| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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COUNTERPOINTS Energy Crises in Heaven and Earth
Lately I've been immersed in two different kinds of energy crises. The daily newspapers report on the power shortage we Californians are experiencing, with rolling blackouts and escalating power bills. Meanwhile, the weekly journals Nature and Science bring updates from a larger arena-the whole universe. To cosmologists, our earthly annoyances are trivial compared to the surprises that have hit them in the past few years. Just when they thought the Big Bang had explained almost everything we see out there in the galaxy and beyond, three immense and mysterious new energy sources have emerged. While we suffer on the home front from too little power, the rest of the cosmos appears to have much too much. Both these energy crises stem from a lack of understanding. The astrophysicists don't understand the scientific basis of their newly observed phenomena. California's politicians don't understand how to manage and allocate the available energy sources.In space, astronomers are detecting cosmic rays with a billion times the energy of anything we can create in an accelerator. No one knows where these penetrating particles originate or how they are generated. Furthermore, astronomers say, they shouldn't be reaching the Earth at all. As particles speed through space, they lose energy by colliding with interstellar material and cosmic background radiation. Current physical theory predicts that no cosmic rays should exceed a calculated energy, but the rays being regularly detected are far more energetic than the cut-off. Since conventional theories can't explain them, it's likely that the rays are sending us messages about the origin of the universe, or of a new physics as yet unknown on Earth. Another strange energy source in space is the gamma ray burst. Unlike cosmic rays, gamma rays are generated by nuclear reactions in stars and are not detectable at Earth's surface because they are absorbed by air molecules. When the Compton Gamma Ray Observatory was launched into orbit far above the atmospheric barrier, about once a day it registered powerful sources of gamma rays that lasted only a few seconds. These bursts, which can come from any direction in the sky, show by their red shift that they are billions of light years away, meaning they had occurred fairly early in the history of the universe. (The wavelength of light moving away is lengthened-shifted to the red end of the spectrum-just as we hear a departing train whistle shifted down to a lower tone.) Gamma-ray bursts are the most energetic displays ever perceived. Each one is equivalent to burning the entire mass-energy of the sun in a tenth of a second. The physical process that produces them so far remains a mystery.Super-energetic cosmic rays and gamma ray bursts are astounding, but more fantastic still is the recent discovery by several astronomers that some weird force is driving the expansion of our universe and accounts for two-thirds of the energy in it. Observations of supernovae in other galaxies seem to prove that the universe is not only expanding, but the rate of expansion is accelerating. When we look through telescopes at other galaxies, we're looking back in time, because the light left those distant universes as much as billions of years ago. Since gravity tugs all stars and galaxies toward each other, its force should be putting the brakes on the rate of expansion. Therefore, the more distant galaxies should be receding faster than the nearer galaxies, which have had a longer time to be slowed by gravitation. But in fact, it's the other way around, the exact opposite of what cosmologists expected. This "dark force" has resuscitated one of Albert Einstein's discarded ideas. When he was formulating his new theory of gravitation early in the 20th century, Einstein tried to explain why stars and galaxies remain about the same distance apart despite the gravitational force drawing them together. To offset gravitation, Einstein hypothesized a universal repulsion between celestial objects that required adding a fudge factor he called the Cosmological Constant to his equations of general relativity. When Edwin Hubble observed in the 1920s that galaxies are actually rushing away from each other, as though the universe had begun with a Big Bang, the Cosmological Constant was no longer needed, and Einstein called it the biggest blunder he had ever made. But he may have spoken too soon. Along with these new energy riddles, we are still puzzling over the older one of dark matter. Visible stars account for only a fraction of the gravitational mass of galaxies. No one knows what the rest of it, the dark matter, consists of. By Einstein's famous equation, mass is also a form of energy, so there's an awful lot of hidden energy lurking out there. A rough inventory of energy in the universe indicates that 4 percent of it is conventional matter, 20 to 30 percent dark matter, and 66 to 76 percent the dark energy driving cosmological expansion. It's ironic that John Horgan, editor of Scientific American, wrote a book five years ago called The End of Science: Facing the Limits of Knowledge in the Twilight of the Scientific Age. His thesis was that we understand so much of how the world works, that with relativity, quantum mechanics, and the Standard Model of elementary particles, the rest is just dotting the iotas and crossing the taus. He worried that scientists in the 21st century wouldn't have any important problems to work on. Well, here we are in the very first year of the 21st century with 96 percent of the cosmic structure admittedly beyond our present comprehension. It seems like a pretty good time to be getting into basic science. We have known for decades that the four percent we think we do understand, including quasars, pulsars, white dwarfs, red giants, and all the stars, shine because of nuclear fusion reactions taking place in their interiors. But in a universe bathed in nuclear radiation, expanding by nuclear forces, shining by nuclear power, many members of the only species that has (so far as we know) any comprehension of these matters dread all things nuclear. Down here on Earth, in the beautiful state of California, we wish we could tap into some of these superfluous sources of celestial energy. Instead of dark matter, dark forces, and dark energy, we have dark houses and dark factories. Instead of cosmologists trying to explain world-shattering rays, bursts, and blasts, we have politicians trying to explain why they haven't been able to repeal the law of supply and demand and the law of the conservation of energy. Fossil fuels are frozen sunlight, and so the energy we get from burning them can ultimately be considered a form of nuclear power. However, these fuels have been processed through carbon life forms-our ancestors and their relatives-and have picked up some nasty latent pollutants, notably carbon monoxide and carbon dioxide. Meanwhile, nuclear fission itself, which, to date, is the only realistic alternative to fossil fuels, has been anathema in both California and the nation. Following the political principles of NIMBY (Not In My Backyard) and NIMTOF (Not In My Term Of Office), California built no new power plants for a dozen years. Meanwhile, Silicon Valley, other industries, and the growing population have sucked up more and more power. This has left us at the mercy of suppliers in other states, who have charged what the traffic would bear. Instead of talking about how myopic they were to get us into this situation, our political leaders blame the Texas suppliers for being so greedy. The energy needed to keep our five thousand shopping malls air-conditioned is infinitesimal compared to the galactic and extragalactic sources observed. But we're almost totally dependent on our mother star, the sun, whether it's in the form of fossil fuels or the diurnal toasting that keeps our bodies and environment in the viable temperature range. Feeding on nuclear fusion deep inside herself, the sun delivers the luminous milk that nourishes our planet and keeps life chugging along. Many scientists now believe the greatest long-term threat to life on Earth is the rising atmospheric temperature due mainly to carbon dioxide from fossil fuels trapping the sun's heat and creating a "greenhouse effect." Fossil fuels also produce acid rain and air pollution that impair the quality of life and cause lung diseases, from which many thousands die each year. The only significant nonsolar source of commercial power on Earth is nuclear fission. There's no evidence that anyone has died from nuclear power in this country. Even the glitch at Three Mile Island, which scared the wits out of millions, did not cause a single death. Nuclear power, which in California provides about 20 percent of our energy needs, has both a great advantage and a great disadvantage. The great advantage is that nuclear reactors don't contribute greenhouse gases to global warming. The great disadvantage is that the "ashes" of the fission process are potentially dangerous, long-lived, nuclear wastes.Nevertheless, broad scientific illiteracy spares people from balancing the benefits and risks of each form of power themselves and leads them to focus on nuclear perils whipped up by an hysterical media, which ignores or downplays the familiar but far greater damage currently being caused by fossil fuels. After several decades of not building any new nuclear plants in this country, concern about global warming has led people to reconsider the issue and the possibility that the byproducts of nuclear power may in fact be less hazardous than those of fossil fuels. This past June, Richard Muller, a climatologist from University of California at Berkeley, participated in an American Association for the Advancement of Science symposium at the University of California at Irvine titled "What Scientists Think They Know about Science." Muller told his audience that carbon dioxide is the most toxic pollutant in the world today because it causes global warming. He went on to say that he thought all power stations that burn fossil fuels should be replaced by nuclear reactors, and that those who oppose nuclear power are "pseudo-environmentalists" whose efforts are likely to destroy rather than protect Earth's ecology. Antinuclear sentiments are hardly new. Twenty years ago, a publisher asked me to write a book about energy. The project came to a grinding halt when I presented the chapter on nuclear power. As a scientist trained in nuclear physics and nuclear medicine, I tried to offer a balanced account of the pluses and minuses of nuclear power. My editor, a nonscientist, refused to acknowledge that there could be any positive aspects of nuclear power. Like many then and now, he was certain that everything nuclear was evil. After a few sessions of fruitless debate, we agreed to abandon the effort.Although opposition to nuclear power remains widespread, it is not universal. France, which lacks natural fossil fuel reserves, derives 75 percent of its energy from nuclear reactors. A few years ago when I was visiting some friends in the Loire Valley, they proudly took me on a tour of their neighboring nuclear plant. The elegant engineering and professionalism of the operation impressed me. La Belle France manages to maintain excellent safety records and makes enough excess power to supply neighboring nations such as Germany. In Germany, on the other hand, antinuclear sentiment is fierce, and the present government, under pressure from the Greens, has decided to phase out all of its 19 nuclear stations, which supply nearly one-third of the nation's power. They propose to replace this loss with renewable sources, mainly wind power. In Germany last summer attending a scientific conference, I traveled for three hours between Jena and Dresden, and saw many large windmills punctuating the landscape. It was one of the hottest days of the year, with power demand at its peak, and not a rotor was moving in the still air. If this program is carried out, Germany may find itself in the same dependent relationship with France that California now has with Texas. It's a marvelous opportunity for Gallic revenge on a current competitor and historical enemy. Meanwhile, having experienced a few outages, Californians seem to be changing their minds about nuclear power. A recent Field Poll found that 59 percent now favor building more nuclear reactors, a reversal from the sentiments of a few years ago. Even if it should become politically possible to build them, years or decades would pass before nuclear sources could come on line. For now, the state is frantically constructing gas, diesel, and coal burners to belch more heat-trapping gases into the globe's protective sheath. After reviewing the energy crises in heaven precipitated by new phenomena beyond our understanding, and the local one on Earth due to innumeracy, political posturing, and unwillingness to understand what is already well known, we are left with some crucial questions. How do super-cosmic rays break their theoretical energy barrier? What makes distant suns dissolve into gamma rays in the blink of an eye? What is the composition of the dark matter that so greatly outweighs everything we can see? What mysterious force drives our universe to expand faster than gravity can rein it in? And finally, one more immediate conundrum closer to home: Why can't California, the fifth largest economic powerhouse on planet Earth, get its scientific and political act together to keep the lights on? Jerold M. Lowenstein is professor of medicine at the University of California at San Francisco. jlowen@itsa.ucsf.edu |
