My good friend Stavros pointed out that my previous post requires more explanation in places. I'll begin with a brief discussion of Nobel Laureate Brian Josephson. The other topics I'll write about later or leave to Stavros.
Josephson is a major personality in solid state Physics, particularly semiconductors. His work was instrumental in developing silicon microchips and justifiably earned him the Nobel Prize in Physics. In the years since his ground-breaking research, however, he has fallen victim to some of the claims of pseudo-science.
As a brief digression that does not do the subject justice, there is a marked difference between what we commonly call science and what we commonly call pseudo-science. Science involves forming hypotheses (or theories or educated guesses—take your pick of terminology) about how an effect comes about, and then through experiments trying to determine if that hypothesis is supported. Ideas are never proven, they only withstand disproval. Scientific hypotheses are obligated to account for what we observe (that is, what we think we know). We refer to this characteristic of scientific hypotheses as falsifiability, and scientists generally frown upon hypotheses that are not falsifiable—hypotheses that cannot be shown to be false. Further, science places the burden of experiment on the proposer of a hypothesis, either to perform experiments himself or to suggest experiments to other scientists. In contrast, pseudo-science makes hypotheses that purport to explain effects which might be real or might be contested, but these hypotheses need not conform to current knowledge not lend themselves to experimental testing, and the pseudo-scientist typically neglects experimental confirmation entirely.
As science has progressed, the theories have become more and more complicated (as a rule), making it difficult for the lay individual to judge at first blush whether an idea is credible or not. In addition to falsifiability, credibility requires that the theory account for relevant well-established phenomena. Most people only hear the jargon of science, used to describe credible research, and consequently throwing terms like "quantum", "resonance", or "electromagnetic" into an explanation can make the purest hogwash sound scientific.
Scientists are supposed to know better, at least when a theory overlaps their areas of expertise. In the case of Dr. Josephson, the expertise lies in Physics, and the pseudo-science is homeopathy. He is not alone; a regrettable number of other scientists have lent their names and reputations to equally undeserving ideas when they should have known better.
Homeopathy begins with the idea that, in dilution, harmful substances can confer a healing or preventative benefit. On its face, this does not seem entirely unreasonable, since it resembles the practice of vaccination. While homeopaths are quick to point out this similarity, homeopathy actually derives from the "law of similars," one of the bases of Medieval magical theory. Homeopathy takes the idea of dilution even further, with the hypothesis that if a little of a substance is a good thing, then less is even better. Certainly, it's less likely to cause illness. The most "potent" homeopathic preparations are so dilute that there is not even one molecule of the active substance in any commercially available quantity.
If this sounds odd, it should. A useful analogy might be a flashlight that grows brighter as its batteries fail. Homeopaths recognize this absurdity, and attempt to explain it away by claiming that water has a "memory" of substances dissolved in it to the point of effective non-presence.
Someone with a high-school level of science education should be highly suspicious of this claim. A water molecule comprises two hydrogen atoms and one oxygen atom. The manner in which these atoms bind to one another is well understood, and leaves little room to store information. In addition, the molecules in a fluid are in constant random motion. Again, there is little room for a "memory" of once-present substances.
This reasoning should make anyone skeptical of homeopathy. Still, homeopaths make claims, and these claims are falsifiable. The burden of demonstration lies with the claimant, so these homeopaths are obligated to perform properly controlled experiments testing their hypotheses if they expect anyone else to take them seriously.
James Randi has a long-standing challenge to the purveyors of pseudo-science and other delusions. If they can demonstrate their claims under rigorous experimental conditions, they will win one million dollars. Mr. Randi has had an ongoing conversation with prominent homeopaths in an attempt to have them submit their claims to such experiments. I'll let Mr. Randi have the last word on this topic: "That challenge, folks, is the one thorn the quacks cannot remove from their collective foot. It's always there, being dodged and belittled, devalued and denied. But it remains."