look/stare/gaze into space
stare (off) into space
To stare vacantly or absentmindedly at nothing in particular, usually while one is preoccupied with or distracted by thoughts of something else. I sat at the back of class, staring off into space, when suddenly the solution came to me. He just stared into space as his parents lectured him on the importance of paying attention during class.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
look/stare/gaze into ˈspace
look straight in front of you without looking at a particular thing, usually because you are thinking about something: I asked her twice if she was ready to leave but she just sat there staring into space.Farlex Partner Idioms Dictionary © Farlex 2017