Hi, this is Wayne again with a topic “The dark matter mystery”.
Kerstin PEREZ So dark matter is matter that is creating gravity in the universe, but is not absorbing or reflecting light.. So I need to break that apart. A little bit.. So, first of all, what’s gravity In essence: gravity is what holds the universe. Together.
Gravity holds us down on the Earth, holds the Earth in orbit around the sun, and it holds the sun and other stars orbiting around in galaxies.. The second part of that is what is matter Probably somewhere back in elementary or middle school science class. We learned that everything on Earth is made up of atoms and molecules and that atoms are made up of nuclei that are being orbited by electrons. As particle physicists.
We know that that’s not. Quite all. There is to matter in the universe.. For example, we know that the electron has some heavier cousins, the muon and the tau.. We know that the electron, the muon and the tau have these very light. Cousins called the neutrinos., And we know that nuclei are in fact made up of constituent particles called quarks.. So for a particle physicist, when we talk about matter, that’s what we mean.. We mean these little constituent, particles.. Ok! So now, let’s go back and put that together about what dark matter is., So dark matter is matter, meaning it’s some kind of new particle that is creating gravity in the universe.. So it’s helping hold everything together out in space., But it’s not absorbing or reflecting light, meaning that we can’t really observe it using our standard astronomical techniques.. So the first question is as a scientist: why is dark matter important to study at all And the way to think about that is to realize that everything we have ever studied here on Earth, looking at chemistry or biology, studying animals or humans or rocks or the Planets or other stars, all of that only makes up 20 % of the universe. And the other 80 % of the universe.
We don’t know what it is., And so that is the fundamental question of trying to understand what dark matter: is., SPEAKER, 1 — of galaxies. KERSTIN PEREZ. The idea of dark matter actually started back in the 1930s. Fritz Zwicky was looking at observations of galaxies moving around each other within clusters., And he noticed that these galaxies were moving very, very fast.. In fact, they were moving so fast that it seemed that the cluster of these galaxies shouldn’t be held together at all.. Galaxies should just be flinging apart into space., And so he hypothesized that there needed to be some new kind of matter that was holding these clusters.
Together. And he called that dark matter.. So how do we as scientists look for dark matter? Well, we can split ourselves into theorists and to experimentalists. Theorists start by looking at how the particles we do know and love interact with each other and the underlying math of how all that works.. And then they look for problems in it., SPEAKER, 2, [, INAUDIBLE, ]. The temperature and then — KERSTIN PEREZ, So this is what’s called the standard model of particle physics.. It is the most precisely formulated physical theory that we’ve ever written down.. However, there are holes in it., So, for example, it doesn’t describe why neutrinos have mass.. It doesn’t describe what dark matter: is. SPEAKER 3, Everything in the standard model, all the — KERSTIN PEREZ, And so theorists like to start with this underlying math.
Look for where there are holes in it things, it doesn’t predict and try to fix it., And then they come to us, the experimentalists and they say well, we have this great idea.. This is how we could fix all these problems in the standard. Model. And look. It predicts this new kind of matter.. Could you guys go out and look for it? So, in essence, what we are all doing is we are building giant detectors and we are looking for something new and unexpected to happen within those detectors.. A fundamental challenge of dark matter detectors is: how do we tell the difference between these particles that are coming from space all the time and are due to standard astrophysics from some new particle signature? That could tell us something about dark matter. So there’s a lot of different ways that different experiments go about this.
Some experiments put themselves deep underground, where those regular particles can’t reach them.. So these are deep underground mines or even underneath a mountain say in Italy., Then there’s what the particle collider experiments do.. So this is like the Large Hadron Collider at CERN.. It takes protons which are particles, we know and love accelerates them up to almost the speed of light smashes them into each other. Taking the energy of these protons and trying to convert it into new mass., And they are looking for some new particle to come out of this collision, that has properties that are consistent with what we know about dark matter.. The last kind of experimentalists are what I do.. We actually use particle interactions that are happening in space in order to look for dark matter..
So in essence, we are using the universe like a giant particle collider.. We are using those collisions that are happening out in space anyway and then observing them here on Earth.. So, where we stand right now, is that theorists have done an amazing job of giving us a suite of really well-motivated candidates for what this new dark matter could be.
The experimentalists have risen to the challenge and have come up with a lot of experimental ideas for How we are going to search for that new form of matter within the next decade.? So what I think is really exciting is that within the next decade or two we will have the experimental capability to look for what are currently the best motivated candidates. For what dark matter could be. [ MUSIC PLAYING ] .