# Leap second

A leap second is a little “oops” correction factor designed to make up for the difference between the two major clocks – the coordinated universal time (abbreviated “UTC” for you lazy people out there) vs mean solar time (abbreviated “mean solar time”).

As a general rule of thumb, anytime you get scientists involved, you get three events. First, they will abbreviate – ie. UTC. Second, they will attempt to quantify it to an absurd degree (we’ll talk about it in the next paragraph). Third, they will wear always appear while wearing white lab coats or handling beakers. Or you could get someone measuring in a beaker, while wearing a lab coat – that’s how you can tell he’s an especially smart scientist.

Anyways, the UTC is based on scientists. So in 1967, they defined the length of 1 second. I’m not kidding, it’s precisely 9,192,631,770 oscillations between two metastable states of a cesium isotope (Cs-133). Oh, really science? No thank you, I think I’ll stick to1-Mississippi” instead of, say, counting to 9 million!!

Turns out that the scientists – who apparently love large numbers (compensate much?) – outsmarted themselves. Remember, before UTC, we had already established “time” based on mean solar time. Mean solar time is the rotation of the earth around its axis in conjunction with its rotation around the sun.

The bottom line: mean solar time is 0.6 seconds slower (per year) than UTC time. With 2 different definitions of time, as you move between systems, there are all sorts of implications like quantum warping and also bending time.  Whoa, mind.. blown..

{Sidenote: This 0.6 seconds is only at this time: solar days become a tiny bit longer every century – something about tidal friction and glacial rebound slowing down the rotation speed – so there will be an even bigger difference between solar time and UTC time as time goes on!}

The IERS is the organization which is in charge of administering leap seconds. So what does IERS stand for? Good question. It stands for The International Earth Rotation And Reference Systems Service… Wait, what? Yeah, as you can probably guess, there was something lost in translation for these abbreviations otherwise you’d get some completely different terms.

Also, if you read it, it almost sounds like “Tire” and “Arse”. I like my “Tired Ass” term better than “ERSSSSS” (“IERS” being pronounced by someone who just got their tongue pierced).

Sorry, off-topic as usual.

Leap seconds are added about once every 18 months. So, the next leap second is going to be added in 6 months from now – on June 30, 2012.. Why are we hearing about leap seconds now in the news? There was just a world summit on whether or not to abolish leap seconds and switch to a universal system. I guess adding one second every 18 months is a big deal. I haven’t seen an overreaction that bad since I joked about having HIV to my ex-girlfriend.

Ok, but seriously. A lot of things depend on precise timing like computers and GPS .. or our national missile defense system.

Ok people at the world summit: STILL WANT TO COUNT TO 9 MILLION NOW? I think I will stick with “1-Mississippi” and launch my country’s missile first.

Chris