Clearing Fusion Off the Table Top
Most of the news media seem to have uncritically swallowed the exciting news out of Utah about “fusion on a table top.â€
In light of the laws of nature, it is probably worth putting the matter straight.
It is possible for two deuterium (heavy hydrogen) nuclei to undergo fusion with the release of a good chunk of energy, about a 50th of what is released in the more familiar nuclear fission. The sun gets its energy from similar processes. To do so on Earth, on an economic scale, has been an objective of programs in most of the industrialized nations for many decades. But progress has been slow, the prospects for ultimate success uncertain and the programs costly. The reason for the problems is that deuterium nuclei are electrically charged. They repel each other and heroic measures are necessary to bring them close enough to permit fusion. We mortals cannot change those facts; we can only strive to work through them.
Given the mysteries of quantum mechanics, however, there is always a certain level of fusion that occurs even with the ordinary deuterium molecule, which undergoes what is called spontaneous fusion every so often. The problem is that “every so often†means about once every X years, where X is a number so large, followed by 63 zeroes, that it is far, far longer than the age of the universe. So there is no rule against “it†happening, but we shouldn’t hold our collective breaths waiting. People have been seeking ways to speed up this so-called cold fusion process, and there have even been some good ideas that failed. It is not an empty dream.
Did the Utah team achieve cold fusion? No. Most scientists have responded to this question from the media with diffidence: We know so little. Of course we have learned to be cautious, but the answer in the case of the reports out of Utah should have been unambiguous, if only to cut off the kind of wishful thinking with which the country is now awash. The fusion process produces energetic radiation (that’s where the energy comes from), and half the time an energetic neutron (a familiar sub-atomic particle). If the Utah scientists had really produced cold fusion at any substantial level, they would have been bathed in a deadly beam of neutrons that fried them to a crisp. If they had produced as much as a watt of power through fusion, there would have been over a trillion neutrons per second, which would be lethal in a very short time. That they lived to hold their press conference is clear and unambiguous proof that they did not produce any noticeable amount of power through cold fusion.
Why do we care? Because the provision of adequate energy sources for the future is a major responsibility of the scientific community, and it is not made easier when cheap and easy solutions to hard problems find their way into the body politic. When the Department of Energy goes to the Congress for support for the real (and expensive) fusion program, they will have extra trouble because there will be those who really believe there are easy answers. There may be, but these are not the ones. Such distractions impair our will to attack the hard jobs. Of course we dream of breakthroughs, that’s what dreams are for, but then we wake up.
Spontaneous fusion is possible. It happens naturally, though at an excruciatingly slow rate. It is not a new idea. Anything that can speed up that rate by about 10 factors of a million would be wonderful. There was a great idea a couple of decades ago that the process could be speeded up by the necessary amount by using muons, another kind of short-lived subatomic particle that can only be made in an accelerator (though muons are the prime ingredients of the cosmic rays that rain on us from the skies). That idea barely worked, and there are reputable people still trying to improve it.
What the muon does is to attract both of the deuterium nuclei and bring them together to distances less than a 100th of normal--and that makes a big difference. There are technical reasons why it didn’t quite work, but the principle was sound. Anything short of bringing the nuclei much closer together won’t work, and in particular, atomic processes such as embedding them in a metallic matrix don’t even come close. This isn’t to say that it is impossible to speed up the spontaneous fusion process--the closer the nuclei, the faster it goes--but only that there is too far to go.
The media have confused the possibility of enhancing spontaneous fusion, which is real, with the possibility of enhancing it enough to provide sensible amounts of energy on a table top, which is not. This is not just a matter of factors of two, but of one followed by 60 or 70 zeroes.
Enhanced fusion per se shouldn’t bother us, and should be hailed as a marvelous discovery and a beautiful demonstration of the laws of nature, provided the discovery stands the test of peer scrutiny. Sufficiently enhanced cold fusion to make useful amounts of energy in ordinary matter, without the discovery of a new subatomic particle like the muon, would mean that all we know about the science of electrons, deuterons and solids is completely wrong, not just slightly wrong. Of course it could happen, but if I were a bookie, I’d happily make book on that.
