about three days ago I was asked by the writer of “Oopsmymistake” to update about dark matter, so today I decided to write something more about it, here you go.
Last time I talked about dark matter as stuff that fills about 25% of all matter in whole Universe but we can not feel it and the only way to observe it is by its gravitational effect, for example it is extremely important in whole galaxies.
Now there are some things that I did not mention because actually there are more things that we can deduce from its behavior.
As I said, it is assumed that dark matter is composed of new kind of particle/s beyond standard model.
Lets assume that this is right, now this particle does not react much as we know, it has to be electrically neutral, otherwise it would react through electromagnetism and we would be able to observe the photons which would come out of the interaction.
Also dark matter still exists which means that it has to have half life at least the age of Universe (top and bottom quarks for example do not form anything because simply they are not here, they have too small half life).
We know that it does not interact much, otherwise it would concentrate in the middle of galaxies and not all around. So dark matter can not interact via strong nuclear force.
Now this kind of hypothetical particle is called WIMP – Weekly Interacting Massive Particle.
It is assumed that the mass of such WIMP is about 10-1,000 GeV which is roughly around Higgs boson and other bosons like W and Z.
The amount of WIMPs with such a energy almost perfectly corresponds to the real amount of dark matter. Also model of super-symmetry predicts such particle with the properties we know now. It is definitely more complicated but it is called the WIMP miracle, while it could be just coincidence.
Scientists think that with this model WIMPs should interact with Higgs boson which would create something we call: “The Higgs portal” because Higgs boson would be the particle through which we would be able to observe whole dark universe (the portal between standard model and dark matter).
Of course particle physicists designed special detectors to detect WIMPs. There are two main way to do that, first is cryogenic, which is the detection of heat made by WIMP interacting with some super cooled element and the second one is to measure flash of light during interaction of WIMP and liquid xenon or argon. Such detectors are buried deep under Earth so that normal radiation does not disturb it.
Approximately in the volume of cup of coffee is always one WIMP and it is assumed that they travel at the speed of hundreds of kilometers per second, which means billions of them whizzing through you every second. Also about 10 interactions of WIMPs happen every year with atoms in your body (this is kind of similar to neutrinos).
PS: if you did not understand some terms I will mention them in next posts: Standard Model, Higgs boson and so on..