Ceasar's last breath

Yesterday, 15 March, was the anniversary of the assassination of Julius Caesar in the Roman Senate. Scientists have long used the moment of his death as an illustration of the concept of large numbers in chemistry and principles about distribution. The idea is basically this: the molecules released when Caesar exhaled his last breath have become so widely distributed that, every time we take a breath, we inhale one or more of those molecules.

Here's a link to an article and to a podcast (an audio file) on the topic: NPR : Commemorate Caesar: Take a Deep Breath!