In 1983, the metre was redefined to be "the length of the path travelled by light in a vacuum in the time of 1/299792458 of a second."

In 1975 the speed of light was 299792458 metres per second.

In 1969, for example, it was 29979250(10) metres per second. (The number in parenthesis is "the standard-deviation uncertainties in the last digit", but grandpa does tend to complain about how far they used to walk and then mumble a few statistics)

The idea is a 10K race where each member runs his/her allotted number of metres based on the definition of the metre on the date of the runner's birth. They will also be carrying any physics books published with pertinent speed of light at the time. Given the theoretical length of the race, there may be clear advantages to recruiting older runners with smaller metres and fewer books in the intervals between speeds of light.
-- 4and20, Aug 17 2012

NIST Woodstock, 1969 http://physics.nist...Archive/1969RMP.pdf
I remember when the speed of light was [4and20, Aug 17 2012]

//where each member runs his/her allotted number of metres based on the definition of the metre on the date of the runner's birth// - so you'd have to run 299,792,458 metres? Could take a while.
-- hippo, Aug 17 2012


I think this means “runs 10,000 * x, where x is the official length of the meter at the time of the runner’s birth”. As this distance (10,000 or 1 m) hasn’t changed by an amount measurable with ordinary track and field equipment, it wouldn’t have any but perhaps a psychological effect on any races (ie: “it may not be measurable, but I *know* my lane is a little shorter than yours!”)

It might be more fun, for each track meet, to define and use a meter the old fashioned Chris Huygen’s way: take a bit of string, hang a bob on it, set it swinging, fiddle with its length ‘til everybody standing around with their stopwatches agrees this pendulum is making one complete cycle each second, then use this to measure out all the courses. Thus high altitude places or ones with low local ground density would get slightly shorter (on the order of a few 0.1%) meters than others, and runners would flock to them in order to set new personal bests, national and world records. Of course, the process could be humanized/politicized, with the folk measuring the pendulum all frantically trying to cheat for whatever ends, possibly making this part of before the start of the meet a better spectator sport than the actual races.
-- CraigD, Aug 17 2012



random, halfbakery