隔空

from a distance; through the air; remotely (esp. by means of telekinesis, magic, technology etc)

to separate / to partition / to stand or lie between / at a distance from / after or at an interval of

empty / air / sky / in vain

to empty / vacant / unoccupied / space / leisure / free time

to converse with sb by shouting from some distance away / (fig.) to say sth intended for the ears of sb who is not in one's presence (often, by making a public statement or by posting online)