How Does Transparency Work?

Today on the podcast, we'll be tackling the question, how does transparency work? Sometime old, how can your kids eat cookies without you knowing? Well, I don't think they need to be transparent to do that. We're wondering about why light can pass through some kinds of things and not others. What is the microscopic picture of transparency? Please don't be shy, write to us two questions at danielandhorhay.com.