Why is the glass of a fluorescent light bulb white, and not clear? What�s the secret ingredient that gives Budweiser beer its distinctive light taste? Why are there grooves on every step of an escalator? And just how does a top of the line fire extinguisher put out a fire using only dry chemicals? Find out the answers to these questions and more in this episode of �Who Knew? With Marshall Brain.� Take a fast-paced and fact-filled adventure into the world of product design, manufacturing and testing as we go behind-the-scenes to find out how people and machines create some of life�s most fascinating things.