Smooth Ride for Photosynthesis

As a kid growing up in Missouri, I would’ve said the best way to get down a hill depends on the season. A sideways roll worked well during the summer when the ground was dry, but winter called for a speedy trip on a Flexible Flyer sled with steel runners. The bumpy, dizzying nature of the roll technique meant only a couple of trips down the hill. In contrast, the smooth ride on a snow sled provided hours of entertainment—until it got too dark or cold outside.

Let’s consider a similar scenario in the tiny world of quantum mechanics that suggests purposeful creation. Quantum mechanics is an attempt to understand the behavior of matter and energy on the minute scale of atoms and subatomic particles. Recently, scientists discovered quantum mechanical processes in plants and bacteria that allow photosynthesis to operate like a snow sled instead of a bumpy roll.

Plants use photosynthesis to extract energy from sunlight and then convert the energy to a form usable by other life-forms. It starts when certain wavelengths of light dislodge electrons in plant proteins, imparting energy to the electrons in the process. The energy stored in those electrons must move along the protein where other chemical processes store the energy in molecules for future use.

For many years, biologists thought random molecular motion provided the mechanism for transporting that energy along the photosynthetic proteins. As the molecules “bumped into” one another, the energy passed from one molecule to the next.

However, experiments during the last couple of years demonstrate a far more efficient process in operation.¹ From a classical perspective, electrons behave like independent balls. Quantum mechanics allows the electrons to couple together and move in coherent fashion. Like the runners on a snow sled moving over packed snow, these coupled electrons would move energy along the protein much more quickly than uncoupled electrons (which would make for a bumpy ride). A team of scientists from the United Kingdom devised a clever experiment using multiple lasers to test which process operated in photosynthetic proteins. They found strong evidence for quantum coupling between electrons.

Photosynthetic organisms played a critical role in transforming Earth from a formless, uninhabitable planet to one teeming with life in a diversity of habitats. One of the most important steps in that transformation involved the generation of a permanent oxygen component in the atmosphere. Diatomic oxygen (O₂), efficiently coupled via quantum mechanics, provides—like no other molecule—the capacity to extract the energy required by large-bodied, complex organisms.

This research indicates that photosynthesis would not proceed efficiently enough for life’s requirements without the coupling that quantum mechanics allows. As bizarre as quantum mechanical processes appear, they play an essential role in ensuring that this universe can support complex life like human beings. It’s a smooth operation that points to purposeful creation.

Reference:

¹ Ian P. Mercer et al., “Instantaneous Mapping of Coherently Coupled Electronic Transitions and Energy Transfers in a Photosynthetic Complex Using Angle-Resolved Coherent Optical Wave-Mixing,” Physical Review Letters, 102 (2009): 057402. See also Michael Schirber, “The Quantum Dimension of Photosynthesis,” Physical Review Focus (February 13, 2009); https://focus.aps.org/story/v23/st5 (accessed April 24, 2009).