Dark Matter is a big area of interest in astronomy. The make-up of the universe is a fairly recent discovery, and has revealed to us that normal matter makes up only 5% of our universe, whilst dark matter makes up 27%.
A short summary of dark matter’s origins
Dark matter came to be when there were huge discrepancies between expected and actual velocity.
Astronomers noticed outer stars in galaxies orbit at much higher speeds than expected. After many decades it was concluded that the outer areas of galaxies were much more massive than we thought. This invisible mass was named dark matter.
If you’re looking for a more in-depth article on how we discovered dark matter, click here!
So what actually is dark matter
Dark matter makes 27% of the universe, but it doesn’t interact with the electromagnetic force (Photons, Light).
We can’t see it, and we’re having a lot of trouble figuring out what it’s made of.
But there are some ideas on what dark matter is. All that we know, is that dark matter is made of some exotic particle that we’ve simply not come across yet!
We used to think dark matter could be MACHOs. Dim stars, brown dwarfs, unlit planets. MACHO stands for MAssive Compact Halo Object, and they’re actually just normal matter.
Johnny Bravo is the ideal example of a MACHO.
It turns out, there have only been a couple of cases of MACHOs, not enough to account for every case of dark matter. It’s something entirely different.
WIMPS stands for Weak Interacting Massive Particles. We have no clue what they are, but they only interact with the gravitational force, and not the electromagnetic (light).
A photino is the development of the WIMP theory, which pairs with the photon. There’s such minimal information on the photino, so these two sentences cover basically everything about them.
On the left I’ve used Greg Heffley as an example of a WIMP, since there’s no suitable diagram or illustration of one yet.
Another hypothetical particle is the axion. It is a charge-less particle that does react electromagnetically, but very weakly for it to make a significant difference to ordinary matter. It also reacts gravitationally, just like ordinary matter.
Some have even hypothesised that the neutrino could be responsible for dark matter!
All that we know, is that they’re very attractive 😉