The Universe might be a Perfect Fluid

As always, where to begin the discussion is difficult so we shall simply begin with the following statement;

Boson stars consist of four neutron stars conjoined in the same configuration as helium nuclei, and as giant or macroscopic bosons, these ‘Boson Stars’ in fact form the bulk of the missing or dark matter of our universe.

If that sentence at first seems a bit bland, the equivalent mathematical ‘sentence’
(a description physicists call an equation of state), is even more so.

w = 0

In cosmology, the equation of state refers to a property of materials which fall into a class termed ‘perfect fluids’, the properties of which are completely specified by giving its density and its pressure, and the equation of state gives the relation between density and pressure.
This relation is indicated by the symbol w, defined by w = pressure divided by the density times the speed of light squared.
The equation of state is crucial to understanding how a material will behave as the Universe expands and also governs the way in which the Universe will expand if dominated by a fluid of that equation of state.

The simplest case is w = 0, corresponding to no pressure, and refers to material where no forces are acting other than gravity and motion is non-relativistic (slower than the speed of light).
These could be fundamental particles or the ‘fluid’ in question could be made up of individual stars or even galaxies, neither of which have significant non-gravitational interactions.
The other important case is w = 1/3, which represents radiation, or more generally the fluid made from any relativistic particles.
A Universe dominated by radiation decelerates more strongly as it expands.
Not all types of material possess a unique equation of state, which requires there to be a unique pressure associated with any particular density.

Notwithstanding the fact that one of the most common modern usages of the term equation of state refers to dark energy, and indeed often the symbol w is used specifically to mean the (effective) equation of state of dark energy where w = -1, this paper does not discuss dark energy.

All fundamental particles in the Universe are divided into two classes, known as bosons and fermions.
Whether particles are bosons or fermions determines how they behave quantum mechanically. Bosons behave as indistinguishable particles, meaning that if the locations, velocities etc. of two particles are swapped, their quantum state is unchanged.
You cannot tell which particle is which. This is known as Bose-Einstein statistics, from which the term ‘bosons’ derives. Fermions, by contrast, are distinguishable particles.
Bosons are a candidate to be the dark matter in the Universe, and have even been postulated to condense into stellar-like objects known as ‘boson stars’.
While all known types of star, including white dwarfs and neutron stars, are made of fermions, there has been speculation about whether it is possible to form stellar-like objects from bosonic particles.
The most interesting possibility would be to construct stars from dark matter, although we do not know what dark matter is. The favoured assumption is that dark matter is made of fundamental particles, and given that it seems as likely as not that those particles might be bosons.

The properties of boson stars can be studied using a similar set of stellar structure equations to those used for more conventional stars; in particular the equations are quite similar to those describing neutron stars, and they result in similar properties.
Boson stars would be highly dense, and like neutron stars possess a maximum mass beyond which they are believed to collapse into black holes.
A related idea is that dark matter in galaxies could be in the form of giant halos of bosun stars and that the galaxies are embedded within those ‘halos’.

Just as helium nuclei (alpha particles) are bosons, four neutron stars in the same configuration as the two protons and two neutrons of the helium nucleus can form a boson star that resembles an alpha particle.
Four neutron stars stuck together like this would share similar properties with the helium nuclei, bur the most staggering similarity of all is that they will be bosons!

Like helium, they will be inert and will not want to react with other objects or matter.
They will have the properties of a superfluid, which opens up all kinds of possibilities for cosmology. The most striking of which is that as far as these dark matter boson stars are concerned, we can now describe dark matter by a single equation of state,
and that equation of state appears to be w = 0!

Giant elliptical galaxies are in fact comprised of trillions of these neutron star bosons and are much larger than the visible part of the elliptical galaxies.
Because they are bosons, collisions between these boson stars will cause waves that destructively interfere and will cancel one another out.
Toward the center of these dark matter galaxies, the density of the dispersion of the boson stars will increase, until they are nearly on top of one another near the center.
In this volume of higher density, collisions will be more frequent, and although the waves cancel each other, there will be an occasional break up of these boson stars as one or more neutron stars are dislodged in the collision.

The implication here is crucial, because when these four neutron star bosons break up they instantly stop behaving as bosons! The fragmented neutron stars and their components now suddenly behave as fermions!
The key point to remember here is that these separated neutron stars (the debris of the collisions of the boson stars) will no longer be excluded from Pauli’s principle.
Only a few percent, say four, of these boson stars within any galaxy will undergo this transformation due to collisions from bosons to fermions. That 4% will become what we perceive as our visible Universe, but the giant elliptical (spherical) galaxies in which they are embedded will forever remain invisible to our detection using any form of the electromagnetic spectrum to do so.

Physicists are in fact correct when they state that the so-called dark matter is probably non baryonic, meaning it is not made of ordinary matter.
This is because these four neutron star bosons will remain in this form for eternity, unless they collide with one another, and even then only four percent of the time will such collisions dislodge a neutron star.

So our Universe would appear to have three primary cases for equations of state, and in descending order of dominance, they are w = -1, w = 0 and w = 1/3.
Together they describe our Universe as a whole. The first one describes dark energy when using a cosmological constant. The second one describes a Universe composed of a single substance, in this case boson stars of dark matter that have the potential to change into fermions as soon as their shape is disrupted. The third case is of course, radiation, and includes all radiation in existence, caused by interactions with the fermions that make up the 4% of matter observed in the Universe.

W = 0 defines the invisible (and radio silent) giant elliptical galaxies as a whole and
w = 1/3 defines that central fraction of the dark matter boson star galaxy where collisions take place that lead to the implementation of the second law of thermodynamics for that fraction of boson stars which have disintegrated into fermions.
The single, double and triple neutron stars that make up the four percent of debris will go on to become single, double and triple bright stars as their composition and position in space-time empowers them to become obvious candidates to facilitate such a manifestation.

In conclusion, it is important to remember that a neutron star has the correct composition to become once again an ordinary star like our sun, as long as its neutrons can be released they will become what are known as free neutrons.
So, in effect, those 4% of fermions that make up all ordinary matter have the ability to run the entire cycle of the second law of thermodynamics and end up again as neutron stars, which can in turn transform into ordinary stars that convert hydrogen into helium, while changing a small amount of their mass into energy we perceive as photons as well as account for all the gas and dust in the Universe.

All that we observe in our Universe is merely the debris near the cores of galaxies that are much larger than the parts we do observe.