Quantum Biology

If quantum mechanics hasn’t profoundly shocked you, you haven’t understood it yet. 

-Neils Bohr

There was a time when the newspapers said that only twelve men understood the theory of relativity. I do not believe there ever was such a time. There might have been a time when only one man did, because he was the only guy who caught on, before he wrote his paper. But after people read the paper a lot of people understood the theory of relativity in some way or other, certainly more than twelve. On the other hand, I think I can safely say that nobody understands quantum mechanics.

-Richard Feynman

 The quotes above are more reflective of the nature of the quantum world than of any fundamental disagreement between the two great physicists. The quantum world does not conform to classical logic, but instead resembles some Buddhist teachings as suggested below: (if this interests you check out this fascinating post)

Anything is either true,

Or not true,
Or both true and not true,
Or neither true nor not true;
This is the Buddha's teaching.

--Nagarjuna (second century Buddhist monk and philosopher), the Mulamadhyamakakarika, Chapter XVIII, verse 8

In my last post (Complementarity and Wave/Particle Duality ) I attempted to describe the strangeness of quantum mechanics. Until recently it was thought that quantum effects could only occur at extreme (cold) temperatures and therefore would not play a role in living systems. In this article for Nature, Phillip Ball describes how this assumption is changing.

"Or so everyone thought. But discoveries in recent years suggest that nature knows a few tricks that physicists don't: coherent quantum processes may well be ubiquitous in the natural world. Known or suspected examples range from the ability of birds to navigate using Earth's magnetic field to the inner workings of photosynthesis — the process by which plants and bacteria turn sunlight, carbon dioxide and water into organic matter, and arguably the most important biochemical reaction on Earth"

"Biology has a knack for using what works, says Seth Lloyd, a physicist at the Massachusetts Institute of Technology in Cambridge. "

 In 2007 Graham Fleming reported on direct evidence of quantum effects in biology leading to near 100% efficiency in the photosynthesis process.

"Our results suggested that correlated protein environments surrounding pigment molecules (such as chlorophyll) preserve quantum coherence in photosynthetic complexes, allowing the excitation energy to move coherently in space, which in turn enables highly efficient energy harvesting and trapping in photosynthesis,"

A more recent study has identified entanglement as a natural feature in this quantum process.

"This is the first study to show that entanglement, perhaps the most distinctive property of quantum mechanical systems, is present across an entire light harvesting complex," (Mohan Sarovar).

There are potentially great implications for this research especially in the area of renewable non-polluting energy.

 "We hope to be able to learn from the quantum proficiency of these biological systems," says Lloyd. A better understanding of how quantum effects are maintained in living organisms could help researchers to achieve the elusive goal of quantum computation, he says. "Or perhaps we can make better energy-storage devices or better organic solar cells."

"These effects, in turn, suggest practical uses. Perhaps most obviously, says Scholes, a better understanding of how biological systems achieve quantum coherence in ambient conditions will "change the way we think about design of light-harvesting structures". This could allow scientists to build technology such as solar cells with improved energy-conversion efficiencies. Seth Lloyd considers this "a reasonable expectation"

 To see a short video that explains some birds may make use quantum effects in flight navigation click here ( The Quantum Robin video ).

Here is a longer video -Jim Al-Khalili - Quantum Life: How Physics Can Revolutionise Biology

And another excellent video by the above mentioned Seth Loyd - Quantum Life

Lee H, Cheng YC, Fleming GR(2007) Coherence dynamics in photosynthesis: Protein protection of excitonic coherence. Science 316:1462–1465

Sarovar M, Ishizaki A, Fleming GR, Whaley KB(2010) Quantum entanglement in photosynthetic light-harvesting complexes. Nat Phys 6:462–467.