Tess and Harry on the Dock
“What time is it?”
“Time—that is, time of day on a clock the way you think of it—is an entirely human construct.”
“Can you ever just answer a simple question?”
“No. You see? I answered a simple question. Much of our time is based on astronomical events. A day is roughly the amount of time it takes the earth to make a complete rotation on its axis; a month is slightly akin to the phases of the moon; a year is close to the amount of time it takes the earth to revolve around the sun.”
“Believe it or not, Harry, when I asked what time it was, I already knew the day, the month, and the year. My bedtime is not determined by the fact that it’s July seventeenth, 2002. Shocking as this might be to you, I wanted to know the hour and minute.”
“Ah, the hour—that is a puzzle. Hours of the day are an especially human construct.”
“Yes, and my bedtime is also a human construct. You and Marie are the humans who constructed it.”
“We can trace the hour all the way back to ancient Egypt. And while the Egyptians used twelve constellations to divide the night into twelve hours, our modern hours are unrelated to astronomical events.”
“If I had a bedtime in ancient Egypt, this information would be extremely useful.”
“Right. You wanted to know the time. Until less than two hundred years ago, every community kept its own time, based more or less on the movement of the sun through the day.”
“So even if it was my bedtime in Madison, we could keep different time on the island and I could stay up another twenty minutes?”
“But sadly for you, when railways and other forms of rapid transportation came along, we needed to standardize our time, so we divided the world into twenty-four time zones, one for each hour of the day. But that was completely arbitrary. We could have created thirty-six times zones, or forty-eight time zones. Or three hundred and sixty time zones. But now we agree that, even if, for instance, Terre Haute, Indiana, and Bangor, Maine, are separated by almost twenty degrees of longitude, it’s the same time in both places, because they’re both in the Eastern Time Zone. ”
“But it’s not really the same time?”
“It takes the sun four minutes to move through one degree of longitude, so noon in Bangor, according to the sun, happens almost eighty minutes before noon in Terre Haute.”
“That’s ridiculous.”
“It is. We should have three hundred and sixty time zones, one for each degree of longitude. Then the difference within one time zone could never be more than four minutes.”
“That makes more sense.”
“But of course, you would have to change the time on your watch every time you traveled east or west sixty-nine miles.”
“That’s ridiculous, too.”
“Both scenarios are ridiculous, but you’ve got to choose one or the other.”
“Which one gives me a later bedtime?”
“Let me put it this way, Tess. In New York it’s past your bedtime. In San Francisco it’s before your bedtime. But here in the Maxwell’s Island time zone, it’s exactly your bedtime.”