The ambient temperature and relative humidity have been at uncomfortably high levels lately. A fellow gym rat and I observed that even the air conditioned gym feels clammy, too. The discomfort has affected our performance and times regarding our Expresso workouts.
We got into an informal discussion about time in general. My pal related that he’d heard a recent lecture regarding our perception of time. For instance, if we’re feeling bored. Maybe waiting in line at the supermarket, time seems to drag along slowly. Meanwhile, if we’re involved in a fun activity, perhaps an afternoon at a theme park, time passes quickly. I recalled how a period of six weeks seemed like an eternity when I was still a young grade schooler. Now, in my middle age, six weeks passes by very fast. I think we’ve all experienced the various illusions our mind plays with time. That’s why we have standardized time measurement values.
I’m guessing that Cro-Magnon people first measured time in units of days. They didn’t have an atomic clock (as pictured right). Eventually, cycles of the moon were important. Perhaps, later on, those people discovered a cycle of the sun, too. These values eventually led to the development of calendars. Much later, clock time likely went through a similar development.
As a child, my friends and I liked to have camp out sleep-overs in our backyards. These times were often spent pondering the big questions. We wondered what the edge of the Universe was like. How huge is the Universe. We also tried to imagine the smallest possible particle. What could possibly be the shortest measure of time? We figured, correctly that there is an infinate amount of size and smallness in the Universe.
Hypothetically there are infinite amounts of time from largest to smallest, both directions. That has begged the question, what are the largest and smallest official units of time acceptable in scientific research? I like to know these factoids because you never know when you might need that information for a cocktail party, the chance that a kid wants to know or a blog post needs to be fleshed out. After one of my sleepovers with a friend I decided to go to the library to find out for myself.
There was no such thing as the Internet back then. It turns out that in the grand scheme of time measured in long units is simpler to grasp. Geologic time has been standardized for our convenience.
The very longest division of geological time is called the eon. We happen to be living during the Phanerozoic eon. Eons are further divided into eras. Our era is the Cenozoic Era. We have a smaller time unit known as Periods. We’re living during the Neogene Period. Finally, Periods are divided into epochs. Our particular time is the Holocene Epoch. We can step away from Geologic Time and start to use conventional reckoning. We know about millenia or thousands of years. There are centuries for hundreds of years. Then there are decades, years, months, weeks and days.
From macro time we can go to clock time and micro time. We’re quite familiar with hours, minutes and seconds. It’s the divisions of a second where things get existentially interesting. Time gets so short that we have trouble imagining it. I think our mind has an easier time imagining huge things like infinite space and infinite duration of time. Not so when we go the other direction. Anyone who’s watched a track meet or took in the Olympics has seen displays of elapsed time for an event. Often, those are measured in the hundredths of a second. Sometimes you might see a thousandth of a second (millisecond) for some sort of speed oriented event somewhere. But when events happen much, much quicker, you need other names for times that are calculated with long strings of zeros.
These are the units of measure I could have named as a ten year old boy watching the sky at night with my best friend. We have the microsecond for a millionth of a second. We may have heard about the nanosecond which is a billionth of a second. The next names aren’t only imaginary, but the concepts are mind-blowing, too. A picosecond is a trillionth of a second, a femtosecond equals a quadrillionth of a second. There is the attosecond or one quintillionth of a second. By the way, 12 attoseconds is the shortest amount of time our state of the art instruments can currently measure accurately. My favorite is the zeptosecond which comes out to a sextrillionth of a second. The smallest measure along the metric scale is the yoctosecond which is a septillionth of a second in the short scale. If you blink your eyes you’ll miss all of these measurements.
There is one other short unit of time. It’s the Planck unit of Planck time. I won’t even try to explain this one very far. The Planck units are in the realm of where most people’s heads begin to hurt. The very short explanation is that Planck time was first proposed by Max Planck. He said a Planck unit is the amount of time it takes a photon to travel a unit of Planck length (of course). A Planck length is equal to 10 to the minus 35 metres. Extremely short span in an extremely short time. This is the shortest theoretical time ever possible. The number is 10 to the minus 43 seconds. Beyond that speed, atomic particles have no charge.
If you want to know more, I suggest a course in Calculus and some time spent studying physics. It is beyond the scope of this blog to make your head hurt any worse.
The Blue Jay of Happiness wonders how long these are in relation to bird years.