Most recent answer: 04/04/2013

I was reading about the anti matter, and learnt that this is the oposite of regular matter in its properties, right? So, my question is: Does the dark matter also have its own oposite, an anti matter of dark matter? How is it called if it exists, anti dark matter ? Thanks in advance, luv your website.
- Renato Bigonha (age 27)
São Paulo, Brazil
We don't know at the current time what dark matter consists of, so we can't say with confidence whether it has a distinct antimatter form (like e.g. positrons for  electrons) or is its own antimatter form (like e.g. photons). I think the closest to a consensus guess about dark matter is that it consists of WIMPs- weakly interacting massive particles. There are a variety of possibilities for what these WIMPs might be, some of which are their own antiparticle and some of which aren't.

As it happens, I just heard an outstanding colloquium yesterday by Dan Hooper from U. Chicago in which he presented some nice evidence for gamma rays from what may well be WIMP-anti-WIMP annihilation. So if that interpretation holds up, it looks like the biggest constituent of dark matter does indeed have an anti-matter partner.  They would be present at virtually the same concentration.

Incidentally one property of matter/antimatter is the same, not opposite: the rest mass.

Mike W.

(published on 04/04/2013)