What's the half life of dark matter?

Unknown that it has a half-life. Even if it did, it would decay into a different form of dark matter.

 

Also unknown is almost every other question you may ask about dark matter.

There are models where dark matter particles decay (and/or annihilate) and experiments have tried to detect the expected radiation from this. So far unsuccessfully. So maybe it doesn't decay. Or so rarely that the signal is too weak to detect.

37 minutes ago, Airbrush said:

Also unknown is almost every other question you may ask about dark matter.

Apart from how much is there and where is it!

1 hour ago, Strange said:

There are models where dark matter particles decay (and/or annihilate) and experiments have tried to detect the expected radiation from this. So far unsuccessfully. So maybe it doesn't decay. Or so rarely that the signal is too weak to detect.

But what could we detect? Not photons, since that requires the EM interaction.

32 minutes ago, swansont said:

But what could we detect? Not photons, since that requires the EM interaction.

Good point. I saw something about this earlier. I’ll look into it again...