Bad Science by Ben Goldacre Read Free Book Online

substance.”
    For perspective, there are only around 100,000,000,000,000,000,000,000,000,000,000 molecules of water in an Olympic-size swimming pool. Imagine a sphere of water with a diameter of ninety million miles (the distance from the Earth to the sun). It takes light eight minutes to travel that distance. Picture a sphere of water that size, with one molecule of a substance in it: that’s a 30C dilution. 5
    At a homeopathic dilution of 200C (you can buy much higher dilutions from any homeopathic supplier) the treating substance is diluted more than the total number of atoms in the universe, and by an enormously huge margin. To look at it another way, the universe contains about 3 × 10 80 cubic meters of storage space (ideal for starting a family); if it were filled with water and one molecule of active ingredient, this would make for a rather paltry 55C dilution.
    We should remember, though, that the improbability of homeopaths’ claims for how their pills might work remains fairly inconsequential and is not central to our main observation, which is that they work no better than placebo. We do not know how general anesthetics work; but we know that they do work, and we use them despite our ignorance of the mechanism. I myself have cut deep into a man’s abdomen and rummaged around his intestines in an operating room—heavily supervised, I hasten to add—while he was knocked out by anesthetics, and the gaps in our knowledge regarding their mode of action didn’t bother either me or the patient at the time.
    Moreover, at the time that homeopathy was first devised by Hahnemann, nobody even knew that these problems existed, because the Italian physicist Amedeo Avogadro and his successors hadn’t yet worked out how many molecules there are in a given amount of a given substance, let alone how many atoms there are in the universe. We didn’t even really know what atoms were.
    How have homeopaths dealt with the arrival of this new knowledge? By saying that the absent molecules are irrelevant, because “water has a memory.” This sounds feasible if you think of a bath or a test tube full of water. But if you think, at the most basic level, about the scale of these objects, a tiny water molecule isn’t going to be deformed by an enormous arnica molecule and be left with a “suggestive dent,” which is how many homeopaths seem to picture the process. A pea-size lump of putty cannot take an impression of the surface of your sofa.
    Physicists have studied the structure of water very intensively for many decades, and while it is true that water molecules will form structures around a molecule dissolved in them at room temperature, the everyday random motion of water molecules means that these structures are very short-lived, with lifetimes measured in picoseconds, or even less. This is a very restrictive shelf life.
    Homeopaths will sometimes pull out anomalous results from physics experiments and suggest that these prove the efficacy of homeopathy. They have fascinating flaws, which can be read about elsewhere (frequently the homeopathic substance, which is found on hugely sensitive lab tests to be subtly different from a nonhomeopathic dilution, has been prepared in a completely different way, from different stock ingredients, which is then detected by exquisitely sensitive lab equipment). As a ready shorthand, it’s also worth noting that the American magician and debunker James Randi has offered a one-million-dollar prize to anyone demonstrating “anomalous claims” under laboratory conditions, and has specifically stated that anyone could win it by reliably distinguishing a homeopathic preparation from a nonhomeopathic one using any method they wish. This one-million-dollar bounty remains unclaimed.
    Even if taken at face value, the “memory of water” claim has large conceptual holes, and most of them you can work out for yourself. If water has a memory, as homeopaths claim, and a 1 in 10 60 dilution is fine,