Why do we hum?

Chris Smith from The Naked Scientists takes on YOUR questions. Can contact eyes make your eyes better than perfect vision? How intense can deja-vu be? Why do we hum? Why are there more jetstreams in the Northern Hemisphere? Why doesn't armpit hair grow like head hair? Why are mushroom clouds mushrooms? Can you be allergic to electricity? And why does gravity attract mass? Plus, they say in space, no one can hear you scream, how true is that... Like this podcast? Please help us by supporting the Naked Scientists