Someone recently made the assertion to me that Motherboxes in the DC Universe can open Boomtubes into different universes.
This was the first time that I had heard this claim. I had always thought that Boomtubes were limited to locations within the current universe. For example, in the Earth-2 universe, Motherboxes could open Boomtubes to any location within that universe, but could not open Boomtubes to any location in the Earth-3 universe. I searched the Internet but could not find any definitive answer to the question.
Can Motherboxes open Boomtubes to different universes?