It's one thing to be electromagnetically inert, but if it is matter, it has mass, and if it has mass then it must be possible to collide with it. That we can't suggests it does not exist.
It's one thing to be electromagnetically inert, but if it is matter, it has mass, and if it has mass then it must be possible to collide with it. That we can't suggests it does not exist.
Yes, and dark matter will interact with visible matter gravitationally. When we say "doesn't collide with normal matter", it is not exact. It just means "the interaction length is very very long". Same for neutrinos. Their interaction length is huge as well: 1 TeV Neutrinos have an interaction length of 2.5 million kilometers.