roughly written as: “curvature = mass-energy something multiplied by density”.

## A funny article, very short, published by Erwin Schrödinger

In 1917, Albert Einstein revised his theory by introducing the “cosmological constant”. This constant, in his mind, was an intrinsic curvature of space—so it was on the left side of the equation—that would allow him to counteract the gravitational pull exerted by matter and the energy within it. Einstein wrongly expected to obtain the stable and eternal universe that everyone believed in at the time – even though it was soon discovered that the effect of is probably an acceleration over a long period of expansion. Curiously, the following year, one of the fathers of quantum mechanics, Erwin Schrödinger, published a funny article, Very Short, where he explained that we could pass to the other side of the equal sign. An exercise in early arithmetic, but whose importance Einstein immediately understood: initially in favor of effects, passed in favor of causes.

To understand, imagine a piston in a vacuum.

*This article is taken from the journal Les Indispensables de Sciences et Avenir n°209 dated April/June 2022.*

General relativity posits that the curvature that prevails at a point in space-time—think of the deformation of the mattress by the weight of a Petenck ball—is proportional to the density of matter and energy that is there (since by virtue of ) the equation E = mc², matter and energy are two sides of the same thing and *to weigh *So both). So general relativity is roughly written as: “curvature = mass-energy something multiplied by density”.

## A funny article, very short, published by Erwin Schrödinger

In 1917, Albert Einstein revised his theory by introducing the “cosmological constant”. This constant, in his mind, was an intrinsic curvature of space—so it was on the left side of the equation—that would allow him to counteract the gravitational pull exerted by matter and the energy within it. Einstein wrongly expected to obtain the stable and eternal universe that everyone believed in at the time – even though it was soon discovered that the effect of is probably an acceleration over a long period of expansion. Curiously, the following year, one of the fathers of quantum mechanics, Erwin Schrödinger, published a funny article, Very Short, where he explained that we could pass to the other side of the equal sign. An exercise in early arithmetic, but whose importance Einstein immediately understood: initially in favor of effects, passed in favor of causes.

To understand, imagine a piston in a vacuum. If the space is really empty, you can easily slide the piston in either direction as there is no pressure difference between the outside and the inside. *(see picture below)*, On the other hand, if there is some energy in every cubic centimeter of space, then by pulling the piston you increase the volume inside, so it has energy, which means you must *to work *To give it this energy: you are fighting against a “suction” effect inside the piston, a negative pressure. if the density * *Vacuum energy is constant, this effort is equal to the vacuum energy introduced into the piston and you are fighting against pressure *P *equal to the inverse of the density , This is the vacuum energy equation of state: *P *, *-D*,

**if the space is empty**, a piston slides smoothly (left). If it has energy, then counter energy must be supplied to pull the piston. (Bruno Bourgeois for Science and the Future)

* “Biggest Mistake” [sa] life”*

However, according to general relativity, energy including compression, weight and pressure contribute to weight. To be precise, the gravity produced by a region of space where density d and pressure is *P * Equal * *+ 3 *P*, For constant vacuum energy, this gives the gravitational equivalent of –*2D *, a negative gravity: a… repulsion! Schrödinger therefore explained briefly: instead of viewing as an internal curvature that prevents the universe from collapsing, it can be thought of as the internal energy density of a vacuum, whose pressure is negative and therefore a repulsive gravity. uses. Einstein agreed, but *“It is only of interest if we imagine a factor that can evolve over time”, *He replied. In other words, if instead of imagining an internal energy-rich vacuum, one would assume that it is bathed in matter likely to vary in space and time. However, he rejected the idea prematurely, as it led *“To venture very deeply into the depths of theory”*, The multitude of current models aimed at explaining dark energy attest to the relevance of the comment!

The mathematical demonstration that the universe could not balance, then the discovery that it was indeed expanding, prompted Einstein to drop the cosmological constant and qualify it as *“Biggest Mistake” [sa] life”*, All this history has been forgotten. Yet, more than a century ago, two of history’s greatest physicists had already set the terms of the current debate. And it seems Einstein’s biggest mistake was not realizing how right he was, once again…

*by René Coulier*

Analyst. Amateur problem solver. Wannabe internet expert. Coffee geek. Tv guru. Award-winning communicator. Food nerd.