The Human Eye Can Detect The Faintest Light Beams


Research conducted by a team of experts from Rockefeller University and the Research Institute of Molecular Pathology has revealed that the human eye can detect the faintest light beams.

Previous studies have found that human sight can observe flashes ranging between five to seven photons. The study was led by Prof Alipasha Vaziri from The Laboratory of Biophysics, and Neurotechnology at Rockefeller. It was published earlier this week in Nature Communications.

A photon is the smallest unit that exhibits quantum properties, of which light consists. We are aware of very small particles of light. Something a man-made instrument cannot yet do, unless it is cooled and isolated from any noise.

Researchers also found that the perception ability of the human eye is enhanced when a second photon is flashed, a few seconds later.

Previous experiments did not have the appropriate technology to test these claims or to measure the activity. Vaziri goes on to say that it’s hard to create sources of light that contain a precise number of photons. A lamp or laser would not be appropriately designed to dim their light in order to obtain a single photon.

Usually, you can dim the light to remarkably low intensities, but you cannot determine the exact number of photons carrying light. However, Vaziri and his team have built a light system used in quantum optics, called „spontaneous parametric down conversion.” This arrangement generates two photons with complementary colors.

For this experiment, a photon was sent to the subject’s field of vision, while the other one was sent to a detector. However, many scientists call the study inconclusive, as most subjects who were tested did not see the photon, or simply guessed that it was there.

The important thing in this study was not necessarily the ability of the human eye to see the photon or not, but the amazing fact that scientists managed to create a single photon source in laboratory conditions.

The team now wants to confirm their findings with a larger sample of subjects, to see whether the human eye can actually perceive individual photons. Our visual system apparently has the capacity to respond to several photons, and it is yet unclear if it can react to less than five to seven photons.

Image Source –Wikipedia