What Is Time?

Susan Lindee (history and sociology of science). "Time is a critical parameter of truth. Much of what was true in 1700—indisputably true in every sense that matters—had become untrue by 1890. If you want to know if something is true, you must first know what time it is."

Daniel Richter (history). "Time is the culturally determined vocabulary through which people describe the relationship between change and continuity. It’s also a magazine."

David Roos (biology). "Time flies like an arrow, but fruit flies like a banana."

Ralph Rosen (classical studies). "Despite the many continuities we often find between ancient cultures and the modern world, the ancients remain especially alien to us when it comes to notions of time. I often wonder how people conceptualized the idea of an ‘appointment’ in an age without wristwatches."

Susan Stewart (English). "Time is a cormorant who devours (Shakespeare) or what calls on the lazy leaden-stepping hours (Milton). ‘Time feels so vast that were it not/ For an Eternity—/ I fear me this Circumference/ Engross my Finity’ (Dickinson). I follow Wallace Stevens and Heraclitus in believing time is the Schuylkill, a river in mid-earth."

Rudra Sil (political science). "Time is perhaps the biggest obstacle late-developing nations have had to overcome during the past century: the communists tried to transcend time, the post-colonial nations tried to compress time—all in a frantic bid to do what Western countries took centuries to accomplish."

Sheldon Hackney (history). "Thank goodness that time passes. Otherwise, there would be no historians. The other aspect of time that keeps historians employed is that the past does not stand still. It changes every time we look at it."

David Stern (Jewish studies). "For classical Jewish tradition, time is a continuum in which the past is what is worthy of being remembered because it is significant for the present, and the future is a promise precisely because every moment holds the possibility of bringing the ultimate fulfillment in the shape of the messianic fantasy. A Yiddish saying sums it up: Sleep faster; we need the pillows."

Max Tegmark (physics and astronomy). "After Einstein, we think of time as a fourth dimension. Our personal time slows down if we move, so flying near the speed of light is like traveling to the future in a time machine. Time runs faster in my 4th floor office than on the ground floor of David Rittenhouse Laboratories because of Earth’s gravity. But that effect is too small for me to use it as an excuse."

Ponzy Lu (chemistry) "This is hard. I’m still thinking."