The Time will stop on June 30 for a second, know why?
According to experts, Earth's rotation is gradually slowing down a bit, so leap seconds are a way to account for that.
Leap seconds were first introduced in 1972, and at that point, atomic clocks and astronomical clocks were already off by ten seconds, so researchers added ten seconds all at once in 1972 to the world's astronomical clocks. The last leap second was added in 2012, but in the early 1980s, time scientists were adding them every year.
Now in 2015, most of us won't notice the addition, which happens at 23:59:59 coordinated universal time (UTC), or 7:59 p.m. ET, unless we deal in timescales shorter than a second, or if we use a computer program that crashes because it can't handle the leap second.
This is the case according to the time standard that people use in their daily lives - Coordinated Universal Time or UTC.
"It's a major interruption mostly because there are a lot of systems that aren't prepared to handle the leap second correctly," says Judah Levine, a physicist at the National Institute of Standards and Technology (NIST) in Boulder, Colorado. Leap seconds occur irregularly, which makes it hard for programmers to test their fixes, he explains.
Levine is responsible for making sure the nation's timekeepers at NIST can handle the leap second. When it comes time to adjust their clock, NIST will transmit 23:59:59 UTC twice, Levine says. "Once when that time arrives, and once again for the leap second."
So 6 p.m. mountain time—the NIST offices in Colorado are seven hours behind UTC—on June 30 will be stressful. "There's a full panic mode just before and after 6 p.m.," he says.
