A new study published in the journal Nature Communications reveals that the human eye is capable of an amazing feat, detecting just a single photon of light.
Through tests designed to test the limits and capabilities of human vision, it has been observed that the human eye, in the darkest of environments, is capable of detecting a single photon, the smallest measurable unit of light particles.
According to Alipasha Vaziri, lead researcher from the Rockefeller University, “If you imagine this, it is remarkable: a photon, the smallest physical entity with quantum properties of which light consists, is interacting with a biological system consisting of billions of cells, all in a warm and wet environment. The most amazing thing is that it’s not like seeing light. It’s almost a feeling, at the threshold of imagination.”
The tests that led to this discovery involved participants that were left alone in a dark room for forty minutes, enough time for their eyes to adjust by dilating the pupils. They were then instructed to look into an optical measuring device. When they pressed a button, a noise would be emitted, and as well as the possibility of a small amount of light. Their task was to determine whether or not the beep was paired with the light, or if the beep was unaccompanied.
In addition to their determination, a confidence level in their conclusion was also documented. A level one score indicated an unsure response, while a level 3 score implied a certain response.
The results showed that, despite being wrong quite a lot, the average number of correct answers was higher than if the participants simply guessed the entire time. Also, the level of confidence was very high among the correct answers, but less so among the incorrect answers.
What makes this so impressive, despite the less than perfect scores, is that any given individual photon only has a 1 in 10 chance of reaching the back of the eye once it enters. The vast majority of the time it ends up being absorbed by any one of the billions of cells in between the cornea and the surface of the retina, where the light is detected and transmitted to the brain.