Water memory

Water memory is the purported ability of water to retain a memory of substances previously dissolved in it even after an arbitrary number of serial dilutions. It has been claimed to be a mechanism by which homeopathic remedies work, even when they are diluted to the point that no molecule of the original substance remains, but there is no theory for it.

Water memory is an example of pseudoscience and contradicts the scientific understanding of physical chemistry and is generally not accepted by the scientific community. In 1988, Jacques Benveniste and colleagues published a study supporting a water memory effect amid controversy in Nature,^[1] accompanied by an editorial by Nature's editor John Maddox^[2] urging readers to "suspend judgement" until the results could be replicated. In the years after publication, multiple supervised experiments were made by Benveniste's team, the United States Department of Defense,^[3] BBC's Horizon programme,^[4] and other researchers, but no one has ever reproduced Benveniste's results under controlled conditions.