Homeopathy is a supposed medical practice based on the ideas that "like cures like" and that dilution increases potency – ideas that contradict all known medicine, chemistry and physics. Despite clinical trials showing that it has no effect beyond that of a placebo, it remains one of the dominant alternative medicines.
The absurdities underlying homeopathic medicine are well documented. Given that homeopathic remedies are typically diluted to the point that not even a single molecule of the active ingredient remains in solution, there is no plausible mode of action. Purported explanations for homeopathic efficacy, such as claims that water has a "memory" of substances previously dissolved in it, would overturn most of modern science if true. The evidence available indicates that homeopathy works solely through the placebo effect and that homeopathic claims can be dismissed as fantasy.