"proven the existence of dark matter," to me, says that we've proven that there's a thing with some known properties that needs a lot more explaining. And that'

"proven the existence of dark matter," to me, says that we've proven that there's a thing with some known properties that needs a lot more explaining. And that's the actual intent of the people who are saying it, too. Same thing with dark energy, although even fewer of the properties of dark energy are known.