The whole purpose of a riddle is to misdirect a person into overanalyzing an obvious answer. The part about the Harvard students and the kindergarteners is put into the riddle for a reason - not just an interesting sidenote. For those of you who said pressure, air, molecules, the Dahli Llama, Einstein's Theory of Relativity, or any other ridiculous answer, think to yourself how in the hell a kindergartener would know what any of that stuff is. When you ask a small child a long drawn out question, they concentrate on the very last thing you say. When you ask "Can you solve this riddle?", they are not thinking of a solution but merely answering your question by saying "No". Harvard, the American cliche for really smart kids, was thrown into the riddle to show that most adults will overanalyze a question simply because they think riddles are supposed to be extremely difficult to solve, when in fact, they are the opposite if you think outside the box.
The answer is "No". This is not arguable, unless of course you are a bumbling moron or a mad scientists hell bent on proving your crackpot dumbass ideas.