The End of the World As We Know It?

Richard A. Posner does not impute nefarious motives to researchers conducting high-energy particle collision experiments. But in his latest book, Catastrophe, Posner does suggest that one of these experiments could trigger a “strangelet scenario”—a chain reaction that will condense the entire Earth into a tiny ball just 100 meters in diameter.

Posner is not a scientist: rather, he is a law professor at University of Chicago and a federal appellate judge on the Seventh Circuit. Rumor has it Posner was considered—briefly—for the post of Harvard Law School dean in 2003. (He quickly took himself out of the running for the job.)

Beyond the legal world, Posner is renowned as a prolific and insightful scholar: he is the author of more than 30 books, and—according to one list—number 70 on the list of most frequently-cited public intellectuals alive. (Granted, Posner did compile the list himself.)

Posner argues that his background as a lawyer and an economist need not disqualify him from opining on the “strangelet” question. Fifty pages of footnotes attest to the fact that Posner is no scientific dilettante. But is he an alarmist?

THE END OF THE WORLD AS WE KNOW IT

Posner considers a slew of world-ending scenarios with REM-style enthusiasm. He reports one scientist’s estimate that there’s a 1 in 100,000 chance of an asteroid smashing earth in any given year and killing a billion people. Alternatively, Posner speculates, “superintelligent robots” might turn on their human creators and “kill us, put us in zoos, or enslave us.”

Several of Posner’s disaster set-ups feel like they’ve been ripped from the scripts of Hollywood blockbusters (think Armageddon or The Matrix). But his strangelet scenario deserves special consideration here at Harvard because particle accelerators figure prominently in the work of several of the University’s most prominent physicists.

Posner blows the whistle on the Relativist High Ion Collider (RHIC)—affectionately known among physicists as “Rick”—a federally-financed research facility on Long Island.

RHIC, which generates high-energy subatomic collisions between gold ions, quietly opened for business in 2000. Even RHIC’s sharpest opponents calculate the risk of a world-ending “strangelet scenario” to be very, very small. According to Posner, an upper-bound estimate of the danger of a strangelet disaster is 1 in 500,000 over the 10-year period for which RHIC will be in operation. An alternative estimate from Swiss and Israeli scientists puts the danger at 1 in 500 million. But although the likelihood of a strangelet catastrophe is minimal, should we be playing the odds with the future of mankind?

Posner takes a midpoint between the two disaster estimates, and he posits—for the sake of argument—that the likelihood of a world-ending strangelet scenario over the next decade is 1 in 10 million. In other words, there’s a 1 in 10 million chance that 6 billion people will die at some point in the next decade because of RHIC. Thus on average, we would expect RHIC to kill 60 people per year. Is that a sacrifice we should be willing to make to push the frontiers of physics forward?

Admittedly, the results of the RHIC experiments could be fascinating. They could “give us insight into the conditions of the early universe, and perhaps also the mechanics of super-dense conditions in black holes,” according to Physics Department Chairman John Huth.

But are those insights worth dying for?

After reading Catastrophe, I spent several sleepless nights worrying about the 600 innocent souls who—in our hypothetical world of risk-benefit analysis—will be swallowed alive by an out-of-control strangelet sometime in the next decade. I was so furious that I started rounding up fellow socially-minded Harvardians to head to RHIC’s Upton, N.Y. home and protest this travesty. In a fearful fury, I decided to check with Harvard’s crack team of experimental high energy physicists to see whether Posner’s calculations are on-target.

SAFE AT ANY SPEED

The verdict was a unanimous “no.”

“I don’t believe there’s any such risk at any particle accelerator,” George W. Brandenburg, director of Harvard’s High Energy Physics Lab, wrote in an e-mail.

“I would say the risk is, for all intents and purposes, zero,” Huth added.

“I just don’t think it’s a concern,” Leverett Professor of Physics Gerald Gabrielse said in a telephone interview. “It should sell some books, though.”

If the conditions in RHIC could produce a strangelet disaster, physicists argue, then we would probably be dead already.

“[T]he concentration of the energy (which is what matters for creating new and exotic particles) achieved by RHIC is much less than what Tevatron has been doing for many years,” Associate Professor of Physics Masahiro Morii wrote in an e-mail, alluding to a federally-financed accelerator west of Chicago.

And the energy concentrators reached inside the Tevatron are child’s play on a cosmic scale. According to Morii, “the universe has its own ways of accelerating particles to energies that we experimental physicists can only dream of.”

Gabrielse said that high-energy collisions that could be produced inside RHIC already occur—naturally—on the lunar surface. “There have been highly energetic cosmic rays colliding with the moon for a long time, and these sorts of things don’t seem to have happened,” Gabrielse said.

To Posner’s credit, Catastrophe does anticipate Gabrielse’s counter-argument. Posner writes that “a cosmic ray hitting a fixed target such as the moon will tend to scatter the nuclei that it hits, making it less likely that they will clump”—and thus produce strange matter—“than if the collision were head on,” as it would be inside RHIC. So, the fact that the moon has existed for 4.5 billion years without condensing into a tiny ball does not necessarily refute Posner’s argument.

But Harvard physicists’ rejection of Posner’s calculation suggests the risk of catastrophe posed by RHIC might fall within a margin that most of us would be willing to tolerate.

YOUR MONEY OR YOUR LIFE

Americans seem willing to incur some costs in the name of science—as indicated by the fact that Congress is picking up RHIC’s $2 billion tab.

But how can we monetize the minimal risks to human existence posed by particle accelerators?

Here, Posner turns to North Harvard Yard—and specifically, to Cogan Professor of Law and Economics W. Kip Viscusi ’71.

In a 2003 paper, Viscusi and economics grad student Joseph E. Aldy ask: how much income are we willing to forego in order to decrease our risk of mortality?

For example, how much of a pay cut would a police officer be willing to take for a less dangerous beat? How much are consumers willing to spend on smoke detectors or bicycle helmets?

By multiplying the cost of these precautions by the probability that they will avert an untimely death, Viscusi and Aldy seek to gauge “the value of a statistical life.”

The authors conclude that “the value of a statistical life for prime-aged workers has a median value of about $7 million in the United States.”

So is the price-tag for life on earth equal to the Viscusi and Aldy figure—$7 million—multiplied by the global population (roughly 6 billion)?

Not quite, Posner explains.

First, Viscusi and Aldy’s method would produce a much lower estimate for “the value of a statistical life” in a Third World country, where workers might—out of necessity—accept much greater risks for higher pay. (Many will find this observation so repugnant that it renders the entire “statistical life” approach illegitimate.)

Second—and this is perhaps Posner’s most perplexing point—we tend to value our lives less as the risk of mortality grows more remote.

Princeton philosopher Peter Singer argued in a recent New York Times review that Posner’s argument on this point is “bizarre.” But upon closer examination, it seems rather intuitive.

As Posner notes, it would take quite a large wad of cash—perhaps many billions of dollars—to convince most of us to engage in a round of Russian roulette, where the probability of death is one in six.

Yet at some point, we are unwilling to pay any more money for a slightly better safety belt. That doesn’t mean we place zero value on our lives. But ultimately, Posner writes, “the difficulty…that people have in grasping miniscule probabilities would cause them to ignore the risk completely and thus demand zero compensation for bearing it.”

According to Baird Professor of Science Gary J. Feldman, “the public is very poor at risk analysis, let alone risk-benefit analysis.”

“[R]isk-benefit analysis is only useful if the risk is non-zero,” Feldman wrote in an e-mail. “But in the strangelet scenario, “the risk is sufficiently close to zero that risk-benefit analysis is not helpful.”

GLOBAL WARNING

But Posner’s analysis is helpful when one considers several catastrophes in which the risk is more substantial.

For example, Posner argues quite sensibly for bolstering efforts to reduce global warming. And he calls on ordinary citizens to beef up their math skills so that they can make educated choices in the face of catastrophic risks.

Perhaps most importantly, Posner’s book sends a strong message to us humanities and social sciences concentrators. Our physicist friends seem to be not guilty of endangering the Earth with their expensive particle accelerators. But just as science concentrators don’t docilely demur on questions of politics and economics, we should keep an eye on the folks hunkered down in Harvard’s state-of-the-art labs.

Posner is one of two prominent economists to wander into the tricky realm of the natural sciences in recent months. (The other, our esteemed University president, is thanked for his advice in the preface of Catastrophe.) Just as Lawrence H. Summers’ sojourn into behavioral genetics elicited several less-than-rave reviews, Posner gets mixed marks from physicists for his musings on subatomic matter.

But as Posner writes, “social control of science cannot be left to the scientists.” In challenging his readers to wade into the arcane debate over strangelet disasters, Posner brings particle physics to the masses. By framing cost-benefit calculations in lucid prose, Posner helps the non-economists among us make decisions in the face of unlikely but potentially earth-shattering risks.

So run to The Coop and pick up a copy of Catastrophe. But on the way, follow Posner’s risk-reducing advice: strap on a bicycle helmet, buckle up your safety belt, look both ways before you cross the street…and watch out for particle physicists on the loose.