Icy claim that water has memory
Exclusive from New Scientist Print Edition
Claims do not come much more controversial than the idea that water might retain a
memory of substances once dissolved in it. The notion is central to homeopathy,
which treats patients with samples so dilute they are unlikely to contain a
single molecule of the active compound, but it is generally ridiculed by
Holding such a heretical view famously cost one
of France's top allergy researchers, Jacques Benveniste, his funding, labs and
reputation after his findings were discredited in 1988.
Yet a paper is about to be published in the reputable journal Physica A claiming
to show that even though they should be identical, the structure of hydrogen
bonds in pure water is very different from that in homeopathic dilutions of
salt solutions. Could it be time to take the "memory" of water seriously?
The paper's author, Swiss chemist Louis Rey, is using thermoluminescence to study
the structure of solids. The technique involves bathing a chilled sample with
radiation. When the sample is warmed up, the stored energy is released as light
in a pattern that reflects the atomic structure of the sample.
When Rey used the method on ice he saw two peaks of light, at temperatures of around
120 K and 170 K. Rey wanted to test the idea, suggested by other researchers,
that the 170 K peak reflects the pattern of hydrogen bonds within the ice. In
his experiments he used heavy water (which contains the heavy hydrogen isotope
deuterium), because it has stronger hydrogen bonds than normal water.
After studying pure samples, Rey looked at solutions of lithium chloride and sodium
chloride. Lithium chloride destroys hydrogen bonds, as does sodium chloride,
but to a lesser extent. Sure enough, the peak was smaller for a solution of
sodium chloride, and disappeared completely for a lithium chloride solution.
Aware of homeopaths' claims that patterns of hydrogen bonds can survive successive
dilutions, Rey decided to test samples that had been diluted down to a notional
10-30 grams per cubic centimetre - way beyond the point when any
ions of the original substance could remain. "We thought it would be of
interest to challenge the theory," he says.
Each dilution was made according to a strict protocol, and vigorously stirred at
each stage, as homeopaths do. When Rey compared the ultra-dilute lithium and
sodium chloride solutions with pure water that had been through the same
process, the difference in their thermoluminescence peaks compared with pure
water was still there (see graph).
"Much to our surprise, the thermoluminescence glows of the three systems were
substantially different," he says. He believes the result proves that the
networks of hydrogen bonds in the samples were different.
Martin Chaplin from London's South Bank University, an expert on water and hydrogen bonding, is not so sure.
"Rey's rationale for water memory seems most unlikely," he says.
"Most hydrogen bonding in liquid water rearranges when it freezes."
He points out that the two thermoluminescence peaks Rey observed occur around the
temperatures where ice is known to undergo transitions between different
phases. He suggests that tiny amounts of impurities in the samples, perhaps due
to inefficient mixing, could be getting concentrated at the boundaries between
different phases in the ice and causing the changes in thermoluminescence.
But thermoluminescence expert Raphael Visocekas from the Denis Diderot University
of Paris, who watched Rey carry out some of his experiments, says he is
convinced. "The experiments showed a very nice reproducibility," he told New
Scientist. "It is trustworthy physics." He see no reason why patterns of
hydrogen bonds in the liquid samples should not survive freezing and affect the
molecular arrangement of the ice.
After his own experience, Benveniste advises caution. "This is interesting work, but
Rey's experiments were not blinded and although he says the work is
reproducible, he doesn't say how many experiments he did," he says. "As I know
to my cost, this is such a controversial field, it is mandatory to be as
foolproof as possible."