By the Second

Time out.

A second of silence for Big Ben.

No, Ben hasn’t died. But he’s showing his age. Slowing down …

“Big Ben” is what people call the tower at the northern tip of the Houses of Parliament, in Westminster, London. But Big Ben is actually the clock at the top of the tower. The clock is renowned for its accuracy. But it is best known for its 13 1/2-ton bell that chimes every 15 minutes. In a tradition beginning with the Royal Greenwich Observatory, the chimes of Big Ben have been broadcast almost every day since 1924 as a daily time signal by the British Broadcasting Corporation (BBC).

If the name Royal Greenwich Observatory rings a bell, it’s not just Big Ben. From 1675 until 1998, astronomers at the Observatory figured out what’s what and when’s when in England. Because of the popularity of the Observatory’s The Nautical Almanac, which used the longitude of Greenwich for time calculations, in 1884 astronomers and navigators established the Greenwich meridian as the Earth’s prime meridian (0° longitude). Now all international time zones are calculated by Greenwich Mean (or Meridian) Time (GMT). Not counting Daylight Saving Time fluctuations, New York (Eastern Standard Time) is GMT -5, or five hours earlier than GMT. Israel time is GMT +2.

It is worth noting that a meridian is an imaginary vertical line dropped from the North Pole to the South Pole, passing through a given point. The GMT plumb line passes through Greenwich, London.

But hold a sec. Greenwich Mean Time has been getting meaner than ever.

Officials say the famous clock at Britain’s Parliament — used by Londoners for decades to check the time — has recently been slow by as much as six seconds.

The 156-year-old clock chimes every 15 minutes and emits deep bongs to mark the hour. Its inaccuracy was noticed by staff at BBC radio, which broadcasts the bongs live at 6 p.m.

Parliamentary officials said Tuesday that mechanics had corrected the clock to within “normal parameters” — within two seconds of the right time. They will continue to adjust it by placing pennies on the pendulum — or removing them — to fine-tune its speed.

So, in London, time is money; but only a few penny’s worth. It’s enough to drive Teutonic time tabulators mad.

If you didn’t hear the U.S. Naval Observatory (USNO) guffaw at the news, there’s a reason. The USNO is charged with maintaining the Department of Defense reference for Precise Time and Time Interval (PTTI). They have their own time on their hands.

GMT is still used for time zones, but to know what time it is, really, the new standard is “Coordinated Universal Time” (abbreviated UTC). And don’t look now, but we’re losing time by the nanosecond. Not to worry, though. With the government running time, they get a second chance.

The earth travels around the sun in 24 hours, give or take a few seconds. Until the early 1960s, that was the standard for all time measurement. But the precision of atomic time had the allure of the fabled mechanical nightingale that an emperor chose over the real nightingale’s song.

It didn’t take long for scientists to discover that there was a problem. Atomic time was not in sync with World time. So, while we weren’t looking, since 1972, scientists have been sweeping “leap seconds” under the UTC rug.

But, once reality gets too virtual, you’re asking for trouble. “If a leap second happens, the operating system must somehow prevent the applications from knowing that it’s going on while still handling all the business of an operating system,” Steve Allen, a programmer with California’s Lick Observatory, told Wired.

Essentially, you’re teaching computers to lie. And that is about as safe as eating wild mushrooms.

The coming year, 5776, is a shanah me’uberes — a “leap” year. Ours is a lunar calendar, but each lunar month is about 11 days shorter than a solar month. So, after a few years, Pesach could come out in December. But the Torah (Devarim 16:1) says, “Keep the month of spring, and bring the Korban Pesach to Hashem, your G-d, for in the month of spring, Hashem, your G-d, brought you out of Egypt …”

To keep Pesach in the spring, we have an adjustment built into our system, adding an occasional month before Pesach. This is intrinsic to the calendar, not a kludge fix.

We can rely on science … up to a point. Moshe Rabbeinu knew the issues when he “misquoted” a prophesy:

“Thus said Hashem, ‘At about midnight, I will go out into the midst of Egypt.’” But Hashem told Moshe, “At midnight,” not “about midnight.” Rashi explains that Moshe knew Pharaoh’s astrologists might miscalculate the time of Yetzias Mitzrayim and claim Moshe was lying. So Moshe added in enough wiggle room to anticipate their error.

Today, astronomers are still wiggling leap seconds.