Ok guys here is what you are talking about.
It isn’t molecules in the same tank that do that, rather Electrons from the same molecue that do that. True that it doesnt matter when, per se, they were in the same molecule, but the difficulty lies in establishing the positions of the two communicative ends. Basically what is happening is as you rotate one elctron, you rotate the other simultaniously, in the same direction, to the same degree. This has already been proven over distances further than 1 light second away (there was after all, a Few Scientifically useful things that came of the apollo missions), but like I said, the hard part is getting the what needs to go to other end To the other end. It would take years for your walkie talkie to get to by which time the elctrons actaully needed have more than likely leaked away into space (they are rather small buggers). Just my .02
Good Luck All