2023-12-18-editorial
February 18, 2023.
Why cosmology, astrophysics, and theoretical physics have been stuck for 50 years.
The "current standard model" only works thanks to two ingredients: dark matter and dark energy. Dark matter, with positive mass, serves to ensure the confinement of galaxies and galaxy clusters, to explain the flat shape of their rotation curves, in a completely ad hoc way. Indeed, how is its distribution in space determined? Simply by making it reproduce these rotation curves. Millions have been spent everywhere to try to capture it, in mines, tunnels, in space. Thousands of articles have been published in these top-level journals, which are nothing more than speculations on its nature. In vain. They tried to capture the candidate considered most likely, the neutralino, in a kilogram of xenon, then ten, then a hundred, then a ton, several tons.
No more neutralino than butter in a brook.
The dark energy has been assigned a positive energy value and a negative pressure, which may seem paradoxical given that pressure (scalar) is above all an energy density. The law of the expansion of the universe is derived from a solution of the Einstein field equation. The "source" of this dynamics is found in the second member. It is an energy density rho c^2. Therefore, there are two terms. First, the one translating the action of mass, according to the famous Einstein equation E = mc^2. The other term is the pressure. All of this is homogeneous, measured in joules per cubic meter.
What does this second term account for? In the matter phase, it is the volumetric energy density of the kinetic energy of the masses composing the universe, according to the equation of state:
In the radiation era, in addition to the volumetric energy density of photons: h nu, multiplied by the number of photons per cubic meter, we have the radiation pressure, corresponding to the following relation, equivalent to "a photon gas equation of state":
According to the Einstein equation, the basis of General Relativity:
A positive pressure is synonymous with deceleration of the expansion movement.
On the contrary, to account for a movement of acceleration of the cosmological expansion, it is necessary to have something associated with a negative pressure.
If we consider that this pressure related to dark energy is a volumetric energy density, it would lead to conclude the existence of negative energy states (see the works of Nathalie Debergh).
But they are discarded, by a sleight of hand, by giving this new component, of unknown nature, an "equation of state":
The choice w = -1 (which is not justified by anything) allows to obtain an equivalent volumetric density, in kilograms per cubic meter, positive. This then allows to complete the pie chart describing the content of the universe in observed masses, unobserved, positive, that of dark matter, and then in "equivalent-matter", translating (in kilograms per cubic meter) a mysterious repulsive power of the vacuum, associated with the cosmological constant Lambda.
In the: the Janus model, what causes the acceleration of the cosmological expansion is interpreted as the sum of two terms:
-
The energy density (negative) associated with mass, according to E = m c^2, with E and m negative.
-
A negative pressure, considered as a negative energy density associated with the negative kinetic energy of these same particles.
There is then a fundamental difference between these two interpretations. Since the cosmological constant is, as its name indicates, invariant over time, it corresponds to a mysterious repulsive power of the vacuum which is then associated with a constant energy density, insensitive to the expansion movement and the decrease in density, linked to the expansion. If a is the "scale factor", evoking the "size of the universe", any density of something will vary, in principle, as 1/a^3.
The consequence is that the universe, thus propelled by the constant negative pressure, associated with the hypothetical "vacuum energy", then expands according to an exponential law as a function of time.
In the Janus model in the matter era, the dynamics of the expansion is attributed to the dominant content in negative mass: This negative mass then takes on two roles: that played by dark matter and that played by dark energy. This energy density then decreases as 1/(a^3). The future of the universe is then different. Deprived of this engine over time, its expansion then becomes quasi-linear, tending towards an asymptote.
These two ways of seeing things deserve to be put in perspective. We had composed an article, very structured, first sent to Physical Review D in November 2022. Immediate rejection, without submission to referee, with the only mention "not suitable" ("not appropriate"). Second submission, to Astrophysical Journal. Same thing, on February 12, 2023, with also a refusal to submit to a referee. You will read the contents of these response messages preceding the article.
**English version. **
*In fact, the journals systematically refuse to submit our articles to referees, for five years. There have therefore been about ten rejections. *
This marks a fundamental malfunction of the scientific publication system. Yet, they remain open to speculation. We can cite two examples. For Physical Review D, we can mention an article where this figure of French cosmology, Aurélien Barrau (note the remarkable richness of his Wikipedia page) is a co-signatory
[On Physical Review D, 2019](article Barrau)
What do the authors of the article propose? A model where dark matter could constitute the "relic" of collisions between "mini-black holes", located "at the Planck time", that is, in the most distant state of the universe (inaccessible to any observation). Hypothetical "mini-black holes". Let's translate the title:
- **Dark matter as a relic of the Planck era, without too many exotic assumptions **(...). *
Suggested tests, with regard to possible observational data: nothing. A perfect illustration of the sentence by the mathematician Jean-Marie Souriau:
- A physics without experience and a mathematics without rigor.
Regarding dark energy, the scientific community has been in an uproar since the publication in Astrophysical Journal and Astrophysical Letters of two articles.
The first.** The second. ****A scientific blogger gives his comment here**.
To simplify, on the blogger's page, listen to his voice comment.
What is it about?
We saw that the property of this dark energy is to present itself as a component of constant volumetric density, insensitive to the phenomenon of cosmological expansion. Consider...