How are you defining empty? Sans rabbit?
Have you availed yourself of every available detection method and/or device??
Are you certain the rabbit did not drop something on the way out?
Do you believe in nothing??
If you ignore the “known”, will the nothing replace you?
Do you know the chord changes to “existential blues”?
Are you cornfused yet?
Edit (don’t make me come over there and slap your faith)