In 2002, two groups of mountaineers were descending a snowy gully after reaching the summit of Oregon’s Mt. Hood. Below them, a third group was heading up. The members of each group were roped to one another, but, because the climb wasn’t terribly difficult, they were not anchored to the mountain itself. If one climber were to slip, his rope-mates were supposed to throw themselves to the snow, dig in their ice axes, and—theoretically—arrest the fall.
Suddenly, one of the men in the top group fell, plunging down the gully so fast that the other men on his rope were yanked down as well. The falling group’s rope then snagged that of the next team, dragging those climbers down in turn. Seconds later, the third group of mountaineers was pulled into the scrum. Finally, a total of nine climbers plummeted into a crevasse that spanned the bottom of the gully. Three were killed.
Since one climber can usually arrest a partner’s fall, using ropes in this fashion generally makes climbing safer. But there’s always a chance that one falling partner will drag another down with him. When multiple groups of roped mountaineers entered that gully on Mt. Hood, they created a bigger risk: that of getting unintentionally linked to a group of falling climbers they didn’t even know. All it took was one misstep by a single climber to entangle nine people in the deadly plunge, all bound together by the very device they relied on for their safety.
Scientists who study disasters would call this a “tightly coupled system.” Imagine a fleet of trucks moving cargo across the country. That’s a loosely coupled system. If one truck breaks down or crashes, it doesn’t affect the rest. Now imagine that same cargo being hauled by a train. That’s a more efficient but less flexible system. Train cars are literally coupled; trucks can take different routes or travel at different times. Each approach has certain advantages, as well as different kinds of risks. Trucks crash more often than trains, but a train wreck can cause wider devastation. In 2013, a train pulling 72 tank cars filled with crude oil crashed in a quiet Quebec town. Forty-seven residents perished in the ensuing fire.
Tightly coupled systems are all around us. In recent years, our communications platforms, our global supply chains, and our increasingly automated homes have all become more deeply connected in vast networks.
The electric power grid is one famous example. Utilities in different regions link their transmission lines to shuffle power around as demand dips or surges. But those close connections are a bit like the interwoven fuses in a string of firecrackers. Once the fuse is lit, a spark can propagate unstoppably down the chain. On August 14, 2003, a short circuit on a high-voltage line in Ohio led to a cascading series of failures that ultimately shut off power to most of the Northeast. The blackout even jumped the border into Canada.
Everything moves faster in a tightly coupled world. A generation ago, office memos had to be written on typewriters and photocopied for distribution. Today, every keyboard is connected to a network. You can send an email to hundreds of colleagues—or post a tweet visible to millions—with a single click. Tight coupling allows communications to move with breathless efficiency. But it also allows mistakes to multiply just as briskly. If you’ve ever hit REPLY ALL when you actually meant to send a snarky email to a single colleague, you’ve experienced the risks of a tightly coupled network.
Today, most critical functions operate over networks like these. Chemical plants and pipelines use digital industrial-control systems to operate valves and pumps that, in an earlier era, would have been controlled by human hands. These systems are highly efficient and usually more reliable as well. (A computer doesn’t doze off while waiting for instructions.) But tight coupling also makes it possible for tiny errors to cascade into far-flung chaos. Two decades ago, a technician made a small error while updating a control-system database on a Washington State pipeline network. That error shut down the control system, which prevented a valve from opening. A hundred miles away, the pipeline ruptured, spilling 237,000 gallons of gasoline and killing three boys.
These types of digital control systems are even more common today. Their designers have worked hard on making them more secure. But nothing is foolproof. And, because many such systems are connected to the Internet, they can be vulnerable to intrusion. Hackers have infiltrated control systems in a German steel mill, a dam in Westchester County, and Ukraine’s power grid, which they managed to partially black out in 2016.
“Tightly coupled systems have little slack,” writes Yale sociologist Charles Perrow, who developed the concept. He notes that organizations have many incentives to tighten the links in their operations. Businesses save money when they squeeze out redundant suppliers and adopt “just-in-time” supply chains. Case in point: Almost all the meat in U.S. supermarkets today comes through a handful of large suppliers. That consolidation has brought down prices. But when the coronavirus started circulating in the nation’s small number of meat-processing plants, the resulting crisis threatened our food supply. Our tightly coupled distribution system gave farmers no backup option for getting their meat to market.
The U.S. medical system got a similar pandemic wakeup call. After years of streamlining supply chains—and relying heavily on manufacturers in China—hospitals and pharmaceutical companies struggled to obtain vital supplies when the Chinese pipeline went dry. (In a sense, the pandemic itself reveals how our tightly coupled system of global air travel helps viruses spread.)
Tight coupling is a growing fixture in our personal lives. Do you use a personal assistant such as Apple’s Siri or Amazon’s Alexa? Maybe you have Amazon’s Ring video doorbell or Google’s Nest security system. These systems offer plug-in convenience. But they also mean your home is now coupled to vast networks. Ring employees have been fired for using the system to spy on customers. Ring also has a program in which police departments can solicit access to homeowners’ doorbell cameras, in effect, creating ad hoc surveillance networks. The Electronic Frontier Foundation says this practice poses “grave threats to the privacy of all communities.”
In the Internet’s early days, digital utopians envisioned a world of diverse information sources and “citizen journalists.” But instead of becoming more loosely coupled, our news and information started flowing mostly through a few mega-channels, especially Google, Facebook, and Twitter. These data giants now have unprecedented power to squelch or amplify viewpoints of their choosing. At the same time, their networks can allow harmful content—anti-vaccine theories, say, or Antifa riot plans—to be spread with passionate intensity.
We can’t easily unwind the tightly coupled networks surrounding us. But we can look for ways to “consciously uncouple” when possible. The MagSafe power cord, which Apple introduced on some laptops in 2006, is a great model. Before that, cords plugged stoutly into laptops; if you tripped over one, the laptop went flying. The MagSafe cord connects to the laptop with a tiny magnet, so it detaches with a gentle tug. Your computer is now loosely coupled to the wall, in other words. No more flying laptops.
We could use more innovations like that. We want the advantages that coupling brings, but we need to be able to disconnect more easily. And we need to remember that not every network needs to be coupled as tightly as possible. The pandemic has taught us that efficiency isn’t everything. A few more supplies in the warehouse, and a few more vendors in the supply chain, can make a lifesaving difference. And the violence that followed George Floyd’s horrific death should teach us a lesson about our tightly coupled media channels. Platforms that amplify the most extreme and polarizing voices are like a too-tightly-coupled power grid. They encourage chaos to spread unchecked. A more loosely coupled communications network might just be a force for moderation.
We all need to unplug now and then.
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