In 1989, two scientists announced a breakthrough that was supposed to give humanity nearly free energy — then it all fell apart

In March 1989, chemists Martin Fleischmann and Stanley Pons announced at a press conference that they had achieved nuclear fusion at room temperature, in a simple tabletop electrochemical device — something that normally requires temperatures comparable to the interior of a star.

The news spread instantly, promising a virtually unlimited, clean energy source with none of the radioactive waste typical of conventional nuclear reactors.

The problem: dozens of laboratories around the world that tried to reproduce the experiment in the following weeks and months mostly failed to get the same results, and the scientific community quickly deemed the original findings insufficiently substantiated.

Since then, the topic of "cold fusion" (today more often called low-energy nuclear reactions) has remained on the fringes of mainstream physics — a small number of researchers still run experiments in this direction, but none has produced a widely accepted, reproducible result.