Figure of speech. We shouldn't take the Bible word for word. I believe It is more deeper than that
20 And I saw an angel come down from heaven, having the key of the bottomless pit and a great chain in his hand.
2 And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and bound him a thousand years,
3 And cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season.
I believe this is what Disciple of Sagan was talking about. Sounds rather physical to me.
Should we take John 3:16 as a figure of speech as well?