[zeristor]

Also by that count all matter in the universe interacts with all other matter in the universe (OK out to the limit of the CMB).

So I am hedging my bets by saying it's wrong, or that it's so obvious its redundant.

[stan_rogers]

In this case, the "we" was a stand-in pronoun for the Milky Way galaxy, of which we are part. It would have been linguistically tortuous to have phrased it in any other way; "we" was the appropriate pronoun, no matter how much it may embarrass you to be implicated in the action. Natural languages are not instances or implementations of propositional calculus.