Looking at What Dark Matter Does Within the Universe Can Provides Clues to What Dark Matter Might Be.
INTRODUCTION
This is the fifth paper in a dark matter series.
What is dark matter? This is one of the biggest questions plaguing physicists today. What is known about dark matter, not very much. Here is the list;
Dark matter makes up about 85% of the matter in our universe and about 27% of the total energy as compared to normal matter which makes up 15% of the matter and about 5% of the total energy.
- Dark matter only interacts with normal matter via some form of gravity or gravity like force.
- Dark matter does not interact within any normal matter via electromagnetic interactions, or any other interactions other than gravity.
This is pretty much all that can really be said about dark matter.
Despite the limited knowledge about dark matter multiple experiments and papers have been written about what dark matter might be. The current general consensus in the modern physics community is that dark matter is most likely some kind of exotic particle. Over the last 30 years numerous experiments have been run to try and detect a dark matter particle, so far all have failed.
Maybe if today’s physicists took a step back and looked at what it is dark matter does in our universe, and how it does what it does maybe there would be more progress toward understanding what dark matter is.
Looking at how dark matter interacts within the universe is what this paper is discussing.
DISCUSSION
The most important characteristic of how dark matter interacts with the universe is the hypothesis set out in the very first paper of this series, Dark Matter; A Galactic Dyson Sphere. The hypothesis is that the dark matter halo around galaxies protects the stable galactic space of the galaxy within the halo from the expanding space of the universe outside of the dark matter halo. This is a critical characteristic for dark matter because if the dark matter halo were not in place, the space within galaxies would not be stable. That is, once exposed to the expanding space of the universe, the space within galaxies would also expand and this expanding galactic space would adversely effect star and galaxy formation throughout the universe.
Beside keeping galactic space stable, the dark matter halo around galaxies also helps to maintain the stability of the matter within that dark matter halo. That is, the dark matter halo allows for the surrounded normal matter to clump and form the stars of the galaxy. The dark matter halo also gravitationally interacts with the embedded normal matter creating the stable galactic and stellar motion seen in galaxies throughout the universe today.
Having just briefly covered the interaction between dark matter and normal matter in the universe, the next questions is how does dark matter interact with the universe?
It is known that the universe is expanding and has been expanding since the beginning, the big bang. If there were no dark matter present to help initiate the clumping of normal matter it is unlikely that the first stars and galaxies would have formed. Specifically, it was covered above how dark matter is necessary for the formation of stars and galaxies, and for maintaining the stability and motions of galaxies, stars and planets. Without dark matter present in the beginning, normal matter would be expanding with the space of the universe. If any clumping of normal matter could have occurred and started to form stars and galaxies, the space of the universe would be expanding in and around these first proto-stars and galaxies. Ultimately the expanding space of the universe would cause any possible galaxies and solar systems to crumble and the galactic dust and matter would spread out and not be able to clump and form new galaxies stars and solar systems.
The only possible conclusion that can be reached, given the current structure and function of our universe, is that dark matter has been around since the big bang. Additionally, it has been providing stable space for galaxies, stars and planets to form. Now the question is how does dark matter and normal matter interact with the expanding universe?
Looking a normal matter first, the evolution of our universe as we know it today shows that normal matter had very little interaction with the expanding universe. Normal matter simply expanding along with the space of the universe. What normal matter did do was interacted with the stable space provided by dark matter and dark matter in turn interacted with the universe. Current astronomical observations show that for the most part the galaxies of the universe are moving, or expanding, away from each other. In other words, as the space of the universe expands it is pulling the galaxies of the universe along with it. More precisely, the expanding universe is pulling the dark matter halos of the universe along with it as it expands. The normal matter galaxies, stars and planets are simply along for the ride within the dark matter halo.
When looking at galaxies moving away from each other with the expansion of the universe space, the question becomes how are all of the dark matter enclosed galaxies moving? There are three general possibilities for this, the first is that the dark matter halo surrounding galaxies is actually part of the expanding space of the universe. That is, just as normal matter is embedded in dark matter halos, the dark matter halos holding the galaxies is embedded in the expanding space of the universe.
Another possibility is that the dark matter halo and its embedded galaxy is simply floating in the expanding space of the universe. The third possibility is that the dark matter halo and its embedded galaxy is kind of sticking to the expanding space of the universe. Sticking can best be thought of as something in-between floating and embedded.
Of the three possibility above, the simplest option, and the most likely option, is embedded. The dark matter halo is actually embedded in the expanding space of the universe. An embedded dark matter halo is most consistent with the expansion of the universe in both the beginning of the universe, and the current state of the universe. There is also the issue of Ultra Diffuse Galaxies. Specifically, Ultra Diffuse Galaxies have far fewer stars than out Milky Way Galaxy, but these galaxies are the size of our Milky Way Galaxy. Ultra Diffuse Galaxies also do not have a dark matter halo. This exposes the stars of the Ultra Diffuse Galaxy to the expanding space of the universe thus spreading out stars of the galaxy. Having the stars of the Ultra Diffuse Galaxy actually embedded in the expanding space of the universe is the most direct way to account for their dispersion of the Ultra Diffuse Galaxy stars after the loss of its dark matter halo.
As for the floating option, it is analogous to a piece of wood floating along the surface of a river. Dark matter halos are not part of the space of the universe, rather they sit in/on the space of the universe and simply move along at their pace. The issue with floating is that there is a high probability that not all dark matter halos and their embedded galaxies would move at the same rate. This doesn’t match with what is currently observed in the universe regarding galaxies all moving away from each other in a consistent manner.
As for sticky dark matter halos and their embedded galaxies, they too have the issue of moving at inconsistent speeds making this an unlikely relationship between dark matter halos and the movement of the universe space also.
THINKING OUTSIDE OF THE BOX
What if dark energy is actually a force that works on dark matter? If the dark matter halos are embedded in the universe space, then as the galaxies get pushed and/or pulled along by the dark energy, the the dark matter halo enclosed galaxies would pull the universe space with along with them. Additionally, recall that 85% of the total mass of the universe is dark matter. And, current theory is that there are dark matter filaments spread throughout the universe space. There is also the possibly up to 50% of normal matter spread out throughout the universe space known as the WHIM1.
The above is a unique hypothesis. It is known that the universe is expanding and the current belief is that the rate of expansion is increasing. The accelerating rate of the expansion of the universe space is currently hypothesized to be caused by dark energy. Like dark matter, nothing is currently known or understood about dark energy. So, with dark energy interacting with the dark matter galactic halos, dark matter web through out the galaxy, and dark matter interacting with the WHIM, this would result in an even expansion of the universe space. This is consistent with current observations.
It is clear that this hypothesis currently cannot be proven or tested. However, it also cannot be disproven. It is simply a “start” toward critically thinking about what is seen and known about our universe and to come up with some thought or idea as to how things in the universe might work. Maybe this dark energy and dark matter interaction will be the basis of some other theory, or the stimulation of thought about how the current unknowns in our universe might work.
CONCLUSIONS
The time line of the universe with respect to dark matter and normal matter goes something like this. Dark matter and normal matter are both formed at the beginning of the universe. The amount of dark matter is over 5 times greater than the amount of normal matter. Dark matter makes up about 85% of the total matter in the early universe while normal matter makes up the remaining 15%. And, the space of the early universe is expanding all around thus causing both dark matter and normal matter to spreading out in the universe space.
Normal matter interacts with dark matter. Normal matter starts to combine with dark matter carving out a stable space for the normal matter where it ultimately starts to clump together. However, the space of the universe is still expanding and it is spreading the dark matter out in the expanding space. That is, the dark matter is moving with the expanding space of the universe. And, the dark matter is bringing the normal matter within its protected space along for the ride.
This is the process of the early universe ultimately resulting the expanding universe that we see today. Enough normal matter was able to combine with dark matter to create the universe we see today, and to create the universe that is still waiting to be discovered and understood.
Written by
Steve Guderian
1 https://en.wikipedia.org/wiki/Warm%E2%80%93hot_intergalactic_medium
