There are a number of technologies associated with Tech Level 9, notably protium fusion, antimatter production and use, and A-grav. While these may sound like unrelated technologies, they are all based on the same principle: the control of weak interaction forces. Prior to TL9, the electromagnetic force was the only force truly under human command.
With control of the weak interaction force, it became feasible to fuse two protons into a deuteron. This meant that it was no longer necessary to sift out the small fraction of deuterium contained in natural hydrogen; it could be created at will. This drastically dropped the price of deuterium to 1-10% of its previous cost. This has boosted fusion back to the main energy source in most location, though solar energy is still competitive in certain situations. Conversion of protium to deuterium produces only a small amount of energy (by nuclear standards) and with thermal and neutrino losses, little or no useful power is produced by the operation. However, the resultant deuterium can be efficiently fused into helium, releasing large amounts of energy. Efficient deuterium production plants tend to be large, so most fusion-based spacecraft use deuterium as fuel and do not contain protium to deuterium converters. There are, however, a few exploration vessels that do carry p-d converters, allowing refueling from any locally available hydrogen source.
Isotopic field generation, commonly known as "A-grav" is probably the most ubiquitous of the weak force technologies. Despite its common name, it actually is due to a weak-force field that pulls "up" quarks in one direction and "down" quarks in the other direction. Since protons consist of two "up" quarks and one "down" quark while neutrons consist of one "up" quark and two "down" quarks, protons and neutrons will be pulled in opposite directions. The direction an object will be pushed or pulled depends on the relative concentrations of protons and neutrons in the body. Humans, being mostly water, are proton rich. Objects of heavier atomic number, such as iron, are neutron-rich. Planetary bodies may be either. While isotopic field generators are now commonly used for local levitation and for planet-to-orbit transfers, care is required: an isotopic polarity that is repulsive over one surface, such as water, may prove attractive over areas containing metal ores. These attraction differences are generally also believed to account for the sickness experienced by most species subjected to strong isotopic fields. The most common explanation given is that sodium and chlorine are both repelled by a field tuned to attract proton-rich materials, but that this is the actual cause of "a-grav sickness" has not been conclusively demonstrated. The short-range "a-grav" fields commonly used to make surfaces repulsive or attractive actually use combined electroweak forces which either attract or repel both proton-rich and ferromagnetic materials. Most common materials are either one or the other, so they are generally quite effective. However, some materials are not, and will be attracted to what is commonly regarded as a repulsive field; as such, occasional polarity reversal is needed to properly clean these materials. For antimatter storage, very strong pure short-range weak field generation is used; both anti-hydrogen and anti-methane are proton-rich. The occasional proposal to use anti-helium is nonsense.
In addition to providing for its storage, weak field technologies have also provided for the efficient generation of antimatter. Previously, proton-antiproton generation was a somewhat hit-and-miss proposition produced by colliding particles together, normally electrons and positrons, also producing a variety of undesired mesons. However, with the application of sufficiently strong and properly tuned combination of electro-weak fields, protons and antiprotons pairs can be directly boiled from vacuum. This does, of course, require significant amounts of energy. Despite the all too common talk, antimatter is not an energy source, merely a very efficient energy storage mechanism.
All the weak force technologies require weakly interactive massive particles (WIMPs) for operation. WIMP concentrations and current flows differ profoundly across the Cluster, making WIMP collection and interstellar transport one of the most important parts of interstellar trade. Systems that would otherwise be unimportant backwaters have become wealthy due to the WIMP currents present. Some extra-stellar regions have been proposed for WIMP collection; however, the transport times and costs currently make this uneconomical.