Olympic starters are forbidden from reacting faster than a tenth of a second
Officials treat anything faster than a blink of an eye as a false start, assuming the athlete must have guessed the gun rather than heard it.
When an elite sprinter crouches in the blocks, they are waiting for a sound to travel a biological circuit that has a hard physical speed limit. Once the pistol fires, the sound waves must hit the ear, trigger the auditory nerve, and send a signal through the brainstem before motor commands can finally rush down the spinal cord to the muscles. This entire neural relay takes time. World Athletics rules dictate that any movement detected within 0.1 seconds of the gun is a foul, as empirical studies show it is physiologically impossible for a human to process the sound and move their limbs any faster without anticipating the shot.