Can a Mobile Phone Unlock a Car?

What's a light-year, why is the earliest dawn not on the solstice, is the Sun hotter in South Africa, what causes neuropathy, can batteries short out in my pocket, is there a non-surgical solution to a squeaky voice, can my cell phone unlock my car and why does tapping a cup of cocoa make the pitch go up? Join Dr Chris for this week's festive selection of scientific conundra, on Talk Radio 702... Like this podcast? Please help us by supporting the Naked Scientists