Why a helium balloon flies backwards when you hit the brakes

How can algae microbots deliver drugs for bladder cancer? Why does a helium balloon fly backwards when you hit the brakes in a car? Does the Sun make ash? Will removing your gallbladder affect your cholesterol? Is there a symbiotic relationship between spiders and antelopes? Can cloud seeding affect rainfall? What causes restless legs? Why are global sperm counts dropping? And what holds the universe together? Dr Chris Smith and Clarence Ford have the answers... Like this podcast? Please help us by supporting the Naked Scientists