There's an additional second, a leap second, at the end of 2016. They occur around every 18 months in relation to Earth's revolution. (Dan Kitwood/Getty Images)
By Darryl Veitch
To the time-poor of the world: take heart, for 2016 is a generous year. Not only were you granted a leap day on February 29, you will soon score a New Year's Eve countdown bonus, a leap second, to hold off 2017 for a final sip or regret.
Whereas leap years add a day to align the calendar with the seasons, leap seconds align our everyday clocks with the Sun's position in the sky, that is, with the Earth's rotation.
Currently our planet takes roughly 86,400.00183 seconds (on average) to turn, instead of the expected 86,400 seconds you get by multiplying 24 hours by 60 minutes by 60 seconds. This may not sound like a great difference, but it amounts to a full second every 18 months. If left unchecked, it would become noticeable over time, and ultimately become problematic.
How did we get into this awkward situation? Why not just define a second so that there are exactly the right number? This sensible idea was tried in 1874, but hit a snag: the Earth keeps changing.
In terms of today's standard SI second (defined via atomic physics), the above discrepancy is due to the fact that the day is losing about 0.0015 seconds per century, due largely to tidal friction.
Not only that, it also changes quite erratically due to mass redistribution. For example, it is slowed by oceanic thermal expansion due to global warming, just as a playground spinning seat slows, via the conservation of angular momentum, when you place your body farther from the center.
The Year in Photos 2016
EXPAND GALLERY
Leap seconds are used to make sure our usual timekeeping system, Coordinated Universal Time (UTC), never gets more than 0.9 seconds away from the Earth-tracking alternative, Universal Time (UT1).
But unlike leap years, leap seconds cannot be calculated centuries in advance. Because the Earth moves erratically, it must be observed closely, and leap seconds scheduled on an as-needed basis.
In UT1, seconds actually vary in duration, being stretched and compressed to match the Earth's variations. In UTC, all seconds are standard SI seconds, which is much simpler, but it means that if you want to slow down or speed up UTC, there is no alternative but to jump.
All the leap seconds so far have been "positive", meaning that an extra second is inserted, corresponding to jumping the clock back, and so slowing it down.
Time's up for the leap second?
The leap second system has been with us since 1972. It represents an important chapter in the entangled history of civilian timekeeping, and of the definition of the second itself. Its days, however, may well be numbered.
For a number of years, support has been growing within the International Telecommunications Union, the standards body governing leap seconds, to abolish it.
The chief reason is complexity. Simply put, hardware and software can and do get things wrong. And the potential impacts are serious, from failures in navigation leading to collisions, to erroneous financial transactions, computer crashes and the inability to specify UTC times reliably into the future, because the leap second times are not yet known!
Because UTC jumps back at a leap second, effectively the second before the leap is repeated. Managing such "time travel" is inherently complex and error prone, so much so that in many cases the recommended action is to simply shutdown the system and restart it after the leap.
Ho Hum 2016 Draws to a Close
Mark Lennihan/AP
With a new year in sight, 2016 is primed to wrap up as a mixed bag of incremental economic achievements and setbacks.
On the one hand, the economy tacked on nearly 2 million new jobs between January and November, averaging more than 180,000 additions per month and extending the labor market's job gain streak to 74 months.
Average hourly earnings were up more than 2.4 percent on the year, home prices surged to all-time highs, and major stock indexes climbed to record-setting levels after a bumpy start to the year. The Federal Reserve even felt comfortable raising its benchmark interest rate for only the second time in a decade.
But the U.S. wasn't exactly firing on all cylinders. Exports were made less desirable because of a strong dollar, economic growth stagnated during the first half of the year, and 2016 began as the worst-ever start to a calendar year on Wall Street. Improvement in wages and home values have varied nationally and left some out to dry. And business investment and productivity gains – which are considered to be drivers of quality of life increases for workers – were few and far between.
Political rhetoric at times made it difficult to decipher exactly how well the economy performed in 2016 and the years immediately preceding it. But most analysts tend to think the U.S. is on pretty stable footing in the midst of a long-running recovery with more fuel left in the tank.
Still, 2016 in some ways was a disappointing year, especially during its first six months. Click through to look back on the single biggest drags on America's economic performance this year.
1. Political and International Uncertainty
(Joe Raedle/AP Photo)
Uncertainty was the name of the game in 2016. Uncertainty over the health of the Chinese economy dragged on stocks at the start of the year and generated international trade turmoil. Uncertainty over the U.K.'s Brexit vote sent the stock market reeling and bloated domestic bonds.
And uncertainty over the U.S. presidential election dragged on consumer confidence metrics and, according to some analysts, spooked consumers into pulling back on spending, at least in the immediate buildup to Election Day.
"The election campaign has probably created a degree of uncertainty that has impacted growth. We've seen financial markets reacting to pretty much every twist and turn in the campaign, so it's logical that there would be some feed-through to growth," Luke Bartholomew, fixed income investment manager at Aberdeen Asset Management, said in a statement in October.
Consumer confidence has soared to a 15-year high in the aftermath of the presidential election, and America's major stock indexes have climbed to never-before-seen levels, with the Dow Jones industrial average closing in on the significant 20,000-point benchmark.
Analysts generally expected consumers to feel more optimistic once a particularly divisive campaign season came to a close, and it's not terribly surprising to see Republicans' views of the economy perk up in the aftermath of the election.
Expectations of decreased private sector regulations and lower corporate and personal tax rates under President-elect Donald Trump have stoked investor sentiment, and expectations are high for next year.
But 2017 will not be without uncertainty. Trump's ability to push legislation through Congress – particularly infrastructure spending plans that aren't likely to be welcomed with open arms by GOP lawmakers – remains a question mark. And just how much he'll be able to help the economy is anyone's guess. He has suggested he'll be able to get economic growth as high as 4 percent, but the Federal Reserve expects growth to actually slow under Trump, hitting an expansionary clip of just 1.9 percent by 2019.
2. Productivity
Achmad Ibrahim/AP
One of the single largest – and simultaneously least discussed – drags on economic growth in recent years has been productivity stagnation.
Productivity measures U.S. workers' output per hour and can lead to wage gains for employees. Companies that produce more goods or services without increasing working hours turn a higher profit and are then free to boost compensation.
But the Bureau of Labor Statistics' productivity tracker has declined in three of the last four quarters and in 10 of the last 23 quarters dating back to 2011.
"The importance of productivity growth to the economy would be difficult to overstate. For example, gains in labor productivity – the amount of real [gross domestic product] produced per hour of work – are the only known way to increase standards of living over the long run," said a report published last week by the Federal Reserve Bank of Cleveland. "Since the Great Recession of 2007-2009, the average rate of productivity growth has been low compared to the long-run average that prevailed before."
Productivity is driven by corporate investment into equipment, structures and technology that allow employees to work more efficiently. But such nonresidential fixed business investment only appeared to turn a corner as 2016 wore on, climbing slightly in the second and third quarters after declining for two consecutive quarters. Such a back-to-back decline hadn't occurred since the Great Recession.
Investment appeared to be trending up at the end of 2016 and could improve further as 2017 gets underway, considering investment in physical structures enjoyed its best quarter in a year and a half during July, August and September. But general investment and productivity sluggishness undoubtedly restricted economic growth and hourly earnings metrics this year, especially in the first half of 2016.
3. Strong Dollar
Strdel/AFP/Getty Images
The strong dollar has been great news for Americans traveling abroad, as they get more bang for their buck when exchange rates are factored in. It's also been positive for imports, as companies and consumers can bring items into the country more affordably.
But the strong dollar has been bad news for domestic exporters, particularly in the goods-production sector. U.S. manufacturing outfits ended November with 78,000 fewer employees than they started the year with, in part because demand for American-made goods dropped in an already volatile international market.
The strong dollar also hurt domestic companies operating overseas as their goods became relatively more expensive internationally. Currency strength was regularly cited in earnings reports throughout 2016 as a primary contributor to underwhelming corporate performance.
Exports are ultimately a net boon to GDP calculations, while imports are a drag. The strong dollar effectively stymied demand for American exports while increasing the viability of imports into the country, thereby contributing to the national trade deficit and weighing on quarterly GDP reports.
And emerging market countries and international bodies indebted to the U.S. weren't particularly eager to see the dollar remain strong, since debt repayment becomes more expensive for countries whose currency isn't going up.
4. Inequality
iStock
The rich-poor divide and the decline of the American middle class have been playing out for years. And although new wage metrics indicate lower-income Americans have seen larger-than-normal gains in recent months, U.S. citizens have nonetheless gravitated toward the poles of the income spectrum over the course of the past decade.
The middle class has traditionally been counted on as a significant driver of domestic consumer spending, so its decline has undoubtedly hurt consumption metrics.
But inequality is more than just wages. Job growth in much of 2016 was dominated by the services sector, particularly low-paying retail and food services jobs. The U.S. created nearly 2 million new positions between January and November, but not all of them are what many Americans would consider to be "good" jobs.
The rural-urban divide came to the forefront during election season, as cities have enjoyed disproportional growth in the aftermath of the Great Recession, while those outside of major city centers have seen labor markets dry up. Even housing prices, which nationally rose to all-time highs in the latter half of 2016, have not enjoyed an even recovery. Home price metrics consistently indicate that the housing markets in significant portions of the country have yet to return to where they sat before the real estate bubble burst.
The inequality prevalent in the U.S. in 2016 allowed a candidate like Trump to tout a message of economic malaise that seemed reasonable to millions of Americans, even though national employment and wage metrics indicated the country was broadly headed in the right direction. Economic indicators are the sum of their parts, and not all aspects of the U.S. economy were firing on all cylinders.
5. Inventories
Stephen B. Morton/AP
America's inventory correction made progress in unwinding itself as the year went on, but inventory dynamics were a significant factor in the weak economic growth seen in the first half of the year.
Through a combination of factors – notably a West Coast port slowdown that was resolved last year but made it difficult for companies to import and export products from major ports in trade hubs like California and Washington – companies ended up with an excess of product and supplies on factory shelves.
But storing materials can become expensive over a prolonged period of time, so an inventory correction developed in which domestic companies sold off their excess products rather than ordering more, leaving suppliers out to dry and ultimately undercutting economic growth metrics.
The tail end of 2015 was hit by the inventory correction, as was the first half of 2016. Lingering effects by the end of the third quarter weren't considered to be a significant impediment to expansion.
A dramatic illustration of the problem can be found in the internet. All computers have software clocks that generally rely on communication with time servers over the network to synchronize to UTC. Network timekeeping is a core internet service, and at its heart are the Stratum-1 servers, which have direct access to reference hardware such as atomic clocks.
We collected data from around 180 such servers around the world during the June 2015 leap second event, and assessed them from two points of view.
First, the clocks themselves: did they jump cleanly and sharply exactly as required?
Second, at the protocol level, that is with respect to the messages the servers send to the computers that rely on them: did they inform them properly of the upcoming leap?
Overall, we found that, at most, 61% of the servers were performing correctly. Many of the servers are well known and highly utilized, potentially impacting thousands of clients, possibly resulting in security vulnerabilities.
An expanded experiment is currently underway for the 2016 event, involving almost 500 servers, including from the widely used ntppool project.
This is part of a broader network timing project at UTS led by myself together with Dr Yi Cao, which aims to refashion the global system, and in particular to make it scale in a trusted way to the Internet of Things.
Finally, we must point out that leap seconds occur simultaneously across the globe, and it can't be midnight everywhere.
Thus, as I confirmed with Dr Michael Wouters, responsible for Australia's reference time at the National Measurement Institute, for us it will occur at 11am AEDT on January 1, 2017. Save the last sip till then.
This article was written by Darryl Veitch, professor of computer networking at the University of Technology Sydney, for The Conversation on Dec. 29, 2016. It is republished with permission.
Recommended Articles
Diagnosis: Burnout
Sept. 8, 2016
As lives hang in the balance, the health care community is tackling emotional exhaustion within its ranks.
Editorial Cartoons on Donald Trump
May 31, 2012
Photos: Obama Behind the Scenes
Sept. 10, 2014
A collection of moments subtle and grand of the 44th president of the United States.
Hong Kong Model a Graceful Example of Growing Old
Dec. 29, 2016
Growing old 'can be cool,' says the founder of an agency specializing in older models.
Musical Censorship in India and Pakistan
Dec. 28, 2016
September attack in Kashmir triggers a cultural battle between South Asian rivals.
The Best Countries for Aging
Dec. 27, 2016
A sense of well-being later in life often correlates with global geography.
Technology Offers Solutions For the Aging in the Nordic Countries
Dec. 27, 2016
Tech firms are seeking solutions to help older communities in the region age with dignity.
A Bus Horn Goes Viral Around the World
Dec. 23, 2016
A Indonesian phrase that goes viral is a happy reminder that the internet can be a source of joy.
Africa's Good News About Government
Dec. 16, 2016
An entire region of the continent is making its records of public spending more accessible.
Art and Politics on a String
Dec. 16, 2016
Puppetry is woven into the social and political fabric of two Central European countries.
