Chronon
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Word of the Week (104): CHRONON (probability 26962), by David Sutton
A CHRONON is a hypothetical smallest possible unit of time, postulated by those who believe that time may be quantised rather than continuous. In one model it is the time taken by light to travel the classical radius of an electron, though it may be more familiar to Scrabble players as the time taken by certain opponents to draw fresh tiles from the bag after playing what they know to be a phoney.
There are other very small units of time. A YOCTOSECOND is 10 to the -24 seconds; a ZEPTOSECOND is 10 to the -21 seconds; a FEMTOSECOND is 10 to the -15 seconds. Surprisingly ATTOSECOND*, or 10 to the -18 seconds, though well established in scientific literature, is not yet playable. If it's any consolation ATTOSECOND* has an anagram COTTONADES.
But let us proceed to the other end of the scale, pausing only to note the LUSTRUM, a period of five years, the CHILIAD, a period of 1000 years, and the interesting SAROS, a cycle of 6585.32 days in which eclipses of the sun and moon occur in same sequence and at the same intervals as in the previous such cycle. Here we have the well-known if somewhat imprecise divisions of geological time, of which the largest is AEON (or EON). An aeon is divided into ERAS, an ERA into PERIODS, a period into EPOCHS and an EPOCH into AGES.
Then we have the vast spans of Hindu cosmology, the YUGA (or YUG), one of the four ages of the world, and the KALPA (or CALPA), which is one day of Brahma. There seem to be various definitions of this last, but the maha kalpa or great kalpa is often reckoned to be 4,320,000,000 years, or as the Buddha more poetically puts it: 'Imagine a great rocky mountain, 16 x 16 x 16 miles. Take a small piece of silk and wipe the mountain once every 100 years. The mountain will be completely worn away even before the kalpa ends.'
Again, Scrabble players may be more familiar with the kalpa as the time taken for an adjudication to come back when they have played a word they are only 90% sure of.