2) Has dark energy been measured in the lab?

• Knighted in 1992; became Astronomer Royal in 1995.
• Career choice in an alternative universe: music composer.
• Has bet $1,000 that a bioterror or "bioerror" incident will claim one million lives by 2020 (see ww.longbets.org/9).

Death and destruction are not exactly foreign themes in cosmology. Black holes can rip apart stars; unseen dark energy hurtles galaxies away from one another. So maybe it's not surprising that Sir Martin Rees, Britain's Astronomer Royal, sees mayhem down on Earth. He warns that civilization has only an even chance of making it to the end of this century. The 62-year-old University of Cambridge astrophysicist and cosmologist feels so strongly about his grim prognostication that last year he published a popular book about it called Our Final Hour.

The book (entitled Our Final Century in the U.K.) represents a distillation of his 20 years of thinking about cosmology, humankind and the pressures that have put the future at risk. In addition to considering familiar potential disasters such as an asteroid impact, environmental degradation, global warming, nuclear war and unstoppable pandemics, Rees thinks science and technology are creating not only new opportunities but also new threats. He felt compelled to write Our Final Hour to raise awareness about both the hazards and the special responsibilities of scientists.

In calculating the coin-flip odds for humanity at 2100, Rees adds together those improbabilities, including those posed by self-replicating, nanometer-size robots. These nanobots might chew through organic matter and turn the biosphere into a lifeless "gray goo," a term coined by nanotech pioneer K. Eric Drexler in the 1980s. Gray goo achieved more prominence last year after Prince Charles expressed concern about it and Michael Crichton used it as the basis for his novel Prey.

It's not just out-of-control technology that has Rees worried. Basic science can present a threat. In July 1999 Scientific American ran a letter by Princeton University physicist Frank Wilczek, who pointed to "a speculative but quite respectable possibility" that the Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) could produce particles called strangelets. These subatomic oddities could grow by consuming nearby ordinary matter. Soon after, a British newspaper posited that a "big bang machine"--that is, RHIC--could destroy the planet.

The ensuing media flurry led then Brookhaven director John H. Marburger to pull together an outside panel of physicists, who concluded that the strangelet scenario was remote, about a one-in-50-million chance of killing six billion people. (Another panel, convened by CERN near Geneva, drew a similar conclusion.) In Our Final Hour, Rees noted that the chances can be expressed differently--namely, that 120 people might die from the RHIC experiments. He thinks experts should debate in public the merits and risks of such work.

It's possible to tip the balance to civilization's advantage, Rees concludes, believing that environmental and biomedical issues should be higher on the political agenda. To raise the debate above the level of rhetoric, however, the public must be better informed. He looks to the U.S. to take a leadership role. But so far he finds its handling of the controversies over stem cell research and global warming to be wanting: the U.S. "has been rather remiss in tackling issues that are taken more seriously elsewhere in the world, especially environmental problems."

Anthropic reasoning would seem to cast a supernatural pall over science. But Rees doubts that revelations from cosmology will ever resolve the controversy between science and religion. For a start, he sees no qualitative change in the debate since Newton's time: scientific explanations remain perpetually incomplete. "If we learn anything from the pursuit of science, it is that even something as basic as an atom is quite difficult to understand," Rees declares. "This alone should induce skepticism about any dogma or any claim to have achieved more than a very incomplete and metaphorical insight into any profound aspect of our existence." Or nonexistence, depending on the coin flip.

.....

There is substantial evidence to indicate that significant global warming will occur during the 21st century. Because changes have been gradual so far, and are projected to be similarly gradual in the future, the effects of global warming have the potential to be manageable for most nations. Recent research, however, suggests that there is a possibility that this gradual global warming could lead to a relatively abrupt slowing of the ocean’s thermohaline conveyor, which could lead to harsher winter weather conditions, sharply reduced soil moisture, and more intense winds in certain regions that currently provide a significant fraction of the world’s food production. With inadequate preparation, the result could be a significant drop in the human carrying capacity of the Earth’s environment.

The research suggests that once temperature rises above some threshold, adverse weather conditions could develop relatively abruptly, with persistent changes in the atmospheric circulation causing drops in some regions of 5-10 degrees Fahrenheit in a single decade. Paleoclimatic evidence suggests that altered climatic patterns could last for as much as a century, as they did when the ocean conveyor collapsed 8,200 years ago, or, at the extreme, could last as long as 1,000 years as they did during the Younger Dryas, which began about 12,700 years ago.

In this report, as an alternative to the scenarios of gradual climatic warming that are so common, we outline an abrupt climate change scenario patterned after the 100-year event that occurred about 8,200 years ago. This abrupt change scenario is characterized by the following conditions:

The report explores how such an abrupt climate change scenario could potentially de-stabilize the geo-political environment, leading to skirmishes, battles, and even war due to resource constraints such as:

As global and local carrying capacities are reduced, tensions could mount around the world, leading to two fundamental strategies: defensive and offensive. Nations with the resources to do so may build virtual fortresses around their countries, preserving resources for themselves. Less fortunate nations especially those with ancient enmities with their neighbors, may initiate in struggles for access to food, clean water, or energy. Unlikely alliances could be formed as defense priorities shift and the goal is resources for survival rather than religion, ideology, or national honor.

This scenario poses new challenges for the United States, and suggests several steps to be taken:

This report suggests that, because of the potentially dire consequences, the risk of abrupt climate change, although uncertain and quite possibly small, should be elevated beyond a scientific debate to a U.S. national security concern.

Climate Change: Cold, Dry, Storms >>> Reduction in Carrying Capacity: Food, Water, Energy >>> National Security Implications: Border management, Global conflict, Economic malaise

To allay concerns over dwindling oil and mounting carbon residues, President Bush has proposed relying on "clean" coal, a revived nuclear industry and hydrogen cars, which he says could be widely available by 2040. Critics denounce these ideas as either impractical or environmentally outrageous, calling instead for intensified renewable energy development.

Both visions are naive. The dilemma isn't just getting enough clean energy, but getting enough energy, period. As world population quadrupled last century, power consumption increased sixteenfold. With China and India joining the industrialized feeding frenzy, by 2050 our current usage will triple. And neither Bush nor environmentalists know how to meet such demand.

To run the world on biomass fuel (a favorite idea of John Kerry's) would require dedicating an area comparable in size to all land now used for human agriculture. Because sun and wind energy aren't constant, tapping them on a massive scale not only means huge arrays of solar panels and turbines but redesigned grids with vast new storage mechanisms. Atmospheric scientist Ken Caldeira of Lawrence Livermore National Laboratory calculates that if we somehow built 900-megawatt, zero-emissions plants each day for the next 50 years, we'd barely double our current output. Even if we embraced universal nuclear power, there's far too little uranium -- unless we again accept breeder reactors, which proliferate weapons-grade fuel.

Writing in the journal Science, Caldeira and 17 other eminent American and Canadian scientists conclude that the only hope for solving the world's looming energy shortage is to consider things we've barely imagined. They propose a research blitz of previously unimagined proportions, far beyond what any politician is currently suggesting, in search of entirely new carbon-free technologies.

One of them, New York University physicist Martin Hoffert, has resurrected a notion broached during the first Arab oil crisis: orbiting solar collectors in space, where the sun appears eight times brighter, and beaming it to Earth via microwaves ("probably no stronger than your cell phone's"). In 1978, the concept involved a mirror the size of Manhattan; today the idea is smaller reflectors - - possibly balloons made of shiny Mylar -- strung around the Earth. David Criswell and John Lewis, of the universities of Houston and Arizona, respectively, set their sights higher: on the moon, where reflectors could be made from silicates and metals mined on site, rather than hauled expensively into orbit. The moon might also hold the key to practical, clean nuclear fusion, still elusive on Earth but reportedly more promising if He-3, a helium isotope found on the lunar surface and in the atmospheres of Jupiter and Saturn, is used.

Or, they write, if we can't wean ourselves from coal, then seed our own atmosphere with sulfate particles, which would form an artificial cloud cover to counteract greenhouse warming. Or hang a 2,000-kilometer-wide screen in space, which, like a permanent sunspot, might block enough solar flux to compensate for a doubling of carbon dioxide in the atmosphere. Or try to somehow harness the explosive, fleeting potential energy of antimatter. The idea, Hoffert says, is to imagine everything, however outlandish, in hopes that something proves possible. At Chicago's 1893 World's Columbian Exposition, he notes, technology exhibits for the coming century failed to predict airplanes or television.

But to go from imagination to reality requires commitment and investment. Hoffert proposes spending several hundred billion dollars a year over the next 15 years on an Apollo-scale project to force technology for clean, abundant energy. Although both Bush and Kerry declare that market incentives like emissions trading will produce solutions, Hoffert argues that major technologies of the last 50 years, from space travel to atomic power to the Internet, sprang from government mandates, not markets. "Markets only react to short-term opportunities. They're not equipped to address long-term problems like this one," he said.

Last July, Hoffert and his coauthors gathered in Aspen, Colo., with other scientists to brainstorm. Discussions included a proposal by high-altitude-wind specialist David Shepard for suspending turbines on giant kites at 30,000 feet, where jet-stream power is enormous. UC Irvine physicist and science fiction novelist Gregory Benford had a low-tech, low-cost plan: Instead of using crop wastes for biomass energy, we'd save even more carbon buildup in the atmosphere by simply burying them at sea. Much talk involved revolutionizing the electrical grid, possibly with superconductors, or by connecting the entire world so the off-peak side could power the half in shadow, as Buckminster Fuller once proposed.

The keynote speaker was Rice University's Richard Smalley, a Nobel laureate and discoverer of the fullerene, the geodesic carbon molecule named for Fuller. When these "buckyballs" align to form carbon nanotubes, they are the strongest substance known -- possibly strong enough to send a tether into space. An elevator moving along such a nanotube cable to a satellite in a fixed geosynchronous position 22,500 miles above Earth could ferry materials for space- based solar collectors far more cheaply than space shuttle launches.

On Earth, the highly conductive nanotubes might form lighter, more flexible grids, vast enough that we could move all our energy through wires rather than with tank trucks. To these grids, Smalley would connect all kinds of storage, ranging from wind compressed into airtight caves to appliance-sized home units that might be batteries, flywheels, hydrogen tanks -- whatever would let us both tap and feed the total power supply as needed.

Of course, all this is speculative -- the longest carbon nanotube produced so far measures barely half an inch. But Smalley concurs that another Apollo-like project is crucial. Not since then, he notes, have our universities been filled with engineering students inspired by a great challenge. A line graph he projected at Aspen showed the sobering result of subsequent generations diverted to Wall Street or Silicon Valley: As numbers of science and engineering PhDs plummet in the United States, in China and India they've soared.

"Suppose" he said, "from 2004 through 2009 we collect 5 cents from every gallon of oil. We invest the resulting $10 billion per year in frontier energy research. Maybe for the decade after, we collect 10 cents a gallon: $20 billion a year. At worst, we'll create a cornucopia of new technologies and new industries. At best, we'll solve the energy problem before 2020 and lay the basis for peace and prosperity worldwide."

An expensive long shot, but, as Hoffert noted, the U.S. went from the Wright brothers to the first atomic pile in less time than from now to 2050 -- when either we'll have carbon-free energy or face temperatures the Earth hasn't seen for 100,000 years.

"To continue more than another century, we'll have to do all this stuff," he said. "Otherwise, we'll use up all the coal, then maybe methane hydrates on the ocean floor. When we've completely exhausted fossil fuels, civilization will collapse. We'll go back to being hunter-gatherers. It will be much harder for the next intelligent species that evolves because they won't have cheap fossil fuel like we did. They'll have to go directly to fusion and photovoltaic cells. That may not be so easy."

No easier, probably, than imagining Bush's or Kerry's political handlers daring to float so bold a vision. The only thing harder to contemplate is what will happen if some leader doesn't, and soon.