The Minovsky Particle
According to the official guide of Mobile Suit Gundam, Gundam Century and Gundam Officials, the Minovsky Physics Society, while working on the reactor, encountered a strange electromagnetic wave effect in U.C.0065 within the Minovsky-Ionesco reactor that could not be explained by conventional physics. Within the next few years, they identified the cause: a new elementary particle generated by the helium-3 reaction on the inner wall of the reactor, which was named the Minovsky particle or "M" particle. The Minovsky particle has near-zero rest mass - though, like any particle, its mass increases to reflect its potential or kinetic energy - and can carry either a positive or negative electrical charge. When scattered in open space or in the air, the repulsive forces between charged Minovsky particles cause them to spontaneously align into a regular cubic lattice structure called an I-field. An I-field lattice will slowly expand and scatter into space, however, after dense interference it will take approximately 29 days before the region can support normal electromagnetic communication again.
The main use of the Minovsky particle was in combat and communication. When the Minovsky particle is spread in large numbers in the open air or in open space, the particles disrupt low-frequency electromagnetic radiation, such as microwaves and radio waves. The Minovsky particle also interferes with the operations of electronic circuitry and destroys unprotected circuits due to the particles' high electrical charge which act like a continuous electromagnetic pulse on metal objects. Because of the way Minovsky particles react with other types of radiation, radar systems and long-range wireless communication systems become useless, infra-red signals are defracted and their accuracy decreases, and visible light is fogged. This became known as the "Minovsky Effect".
The disruption of electromagnetic radiation is due to the small lattice of the I-field creating fringes that long wavelengths cannot penetrate, and that diffract wavelengths that have similar distance with the fringes. This diffraction and polarization process disrupts the electromagnetic waves. Notice in real life there is a similar experimental particle that could do the same thing in few thousandth of a second, which is still not practical but proves the theory to be correct. A second use of the I-field (and Minovsky particles in general) was the repulsion of charged plasma and chargeless mega-particles from an I-field surface, which was of use both in power generation and armament technology. If controlled, the particles can form fringes of different widths and further interfere with electromagnetic waves of shorter wavelengths. This provides the basis for the miniaturizing of fusion reactors installed in mobile suits since a controlled I-field can block the infra-red waves. This reduces the heat from the thermonuclear reaction and reduces the need for coolant and shielding for the fusion reactors. Without such a field, a pilot would be boiled alive in a few nanoseconds and the suit would burst into superheated gasses, thus explaining many of the series' casualties when the reactor of a mobile suit is pierced with a beam weapon powerful enough to disperse this I-field.
The only counter measure to the "M" particle in the series was to install bulky and expensive shielding on all electronic equipment, but only to counteract the effect it had on electronic circuitry. While this could be done for space ships and naval ships, this ruled out the use of precision guided weapons, such as guided missiles. Due to this, the military use of Minovsky particles ushered in a new era of close-range combat. This is the primary reason for the birth of the Zeon close-combat weapon: the mobile suit.