About quantum biology
Quantum biology is the study of why quantum effects may be integral to how biological systems function.
Quantum mechanics is the best theory we have to explain the fundamental behaviour of the universe at the atomic and molecular level, for very short time and length scales. A key principle in quantum theory is that energy is quantised, and that both matter and radiation display wave-particle duality. As our systems of interest increase in size from the atomic, to collections of molecules such as a protein, there is an increasing likelihood that they can be described as particles and behave as such – following the classical laws of Newtonian physics. However, it has been shown that even very large molecules, consisting of thousands of atoms, can exhibit wave-like properties.
For many years, it was thought these wave-like properties of large molecules could only be observed at very cold temperatures in specialised physics laboratories, and that any thermal increase would induce them to behave as large particles – due to a principle called “decoherence”. Hence, although it was accepted that quantum mechanics must underly biology at one level, above a certain size and timescale biology would be confined to classical outcomes – being as they were too “warm and wet”.
However, many scientists thought that this might not be strictly true, as it was becoming clear that thermal decoherence might actually enhance quantum processes, for example through resonant vibration-assisted transfer processes. Given the important role that thermodynamics may have played in the origins of life, through the dissipative self-organisation of biological molecules, these thermal effects may have driven evolutionary selection for molecules with optimal quantum parameters. This may have been especially relevant for the evolution of complex auto-catalytic chemical networks where the transfer of energy via fundamental charged particles, such as electrons and protons, exploited quantum properties.
Research in quantum biology is also motivated by the fact that there are processes and observations in biology that cannot be clearly explained by classical chemistry. For example, there is evidence that electrons and protons may “quantum tunnel” during key biological processes, that a quantum property called “spin” may enable life to both detect and utilise magnetic fields, while energy may be transferred across large molecular networks using electromagnetic resonance. Moreover, it may also be the case that biology is using light in ways not previously thought of, as metabolism itself produces photons, which can be absorbed by many other biological molecules, suggesting that “photonic homeostasis” could be important. These quantum biological phenomena could well be involved in photosynthesis, mitochondrial and microtubule function, magnetoreception, enzyme function, signalling and inflammation processes, neural function and even consciousness. Hence non-trivial quantum effects such as superposition states, quantum coherence, tunnelling, and entanglement, which have been studied in detail in inanimate matter, may well be manifest in living matter.
One of the most fundamental components of biology is the transfer and dissipation of energy by charged entities, such as electrons and protons. This process is called “reduction-oxidation”, which is normal shortened to “redox”. Indeed, the Nobel Prize winning scientist, Albert Szent-Györgyi, was purported to have said that “life is nothing but an electron looking for a place to rest”. Electromagnetic energy and charge transfer events in biological systems can be partially described using classical models. Quantum biology, on the other hand, focuses on how novel quantum effects might enhance the efficiency of energy via charge transfer in living systems. This research follows from fundamental concepts in quantum theory such as wave-particle duality, which allows for charged particles such as electrons and protons to exhibit wave-like tunnelling effects: to occupy states that are energetically forbidden by classical physics. Quantum tunnelling has been investigated in a number of biological contexts, including mitochondrial and photosynthetic electron transport chains, enzyme function, as well as olfaction and receptor binding.
Wave-particle duality also allows for “quantum coherence” such that an electron, proton, atom, or a group of atoms, exist in “quantum superposition” – in effect, existing as a collection of all possible states. Superposition and coherence have been applied to a variety of biological processes. Photosynthesis, for example, involves absorbing light energy and transferring it across a series of molecules. The efficiency of this light-harvesting and transfer of energy could benefit from coherent superposition states by the simultaneous sampling of all possible energy pathways. Coherent energy transfer is not limited to photosynthetic complexes. Tubulin proteins, which constitute the cytoskeleton of a cell, contain chromophores such as tryptophan, whose free pi electrons may facilitate coherent energy transfer and support collective excitations that result in quantum phenomena such as superradiance.
Quantum concepts such as superposition and coherence have also been applied to the spin dynamics of particles such as electrons and protons. Whereas charge describes the electrical properties of matter, spin describes matter’s magnetic properties. Spin chemistry, in which magnetic fields can change the outcome of chemical reactions, has been hypothesised to be the mechanism by which birds navigate using the Earth’s magnetic field. This avian compass may even employ quantum entanglement, or as Einstein put it: “spooky action at a distance”. Entanglement is perhaps the most extraordinary quantum phenomenon and describes the ability of two entangled particles to “know” the state of the other when one is observed, regardless of distance and instantaneously. This is known as “non-locality”, as encompassed by Bell’s theorem and is a profound departure from classical physics. It has also been suggested that quantum spin might influence the balance of reactive oxygen species and even the functioning of the nervous system and brain. As the Nobel prize winning scientist Roger Penrose has proposed somewhat controversially, the brain may utilise quantum principles to enable it to process information and generate awareness.
Quantum biology is often described as an emerging field, but in many aspects it is as old as the science of quantum mechanics more generally. The founding figures of quantum theory, ranging from Einstein to Schrödinger to Pascual Jordan, postulated on the importance of it in biology, but the experimental techniques of the time were not sophisticated enough to investigate quantum effects in biological systems. Technological advances have facilitated our ability to study these phenomena, coupled with growing interest in their potential importance for our understanding of living systems and health and disease. The study of living systems, which involves both metabolic – energy – concerns as well as how information is stored and shared, borrows from the study of thermodynamics. The interplay of thermodynamics and quantum mechanics may provide new insights into biological systems and for instance, might explain the occurrence of both inflammation and the ageing process.
Visit our Publications and Useful resources pages for further reading, the Glossary for descriptions of key terms, and for talks by a number of scientists working in quantum biology and related fields visit Our conferences and meetings.