Somewhat related: does there exist a technology where I can encrypt something in a manner that it can only be decrypted after a specific future date? If theoretically possible, what would it take for something like that to exist? ie. "We'd need an authority to broadcast some ongoing pseudorandom number generator that can be trusted" or whatnot.
Not necessarily requiring encryption: Shoot it into space on a carefully calculated trajectory. Alternatively, send it as a laser pulse towards something that will reflect it back at the right time.
