## zeptoseconds and yoctoseconds -- 3/26/15

Today's encore selection -- from The Canon: A Whirligig Tour of the Beautiful Basics of Science by Natalie Angier. Fractions of a second:

"What happens ... in subsections of seconds? In a tenth of a second, we find the proverbial 'blink of an eye' for that's how long the act takes. In a hundredth of a second, a hummingbird can beat its wings once. ... A millisecond, 10-3 seconds is the time it takes a typical camera strobe to flash. Five-thousandths of a second is also the time it takes ... a Mexican salamander ... to snag its prey.

"In one microsecond 10-6 seconds, nerves can send a message from that pain in your neck to your brain. On the same scale, we can illuminate the vast difference between the speed of light and that of sound: in one microsecond, a beam of light can barrel down the length of three of our metric-resistant football fields, while a sound wave can barely traverse the width of a human hair.

"Yes, time is fleeting, so make every second and every partitioned second count, including nanoseconds, or billionths of a second or 10-9 seconds. Your ordinary computer certainly does. In a nanosecond, the time it takes you to complete one hundred-millionth of an eye blink, a standard microprocessor can perform a simple operation: adding together two numbers. ... The fastest computers perform their calculations in picoseconds, or trillionths of a second that is 10-12 seconds. ...

"Ephemera, however, are all relative. When physicists, with the aid of giant particle accelerators, manage to generate traces of a subatomic splinter called a heavy quark, the particle persists for a picosecond before it decays adieu. Granted, a trillionth of a second may not immediately conjure Methuselah or Strom Thurmond to mind, but Dr. [Robert] Jaffe observed that the quark fully deserves its classification among physicists as a long-lived, 'stable' particle. During its picosecond on deck, the quark completes a trillion, or 1012, extremely tiny orbits. By contrast, our seemingly indomitable Earth has completed a mere 5 x 109 orbits around the sun in its 5 billion years of existence, and is expected to tally up only maybe another 10 billion laps before the solar system crumples and dies. ... In a very real sense then our solar system is far less 'stable' than particles like the heavy quark. ...

"Scaling down to an even less momentous moment we greet the attosecond, a billionth of a billionth of a second, or 10-18 seconds. The briefest events that scientists can clock, as opposed to calculate, are measured in attoseconds. It takes an electron twenty-four attoseconds to complete a single orbit around a hydrogen atom -- a voyage that the electron makes about 40,000 trillion times per second. There are more attoseconds in a single minute than there have been minutes since the birth of the universe.

"Still, physicists keep coming back to the nicking of time. In the 1990s, they inducted two new temporal units into the official lexicon, which are worth knowing for their appellations alone: the zeptosecond or 10-21 seconds, and the yoctosecond, or 10-24 seconds. The briskest time span recognized to date is the chronon, or Planck time, and it lasts about 5 x 10-44 power seconds. This is the time it takes light to travel what could be the shortest possible slice of space, the Planck length, the size of one of the hypothetical 'strings' that some physicists say lie at the base of all matter and force in the universe."

Natalie Angier

#### title:

The Canon: A Whirligig Tour of the Beautiful Basics of Science

Mariner Books

#### pages:

77-78

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