The Science on the Path

A weed plucked at the side of the path might have found its way to the New World in a seventeenth century sailing ship. Scratches on a rocky ledge evoke colossal mountain-building events on the other side of the world millions of years ago that modified the planet's climate and caused glaciers to creep across New England. The oxygen atoms I suck into my lungs were forged in stars that lived and died long before the Earth was born. It is something of a cliche to say that everything is connecte...