Water memory was a controversial experiment claiming to provide an explanation supporting homeopathy. The results were largely dismissed as being tainted by experimental error.

One possible mechanism invoked was that water molecules, on account of being polar, would form a structured network, thus storing information about other molecules they had been in contact with. I wonder if it is possible to disprove this explanation with an entropy argument. If water molecules did arrange themselves in such a fashion, this would have an effect on their entropy, which in turn would impact other thermodynamic functions such as Gibbs free energy. In other words, it might be possible to look for such an entropic effect by looking at deviations from expected behavior in a steam table. Would the magnitude of such an effect be measurable ?

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    $\begingroup$ It might not appear at the temperature values of steam. Think crystallization. Maybe a phase diagram measurement would show if the liquid phase is not continuous en.wikipedia.org/wiki/Multiphasic_liquid . as far as entropy, no. crystals exist because the system liquid-crystal is the one that conserved entropy, thus the crystal can have diminished entropy. $\endgroup$ – anna v Feb 22 '15 at 8:53

Quite simply, no.

Water memory doesn't appear to violate any physical laws, and the claims made about it are not well-defined or specific enough to be falsified (e.g. with an entropic argument). It's revealing that while a scientist could be convinced that he's wrong, there's nothing that could change the mind of a homeopath.

The best we can do is test the specific mechanisms that have been proposed to produce a memory effect.

For example, most homeopathy theories revolve around some sort of persistent water structure, and this structure would presumably be the result of hydrogen-bonded networks. But it's well-established from experiment as well as computer simulations (e.g. ab initio MD) that hydrogen-bonded networks last for a matter of femtoseconds and therefore could not give rise to long-lasting memory effects.

Indeed, there does not currently exist any plausible mechanism (or evidence) for water memory that does not contradict well-established science. And for this reason the scientific community does not accept it. But, as was seen to be the case with Jacques Benveniste's work, if some evidence were to arise for it then the scientific community would be willing to take it seriously and investigate.

  • $\begingroup$ Re: "there's nothing that could change the mind of a homeopath": That's an interesting assertion. Homeopathy used to be a relatively mainstream field of inquiry, while today it is decidedly on the fringe. While that change obviously could have occurred without any individual homeopaths changing their minds, I wonder if you have any reason to think that it did? $\endgroup$ – ruakh Feb 22 '15 at 19:44
  • $\begingroup$ If a homeopath is unconvinced by the latest evidence (specifically the meta-analyses, which are conclusive) then nothing will convince them. $\endgroup$ – lemon Feb 22 '15 at 19:50
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    $\begingroup$ Who said that a homeopath "is unconvinced by the latest evidence (specifically the meta-analyses, which are conclusive)"? Perhaps (s)he's simply unaware of it, or hasn't looked into the details? Your line of reasoning seems to be, "I know that homeopaths are wrong, so they should know they're wrong -- and if they don't, it must be because they're incapable of changing their minds!" That's pretty facile. $\endgroup$ – ruakh Feb 22 '15 at 20:26
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    $\begingroup$ @NewAlexandria I would argue that it is this postmodern relativism that you seem to be pushing that is hurting science by creating an unhealthy scepticism towards it. $\endgroup$ – lemon Feb 25 '15 at 18:20
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    $\begingroup$ I have decided to upvote you as a gentlemanly close to our civil disagreement $\endgroup$ – New Alexandria Feb 25 '15 at 21:09

Entropy argument might not work here, because amount of information is going to be influenced by number of moles, not by arrangement of individual molecules. In the same fashion as 1TB hard-drive is 1TB no matter what is written onto it. However, more precise crystal structures will tell you exact picture stored in those bits. So measuring, essentially, temperature of different water samples might not be useful.

I would like to also make a note on lemon's reply. In my opinion, rate at which hydrogen bonds are broken and created cannot be addressed here. Just consider Conway's Game of Life spaceships: individual elements change value with rate of game's clock, but structure all together is stable and information is stored.

  • $\begingroup$ Your first paragraph is wrong: a 1TB hard drive containing only zeroes contains much less information than a 1TB hard drive containing the results of a trillion coin flips. Your second paragraph makes no sense to me at all. What do spaceships have to do with clocks and hydrogen bonding between water molecules? $\endgroup$ – David Richerby Feb 22 '15 at 13:41
  • $\begingroup$ ok, my mistake. I talk about Game of Life and spaceships, not just random crafts. $\endgroup$ – aaaaaa Feb 22 '15 at 16:57
  • $\begingroup$ Also, since 1TB of zeros contain no information, hard-drive of scrambled, say reversed, jpges contain same information as disc full of nice pictures. $\endgroup$ – aaaaaa Feb 22 '15 at 17:04
  • $\begingroup$ @aandreev: Not the same information, but the same quantity of information. Maybe even more. $\endgroup$ – Ben Voigt Feb 22 '15 at 19:18
  • $\begingroup$ yes, that is what I meant, amount of information, or entropy $\endgroup$ – aaaaaa Feb 22 '15 at 19:21

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