You reason that if there were no connection between the passageways, the only way the explorer could come out the passage that you named would be if he had gone in that same one. He would have to guess which one you were going to choose, and if he were right, he could come out that one. But you have repeated the test dozens of times. The chances that someone could guess right so often is infinitisimal. The only logical explanation is that the passageway does exist.
A skeptic of the above scenario could claim that the "explorer" was actually a pair of identical twins (one of whom was hiding in the cave before you entered) rather than a single individual. One possible defense against this would involve an uncopiable but verifiable token given to the "first" explorer. - Bill --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majordomo@metzdowd.com