Chapter 13: Theory of Light
Another great contribution to science of Imam Jafar al-Sadiq (A.S) was his Theory of Light. He said that light reflected by different objects comes to us, but only a part of the rays enter our eyes. That is the reason why we do not see distant objects clearly.
If all the rays of light which come from them entered our eyes, objects would appear near to us. If we make a device through which all the rays of light coming from the camels grazing at a distance of 3000 zirah (one zirah is 40 inches) entered our eyes we would see them grazing at a distance of only 60 zirah ie. All these objects would look 50 times nearer to us.
This theory spread far and wide through his students and reached Europe too.
It was this theory, which helped Lippershey of Flanders to make his first binoculars in 1608. Galileo made use of thes binoculars and invented his telescope in 1610. If the Imam had not formulated this theory of light, binoculars and telescopes would not have been invented and made and
Galileo could not have confirmed through visual observations the theories of Copernicus and Kelper that all planets including the earth rotate round the sun. When Galileo was asked why his telescope made heavenly bodies look so near that they could see the mountains of the moon, he repeated the words of Imam Jafar al-Sadiq (A.S) and said : "This telescope collects all the rays of light coming from the heavenly bodies. When all the rays of light coming from the heavenly bodies are concentrated, the objects which are at a distance of 3,000 feet away appear to us as if they were at a distance of only 60 feet."
Before the time of the Imam, it was believed that light from our eyes falls upon different objects so that they could be seen. He was the first to have said that" the rays of the light from different objects come to our eyes and enable us to see them. The rays of light from our eyes do not go out and fall on other objects, otherwise we would be able to see them in the darkness also."
The Imam also put forward a very interesting theory about the speed of light. He has said that light is a kind of motion which is very fast. This is in harmony to the modern theory of light.
The Imam had once said during the course of his lectures that a powerful beam of light could move heavy objects. The light which Moses saw at Mount Sinai was of that kind. It could have moved the mountain if God had so desired. It can be said that by making this statement, he laid the foundation of the theory of the laser.