Science of Light: The Beginning

Ibn Alhazen and pinhole camera >>cdn.greenprophet.com

At the present time, we are fully aware that light can be produced, break up into different wavelength and even carry information, nevertheless, at some point in history people thought that some inner light comes out from our eyes and illuminates things in view (as car head lights do) until a Muslim scientist and polymath, Ibn Alhazen, frequently reffered to as al-Haytham and sometimes as al-Basri, presented his theory of vision (1011-); ray of light are emitted from objects rather than from the eyes, in other words, when we look at something bright, it hurts eyes therefore the light must be entering the eyes but not leaving the eyes.

Consequently, we have became aware that the light is a form of energy. Firstly, the light of the sun is produced when two atoms fuse and release energy.  Secondly, this energy (the natural light) comes from the sun bounces off the objects and enter our eyes. (In fact we are not actually seeing the objects but the reflections of light off the surfaces of the objects.) In that sense, only things that give off or reflect light are visible to our eyes.