Materials science explores the properties of substances—solid, liquid, gas, plasma. But a materials engineer, Dr. David Foster, became fascinated by theoretical materials that occupied multiple states simultaneously. In his 1998 research, he proposed a 'phase-shifting metal' that could oscillate between solid and liquid instantaneously, allowing for weapons applications—a blade that could flow like water yet cut like steel. The theoretical paper was published in a respected journal. Eighteen months later, the journal issued a retraction, citing 'security concerns.' No explanation was provided. When Foster asked why, he was informed that such materials had theoretical existence only and should not be described in accessible literature. Foster shifted to materials that had no weapon applications.

A weapon designer in the 1980s, contracted by a government agency, was given specifications for a melee weapon with impossible properties: it should be both liquid and solid, flow but remain intact, cut without thickness. He spent two years trying to design something that matched the specifications while obeying physics. One day, his supervisor visited and said: 'Stop trying to engineer it. We already know it exists. We're trying to understand how it exists.' The project was abandoned. The designer left the industry and became a philosophy professor. He has never published his work from that period.

On materials science subreddits, when discussion turns to theoretical materials, one comment appears occasionally from deleted accounts: 'Liquid metal weapons theoretically exist if someone has cellular control over their own composition. I saw a paper on this once. It was retracted.' That comment triggers lengthy discussions about what materials could be weaponized by a single individual. One engineer replied: 'If someone could control their physical composition at will, they wouldn't need weapons. They would be the weapon.' That comment has 50,000 upvotes but has never been expanded on.