24 hours never looked so good
Chris Solic
In the spirit of this interminable mid-term exam period, I ask of you to prod again your bear of a test-ready mind, fresh and unwillingly forced from its hibernating hole, to attempt this quick, multiple-choice question.
What was the approximate length of a day, in hours, three billion years ago?
- 38
- 6
- 19
- 105
- 24, duh!
Answer: b
If you responded as I did when I learned this, you may be suffering from the same dumbfounded sensations. Thoughts like, “What? Are you serious . . . ?” may have been prompted. If you got it right, well, a big shout out to you. I’m a fourth-year geology student, someone who studies and is supposed to know this kind of stuff, and yet I didn’t figure it out until just a few months back.
In truth, debate exists as to how long a day really was back then, though consensus seems to have settled on something between four and eight hours. Let’s split the difference and call it six hours. So just how the heck do we get a six-hour day, you might ask?
The length of day (LOD) is altered when any mass on or in the Earth moves, in turn affecting the state of its angular momentum. Over the short term, the LOD can vary by as much as four seconds on any particular day, due in part to atmospheric winds and ocean currents. On the billion-year scale, however, it’s the frictional effect of the tides in the earth-moon system that we need to blame for the protracted length of our school day.
Tides on earth cause angular momentum to transfer from the Earth’s rotation into the moon’s orbital motion, which causes the moon to move away from the Earth and the Earth’s rotation rate to decrease. Extrapolating the present-day values for tidal friction places the Earth and moon in close proximity three billion years ago, resulting in a LOD that may have been as short as four hours.
That’s the science, but what was it like? Well, you’re in luck, because through the wizardry of magical powers carefully gleaned from Harry Potter, I’ve just now returned from imaginary six-hour days in an otherwise unchanged world. A deft adjustment of the spell’s parameters afforded me two different takes on this bizarre event.
I awoke as usual the first day, which is to say 10 minutes later than the time needed to eat breakfast and get to class on time. I was at school 45 minutes later, at 9:45 a.m., unaware of the sun climbing abnormally high in the sky. Switching to my next class at 11:00 a.m., I was struck by the obvious dimming of the outdoor light, which lead me to think that a big cloud front had moved in.
When I emerged from my windowless lecture at 12:30 p.m., I was dumbstruck to find complete darkness waiting outside. What the . . . It was at that point I remembered my magic, and from then on I rolled with it. By 2:30 p.m., the beginning of my laboratory section, dawn had returned. Three hours later I was on my way home after it had again grown dark, the moon zinging across the horizon like an undercover comet. A late dinner heralded the rise of a new sun at 8:30 p.m., and by midnight I was so exhausted from the meteorological mess that I took advantage of the latest darkness to go to sleep.
The next morning was decidedly different. People around me were moving about at a frenetic pace, which I instinctively mimicked. I wolfed down three bowls of cereal in two minutes, and followed that with a mad dash to my car. Despite never once lifting the gas pedal from the floor, I was late for my 11-minute class. Notes were impossible to take from the chipmunk-sounding professor. Thankfully I didn’t have another class until 2:30 p.m., affording me 52 minutes to get to UC for a bite to eat.
At 5:30 p.m., after a barely comprehended, 45-minute lab, my school day was over, though it was no time to relax. I had 38 minutes to get home, cook and eat diner before starting homework. Overwhelmed by futility, I chose Wendy’s drive-thru instead. Having returned home, I tried to change the TV from its fast-forward mode, but it was no use. I went to bed 40 minutes later, thoroughly depressed.
Maybe an eight-hour, real-time school day isn’t so bad after all.
Chris Solic is a fourth-year geology student.
