We could call it the boundary of where matter can exist.

Today, no scientist believes that "organized matter of any kind can exist inside a black hole."

Getting through to whatever gray matter existed in that beautiful head was going to be tough.

The ring's discovery is among the strongest evidence yet that dark matter exists.

They can't, however, really understand any meaning in the words "matter exists."

Objection: Then why does everyone think that matter and an external world exist?

The gaseous state is one of the three basic states, or forms, in which all matter exists.

So, if almost everyone is convinced that dark matter exists, what is it?

All matter exists in three states: solid, liquid and gas.

In short, we think that dark matter exists because it is just about impossible to account for all the evidence with any other proposals.