There are many distinct sub-fields of scientific research around the world that make use of the strange quantum rules to describe our universe, from condensed matter to molecular physics to atomic physics to nuclear physics to particle physics; then there is quantum chemistry, quantum optics, nanotechnology. quantum information, quantum cosmology. quantum gravity; the list goes on. Well, add to this the exciting new area of quantum biology.
Schrodinger's 1944 book
One of the founding fathers of quantum mechanics was the Austrian, Erwin Schrödinger. He is most famous within physics for coming up with the equation that bears his name and which is familiar to every quantum mechanics student around the world. But Schrödinger later wrote a very influential popular science book in 1944 called “what is Life” in which he speculated that the behaviour of living matter at the cellular level can be thought of in terms of pure physics and chemistry and that at such scales, even quantum mechanics would play a role. He also introduced the idea of an “aperiodic crystal” that contained genetic information in its configuration of covalent chemical bonds. It was this book that one of the discoverers of DNA, Frances Crick, claimed was his inspiration.
So does quantum mechanics play a role within the cell? On one level, we have to say that it must. After all, the molecules of life are held together in the same way as any molecule: through chemical bonds subject to the rules of the quantum world. What is far more interesting is whether the weirder features of quantum mechanics also play a role. One obvious one is quantum tunnelling (the subatomic equivalent of walking through walls). This is just one of the areas currently being studied by a new breed of researchers who straddle the boundary between quantum physics and microbiology.
Francis Crick was inspire by Schrodinger
In simple terms, certain genetic mutations take place when a hydrogen bond is broken between two base pairs in the DNA and a new adjacent bond is made. This has been successfully described in terms of a proton quantum tunnelling between two potential wells. Interestingly, many biologists feel sceptical about any need for quantum mechanics at all, while many physicists are scornful of the simple models currently being used to study such complex systems as living cells. Well, that is good news for those brave enough to explore this new frontier of science, as it is not yet too crowded.
One issue of current interest to me personally is the effect of the quantum system’s external environment (within the cell), which it can couple to, causing what is called ‘decoherence’ – a leaking away of the quantum weirdness rather like the dissipation of heat. A number of groups around the world have been studying this effect for the past two decades and the implications of this work are far-reaching. For instance, it may help in our understanding of how cancer develops. You see, in order to generate a cancer cell, a series of mutations must occur in the same cell, each of which is very rare. Therefore, it stands to reason that the chance of several separate mutations occurring in the same cell is truly very unlikely. It has been speculated that if quantum mechanics has a role to play in such mutations it might explain why cancer is so much more common than it should be.
Hi Jim! Congrats on the blog!
Whilst I accept the notion that decoherence and coupling to the environment may play a key role in biology, is it fair to say that just because mutations in oncogenes and tumour suppressors are rare that classical mechanics cannot account for them? Even without quantum mechanics, due to the population of cells and resulting Darwinian selection means that cancer is, or should be, a common or at least expected phenotype.
I refer you to: Nature 458, 719-724 (9 April 2009) | doi:10.1038/nature07943
“All cancers are thought to share a common pathogenesis. Each is the outcome of a process of Darwinian evolution occurring among cell populations within the microenvironments provided by the tissues of a multicellular organism. Analogous to Darwinian evolution occurring in the origins of species, cancer development is based on two constituent processes, the continuous acquisition of heritable genetic variation in individual cells by more-or-less random mutation and natural selection acting on the resultant phenotypic diversity. The selection may weed out cells that have acquired deleterious mutations or it may foster cells carrying alterations that confer the capability to proliferate and survive more effectively than their neighbours. Within an adult human there are probably thousands of minor winners of this ongoing competition, most of which have limited abnormal growth potential and are invisible or manifest as common benign growths such as skin moles. Occasionally, however, a single cell acquires a set of sufficiently advantageous mutations that allows it to proliferate autonomously, invade tissues and metastasize.”
Is your suggestion more related to the role of “quantum Darwinism” [ Nature | doi:10.1038/news041220-12], whereby a superposition of mutations occurs and eigenstates and eigenvalues that result or favour mutations of cancer genes further enhance the cancer cells’ ability to proliferate?
p.s. Like your book “Quantum Aspects Of Life” – quick plug for you there!
Dev,
I enjoyed reading your comment.
First of all can I say, I’m no Scientist but, I do take an interest in those who convey & share their knowledge and thoughts.
I’d like to say that, although I’m quite versed in the notion of ‘Darwinian Natural Selection And Survival’, I’m sceptical as to the accepted and unquestioned idea that it is entirely random mutation driven and, shaped by the environment to manifest in phenotype variations. I’m not entirely convinced that there is no ‘purpose, reason or driving force’ to biodiversity. At the Quantum Level is where I see the the ‘driving force’ behind ‘life’. It’s the precursor to the competitive journey of all life forms. ‘Life’ that isn’t conducive to survival in the environment it resides, moulds into a ‘Bio-freak’ along the way.
What is ‘Life’ anyway? This strange phenomena is an elusive little critter. It’s the proverbial ‘Needle In The Haystack’, the Ghost-like entity that eludes it’s captors. It presents itself in the collective manifestation of trillions of atoms and, goes about its business via it’s host slaves with confident arrogance! Clearly it must reside at the Quantum level. Could it’s passage from place to place or, in and out of existence, cause damage along the way? This is how I consider Cancers, DNA mutations and molecular damage may be caused.
It’s all at Quantum level of ‘life’.
28 July 2010
Hi Anthony,
Glad you liked my comment, I usually don’t post them
I too agree with the notion of quantum drivers involved in biodiversity. There is a lot of emerging work about how quantum processes are involved with mutations, DNA structure, photosynthesis etc. This is quite an interesting time for the field.
I am currently working in science but just wanted to point out that mutations on their own are not sole drivers for “classical” diversity. For example, large sections of chromosomes are usually “swapped” by bacteria and equivalently “shuffled” by eukaryotes during meiosis; transposable elements which are regions of genomes that copy and insert themselves at other positions in the same genome also increases an organisms phenotype diversity. Viral DNA (reverse transcribed from RNA to DNA) litters most eukaryotic genomes again adding to the hosts diversity. There are epigenetic factors where the environment is said to shape the structure of DNA packaging restricting or enhancing gene expression. We must therefore see all these processes in terms of their quantum driving properties e.g. how does QM influence double strand break and recombination, viral RNA mutation rates such as with HIV and so on.
The phrase “goes about its business via it’s host slaves with confident arrogance” is very befitting. I think as the two disciplines of QM physics finally merges with biology that we can finally put ‘life’ whatever it is or is not, into some context.
Hi Dev,
Thank you for your reply.
Can I first of all try to encourage you to post further comments?! It was your original one that spurred me to comment. Your views, knowledge and wisdom are as valid as anyone else and, they enhance Jim’s website with high quality and interest.
Yes, I agree with everything you have replied. We have common agreement on our open minded opinion for quantum drivers being involved in biodiversity. I’m very pleased to hear there is a lot of emerging work about how quantum processes are involved with mutations, DNA structure and photosynthesis. Yes, this is a great time for enquiries and, discoveries into QM interactions & influences, esp as you say on, ‘how does QM influence double strand break and recombination’.
Thank you for extracting and drawing attention to my specific quote ..“goes about its business via it’s host slaves with confident arrogance” ! I chose the words after some consideration, deliberation and a little in trepidation!
Yes, we may well be on a new frontier and, entering a time when the two disciplines of QM physics finally merges with biology, that we can finally put ‘life’ whatever it is, or is not, into some context. I suspect a long journey lays ahead but, time waits for no man and, man waits for no time. Exciting moments await us and, I hope to feel them while I exist here!
Tony Martin
8th Aug. 2010
Speaking of coupling to the environment, cancer cells have different mechanical stiffness to healthy ones. If i recall correctly, they have a lower restoring force … the dynamics are described by a Klein-Gordon equation which is like a macroscopic analog of the QM one.