What is the difference between Dark matter and Antimatter?

Question

I've allways wondered if Dark Matter and Antimatter were close together because Dark matter can't been seen and I would think that antimatter couldn't be seen either. Seeing as antimatter is the opposite of regular matter.

Answer 1

They are very different things!

Anti-matter has the same properties as ordinary matter except that the charges of the basic particles are flipped. For example, an electron is negatively charged, so the anti-matter particle for the electron is positively charged. It is called a positron. There are other, more subtle changes, so the anti-neutron is not the same as a neutron (although both are electrically neutral).

There is a collective term for heavier particles like protons and neutrons which are made out of quarks. They are called baryons. Anti-matter is ultimately made out of quarks also, so is baryonic.

Because anti-matter has charges, it interacts with light (electromagnetic waves) in essentially the same way as matter does. So, large quantities of anti-matter would be visible. Anti-carbon, for example, would have the same density as ordinary carbon and would be black (assuming it was anti-graphite).

Also, anti-matter interacts very strongly with ordinary matter. So strongly, in fact, that the two destroy each other: their mass is converted into energy when they meet.

Dark matter is very different. At this point, we only know about it from its gravitational effects: how it affects orbits of stars in galaxies, or how it bends light around galaxies. We know that it, unlike anti-matter, does not interact strongly with light. That is why it is invisible. We also know that dark matter is not baryonic, so it is not made from quarks at all.

At this time we don't know what dark matter is made from, although there is a lot of speculation. The best guesses at this point all suggest that dark matter is like a heavy analog of a neutrino, which only interacts with ordinary matter through the weak force and gravity, not the electromagnetic force. In particular, dark matter does not destroy ordinary matter like anti-matter does.

Answer 2

Antimatter exists in this "matter" universe for a fraction of a second before it, and its matter opposite annihilate each other.
Antimatter is created in experiments in the particle accelerators.
Dark matter is a theory to explain the "missing" volume in mathematical equations concerning the volume of the universe.