Physics for Bird Brains

Quantum weirdness helps explain how plants make food, animals migrate and humans think.

By John Gribbin, WSJ
July 31, 2015 4:41 p.m. ET

There is a sense in which all of biology is quantum biology. The entangled strands of DNA, the famous double helix of the molecule of life, are held together by a quantum phenomenon known as hydrogen bonding. The way in which those strands untwist and build new double helixes during the process of reproduction is at heart a quantum phenomenon, closely related to the way in which quantum entities such as electrons can be both wave and particle at the same time.

In their remarkable book, “Life on the Edge,” Johnjoe McFadden, an expert in molecular genetics, and Jim Al-Khalili, a quantum physicist, join forces to explain many everyday aspects of life in terms of what is often referred to as quantum weirdness. After teasing the reader with an introduction presenting the puzzle of how birds can detect the Earth’s magnetic field and use it for navigation, the authors lead us gently by the hand through discussions of the nature of life itself, right down to the molecular level and the mysteries of quantum physics. This is material that has been covered in many books but nowhere more succinctly and clearly than here. The authors have an easily accessible style, free from jargon, that can make complex issues clear even to the non-scientist.

Life on the Edge
By Johnjoe McFadden & Jim Al-Khalili
Crown, 353 pages, $28

Thus prepared, we are ready for an explanation of what they call “the quantum robin”—the workings of the magnetic sense organ in birds and other animals. It turns out that this ability is linked to the phenomenon known as “entanglement”: Entanglement involves two or more quantum entities, such as electrons, being in some sense in tune with each other, so that when one of them is prodded the other one twitches—even when they are separated by great distances. And in certain circumstances, as Messrs. McFadden and Al-Khalili explain, this makes molecules in the animal’s sense organ sensitive to the direction of a magnetic field.

(More here.)