Life_on_the_Edge: Coming of Age of Quantum BiologyJim Al-Khalili and Johnjoe McFadden
The book is pillared on Erwin Schrödinger’s "What is Life?", written in 1943, based on a series of public lectures given at Trinity College Dublin and spoken of with almost reverence by the authors. The concept of life and consciousness is quintessentially the most thought-provoking question ever posed by humankind. The suggestion that quantum mechanics may lie at the defining edge between ‘live’ and ‘not-alive’ should invoke interest in the modern day scientist. This way "Life on the Edge" proposes "at least one of the missing pieces in the puzzle of life found within the world of quantum mechanics.”
In this book the authors, introduce two of the fascinating quantum physics phenomena, quantum tunneling and quantum superposition, via a number of seemingly commonplace biological topics: the homing precision of a migrating Robin, enzyme reactions at ‘normal’ temperatures, photosynthesis, and the anatomy of smelling. Most of us are familiar with quantum phenomena thanks to the advent of technologies such as electron microscopes, fast processors and MRI scanners. The weirdness of particles (or rather dual nature) in quantum systems is superposition of states until an observation is made goes well with 'gadenken' experiments like “Schrodinger's cat”. The act of observing the cat - alive or dead - forces the quantum states to become only one. This 'de-coherence’ of states is what separates the quantum world from the classical physics of our everyday world.
The macro world of biology, and everyday other occurrences, is shielded from the weird quantum stuff via thermodynamics - an aspect that has remained the debate between Einstein and Bohr (with Heisenberg). Many animals employ the Earth’s magnetic field to navigate by. It has been proposed that magnetite, found in the tissues of some migrating species such as bees and some birds, may provide the ability to sense weak magnetic fields with the aid of magneto-receptors. An eye pigment, cryptochrome, acts as a chemical compass depending on free radical pairs being in a superposition of singlet and triplet states. This quantum entanglement is familiar to physicists from esoteric experiments involving particles in isolated systems. This ‘de-coherence’ of quantum reactions comes about because of the ‘noise’ of large thermodynamic systems. Nonetheless, the evidence is compelling, even if the mechanisms are not fully understood, some properties of living systems depend on quantum mechanical phenomena such as tunneling, coherence and entanglement (with ample and nice evidence of spooky effect narration).
When an incoming photon (light particle) hits a specialised photo-receptor in the robin’s eye, it creates two electrons that are “entangled” in a quantum sense. Entanglement is one of the most mysterious quantum properties, allowing particles to remain instantaneously connected however far apart they are – which Albert Einstein called “spooky action at a distance”. Experiments show that entangled electron pairs can be extraordinarily sensitive to the orientation of magnetic fields, and the behaviour of the spinning electrons as they move apart in the robin’s eye giving the bird a quantum compass.
In addition to this ability of birds, other systems, photosynthesis and enzyme reactions, are given a compelling discussion in Life on the edge. The evidence of these diverse findings strongly suggests that biological systems employ quantum phenomena at the heart of their macro behaviour. This has huge implications for the study of large-scale quantum systems and their possible technological innovations.
The book is aimed at a lay audience, and in this it should succeed admirably as is delivered from Al-Khalili, accurately and suitably referenced, sufficing further reading and backing up the scientific claims. "Life on the Edge" is a well-written introduction to one of the most fascinating areas of modern science – quantum biology. With about eighty percent of the book, the reader is buoyed with enough references like Extremophiles, Life out of Mud volcano, Miller's experiment on creating Amino Acids rolling drastic methods, Butterfly effect, probability with Tinba virus (with just 20 Kb in size) etc., but in the end there is a philosophical termination to these subjects with "consciousness" taking the theme. The proposed conclusion is that quantum theory can account for human consciousness, put forward by the Oxford mathematician Roger Penrose in 1989 and adopted by a few others.
Their idea is that quantum effects modulate the fluctuating electromagnetic fields in the brain that some scientists associate with consciousness, though there is no convincing evidence for this. Here the authors take a sensibly cautious tone, warning against the argument that, just because consciousness is a mystery, something as mysterious as quantum theory will help to explain it. But they cannot resist asking: “Is it likely that the strange features of quantum mechanics we discovered to be involved in so many crucial phenomena of life are excluded from its most mysterious product, consciousness? We will leave the reader to decide.”