Our daily lives are intrinsically linked to the automatic rhythm of breathing, a fundamental process for sustaining life. However, each inhalation also brings a complex array of molecules into our bodies, offering information about our environment. To interpret this olfactory landscape, humans possess the remarkable sense of smell, enabling us to identify loved ones, detect dangers, and recall cherished memories. The precise mechanism behind this intricate sensory system has long been a subject of scientific inquiry.
During the fifteenth anniversary of Naukas Bilbao in September 2025, Elixabete Rezabal, a professor of physical chemistry at the University of the Basque Country, presented a compelling alternative to the established theory of olfaction. The traditional explanation, proposed by Nobel laureates Linda Buck and Richard Axel in 2004, posits that specialized receptor proteins in the nose detect odor molecules based on their shape, a concept often likened to a lock-and-key mechanism. This model suggests that when a molecule's shape fits a receptor, a signal is transmitted to the brain, resulting in the perception of a specific odor. However, this theory faces challenges in explaining phenomena where molecules with similar shapes yield different scents, or conversely, molecules with dissimilar shapes produce the same odor.
Rezabal highlighted the quantum vibrational theory, developed by biophysicist Luca Turin and his colleagues, first proposed in 1996. This alternative hypothesis suggests that the sense of smell is primarily determined not by molecular shape, but by the unique quantum vibrations of molecules. According to Turin's theory, olfactory receptors are sensitive to these vibrational energies rather than just the physical contours of the molecules. Evidence supporting this theory includes experiments with fruit flies, which demonstrated an ability to differentiate between water and "heavy water"—molecules identical in shape but with different atomic compositions and thus distinct vibrational frequencies.
The proposed mechanism for this quantum sense of smell involves "quantum nasal tunnel," where electrons leverage quantum properties to detect molecular vibrations, similar to the functioning of laboratory spectrometers. When a molecule binds to a receptor, an electron transfer occurs, generating an energy exchange that signals the brain. This transfer is dependent on the molecule's vibrational energy precisely matching the energy required for an electron to transition between quantum states. Luca Turin further explored the practical implications of this theory by founding Flexitral, a company aimed at revolutionizing the perfume industry through the creation of less expensive compounds that mimic the vibrational signatures of costly ingredients.
Rezabal concluded her presentation by emphasizing the significant role quantum mechanics plays in various biological phenomena, including our perception of smell. The growing body of evidence increasingly points to molecular vibration as the fundamental basis for how we experience the world of scents. The Naukas Bilbao event provided a vital platform for discussing such cutting-edge scientific discourse.