| MadSci Network: Neuroscience |
The shortest duration of light that can be detected is very small, likely about 7x10-14 seconds. (Seven times ten to the minus 14 seconds).
Astronauts on the space station, or when traveling to the moon, experience phosphors, or see streaks and flashes of light in their visual fields when the retina is traversed by particles from the Sun or from galactic radiation. These particles can include protons and also heavy ions like Silicone and Iron. As these travel about 45% of the speed of light, we can estimate that they traverse the photoreceptor outer-segments, about 10 micrometers in length, at 45% the speed of light (or 45% of 3x109 meters/second). Divide that length by that speed and you will get the very short interval above.
To your mind, the flash may seem to last much longer, milliseconds, because in the case of cone photoreceptors (color) which respond and reset very quickly, they can reset in a few milliseconds. So the almost infinitely small time of a flash of energy could trigger a response you would perceive.
"Single-photon detection by rod cells of the retina" is reality.
That is described nicely in the following reference:
F. Rieke
"Single-photon detection by rod cells of
the retina"
Reviews of Modern Physics, Vol. 70, No. 3, July 1998
Thus a flash of photons, which travel at the speed of light, would mean you can likely perceive about 4x10-14 second flashes if you are all nice and dark adapted before the flash.
Dr. Mitton
Eye Research Institute
Oakland University
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