Theory of Light

1. Theory of Light Imam Jafar Sadiq (as) Reference: The Great Muslim Scientist and Philosopher, Jafar As-Sadiq

2. Why we cannot see distant objects clearly? • Another great achievement of Imam Sadiq (as) is his theory of light. • Imam Sadiq said that light reflected by different objects comes to us, but only a part of these rays enter our eyes. • This is why we do not see distant objects very clearly. • Distant objects would appear to be bigger to us if more and more rays from these objects entered our eyes. • The Imam said: If we make a device through which all the rays of light coming from camels grazing at a distance of 3000 zirah (1 zirah = 40 inches) entered our eyes we would see the camels as if they were only 60 zirah away and all other objects would look 50 times closer to us.

3. The basis of many discoveries • This spectacular theory was the basis of many inventions and discoveries. • Lippershey of Flanders used this theory to make the first binoculars in 1608. • Galileo made use of binoculars to invent the telescope in 1610. • When Galileo used the telescope to see the moon he was surprised to see that there were mountains, plains and valleys on the moon just like the earth. • It was through the telescope that Galileo realised that earth was not the only world.

4. Finally, man realises that earth rotates around the sun, not vice versa! • If Imam Sadiq had not formulated his theory of light, binoculars and telescopes may not have been invented and Galileo would not have confirmed that the all planets including the earth rotate around the sun. • When Galileo was asked why his telescope made heavenly bodies look so near he repeated the words of Imam Sadiq and said: “This telescope collects all the rays of light coming from heavenly bodies. When all the rays are concentrated, the objects which are at a distance of 3000 feet away appear to us as if they were at a distance of only 60 feet.”

5. Light travels from objects to our eyes, not vice versa! • Before the time of Imam Sadiq it was believed that light from our eyes fall upon different objects so that they could be seen. • Imam Sadiq was the first scholar to reject this idea and said: • “The rays of 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 could have seen then in the darkness also!” • “ We see only those objects which are luminous (glowing).” • “ If they are not luminous themselves, they must reflect light from other luminous objects for us to see them.”

6. The speed of light • The Imam said: “Light is a kind of motion which is very fast.” • These words are in harmony with the modern theory of light and today we know that the speed of light is very fast. • The speed of light has been measured to be 300,000 kilometers per second.

7. The foundation of lasers • During one of his lectures, the Imam said 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. • The above statement laid the foundation of the theory of laser.

8. Summary The Imam’s theories of light can be summarised as follows: • Rays of light are reflected by different objects and enter our eyes. • We do not see distant objects clearly because the rays of light coming towards us are scattered. • If the rays of light are concentrated by some device we can see distant objects distinctly. • Light is a kind of motion which travels at a very high speed. • A strong beam of light can move heavy objects.