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...