Homeopathy is nonsense and superstition diluted beyond all reason and given as a remedy to the grossly misinformed or scientifically illiterate. And yet there persists that very odd creature, the modern homeopath. While the practice is indistinguishable from ritual and witchcraft (with all due apologies to witches), the modern homeopath would like to cloak himself in the respectability of science. That is the path to acceptance, official recognition, and reimbursement. So homeopaths have added a new head to their hydra of pseudoscience—the memory of water.
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Homeopathy was invented (it is not accurate to say it was discovered, which would imply it has some basis in reality) by Samuel Hahnemann in the late eighteenth century. Hahnemann developed his principles of homeopathy from anecdote and superstition without any chain of scientific research, evidence, or reasoning. It is therefore no surprise that more than two hundred years later, scientific progress has failed to validate any of Hahnemann’s ideas (House of Commons 2010).
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Modern defenders have desperately tried to justify homeopathy with scientific-sounding explanations, but they have failed miserably. One such attempt is the notion that water is capable of having memory—that it can physically remember the chemical properties of substances that have been diluted in it.
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However, the evidence does not support this claim. What has been demonstrated is that water molecules form transient bonds with other water molecules, creating a larger ultrastructure—but these water structures are extremely short-lived. They are not permanent. In fact, research shows that water molecules very efficiently distribute energy from these bonds, making them extremely ephemeral. One such research paper concludes: “Our results highlight the efficiency of energy redistribution within the hydrogen-bonded network, and that liquid water essentially loses the memory of persistent correlations in its structure within 50 fs” (Cowan 2005). That’s fifty femtoseconds, or fifty quadrillionths (10-15) of a second. Contrary to Roy’s claims, water does not hold memory. In fact it is characterized by being extremely efficient at not holding memory. Scientists can argue about whether or not water can display ultrastructure lingering for longer than femtoseconds under certain conditions—but they are arguing over incredibly small fractions of a second.
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The notion that water has memory is nothing more than a restating of Hahnemann’s superstitious notion that substances can transfer their “vital essence” to other substances. Water memory is another fiction of homeopathy; it is not based upon any science and is implausible in the extreme.
http://www.csicop.org/si/show/the_memory_of_water