What if water had memory? By Mark Lorch , University of Hull Homeopaths believe water has memory. That is how they explain the “medicinal properties” of their concoctions. Apparently people are treated even though the pill or potion may not contain a single molecule of the medicinal agent. But does water really have memory? That depends on how you define memory. If for water it is defined as the property to have a stable state for sometime, then it has memory, just not a very good one – 50 femtoseconds is its retention time . That’s about 60 million million times shorter than the mythical goldfish’s three-second memory. But with that “memory”, water could not retain any useful information. The memory is just its ability to form an ordered group of water molecules that can last for 50 femtoseconds. It is a bit like a crowd of people all milling around in train station – there are pockets of order where people are standing around looking at departure boards or getting a coffee...