Oh but people DID know who and about WHEN the cube came.
The book Erik picks up in the Library SHOWS the Cube in Odin's hand as he's coming down the Bifrost.
Originally Posted by Moonwing
But she is a scientist - maybe some object was projecting gravity waves and she come to look at it but got some unexpected consequences.
As to how it come to earth? Like the cosmic cube in CA - how it come to earth? No one know. Maybe another long forgotten artifact that was left on earth- the non important little world that no one interested in- for safe keeping after the end of elven age.