Celebrating IYL 2015 and the Story of Light

The National Institute of Technology (NIT) Calicut (India) organized a three-day event Tathva’15 from 30 October to 01 November 2015 at the NIT Campus, Calicut, Kerala, India. The event included invited lectures, workshops and exhibitions. The workshops were desgined to Illuminate the young minds by developing skills in a wide range of engineering disciplines. There were exhibitions on the rich heritage of Indian railways, India’s first 3D printed humanoid robot, Light: Beyond the Bulb, and state-of-the-art electronics by Keltron. There were five invited lectures by experts in different disciplines. I delivered a lecture on the ‘The Story of Light’ covering the Greek era (pre- 8th century C.E.), the Arab-Islamic Golden Age (8th to 15th century C.E.), the European period (16th to 19th century C.E.) and the modern period (20th century C.E. onwards).

Zahid H. Khan delivering a lecture at Tathva'15, NIT Calicut, Kerala. Credit: Tathva'15.

Zahid H. Khan delivering a lecture at Tathva’15, NIT Calicut, Kerala. Credit: Tathva’15.

The lecture on ‘The Story of Light’ started with a brief introduction about IYL 2015, followed by the contribution to optics by Greek philosophers and scientists. Empedocles (490-424 B.C.E.) rectified the wrong notion about darkness and clarified that the true nature of darkness was, in fact, the absence of light. Aristotle (384-322 B.C.E.) performed experiments using camera obscura and showed that the image of the sun was always round irrespective of the shape of the hole with which sunlight was passed. Euclid (330-275 B.C.E.)  showed that light travels in straight lines and he is credited for the discovery of the law of reflection of light. Claudius Ptolemy (90-168 C.E.) studied the properties of light, viz. reflection, refraction, colour and geometry of vision. He tried to derive experimentally the law of refraction using different media and found that the angle of incidence is directly proportional to angle of refraction.

Next, the remarkable contributions made by Arab-Islamic philosophers and scientists were discussed, starting with Al-Kindi (800-873 C.E.) who translated the great works of Greek philosophers, such as Galen and Aristotle and also reinterpreted, commented and extended their works. He gave a technique for analyzing light rays from an object on a point-by-point basis, where he considered each point on a luminous body to be emitting rays in all directions, independent of other nearby points. The work of Ibn Sahl (940-1000 C.E.) on ‘burning mirrors’ led to the discovery of the ‘law of refraction’ of light. The most significant pioneering work in optics was made by Ibn al-Haytham (965-1040 C.E.), who is considered as the pivotal figure in the history of optics and the ‘father of modern optics’. Out of the 96 books he wrote, 55 have survived. His most prominent book is the ‘Kitab Al-Manazir’, the book of optics, in seven volumes, dealing with the theory of vision and the associated physiology of the eye, physiology of perception, and physical optics. The approach adopted by Ibn al-Haytham has been the most scientific. He first performed experiments, which were then used to justify the theories that he derived using mathematical (geometrical) models. Another important contribution to optics during the Arab-Islamic period came by Kamal al-Din al-Farisi (1267–1318 C.E.) who wrote the book, ‘Tanqih Al-Manazir’ (The Revision of the Optics) and gave the first correct explanation of primary and secondary rainbows.

Zahid H. Khan delivering a lecture at Tathva'15, NIT Calicut, Kerala. Credit: Tathva'15.

Zahid H. Khan delivering a lecture at Tathva’15, NIT Calicut, Kerala. Credit: Tathva’15.

During the European period, Isaac Newton (1642-1727 C.E.) made significant contribution to optics and performed the famous experiment on dispersion of white light through prism in which he showed that white light is made up of a combination of all of the colours of the rainbow. The scientific works of Christian Huygens (1629-1695 C.E.), Thomas Young (1773-1829 C.E.) and Augustin-Jean Fresnel (1788–1827 C.E.) led to the development of wave optics. James Clerk Maxwell (1831-1879 C.E.) formulated the classical theory of electromagnetic radiation. The discovery of radio waves by Heinrich Hertz (1857-1894 C.E.) and X-rays by Wilhelm Roentgen (1845-1923 C.E.) contributed towards the understanding of the electromagnetic spectrum.

The last part of the lecture covered the modern period, starting with the successful explanation of the black body radiation by Max Planck in 1900, who for the first time introduced the concept of ‘energy packets’. Next was the radiation theory proposed by Albert Einstein in 1905 to explain photoelectric effect in which he considered light as consisting of discrete, independent particles of energy, which were later called as ‘photons’. The twentieth century witnessed remarkable developments in optical science and photonics following the development of laser in 1960. Transmission of light in fibers for optical communication led to the development of ICTs, which has become an integral part of our life. The lecture concluded with a brief note on the development of blue LED which, in combination of red and green LEDs, can produce the white light, thus revolutionalizing the light technology, providing and efficient and environment-friendly source of light.


image3Zahid H. Khan was born at Akrahra, Uttar Pradesh, INDIA. He obtained his doctorate in Physics from Aligarh Muslim University, Aligarh. He has been a full Professor of Physics in Jamia Millia Islamia – a central university in New Delhi from 1994 to 2015. His academic and research interests are in the fields of molecular & laser physics, materials science, environmental science, ICT in education, and science popularization. He had been a DAAD Fellow at the Ludwig Maximilian University, Munich (1980-81) and Free Unversity Berlin (1981-82). He has vast experience in university administration and has served as Head of Physics Department, Honorary Advisor & Director of FTK Centre for Information Technology, and Registrar of the university during his 39 years of service at Jamia Millia Islamia. The UNESCO has nominated him as a National Focal Point for India for IYL 2015. He is also a member of the Steering Committee of the International Working Group on Ibn al-Haytham based in Paris.

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One thought on “Celebrating IYL 2015 and the Story of Light

  1. Great Work Sir! You have indeed spread the light of knowledge through tireless efforts all through your career. IYL 2015 is no exception to the list. Congratulations for making it a great success.

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