Quantum biology — in layman’s terms

There are some biological phenomena that could be potentially driven by the non-intuitive aspects of quantum theory such as tunneling, superposition and entanglement which are typically not in the subset of quantum mechanics that serves as the foundation for the standard chemistry (orbitals, valence shells etc) and biology most of us have learnt. Quantum biology attempts such an explorative study.

However, most of these models are still speculative and need further validation to establish it is indeed these non-intuitive quantum mechanisms that are behind these biological phenomena.

The biggest open question in all these instances where a non-intuitive quantum mechanism is supposedly at play behind the scenes in a biological phenomena, is

how can such effects happen at biological time scales and in warm, wet and noisy/messy environments? Particularly when the only way we know to date, for creating conditions conducive for such effects to happen, is by cooling down to temperatures close to absolute zero in the Kelvin scale.[3]

Quantum tunneling. The basic idea of quantum tunneling is that particles at the atomic scale (or smaller) like electrons can tunnel through an energy barrier. It is almost like throwing a ball at a window and the ball, in addition to bouncing back off the window, can also appear, at times, on the other side of the window with some probability, without breaking the window.

Where has this been observed (or speculated to be the cause)?

  • Enzymes have been shown to speed up reactions with quantum tunneling. This has been established firmly. [8], [9]
  • There is speculation that quantum tunneling may be one of the causes of genetic mutations.
  • Quantum tunneling appears to play a role in the smell sensory apparatus along with the traditional explanation of lock and key model for odor perception. (There is a fairly contentious debate in the comments section, indicative of how nascent these theories are, between proponents of those who believe structure plays a role just as much as vibrational difference conducive to tunneling right here on Quora Perfumes: What is wrong with Luca Turin’s theory of smell?)
  • Quantum tunneling has been established to be causal to many we know, beyond the domain of biology, one of which is the fusion of hydrogen to helium in the sun — the hydrogen atoms have to quantum tunnel across the energy barrier that prevents the positive charges from coming together to form a helium atom.[4], [5]

Quantum coherence/superposition . The basic idea of superposition is that particles at the atomic scale (or smaller) like electrons/photons can be in multiple states simultaneously. For instance, in the double slit experiment, a single electron/photon can travel though multiple virtual paths and the paths interfere with each other when they arrive at the screen resulting in an interference pattern. [2], [14]

Where has this been observed (or speculated to be the cause)?

  • The conversion of light into chemical energy in photosynthesis is speculated to involve traversal of simultaneous paths from the point of light capture to the reaction center where it is converted to chemical energy. [10] , [11]

Quantum entanglement . The idea here is that a pair of particles, again of atomic dimensions can be placed into a correlated state such even after separation from each other, any change made to one will instantly cause a state change in the other member of the pair, eliminating the possibility of any causal communication link between them. This has been experimentally shown to happen.

Where has this been observed (or speculated to be the cause)?

  • A bird (european robin) exhibits a particular navigation capability (it has more than one) one of which appears to involve two radicals in an entangled state in a molecule, triggered by light falling on a protein, and serving as a sensor of the earth magnetic inclination at a place (unlike the typical north south detection capability in many other animals using magnetite crystals embedded in beaks etc.) [12]

When did we start seeking answers to biological phenomena along these lines?

The possibility that living systems despite being wet, warm and messy environments may leverage off quantum effects that are typically observed under near zero temperatures was first contemplated on by Erwin Schrödinger — one who developed some of the fundamental results of quantum theory.[1]

There have been other speculative proposals for a quantum basis for consciousness, famous among which is Penrose’s proposal and more recently other proposals [6], [7]

It remains to be seen if these non-intuitive aspects of quantum theory indeed play a role in biological phenomena and if they do, are they just isolated cases or have a much broader scale of influence that would merit this interdisciplinary field of study its own name — quantum biology.

Image from the article What is Quantum Biology?

References

  1. Amazon.com: What is Life?: With Mind and Matter and Autobiographical Sketches (Canto Classics) (8601419978748): Erwin Schrodinger, Roger Penrose: Books
  2. Some remarks on quantum coherence
  3. Observation of time-invariant coherence in a room temperature quantum simulator
  4. It’s The Power Of Quantum Mechanics That Allows The Sun To Shine
  5. Quantum Tunneling in Nuclear Fusion
  6. Quantum Cognition: The possibility of processing with nuclear spins in the brain,2016
  7. A New Spin on Neural Processing: Quantum Cognition
  8. Hydrogen Tunneling Links Protein Dynamics to Enzyme Catalysis
  9. Enzymology takes a quantum leap forward
  10. Quantum design of photosynthesis for bio-inspired solar-energy conversion, March 2017
  11. Coherent Effects in Photosynthetic Complexes
  12. The quantum needle of the avian magnetic compass
  13. What is Quantum Biology?
  14. What is the superposition principle in Quantum Mechanics in layman’s terms?
  15. https://youtu.be/_qgSz1UmcBM
  16. https://youtu.be/ADiql3FG5is

Originally published at www.quora.com.

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