Ballotechnic materials are materials that react very energetically when subjected to a shock, without losing their solid (or liquid)1 form. Unlike common high-order explosives, these materials do not release hot gases, but rather stay solid when they release this energy. An often discussed example of this is red mercury.
Red mercury is a type of mercury salt, with the formula Hg2Sb2O7, which is then irradiated in a nuclear reactor. It is claimed that this substance has a density of over 2.0x104 kg m-3, which is extremely high, especially for an oxide. And, as mentioned, it is a ballotechnic material, which means it releases unimaginable amounts of energy when subjected to a shock.
Great, but why is this interesting?
The main reason why this is so interesting is that if red mercury does what it claims, it can be used in the construction of powerful hydrogen bombs. A normal hydrogen bomb works by using a fission explosion to compress a deuterium-tritium mixture so it ignites by fusion. This is rather inconvenient, as created by a fission explosion is not something one does with stuff found in the shed. Deuterium and tritium are very easy to obtain, although I won't give pointers how. The idea is to use red mercury, or another ballotechnic material to create the high temperatures and pressures necessary for fusion. Such a device is called a ballotechnic nuclear bomb, and if were to exist, it would be as dangerous and powerful as it would be small.
The terrorists will kill us all!
The idea of a nuclear bomb that is constructed from readily-available materials plus some red mercury and that is as easy to conceal as, say, the kilos of drugs that are readily smuggled into every country of the world, would no doubt make Evil People very happy. There is, unfortunately for them, a small if: all of it depends on the magic of our ballotechnic material. I will now try to show you why the existence of a ballotechnic material is not very likely, based on the above claims. There is little info available on how such a ballotechnic material would do its thing, so I'll give two possible scenarios. I am a physicist, but not really an expert in explosives, so it could be I missed an elaborate explanation for this phenomenon.
Or won't they?
A ballotechnic material, as mentioned, is characterized by releasing enormous amounts of energy while remaining solid when subjected to a shock. Releasing lots of energy when being subjected to a shock is hardly an uncommon property of materials, in fact, that's how explosives work. The shock breaks molecular bonds, and the material turns into a hot, high-pressure gas due to the heat released.
However, a ballotechnic does not turn into a gas, at least, not instantaneously. It is claimed to be capable of holding its solid state while being heated to fantastic temperatures, while having its chemical bonds ripped to shreds and reorganized. This is very unlikely. Furthermore, the temperature needed to produce fusion is many millions of K, not something even remotely reachable with the energy density in the chemical bonds in solids, not to mention the fact that a solid will turn into a rapidly expanding plasma in nanoseconds when subjected to such temperatures. This can be readily seen when one considers a typical chemical bond represents an energy of a few electronvolts, which corresponds to a temperature of a few tens of thousands K-far less than the millions needed for fusion.
Slightly less unlikely is the suggestion that the the energy is nuclear in origin. It is, however, consistent with the fact that the suggested material, red mercury, is neutron-rich and therefore probably unstable. This does ignore the fact that nuclear reactions tend to require enormous amounts of energy to trigger, orders of magnitude more than conventional explosions. Furthermore, this material will also not remain solid when subjected to the kind of temperatures needed to initiate fusion.
Apart from the physical argument, there is a second argument which may be more appealing to the lay person. A normal scientific discovery is published in scientific journals or maybe a conference. Especially in the former case, they are scrutinized by the editor, and subsequently by one or more peer reviewers. The more outrageous the claim-and ballotechnic properties are quite outrageous-the more serious the scrutiny. A search for papers revealed exactly one serious hit, and that is a theoretical study rather than experimental evidence. One would expect that something as shocking as a ballotechnic material would receive more coverage, in respected journals, if it were real.
The fact there is little if any peer-reviewed evidence, the fact that it seems to fly into the face of conventional physics and the fact the claims are quite wild, but lack detail, suggest that this is not a real material, but rather, a scare tactic. The fact that there are a lot of things written in nonscientific publications on red mercury, but nothing in scientific publications 2 is almost the litmus test for a scientific hoax. The main propenent of the existence of these materials, Sam Cohen, the father of the neutron bomb, stands alone in his opinion, and his opponents include physicists such as the great Edward Teller, who calls it "nonsense".
If they exist, the properties of ballotechnic materials make them very suitable for the creation of small but very potent nuclear weapons. However, as their properties seem to defy the laws of physics
, and there is no evidence
whatsoever, despite the attention to the subject, it is almost certainly a hoax
1: When you are dealing with intense shocks and high temperatures, the difference between liquid and solid behavior is not important on the short time scales we are interested in, and I will not make this distinction in this WU. It's mainly density that matters.
2: If we exclude the red mercury salt HgS, which has a nice red color but has no claimed ballotechnic properties