This June, scientists will add exactly one second to the clock, a seemingly minor alteration that could wreak havoc for computers and websites across the globe.
The last time a "leap second" was added -- June 2012 -- sites like Reddit, Gawker, LinkedIn and Yelp experienced temporary service disruptions. According to Wired, Reddit was down for about an hour and a half -- not such a big deal for what is essentially a massive online bulletin board. Unfortunately, the problem also extended to Amadeus Altea, a large airline reservation system. That reportedly disrupted flight plans for both Qantas and Virgin Australia.
The New York Daily News reports that the problem is primarily the result of many computing systems being unable to recognize "two same seconds in a row."
Of course, Google has a solution to the problem. The search giant employs a technique called a "leap smear," which basically means that a handful of milliseconds are gradually added to the clock before the actual leap second, so the shift is spread over a day rather than enacted at one precise moment.
This all sounds like a pain, but it's not for nothing. The leap second, which was announced Monday by the International Earth Rotation and Reference Systems Service, will be enacted to help account for Earth's slowing rotation.
The planet's rotation speeds up and slows down for a variety of reasons. According to Steven Dutch, a retired professor of natural and applied sciences at the University of Wisconsin, massive earthquakes, for example, can speed the Earth's rotation (making days shorter), while natural changes in various points of elevation in the planet (like undersea mountains) can actually slow rotation over time. Adding a second -- which has actually happened 25 times since 1972 -- may seem like a small way to offset these problems, but in theory, correcting the clock with leap seconds prevents us from eventually having sunset at, say, 8:32 in the morning.
Still, some people argue that leap seconds should be done away with entirely because of how technically disruptive they can be. Proponents say eliminating them would divorce our understanding of time from the sun -- which is problematic for obvious reasons.
For a full breakdown of the pros and cons of leap seconds, read this paper from the University of Cambridge.