It's "dark" in the sense that the (fabled) Dark Ages were dark. They didn't have more cloud cover then. And dark matter is 'dark' as in 'inobservable, except by gravitational attraction'. So we admit it might not even be "matter" by any definition we have; it's just what we're calling this invisible, untouchable, silent elephant in the room. That is very heavy. And might not be an elephant.
Honestly, "invisible matter" might have been a better term, but that too would have been misinterpreted.
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Dark matter absolutely is a crutch.
It's "dark" in the sense that the (fabled) Dark Ages were dark. They didn't have more cloud cover then. And dark matter is 'dark' as in 'inobservable, except by gravitational attraction'. So we admit it might not even be "matter" by any definition we have; it's just what we're calling this invisible, untouchable, silent elephant in the room. That is very heavy. And might not be an elephant.
Honestly, "invisible matter" might have been a better term, but that too would have been misinterpreted.
Honestly, just saying the maths doesn’t always work is much more approachable than dark/invisible matter.