We know that most of the universe is dark matter, but we have no idea what dark Matter actually is. Well, the latest news is that some University of Oslo physicists have now come up with a mathematical explanation that could solve this mystery. By the way, that picture on the left is of Professor Are Raklev, and it is his mathematical model.
The details are here … but basically the key quote at the heart of their idea is this, “We believe that almost all dark matter is gravitinos. The explanation lies in very hard mathematics. We are developing special models that calculate the consequences of these theories and we predict how the particles can be observed in experiments.“.
Ah OK, so clearly he is in the Supersymmetry camp … (well so am I, I love the concept of Supersymmetry, and yet while it is truly beautiful, it has not yet been proven)
Now, there are two specific words here I want to highlight from that quote, they are … “We believe” … yikes. OK, it is still interesting, but until there is actual evidence, nothing has been confirmed, so digest with some salt please.
Anyway, the University of Oslo has a full writeup that describes it all… what you find below is my abbreviated version of that …
“We are looking for a new member of our particle zoo in order to explain dark matter. We know that it is a very exotic beast. And we have found a plausible explanation,” … Are Raklev is now trying to prove that dark matter consists of gravitinos. …
And just what are gravitinos? Hold tight: gravitinos are the supersymmetric partner of gravitons.
Or, to be even more precise:
“The gravitino is the hypothetical, supersymmetric partner of the hypothetical particle graviton, so it is also impossible to predict a more hypothetical particle than this,”…
Step 1: Supersymmetry
Physicists want to find out whether or not nature is supersymmetric. Supersymmetry means that there is a symmetry between matter and forces. For each type of electron and quark there is a corresponding heavy, supersymmetric partner. The supersymmetric particles were created in the instant after the Big Bang. If some of them have survived to today, they may be what dark matter is made of.
The supersymmetric partner of the gravitino is, as Apollon said, the graviton.
“A graviton is the particle we believe mediates gravitational force, just like a photon, the light particle, mediates electromagnetic force. While gravitons do not weigh anything at all, gravitinos may weigh a great deal. If nature is supersymmetric and gravitons exist, then gravitinos also exist. And vice versa. This is pure mathematics.”
But there is a small but. Physicists cannot demonstrate the relationship between gravitons and gravitinos before they have managed to unify all the forces of nature.
Step 2: The forces of nature
One of the biggest things physicists long to do is to unify all the forces of nature in a single theory. In the middle of the last century physicists discovered that electricity and magnetism were part of the same force of nature. This force has since been called electromagnetism. Two of the other forces of nature are the strong nuclear force and the weak nuclear force. The weak nuclear force can be seen in, among things, radioactivity. The strong nuclear force is ten billion times as strong and binds together neutrons and protons.
In the 1970s, electromagnetism was unified with the strong and weak nuclear forces in what physicists call the standard model.
The fourth force of nature is gravity. Even though it is unbelievably painful to fall down stairs, gravity is the weakest of the four forces of nature.
The problem is that physicists have not yet been able to unify gravity with the three other forces of nature. The day physicists gain a unified understanding of all four forces of nature, they will gain a unique understanding of the world. This will make it possible to describe all imaginable interactions between all possible particles in nature. Physicists call this the ToE Theory (Theory of Everything).
“In order to unify gravitational force with the other three forces of nature we have to understand gravity as quantum theory. This means we need a theory in which the particle graviton is included in the atomic nucleus.”
Researchers are now looking for signs of both supersymmetry and the ToE Theory. Discovering the graviton would be an enormous step in this direction.
He is now asserting that dark matter mostly consists of gravitinos.
“Supersymmetry simplifies everything. If the ToE Theory exists, in other words if it is possible to unify the four forces of nature, gravitinos must exist.”
“We believe that almost all dark matter is gravitinos. The explanation lies in very hard mathematics. We are developing special models that calculate the consequences of these theories and we predict how the particles can be observed in experiments.”
The hype that was used to sell this story by some is clearly wrong (not a surprise). You read stuff like, “physicists have now launched a very hard mathematical explanation that could solve the mystery once and for all.” … well yes, but it also might not solve anything at all.
So the key points are these …
- Here is an interesting mathematical model that just might explain dark matter
- They are now using it to work out some predictions in order to verify if it is wrong or not wrong
- Once they have those predictions, it can then all be tested and proven to not be wrong … or perhaps wrong.
- Until that happens and it is confirmed or falsified, it is simply one of many ideas.
Basically … this is science in action, we have no conclusion yet.