Curious Facts About Time

Years ago, I wrote a dissertation on the synchronization of clocks to earn my Master of Science degree, a fact that has come in handy for some work that I'm currently doing now.  Also, it's just freaking interesting stuff.  Some thoughts:

• Every few years, scientists at NOAA introduce a leap second into the official time.  Why?  Because the rotational speed of the earth is slowing down due to tidal friction.  There have been 24 leap seconds added since 1972, which comes out to about 0.65 added leap seconds each year.  At this rate, the day will have 25 hours in about five and one-half millenia.  If you can wait the same span of time since Julius Caesar crossed the Rubicon in his coup d'etat against the Senatus Populusque Romanus (SPQR), then you'll get an extra half hour for your lunch break.
  
• Those same kind folk at NOAA broadcast an AM radio signal from station WWV that reports the current time, accurate to within about a second or so.  That's what all those self-setting clocks listen to, and it's how they set themselves.
  
• There is no such thing as simultaneity, at least not for everyone.  This is a consequence of relativity.  Events that I perceive as being simultaneous may not appear the same way to you, with one or the other happening first.  This has deep implications for cause-and-effect, and it places fundamental limits on just how synchronized two clocks can be. 
  
• Einstein's investigation into relativity began in his childhood.  He reports that he wondered what he would see in a mirror, were he to hold it and go faster than the speed of light.  The fundamental insights of Special Relativity are nothing more than simple algebra problems that follow from the assumption that the speed of light is fixed and the fact that the hypotenuse of a right triangle is longer than its other two sides.  From these two facts, Einstein deduced gravitational lensing and the bending of light itself, time dilation between reference frames moving at wildly different speeds, and the heady conclusion that space itself can be warped and bent.
• Before the Big Bang, there was no time.  Hence it makes no sense to say "before the Big Bang."  Astronomers now know the structure of the universe after only the tiniest of increments after the Big Bang, but nobody can yet say what was there "before," and they never will because there was no before.  The $1,000,000 question is: what started time?  Who wound the clock?
  
• The universe is now bigger than there is time enough for light from one end to reach the other, and it's still expanding faster.  Hence light from the most distant star on your left will never reach the most distant star on your right.
• Buddhists have a saying that the only time is the Now; everything else is simply noise in our minds.  That to find happiness, one need only quiet that noise and live in this moment, the one right now.
• Although today we keep track of local time via standardized time zones, these are only rough approximations.  There exists the notion of a true local time at every point on the globe.  The local time for you, a few miles away from me, is a few minutes different than my own.  Mariners once used this notion (along with a sextant) to find when the sun reached its apex at noon, and by comparison to a known standard (GMT) could compute how far east or west they were of that standard based on the difference between local noon and GMT noon.  Every 15º change in longitude represents one hour's difference in local times.
  
• To make that computation, they needed accurate clocks.  Even a small drift in the clock time could lead to many miles of error in the longitude calculation.  Pendulum clocks -- the most accurate of mechanical land-based clocks -- are useless on a pitching and rolling ship.  In 1714, Britain announced a prize of £20,000 for the first person who could design a non-pendulum clock that would be accurate enough for longitude calculations at sea.  The winner, John Harrison, labored until 1761 before finally succeeding.  The golden age of the British Navy followed shortly thereafter as they used this new tool to build (and later defend) an Empire.
  
• Pendulum clocks placed in proximity on the same wall will eventually synchronize their pendulum motions due to subtle physical feedback motions imparted to the wall.  What appears to be a solid wall is in fact an elastic medium through which the two clocks find a common harmonic swing.
  
• The motion of a pendulum, although described by what may be among the simplest of physical equations, becomes indeterminate and chaotic -- the most complex of dynamic behavior -- when driven by an outside force.  (Hence the unusability at sea!)
• It is possible to determine North if you're lost using only an analog watch.  In our northern hemisphere, point the hour hand towards the sun, and then bisect the angle between the hour hand the the 12 o'clock mark.  That line is the north/south line; north will be the direction further from the sun.  (Same deal in the southern hemisphere, except north is the direction closer to the sun.)  Don't have an analog watch, but you know the correct time, you digital watch wearer, you?  A drawing of an analog watch on a piece of paper works just as well.  Can't see the sun due to overcast?  As long as you can cast a shadow, you do the same thing with a drawing on the ground and a stick.  If all this is too much to remember, then just remember this: wait until noon, and then walk away from the sun.  You'll be walking north.  (Or towards the sun, for you lucky Southern Hemisphereans.)
  
• Not exactly a time fact, but a lost-persons fact: if you are lost, and an aircraft flies overhead and spots you, do NOT wave your arms to attract attention.  That is the "wave-off" signal that signifies that all is well and that you do not need help.
• The Global Positioning System (GPS) that you use in that TomTom navigator in your car works by comparing differential time updates between satellites.  Each satellite is, in effect, an orbiting atomic clock with a radio transmitter.  The GPS you use knows where the satellites should be, and by comparing the differences in reported time from several, it can triangulate its location relative to the satellites.  Commercial and military GPS systems probably have the same precision (i.e., not much variability in their estimates), but the commercial signal is intentionally downgraded in accuracy (i.e., the exact location they decide you're at is not as good).  Even so, the high precision means that even if you don't know where you are to within +/-30 feet, you can still see a two-foot change in position, anywhere on the earth's surface.  Such is the power of the nanosecond.