Cold fusion

Scientists have long wondered if we could create energy through nuclear fusion at low temperatures. This idea is known as cold fusion.

Usually, fusion happens in stars or inside hydrogen bombs. These processes require temperatures of millions of degrees to work. Cold fusion would be different because it would happen near room temperature. There is currently no accepted scientific model to explain how this could work. If it were real, it could provide a cheap and abundant source of energy.

To test this, researchers used a process called electrolysis. They placed a palladium electrode inside a container of heavy water. This container is called a calorimeter, which is a tool used to measure heat.

They applied electricity to the liquid for many weeks. During the experiments, the temperature would sometimes jump from 30 °C to 50 °C. This extra heat was more than the electricity they put into the system. They called this "excess heat." They also looked for signs like neutrons and tritium to prove fusion was happening.

Many people tried to find the history of this idea. In 1927, a Swedish scientist named John Tandberg reported fusing hydrogen into helium. He used an electrolytic cell with palladium electrodes just like later experiments. Later, in 1989, Martin Fleischmann and Stanley Pons made the most famous claims. Fleischmann was a leading scientist at the University of Southampton. Pons worked at the University of Utah. They announced their findings at a press conference in March 1989. This announcement caused a massive sensation in the news.

Many details from these experiments are still studied today. The researchers used heavy water, which contains deuterium, to run their tests. They found small amounts of neutrons and tritium during their work. These tiny amounts are usually only found from cosmic rays or natural decay. In 1989, the United States Department of Energy reviewed the results. They decided the evidence was not convincing enough to provide funding. A second review in 2004 reached the same conclusion.

Many scientists eventually labeled the field as pathological science.

Even though most scientists moved on, some interest remains. A small community of 100 to 200 researchers still investigates these effects. They often use different names like low-energy nuclear reactions or CMNS. In 2019, a failed replication attempt was even published in the journal Nature. This shows that people are still curious about these unusual heat changes. It is a bit like a mystery that people cannot stop trying to solve. They hope to find a way to make the science work correctly.