Could a juiced-up particle accelerator destroy the Earth?

One of the world's largest particle colliders is about to undergo upgrades that will make it considerably more powerful than it is now. The ensuing experiments will once again take us into uncharted scientific waters, prompting critics to warn of a potential catastrophe — one powerful enough to destroy our entire planet.

The world's second most powerful particle accelerator, Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC), is about to enter into its 15th year of service (the most powerful collider being the Large Hadron Collider [LHC] in Europe). The anticipated upgrades will increase the RHIC's ability to produce particle collisions by a factor of 20 over the original design, while operating at a luminosity 18 times greater than before.

Trouble is, none of this was considered during the initial risk assessment. And as pointed out by a duo of concerned legal experts in an International Business Times OpEd, the state of knowledge in nuclear physics has advanced considerably since then. Indeed, in addition to confirmation of the Higgs boson, scientists have discovered quark-gluon plasma — a liquid-like substance with a temperature exceeding 4 trillion K. It's unlike any kind of normal matter we know of, one that recreates the conditions that existed during the first seconds of the universe.

According to Eric E. Johnson, Associate Professor of Law at the University of North Dakota, and Michael Baram, Professor Emeritus at Boston University Law School, it would subsequently be a good idea to re-evaluate the potential for the RHIC to unleash an existential-scale disaster on Earth. They argue that the recently established blue-ribbon commission to evaluate the cost effectiveness of the U.S. Department of Energy's national labs should "take a sober look at one experimental program that raises a bizarre and little-discussed prospect of destroying the entire planet."

Their concern? The formation of micro black holes and small fragments of strange matter called, appropriately enough, strangelets.

Strangelets and Micro Black Holes

Critics are worried that the souped-up collider could produce strangelets — a subatomic object (a hypothetical form of quark matter that contains roughly equal number of up, down, and strange quarks more stable than ordinary nuclei) that could, under the right conditions, start a chain reaction in a runaway fusion process that would convert everything into strange matter. In the words of Sir Martin Rees, it would leave the planet "an inert hyperdense sphere about one hundred metres across."

Johnson and Baram are concerned that some proposed low energy experiments at the LHIC could actually increase the risk of creating strangelets. As noted by Lisa Lyga in Phys.org:

In the original risk assessment report in 1999, the scientists stated that "Elementary theoretical considerations suggest that the most dangerous type of collision is that at considerably lower energy than RHIC." That assessment referenced RHIC's original design energy of 100 GeV. Over the years, lower-energy experiments were performed, and the 2014 run will include three weeks at 7.3 GeV.

The other fear is that the RHIC, or other more advanced particle accelerators, could produce a micro black hole. In fact, a recent study showed that creating mini-black holes requires less energy than previously thought. Symmetry Magazine's Kelly Izlar explains:

When two particles hit dead-on at close to light speed, a small amount of energy greatly concentrates into a tiny space. If extra dimensions exist, the collision could reveal gravity's hidden strength; the energy and density could be high enough to fuse into a microscopic black hole. A micro black hole would be too small and short-lived to have much effect on its surroundings. Scientists' only clue would be a burst of extra particles.

Again, and just to reiterate, even if stable micro black holes could be produced by particle accelerators, they wouldn't be able to accumulate matter in manner dangerous for Earth. Of course, that hasn't stopped animators from speculating about what such a disaster might look like:

A Roll of the Dice?

Many of you will remember these same safety concerns back when the RHIC and LHC were first launched. To address them, various scientific and legal reviews were held, and the subsequent reports concluded that both facilities posed no conceivable threat. One of the reports (which was reviewed and endorsed by a CERN committee of 20 external scientists and by the Executive Committee of the Division of Particles & Fields of the American Physical Society), noted that the physical conditions and collision events aren't anything that doesn't already exist in nature:

The LHC reproduces in the laboratory, under controlled conditions, collisions at centre-of-mass energies less than those reached in the atmosphere by some of the cosmic rays that have been bombarding the Earth for billions of years. We recall the rates for the collisions of cosmic rays with the Earth, Sun, neutron stars, white dwarfs and other astronomical bodies at energies higher than the LHC. The stability of astronomical bodies indicates that such collisions cannot be dangerous.

But that report, and others, were published over six years ago, and as noted by Johnson and Baram, things have changed.

"The original [RHIC] report assumed the RHIC would only run for a planned 10 years. But thanks to program extensions, the RHIC is now entering its 15th year," they write. "The machine has also been continuously upgraded since the report... The suitability of models and assumptions used in the original analysis might be profitably reappraised."

So, in addition to evaluating the cost-effectiveness of the RHIC, Johnson and Baram are hoping it will receive the "the rigorous, independent risk analysis it has long warranted":

A focus on dollars is understandable in this era of belt tightening. But funding decisions for nuclear experiments ought to take risks into account as well. If dangerous strangelets are a possibility, then each additional collision of nuclei presents a roll of the dice. And when we are talking about a possible threat to the existence of the planet, even very small probabilities could be of the ultimate significance.

All this said, and in consideration of the research done to date, the risk appears exceptionally low. But the scary thing here is that we're not talking about zero probabilities. Ongoing investigations into matters such as these are obviously a prudent idea.

Other sources: Phys.org | IBS.

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