Edge can be an interesting venue for mounting a serious conversation about the blackout of August 14th. Within the community is invaluable expertise in many pertinent







areas, not to mention the intelligence that the "Edgies" can bring to the subjects. I am asking for "hard-edge" comments, derived from empirical results or experience specific to the expertise of the participant..... — JB

Participants: Steven Strogatz, Albert-László Barabási

Steven Strogatz

How the Blackout Came to Life [8.22.03]

With so much focus on the Ohio energy firm whose lapses may have triggered the blackout of 2003, it's been hard to remember that the real question is not how it started, but why it spread so far and so fast. Rather than tackle that question head-on, most commentators have reached for the usual metaphors: it was a chain reaction, a cascading failure, a domino effect. All of these are borrowed from the physical sciences. Maybe a better way to look at it is in biological terms.

We already use the language of epidemiology when we speak of "viruses" propagating across the Internet, "infecting" our computers. Likewise, it's tempting to view the blackout, spreading from link to link along the power grid, as a pernicious kind of electrical contagion. But that's not quite the right metaphor, either. The blackout was not caused by an infectious electrical disease; it was caused by the grid's immune response to the threat of such a disease. In other words, the grid suffered a violent allergic reaction, a sort of anaphylactic shock.

Just as the symptoms of a severe allergic reaction are caused not by the offending bee sting itself but by the overzealous response of the body's immune system to it, so the blackout was aggravated by the grid's attempt to defend itself, one power station at a time. Threatened by a torrent of electrical energy gone berserk, or overwhelmed by the sudden loads placed on it, each power plant in turn tripped its circuit breakers, detaching itself from the grid. Though this strategy achieved its desired aim - saving each plant's generator from being damaged - it was too myopic to serve the best interests of the grid as a whole.

What is needed is a more subtle, coordinated mode of response. When our own immune systems are performing at their best, they orchestrate their defenses through countless chemical conversations among T-cells and antibodies, enabling these defenders to calibrate their response to pathogens. In the same way, the thousands of power plants and substations in the grid need to be able to communicate with one another when any part of the system is breached, so they can collectively decide which circuit breakers should be tripped and which can safely remain intact.

The technology necessary to achieve this has existed for about a decade. It relies on computers, sensors and protective devices tied together by optical fiber so that all parts of the grid would be able to talk to one another at the speed of light - fast enough to get ahead of an onrushing blackout and confine it.

The sensors would continuously monitor the voltage, frequency and other important characteristics of the electricity coursing through the transmission lines. When a line appeared at risk of being overloaded, a computer would decide whether to switch on a protective device. At present, such decisions are made purely parochially. Power plants defend themselves first, and don't worry about the consequences for neighboring plants on the grid. Nor do they consider any potentially helpful or harmful actions that those neighbors might be taking at the same time.

In the new approach, each plant would have nearly instantaneous information about all the other plants and power lines in its extended neighborhood. Everyone would know what everyone else was doing and thinking. As threats arose (either from random failures or malicious attacks), the sensors would fire a flurry of warning signals down the optical fibers, and the networked computers would decide which protective devices to activate to contain the threat most effectively. The grid would then be responding as an integrated entity, not as a ragtag collection of selfish units. It would look a lot like an organism defending itself.

Granted, such a distributed control system would cost billions of dollars and, in this era of deregulation, there would be little incentive for energy companies to join forces and build it, especially when the big money is in power generation. But the construction of a systemwide immune network would be well worth the cost. Without it, our overburdened grid is likely to fail more and more often, and might even collapse, with costs that would be incalculable, both economically and in terms of national security. State and federal governments need to step in and provide incentives for utilities to do the right thing.

Of course, even if this new kind of smart defense system were to be built someday, one can already imagine an insidious disorder that might eventually outsmart it and afflict it, a catastrophic disruption of the immune system itself, rather than the grid it's supposed to protect. Such a thing would be the technological analog of AIDS.

A grim prospect, perhaps, but a realistic one. We need to stop pretending that the grid is ever going to be a perfectible machine. Just as bacteria eventually develop resistance to the antibiotics used to kill them, the defense of the grid will require ever-more inventive strategies on our part. We should recognize that the power grid needs to evolve and adapt, just like any other successful living creature.

Steven Strogatz, professor of applied mathematics at Cornell, is author of Sync: The Emerging Science of Spontaneous Order.[Editor's Note: First published as an Op-Ed Page article in The New York Times on August 25th.]

Albert-László Barabási

We're All On The Grid Together [8.22.03]

Once power is fully restored, it will take little time to find the culprit: most likely, it will be a malfunctioning switch or fuse, a snapped power line or some other local failure. Somebody will be fired, promotions and raises denied, and lawmakers will draw up legislation guaranteeing that this problem will not occur again.

Something will be inevitably missed, however, during all this finger-pointing: this week's blackout has little to do with faulty equipment, negligence or bad design. President Bush's call to upgrade the power grid will do little to eliminate power failures. The magnitude of the blackout is rooted in an often ignored aspect of our globalized world: vulnerability due to interconnectivity.

In the early days of electricity, all power was produced locally. First each neighborhood, later each city, had its own power plant. Local generators had to satisfy the peak demands of hot summer nights, when everything from air-conditioners to televisions run full power. That means that the generators were idle most of the time outside of peak hours.

That extra capacity was shared as utilities learned to decrease costs by connecting their facilities and helping each other out during peak-demand periods. The current power grid linked up formerly isolated systems with enough wire to stretch to the moon and back. It requires only a computer keystroke to redirect power produced in New York to the Midwest.

With thousands of generators and hundreds of thousands of miles of lines, the network became so interconnected that even on a normal day a single perturbance can be detected thousands of miles away. This created a whole new set of problems and vulnerabilities, the effects of which have been felt by millions in the past two days.

Because electricity cannot be stored, when a line goes down, its power must be shifted to other lines. Most of the time the neighboring lines have no difficulty carrying the extra load. If they do, however, they will also tip and redistribute their increased load to their neighbors.

This occasionally leads to a cascading failure — a series of lines becomes overburdened and malfunctions in a short period of time. This is exactly what happened in August 1996 when, because of unusually warm weather, a 1,300-megawatt power line in Oregon sagged, hit a tree and went dead. Power was redistributed automatically but the other lines also failed, causing a blackout in 11 Western states and two Canadian provinces.

Cascading failures are common in most complex networks. They take place on the Internet, where traffic is rerouted to bypass malfunctioning routers, occasionally creating denial of service attacks on routers that are not equipped to handle extra traffic. We witnessed one in 1997, when the International Monetary Fund pressured the central banks of several Pacific nations to limit their credit. That started a cascading monetary failure that left behind scores of failed banks and corporations around the world.

Cascading failures are occasionally our ally, however. The American effort to dry up the money supply of terrorist organizations is aimed at crippling terrorist networks. And doctors and researchers hope to induce cascading failures to kill cancer cells.

The effect of power blackouts, economic crises and terrorism can easily be limited or even eliminated if we are willing to cut the links. Strictly local energy production would guarantee that each blackout would also be strictly local.

But severing the ties would also cripple the network. Shutting down international trade would surely eliminate the impact of the Japanese central bank on the American economy, but it would also guarantee a global economic meltdown. Closing our borders would reduce the chance of terrorist attacks, but it would also risk the American dream of diversity and openness.

The events of the past few days — unwanted side effects of our network society — are just one of the periodic reminders that we live in a globalized world. While celebrating that everybody on earth is only six handshakes from us, we need to accept that so are their problems and vulnerabilities.

Most failures emerge and evaporate locally, largely unnoticed by the rest of the world. A few, however, percolate through our dense technological and social networks, hitting us from the most unexpected directions. Unless we are willing to cut the connections, the only way to change the world is to improve all nodes and links.

Albert-László Barabási, a physicist at Notre Dame, is author of Linked: The New Science of Networks.

[Editor's Note: First published as an Op-Ed Page article in The New York Times on August 16th.]