Update on FAQ for the Universe

 kw: update to book review, nonfiction, science, ultimate questions

Yesterday I reviewed Frequently Asked Questions About the Universe by Jorge Cham and Daniel Whiteson. It consists of 20 essays on questions they have received online. I have a couple of items to discuss (one is an error). This doesn't negate how enjoyable and informative the book is. These are side issues.

First, in answering "Are Humans Predictable?" the authors discuss whether neurons are subject to quantum effects. After all, they are rather small and their synapses are tiny, smaller than a bacterium. In fact, with a width of 20-40 nm, a synapse spans about 100-200 atoms. That is small enough that "shot noise", which is typically understood to be about the square root of the number of atoms involved, could be significant. In this case, it amounts to at least 1%. So, if any particular synapse misfires about one time in 100, that adds a random element into our thoughts, purely by quantum effects. 

The above is my analysis, nowhere to be found in the chapter. What I do find is an egregious error: "A single neuron is made of more than 10²⁷ particles." (p. 167) That is the number of particles in a kilogram! [Avogadro's Number, which is the number of nucleons (protons plus neutrons) in a gram of any material, is about 6.02x10²³. The number of neutrons in the average light nucleus is about equal to the number of protons, and the number of electrons equals the number of protons, so the electrons in a gram of "body stuff" come to half of Avogadro's Number. Thus the total number of particles in a gram is almost 10²⁴.] Does a neuron weigh a kilogram? No, it weighs a microgram or so, or about one-billionth of a kg. Thus the statement in the book is off by a factor of a billion.

Secondly, answering the question "Do We Live in a Computer Simulation?" the authors state that the Universe with its rules (the "laws of nature") seems very similar to a computer program…so it just might be so. Is it likely that a godlike computer nerd would program a simulation to have a basic contradiction at its core, that is, that the General Theory of Relativity drives large scale phenomena while Quantum Mechanics drives small scale phenomena, with a very fuzzy dividing line between them? That dividing "line" is at roughly atomic scale, but Buckyballs of Carbon-60 exhibit quantum interference in a two-slit arrangement. Presumably, baseballs could do so also, given sufficiently precise equipment. Furthermore, General Relativity breaks down at the center of a black hole, which is expected to be a singularity of zero size and infinite density; and Quantum Mechanics doesn't allow singularities to exist. It also occurs to me that electrons and quarks are also "described" as having zero size but finite mass, which also implies infinite density. To me it seems that if "someone" has devised a simulation in which we all are players (or maybe just me, and the rest of you are part of the environment), that "someone" has a pathological sense of humor!

A great book inspires all kinds of philosophizing!