The Whole problem

You and your logistic friend are on a secret agent mission...but you are caught by the enemy. To taunt you, they put you into a prison room with 3 pitch black exit slides, 2 of which lead to an artificial black hole for instant death upon falling into it and 1 leading to freedom. All three options look perfectly congruent and which ever tube you or your friend go down, the other must follow. You are both told that you are allowed to inspect each slide one time before making a final decision. You have no idea what to do...but your friend, without a word, walks up to the slides, sticks his head in each for a minute then says, "This one!". You reluctantly follow him in fear of your life but in trust of his intelligence, and next thing you know, you are outside...free! You pull him to the side to inquire about how he knew. He smiles, taps his nose, then calls the agency to arrange a pick up location, leaving you guessing.

(All details are highly relevant)

Based off of the information given...did he really know or was it a lucky guess And if he did...how?