Dilution
by Berg
Image Text: Dear editors of Homeopathy Monthly: I have two small corrections for your July issue. One, it's spelled "echinacea," and two, homeopathic medicines are no better than placebos and your entire magazine is a sham.
Homeopathy is a form of alternative medicine which makes bold claims as to its efficacy without offering any sound science to back it. Although the angles from which one can viably attack homeopathy are as diverse as they are numerous, this particular panel is taking on serial dilution. In a serial dilution, a substance is dissolved in solution. The solution is then divided, and diluted. This dilution is then divided and diluted, and then the dilution of the dilution may be divided and diluted again, and again, and again.
While serial dilution does serve a function in many legitimate procedures, homeopathic remedies prepared using serial dilution are often diluted so much that none of the original substance remains in the final preparation. This point was proven dramatically by noted skeptic James Randi at TED 2007, when he ingested a purportedly lethal dosage of homeopathic sleeping pills on stage. Spoiler alert: James Randi is still alive.
So, back to the comic. The couple in question is preparing a serial dilution of semen and expecting its potency to either remain constant or perhaps increase, resulting in a pregnancy. However, we the ever-so-well-informed xkcd reader know full well that if James Randi isn't dead, then that lovely young woman isn't getting pregnant. If she can't get pregnant, then she can't pass on whatever part of her or her partner's genetic makeup it is that makes them susceptible to a belief in homeopathy. Since the couple's belief in homeopathy is negatively affecting their ability to have offspring, its lowering their fitness (Darwinian fitness, not gym membership fitness). A belief in homeopathy which is so strong that it prevents it's believers from having offspring is therefore an evolutionary dead end, and is not selected for.
This point is underscored by the image text, which is playfully realized in this comic as a letter to the editors of Homeopathy Monthly, a fictional homeopathy magazine which we can imagine is of some import the homeopathic community. The jab against homeopathy is set up with a classic use of the foot-in-the-door technique, opening up with a nitpicky correction about the spelling of "echinacea." Now that the editors of homeopathy are paying attention, the payload is delivered and their passion is called out for being what it is: a complete sham.
July 12th, 2010
Homeopathy is based on two perfectly reasonable propositions:
1. The way to cure an illness is to take something which causes that illness.
2. The smaller the dose, the greater the effect.
I’m sure that, like Alice, there are 4 other perfectly reasonable propositions Homeopathists believe as well.
A 30X dilution, as mentioned in the strip, would dilute the original substance by 10^30 with water. With an sperm count of 10 million/ml, a 30X dilution would yield (on average) 1 sperm per 100 million cubic kilometers of homeopathic fertility preparation.
July 13th, 2010
Great point; this is actually critical to fully understanding the comic. Google searching confirms that there are two standard dilutions in homeopathy, “X” and “C.” A number preceding X indicates that the substance has been serially diluted 1:10 that number of times. A number preceding C indicates that it has been serially diluted 1:100 that number of times.
Thus, as Buddha Buck indicated, the “30X” dilution that Randall mentions is not a 30-fold dilution, but instead a 10^30-fold dilution. The only way one can ever have any material left in a substance that is “30X” diluted is to start with >1 Mmol (gegamol).
Since I estimate a given sperm to have an approximate mass of 5*10^-11 g (or ~3*10^13 amu), 1 Mmol of sperm would be ~3*10^19 g. Of course, only ~15% of human sperm are viable, meaning that you’d really need ~2*10^20 g of sperm; this is something like the mass of the Pacific Ocean.
July 13th, 2010
oops, 1 Mmol is a megamol, not a gegamol…
July 13th, 2010
I laughed my ass off when an ad for homeopathic alternatives came up underneath your explanation.
July 13th, 2010
1. Why would diluting something make it more potent? If they want to get pregnant, don’t they want a non-diluted sample?
2. So there is no such thing as Homeopathy Monthly?
July 14th, 2010
A search of the Internet reveals there are monthly magainzes dedicated to homeopathy, but none named “Homeopathy Monthly.”
I laughed out loud when I did the search. . . more than half of the hits are this comic and web discussion thereof.
August 4th, 2010
Being a bit of a stickler, I should point out that according to homeopathy “theory” the active ingredient in a dilution cures the condition that it would normally cause in non-diluted form. Therefore, being inoculated with a diluted sperm solution would cure pregnancy.
And yes, the homeopathy faithful do indeed believe that the more you dilute the ingredient, the stronger the curative effect becomes, even after there is no active ingredient left, because the water hold a “memory” of the active ingredient.
November 8th, 2011
…*its* lowering their fitness (Darwinian fitness, not gym membership fitness). A belief in homeopathy which is so strong that it prevents *it’s*…
Your apostrophe has wandered to the wrong “its”.
…*it’s* lowering their fitness (Darwinian fitness, not gym membership fitness). A belief in homeopathy which is so strong that it prevents *its*…
November 11th, 2011
It’s irrelevant whether it’s “it’s” or it’s “its”, isn’t it? Honestly, I don’t care how many English teachers or grammar sticklers argue this point. The possessive and the contraction should *both* be spelled “it’s”, since the applicable rules both indicate it’s use in that instance. As far as I’ve ever been able to discern, the only use of “its” should be a pluralization. It’s common sense (something English rules rarely follow). If you disagree, I challenge you to form a sentence which confuses the two: It’s obvious, as it’s context always acts as a clue to it’s meaning no matter how many its there are.
This is a rule which should be corrected.