How surprised should we be if 4 billion years of evolution have taught the living cell to exploit quantum mechanics in ways that human physicists have not yet discovered? Science has made great progress in the last century via reductionism, understanding the parts and building up to an understanding of the whole. The idea of a direct link between micro-world of quantum mechanics and the complexity of life could disrupt that paradigm.
From ancient times, it was obvious to people the world over that life played by different rules. Flowers and frogs could do things that rocks and babbling brooks could never do. Great scientists through Newton and Faraday saw no conflict between their spiritual beliefs and the laws of nature they were discovering. Then, in the 19th Century, organic chemistry was developed, and cells could be viewed through a microscope. Some of the behavior of living things began to find explanations in terms of physics and chemistry. One after another of the abilities of living cells were explained with the same laws that apply to non-living matter. Science and philosophy came to make a bold extrapolation: There is no fundamental difference. Living and non-living matter obey the same laws, and the apparent difference between living and non-living systems is due to complexity only.
This possibility became a presumption and then a dogma. Worse, the laws that governed life were presumed to be physics that humans have presently mastered and understood. Scientific consensus lined up against the idea that life may know something we don’t know.
|Implicitly, the entire mainstream of the scientific community dismissed the possibility that 4 billions years of evolution might have taught the living cell something about physics that contemporary human science has yet to discover.|
Of course, biology continues to hold many mysteries for us: Animal navigation and “extraordinary knowing”; the remarkable efficiency of evolution, and the related problem of the origin of life; why should microwaves cause cancer? — why, indeed, should weak radio waves have any interaction with living tissue? How can biological enzymes be so much more specific than engineered catalysts, and why are they less effective in a petri dish than in a living cell?
In the process of attacking these open questions of biology, will we discover new physics? To date, only a handful of quantum biologists are asking such questions.
The first and most famous proponent of quantum biology was Erwin Schrödinger, a founding father of quantum physics. In the 1930s, he wrote two monographs [republished in one volume] about physics and life. The first one prefigured by more than a decade Crick and Watson’s discovery of the structure of DNA. The second hypothesized that consciousness has an elemental role in the fabric of physics. Though this latter idea sounds mystical and vaguely unscientific to biologists, it is taken seriously by physicists because the postulates of quantum mechanics require* a subjective observer, and reality is not objective or observer-independent, but arises from the interaction between the observer and his representation of a physical system. A world without objective reality? This sounds too fantastical to take seriously, and most scientists don’t.
| “Despite the unrivaled empirical success of quantum theory, the very suggestion that it may be literally true as a description of nature is still greeted with cynicism, incomprehension and even anger.”|
— David Deutsch, independent scientist and inventor of the quantum computer.
Since Schrödinger, there have been reports of experimental results that would seem to support his conjectures about the quantum basis of life, but these have remained on the edge of science, subjected to a rigid skepticism because they would seem to require such a radical re-conception of the reductionist view of science. In the standard scientific picture, physics explains atoms and molecules; atomic physics is the explanation for chemistry; and chemistry explains the behavior of biological systems. The alternative is that the loop may be closed: biology is necessary to explain fundamental physics. (There’s a joke** with the punch line, “God is a biologist.”)
Aside from the quantum mechanical observer, another reason to take this idea seriously is a series of remarkable coincidences first noted by astrophysicists: The “recipe” for our universe contains six fundamental but arbitrary ratios–things like the ratio of the electron to proton mass and the ratio of the electric force to the gravitational force. These ratios give the appearance of being fine-tuned to make life possible. If any of them were just a wee bit different, we would live in a universe that was very much less interesting than the one we do live in. (For example a universe in which the only chemical element is hydrogen, or a universe in which intergalactic gas remains spread thin and never congeals into stars and planets.)
What is the significance of the fact that these “arbitrary” ratios are fine-tuned to make life possible? One explanation would be that consciousness played a founding role, and is in some way responsible for the world we see. The alternative is that there are many universes, (billions and billions) and almost all of them harbor no life, because life is not possible there, so of course we find ourselves in one of the exceedingly rare universes that is capable of supporting life.
Aside from these broad, philosophical arguments, there are two direct observations opening the door to quantum biology. Photosynthesis and magnetic sensors in birds are made possible by quantum superpositions within single molecules. A more expansive view of quantum biology is that life depends on quantum tricks that allow micron-sized systems to explore many possibilities simultaneously, and enable single molecules to flip switches for entire cells. These are considered radical ideas, outside the mainstream of science, but perhaps they provide a fertile hypothesis for exploring many mysteries of biology.
Stunning reports of the quantum influence of living systems have been dismissed as not worthy of review or replication, because we know “as a matter of theory” that they must be mistaken. Robert Jahn, while Dean of the Princeton University School of Engineering, began an investigation of ways in which living systems (including humans) can affect quantum noise in a resistor [book]. Though his experiments were expertly and meticulously documented, they were never permitted publication in journals of physics, and in fact Dr Jahn’s reputation and career suffered just for having undertaken such experiments.
There is a line of experimentation from Russia reporting that plants and even bacteria are able to transmute chemical elements, a process which humans know how to do only with high-energy nuclear physics [book]. These experiments have never been replicated in the West, and the implications would be revolutionary if confirmed.
Roger Penrose, one of the most brilliant and original minds in mathematical physics, has been speculating on quantum theories of consciousness for thirty years, making specific and testable proposals. It is scandalous that his work is dismissed as “crackpot” by people who don’t understand it. There is a mainstream view that consciousness arises from computation, and that digital computers have, in principle, everything necessary to qualify as conscious, living beings when we learn how to program them a bit better. Though this hypothesis is far from being a proven fact of science, challenging the dogma can be hazardous to a scientific career.
Stuart Kauffman is another expansive thinker who has investigated the connections between quantum mechanics, biology and consciousness. He notes that many proteins, including about half of all neurotransmitters, are in a state of “quantum criticality”, which means they are poised on a knife edge, easily nudged between two configurations. Why would this be true? In designing a classical machine (for example a tiny transistor, etched on a microchip), human engineers make sure that the system’s performance is reliable by making it just large enough that quantum fluctuations cannot affect its behavior. There are plenty of biological systems that are also designed to be stable in this way; the DNA molecule, for example, stores information reliably over long periods of time. But natural selection seems to have gone out of her way to use neurotransmitters that are unreliable. Their behavior (and our thinking) are affected by quantum events at the smallest level. This could be a useful feature of the brain if quantum events in living systems are not random, but are guided by a larger coherence, or by consciousness as an entity, or maybe these two are different aspects of the same thing.
In 2002, a molecular geneticist from University of Surrey outlined a bold theory of quantum evolution based on extrapoloation of a well-established but paradoxical phenomenon. In the Quantum Zeno Effect, continuous observation of one quantum variable prevents a system from evolving. (“Watched water never boils.”) It is theoretically possible, in this way, to prevent a radioactive nucleus from decaying. The Inverse Quantum Zeno Effect is yet stranger: By very gradually changing the quantum variable under observation, it is possible to guide a quantum system efficiently from one state to another. In a simple demonstration (try this at home!), a series of rotated polarized filters can nudge vertically polarized light around until it becomes horizontally polarized, though the overlap between the initial and final wave functions is zero. In this book, Johnjoe McFadden speculated that biological evolution might be directed toward states of higher fitness by a biological version of the Inverse Zeno Effect. Fifteen years later, only a handful of scientists around the world are discussing and developing these ideas. We are so busy working out the details of our existing framework (and writing grant proposals to compete for next year’s funding) that we have no time to consider speculations outside the box.
Mcfadden stopped short of proposing an observer within the living cell that is driving its evolution, a deus ex machina, but connection to Penrose’s work presents a tantalizing possibility. Perhaps the contentious “observer problem” of quantum mechanics is essentially related to free will, awareness and the sense of self; perhaps the quantum observer within is what separates living from non-living things, and is the source of the characteristic behaviors that strike us as goal-oriented.
These intriguing ideas touch our foundational sense of who we are and the nature of the world in which we live, but the enterprise of science today is not well adapted to address them. Funding is risk-averse—a sound basis for business decisions, but a disaster for the healthy practice of basic science. Hypotheses about quantum biology are easily dismissed as “crackpot”, and indeed most are likely not to pan out. But you have to kiss many a frog before you find your prince. If we are ever to address these foundational questions, we—the community of scientists—will have to be willing to consider and to test a great number of crazy ideas along the way.
We know the quantum world primarily from single-particle systems. All of atomic physics, chemical bonds, orbitals etc. is modeled from equations of the hydrogen atom, because for more than one electron, quantum mechanical equations are impossible to solve. Quantum physics of many entangled particle is notoriously intractable to computation, so we have only semi-empirical theories of chemistry and solid state physics. With quantum symmetries, we can explain simple, uniform order—for example, lasers and crystals. But theory suggests the possibility of a single quantum state that comprises many atoms in a complex array; indeed, a system may be in a superposition of several such states simultaneously. We know nothing of such systems, or what properties they might evince; that is, we know how to write down the equations for such systems but to solve the equations is far beyond the capability of any computer we know how to build. Quantum mechanics of complex systems remains an experimental science, and evolution has had time to perform a great many more experiments than have humans.
* There is an alternative formulation of quantum mechanics where observers are not outside of quantum physics, but this formulation carries the baggage of a truly gigantuous number of extra universes, all them completely unobservable. It is called the “Many Worlds Interpretation”.
** Escalating reductionism: Biologists think they’re chemists, chemists think they’re physicists, physicists think they’re mathematicians. Of course, mathematicians think they’re God, but what they don’t realize is that God is a biologist.