Saturday, November 21, 2015

Transmutation As an Energy Source

Perhaps we on Earth are not as close to asymptotic technology as we think. Transmutation of elements, otherwise referred to as alchemy in ages past, might be part of asymptotic physics but we are unaware of simple means of doing it. Current methods of transmutation involve either reactors or particle accelerators. In the first, a flux of neutrons from the fission of uranium is funneled into a target, where the neutrons are absorbed and the atomic weight of the target material increased. Decay processes of the resultant nucleus lead to a nearby element, the result of the transmutation. In the second, charged particles are emitted and either directly impacted on a target medium, or used as the energy source in a neutron generator, where neutrons are freed from a nucleus like deuterium and then proceed to do the same thing a reactor-generated neutrons.

Neither of these methods is suitable for making industrial quantities of desirable elements, and they have the side effects of producing undesired radioactive elements which have to be dealt with. The cost of the equipment is also large, especially in comparison with the tiny amount of material that can be produced. The methods are used for some specialist purposes, such as the production of certain radioactive isotopes which are used in medical treatments and measurement devices used, for example, for finding flaws in cast metals. Any object other than cast metals can also be scanned, and devices like x-ray scanners can be produced based on the radioactive output of these materials. Radioactive isotopes can also be produced for power sources for interplanetary probes or remote locations on Earth. Amounts of materials produced, however, are small in comparison with industrial uses, and cleanup methods for removing co-produced radioactive isotopes must be employed before these isotopes are ready for use.

An alien civilization which used certain non-radioactive elements or specific isotopes industrially might be able to produce them in a more efficient way. At this point there is no confirmed method on Earth of doing it, but nuclear physics is not a field that has explored all the corners of science where such a method might be lurking. The theory which is used to predict nuclei properties is not solvable in most situations, and the data used in it is not all collected. Progress continues and will continue for some time.

The most elementary view of nuclear physics comes from the curve of binding energy, which is the amount of energy released upon the formation of some nucleus divided by the number of nucleons, protons and neutrons, in it. The curve is like a bathtub, with iron at the bottom, and hydrogen at one end and the transuranics on the other. Fusion produces energy by nuclei at the lower end moving toward the center, and fission does by nuclei at the upper end moving toward the center. Both of these are energy sources, the first happening in the sun and providing us with photons, and the second being used for nuclear power plants, based on the amounts of uranium we dig out of the Earth’s crust.

The curve of binding energy is better seen as a pond, with the two variables describing it being the number of neutrons and the number of protons in the nucleus. The bottom of the pond is very bumpy, not smooth, as there is a great deal of structure in a nucleus. There are no known sources of energy that arise from moving from one bump to another except for the use of radioactive elements in radioisotope power generators. The problem in using the transmutation of non-radioactive isotopes for power sources is the non-radioactivity, which is another word for stability. Nothing happens unless a means for affecting the nucleus is done, such as by hitting it with a particle.

There is a current buzz in our media about doing this, under the name of Low Energy Nuclear Reactions, and the claim is that there are pathways to releasing the energy between these binding energy bumps that do not require much input energy. No substantiated claims or confirmed theories exist, nor do any replicatable experimental setups, but a small hubbub exists concerning yet unsubstantiated claims and unconfirmed theories. These claims and theories do not have the same level of quality as nuclear physics in major institutions would require, and likely have little substance. However, that does not mean that an alien civilization, which has a complete understanding of both nuclear physics related to nuclei, and methods of concentrating energy on some particles and delivering it to a stable nucleon, could not have discovered a method or methods of exploiting the bumps in the two-dimensional surface of binding energy
The fact that we have not discovered such a phenomena is not any indication of its non-existence. A look at the extensive investigation that was required to locate higher-temperature superconductors indicates how elusive such a goal might be. Other examples for the chemical industry exist and likely elsewhere.

If the alien civilization did that, and it only worked with a few elements or isotopes, or even one only, it might serve as a power source that could replace radioisotopic power generators, or even become more widely used. If the method extended to multiple elements or isotopes, transmutation could be used to develop more substantial sources of certain isotopes, perhaps even some materials that they might use in small quantities in certain applications, such as dopants for semiconductors.

What effect might this have on our projections of star travel? Little. This source of power does not have the energy concentration of antimatter, far, far from it. It likely would not have the same power density as a well-designed reactor for an interstellar probe. But exactly how much it could provide is even more a mystery that its existence. Nothing to do but wait and see.

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