kelvin@fourmilab.chWith the recent reports of electrochemically-induced cold fusion of deuterium has come reexamination of other mechanisms that have been claimed to or might theoretically induce fusion, in addition to the gravitational, magnetic, and inertial confinement routes which are well-researched.
One little-known mechanism that may be worth of study, particularly if one anticipates the advent of atomic-level fabrication of mechanisms, is the phenomenon of ``piezofusion.'' Experiments have detected neutron emission consistent with d-d fusion when a crystal of lithium deuteride is fractured [Klyuev86]. This is believed to be the consequence of deuterons being accelerated by KEv electric fields generated by a propagating crack in the crystal. This can be thought of as the subatomic analogue of crunching wintergreen Life Savers in the dark.
If real, this observation suggests that mechanically compressing atoms, particularly when mechanical advantage can be employed in conjunction with an electric field, might induce fusion. If a randomly propagating crack in a crystal can cause fusion, how much more effective a job would a molecular-scale machine, designed to grab atoms of deuterium, neutralise their electron shielding, and mash them together in the manner of a diamond anvil press, which on a desktop can generate some of the highest pressures ever created in the laboratory?
If we could fabricate a nanomachine with an covalently bound backbone, employing mechanical advantage to induce fusion, we might be able to build an ``atom masher,'' which would release energy by fusion under benign conditions. Whether the energy released by fusion interactions would destroy the machine and, if so, whether it would exceed the energy needed to construct the fusion press are many of the secondary issues that may render the concept fruitless even if it isn't totally bogus in principle.
Also worthy of informed speculation is whether atomic-scale engineering might construct surface or volume-action catalysts which could increase the number of fusions cataysed by a muon during its lifetime of 2 microseconds from the 100 or so measured in a mix of liquid deteurium and tritium to the 100,000 needed to break even energetically--one imagines fabricating pellets so engineered that they would emit an energy pulse when bombarded by a muon beam--like laser-induced pulse inertial confinement but on a tiny, tiny scale. [Cohen&Davies89, McCevoy&O'Sullivan89]
Molecular catalysis in nuclear transmutation is suggested by one of the classics of crank biochemistry, Biological Transmutations, C.L. Kervran, 1971. Anecdotal reports of heavy metal transmutation in poultry also exist.
Cohen, J. S., and Davies, J. D., Nature 338, 705 (1989).
McCevoy, A. J., and O'Sullivan, C. T. D., Nature 338, 711 (1989).
Kervran, C. L., Biological Transmutations, Beekman Publishers: Woodstock, NY, 1966-1971-1980.