Vibration theory of olfaction

The vibration theory of olfaction is a hypothesis that suggests that the sense of smell (olfaction) is based not only on the shape of molecules but also on their vibrational frequency. This theory contrasts with the more traditional shape theory, which posits that odors are detected by the specific shapes of molecules fitting into olfactory receptors much like a key fits into a lock. According to the vibration theory, molecules emit specific vibrational frequencies as they vibrate.