No matter how many times you proofread a manuscript it seems there are always some errors that slip through. Then of course once the book is published you have quite a large number of potential proofreaders and I’m happy to say that many of them have written to me pointing out errors that need correcting. In many cases these are typos of one sort or another, but that nonetheless can create confusion or even worse misinformation. In a couple of other cases your corrections have been more fundamental and in some cases kind of interesting in themselves. Below is a list of those that and have been pointed out to me or that I have discovered, but I’m quite sure that it’s not complete.

The most egregious, and most embarrassing, error is the one I will dispose of first. Several readers have pointed this out to me. It has to do with the calculation of neurons and glial cells in the brain after the new work by the laboratory of Brazilian (I think I called her Argentinian – too much Malbec perhaps) neuroscientist Suzana Herculano-Houzel. Professor Herculano-Houzel, fortunately a friend, was kind enough to write me and say nice things about my book, and then gave me the following correction –

“The average number of brain neurons that we found (you have 80 instead of 86 billion, and it would be nice to have that number right, now that we have it, exactly so that this wrong number doesn’t become, as you say, true as the result of repetition, not experiment); and, if you do the math, we’re missing not 120 billion cells, but (1,100 billion (100B neurons + 1,000B glia) – 171 billion (which is 86B neurons + 85B non-neurons)) = 929 billion cells, faaaar more impressive than a meager 120 billion cells.”

So now you have it directly from the source.

Fred Baker of Minnesota noted that on page 141 I state that the natural log of 100 trillion is about 36. In fact, as Fred points out, “the natural log of 100 trillion is closer to 32 (32.24 actually) instead of 36.” He is absolutely correct. There are two interesting things about this error. One is that it arose because I was being a bit sloppy, using a short cut to make the calculation (although why I needed a shortcut since I have a calculator and could have done it in less than 5 seconds, I don’t know). The shortcut is that e is 2.71828 and therefore 1/e is about 0.36, so I took the reduction to be about 36. Sloppy. And thank you to Fred Baker for bringing this to my attention.

But the other interesting thing about this error is that it doesn’t matter that much. 36 and 32 are certainly within an order of magnitude of each other, and in the context of the calculation (how many memories the brain could form – either a linear multiple of 100 trillion (say 100 trillion divided by 500, about 200 billion) or the natural log of 100 trillion then the difference between 32.24 and 36 is negligible. I’m not excusing the error, merely pointing out that sometimes an error of 3.76 can be devastatingly large and other times it is all but insignificant. Take shortcuts when you can, but be sure they are not dangerous ones.

Bill Robertson wrote to point out that on page 41 I refer to the Cretin’s paradox, and this should be the Cretan’s paradox. I was in fact ignorant (in the bad way) of this myself. Cretan, I have now learned, refers to the philosopher who first enunciated what is now also know as the liar’s paradox, Epimenides, who was from Crete, i.e., a Cretan and not a race of mentally retarded dwarf liars. What is remarkable about this is that I had seen it as Cretin for so long it never occurred to me to question it, and indeed Google accepts Cretin and gives you a list of references ot the Cretin’s paradox. So this is another one of those examples of supposed knowledge that is completely wrong but sticks in the literature anyway. Thank you to Mr. Roberston for the correction.

A particularly egregious error occurs on page 170 where I give the date of Galileo’s publication of his famed Dialogue Concerning the Two Chief World Systems, as 1652. This would have been impossible since Galileo died in 1642. I am sure this was a typo because I know very well when Galileo died, as everyone should – it was the same year that Newton was born. Galileo’s famous publication saw light in 1632.

Several readers have pointed that I mistakenly have Noble for Nobel on p57. This is one of those cases of an overactive spell checker; in tow other instances I corrected i t back to Nobel, but missed this one. Although one reader wondered if I did it on purpose as a wry comment on the prize committee. Wish I was that clever.