A Quantum Origin Of Life ? ( Evolution from Non Living to Living entities)

A Quantum Origin Of Life ?

by : Aria Ratmandanu

" This article is dedicated to the readers, who do not

   know what life is, yet they have life" 

                The origin of life is one of the great unsolved problems of science. In the nineteenth century, many scientists believed that life was some sort of magic matter. The continued use of the term “organic chemistry” is a hangover from that era. The assumption that there is a chemical recipe for life led to the hope that, if only we knew the details, we could mix up the right stuff in a test tube and make life in the lab.

                Most research on biogenesis has followed that tradition, by assuming chemistry was a bridge—albeit a long one—from matter to life. Elucidating the chemical pathway has been a tantalizing goal, spurred on by the famous Miller-Urey experiment of 1952, in which amino acids were made by sparking electricity through a mixture of water and common gases. But this concept turned out to be something of a blind alley, and further progress with pre-biotic chemical synthesis has been frustratingly slow. Most research on biogenesis has followed that tradition, by assuming chemistry was a bridge—albeit a long one from matter to life. Elucidat- ing the chemical pathway has been a tantalizing goal, spurred on by the famous Miller-Urey experiment of 1952, in which amino acids were made by sparking electricity through a mixture of water and common gases. But this concept turned out to be something of a blind alley, and further progress with pre-biotic chemical synthesis has been frustratingly slow. 

                     In 1944, Erwin Schrodinger published his famous lectures under the title "What is Life ?"  and ushered in the age of molecular biology. Schodinger argued that the stable transmission of genetic information from generation to generation in discrete bits implied a quantum mechanical process, although he was unaware of the role of or the specifics of genetic encoding. The other founders of quantum mechanics, including Niels Bohr, Werner Heisenberg and Eugene Wigner shared Schrodinger’s belief that quantum physics was the key to understanding the phenomenon of life. This was a reasonable assumption at the time. Shortly before, quantum mechanics had solved the problem of matter, by explaining atomic and molecular structure, chemical bonds and the nature of solids. It seemed natural that quantum mechanics would soon also solve the riddle of the living state of matter. To a physicist, life seems fundamentally weird, even bizarre, in its properties, and bears almost no resemblance to any other type of physical system. It is tempting to suppose that quantum mechanics possesses enough weirdness to account for it.

        Erwin Schrodinger and his famous "Schrodinger equation". 

                 Although there is no agreed definition of life, all living organisms are information processors: they store a genetic database and replicate it, with occasional errors, thus providing the basis for natural selection. The direction of information flow is bottom up: the form of the organism and its selective qualities can be traced back to molecular processes. The question then arises of whether, since this information flows from the quantum realm, any vestige of its quantum nature, other than its inherent random- ness, is manifested. Biological molecules serve the role of both specialized chemicals and informational molecules, mirroring the underlying dualism of phenotype/genotype. In computer terminology, chemistry is akin to hardware, information to software. 

                        A complete understanding of the origin of life demands an explanation for both hardware and software. Most research in biogenesis focuses on the hardware aspect, by seeking a plausible chemical pathway from non-life to life. Though this work has provided important insights into how and where the basic building blocks of life might have formed, it has made little progress in the much bigger problem of how those building blocks were assembled into the specific and immensely elaborate organization associated with even the simplest autonomous organism [Davies (2003)]. But viewing life in terms of information processing transforms the entire conceptual basis of the problem of biogenesis. Reproduction is one of the defining characteristics of life. Traditionally, biologists regarded reproduction as the replication of material structures, whether DNA molecules or entire cells. But to get life started all one needs is to replicate information. In recent years our understanding of the nature of information has undergone something of a revolution with the development of the subjects of quantum computation and quantum information processing. 

                  The starting point of this enterprise is the replacement of the classical “bit” by its quantum counterpart, the “qubit”. As a quantum system evolves, information is processed; significantly, the processing efficiency is enhanced because quantum superposition and entanglement represent a type of computational parallelism. In some circumstances this enhancement factor can be exponential, implying a vast increase in computational speed and power over classical information processing. 

              The difference between classical bit "Computer" and Qubit  "Quantum Computer"

                   Biological systems are quintessential information processors. The informational molecules are RNA and DNA. Although quantum mechanics is crucial to explain the structure of these molecules, it is normally disregarded when it comes to their information processing role. That is, biological molecules are assumed to store and process classical bits rather than qubits. In an earlier paper [Davies (2004)] I speculated that, at least in some circumstances, that assumption may be wrong. It is then helpful to distinguish between three interesting possibilities: 

1. Quantum mechanics played a key role in the emergence of life, but either ceased completely to be a significant factor when life became established, or was relegated to a sporadic or subsidiary role in its subsequent development. Nevertheless, there may be relics of ancient quantum information processing systems in extant organisms, just as there are biochemical remnants that give clues about ancient biological, or even pre-biological, processes.

2. Life began classically, but evolved some efficiency-enhancing “quantum tricks.” For example, if biological systems were able to process information quantum mechanically, they would gain a distinct advantage in speed and power, so it might be expected that natural selection would discover and amplify such capabilities, if they are possible. 

3. Life started out as a classical complex system, but later evolved towards “the quantum edge,” where quantum uncertainty places a bound on the efficiency of bio-molecular processes. 

             As there is little doubt that some cellular machinery (e.g. photosynthesis) does exploit quantum mechanics , the issue arises of whether quantum enhancement is a product of evolution , or a remnant of life’s quantum origin. 

                     The starting point of my hypothesis is the existence of a quantum replicator, a quantum system that can copy information with few errors The information could be instantiated in the form of qubits, but that is not necessary, the quantum replication of classical bits is sufficient. A quantum replicator need not be an atomic system that clones itself. Indeed, there is a quantum no-cloning theorem that forbids the replication of wave functions. This information might well be in binary form, making use of the spin orientation of an electron or atom for example. Quantum mechanics thus provides an automatic discretization of genetic information. Quantum replicators certainly exist in Nature. The simplest case is the stimulated emission of photons. Henceforth I shall refer to this hypothetical system as Q-life. Let me illustrate the basic idea of Q-life with a simple, and almost cer- tainly unsatisfactory, example. Consider an array of atomic spins embedded in a condensed matter system, defined relative to some fiducial direction. The initial template A may be described by a ket vector such as 

This template then comes into interaction with an arbitrary system of spins B, say,

As a result of the interaction (which may entail many intermediate steps), the following transition occurs 

Symbolically, the overall evolution of the state is AB −→ AA. Because the transition has erased the information contained in state B, the replication process is asymmetric and irreversible, and accompanied by an increase in entropy. The system thus requires an energy source to drive the reaction forward. This could be in the form of an exciton that hops along the array of atoms, flipping the B spins where necessary one-by-one but leaving the A spins unchanged. The foregoing model is very simplistic. A more realistic form of interaction, and a closer analogue of DNA replication, would be if the template array A first created a complementary array

which then generated the original array by “base-pairing”. An additional simplification is that the model described so far neglects interactions between neighbouring spins. Such interactions produce greater complexity, and so increase the opportunity to encode algorithmically incompressible information. 

             How, then, did organic life arise ? Information can readily be passed from one medium to another. At some stage Q-life could have coopted large organic molecules for back-up memory, much as a computer uses a hard- disk. The computer’s processor (analogous to Q-life) is much faster than the hard disk drive (analogous to RNA and DNA), but more vulnerable and in need of a continual input of energy. Robust computing systems require something like a hard disk. Eventually the organic molecular system would literally have taken on a life of its own. The loss in processing speed would have been offset against the greater complexity, versatility and stability of organic molecules, enabling organic life to invade many environments off-limits to Q-life. 

              The hypothesis I am proposing is that the transition from non-life to life was a quantum-mediated process, and that the earliest form of life involved non- trivial quantum mechanical aspects.