A Certain ‘Ring’ to It: The Particle Physics of Smell

Photo by Joseph Greve on Unsplash

Biologists thought they knew everything important to know about our sense of smell. Turns out they had only a partial appreciation of the intricacies of our olfactory connections.

In a superb CuriosityStream two-episode broadcast, ‘The Secrets of Quantum Physics’, UK Professor Jim Al-Khalili covers the quantum physics involved. Specifically, his second episode, called, “Let There Be Life” speaks to the sub-atomic physics which is brought to bear in triggering those mental recollections when encountering a familiar-but-rarely-experienced smell.

For a long while, biologists thought that a given odor molecule fit receptors in our noses, in a hand-in-glove connection. While that starts the process, at the subatomic level a ‘string’ (or ‘band’ more precisely) also vibrates in resonance which helps send the message to the brain: “Hey, do you remember where you were and what you were doing the time you smelled this?” So, as Dr. Al-Khalili muses, our nose is also hearing the smell.

For me, the sensation comes in a nanosecond. I am transported to Hong Kong, standing on the sidewalk outside the Royal Navy’s China Fleet Club, on busy lanes where Arsenal Street crosses Gloucester Road. The smell of diesel-fuel exhaust from the thousands of Mercedes-Benz lorries that traveled the streets in the late 1960s permeates thickly.

Conditions have to be just right before I am mentally transported the 8,100 miles to Hong Kong in 2020, now 40 years hence. The weather needs to be damp, probably a thermal inversion, on a cool day, when several large trucks pass in front of my house. Sometimes it takes me a moment to consciously recall what triggered my reaction to the odor. But without fail, the recollection falls soundly on me.

While we are miracles of biological engineering, we also follow the laws of quantum mechanics in the process.


Link to a photo of the Royal Navy China Fleet Club, before its demolition in 1982:


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