Board Thread:Questions and Answers/@comment-25521424-20161130160919/@comment-996391-20161130165731

The "Ghost Dimension" wasn't a dimension at all.

"I think I understand why Lucy and her friends looked like ghosts now. They were out of phase with our reality. It's like the... The invisible quantum mechanics inside the boxes, moving in and out of our dimension. Lucy and her friends were stuck in between, and now we are, too." "Trapped between dimensions?" "Yeah, that shock wave... That wasn't turbulence... That was that was friction between two dimensions."

- Leo Fitz and Phil Coulson