Dark matter: a topic that matters

An appalling issue for physicists is that there is an ever increasing number of mysteries that we have not been able to solve just yet. One of the topics that keeps us awake at night is dark matter. Today I am going to talk about some of the observations that have led us to theorize about dark matter and the difficulties of measuring it.

Our problems are the following: there are stars orbiting the center of their galaxies faster than it should be possible for them to do. If they were moving at such high velocity, they should, somehow, fly away. But they don’t. Therefore, there must be something offsetting that velocity, and that is where dark matter enters the game. Another strange occurance is the warping of light around a massive body, called gravitational lensing. This is a phenomenon that occurs when a massive celestial body, such as a galaxy cluster, causes a sufficient curvature of spacetime for the path of light around it to be visibly bent, as if by a lens. But there is bending where it is not supposed to be, so there should be some mass curving the spacetime and we just cannot see it. All of these hassles are trying to be explained by the existence of dark matter.

And now, what is dark matter? It is SOMETHING that is in space and fills about 22% of all the universe. To this day, we have not been able to detect dark matter because it does not interact electromagnetically, which means it does not absorb, reflect, or emit electromagnetic radiation. Moreover, it is cold. That means it does not move at velocities comparable to light speed, and it does not interact with ordinary mass, which is everything that the things we know are made of: planets, stars, pizza. These characteristics make it tricky to find ways to measure dark matter.

At this point, scientists had had to get really ingenious to come up with solutions on how to measure dark matter. They have reviewed the standard model, which gives us a list of the most elementary particles in our universe. Sadly, none of them satisfied the required features. Despite these disadvantages, physicists have in hand two methods to try to find it. One, called direct detection, which tries to find the collision between a detector and a particle of dark matter. The other one is indirect detection, which seeks the result of a potential interaction between dark matter particles in our galaxy. There are a lot of “secondary methods” but none of them has yielded results yet. 

So, in conclusion, we know that dark matter must exist, but we “just” do not know what it is made of. Do not panic though, because maybe, and just maybe, this post creates that little spark that could lead you to be the one who will solve the mysteries that lay beneath the concept of dark matter.