light and vision

Representation of the concept of vision today

Interest in vision is not new today. Since ancient times, vision has been a topic that has aroused a lot of interest from doctors, engineers, writers, physicists, among others.

We also know that, since ancient times, the study of light and also the phenomena related to it have been developing. The first attempts to explain them took place in antiquity, when the hypothesis that vision was the result of visual rays emitted by the eyes was proposed. They supposed that these rays came out of the eyes and were directed towards the objects, apprehending their image.

But what was later seen was a difficulty in distinguishing objects when they are in the absence of light. Once this difficulty was perceived, it was concluded that it was not the eyes that emitted the “visual rays”. In fact, the eyes receive reflected light from objects. It is for this reason that a visually impaired person cannot see objects, as he does not perceive the presence of light.

Thanks to questions made in the past, in an attempt to explain vision, it is that physicists of that time understand that the phenomenon of vision is linked to two factors: light and eye .

When we look at the characteristics of objects, such as color, volume and shape, we see that there is a need for these objects to be illuminated by a light source, such as a lamp or sunlight. It is also necessary that the object is within the field of vision of our eyes, and its size also influences the distance at which we will be able to recognize it.

We can see an object because light can reach it, illuminating it and, later, being reflected to our eyes. For physicists, in these situations light travels in a straight line. It is for this reason that, according to the position that an object is in or depending on the position of the light source, a shadow of the object is formed. There is a shadow formation due to the fact that only part of the object is illuminated. This aspect can be evidenced when eclipses happen.

The fact that objects are illuminated by the Sun and the possibility of seeing the light emitted by stars more distant than it, reveal another characteristic of light: that it is able to propagate in a vacuum. Therefore, air and vacuum are transparent to light.

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