Published on the 29th December 2015 by ANSTO Staff
The International Year of Light 2015 (IYL2015) has been a tremendously successful global initiative with thousands of events reaching millions of people in over a hundred countries including Australia. It will be brought to an official close with a ceremony held from 4-6 February 2016 in Mérida, Mexico.
Discoverers of Light
The history of the study of light has involved virtually all the major figures of science, and their stories reveal the human side of science in many different ways.
From the earliest times, many philosophers considered the question of light. Some argued it was a stream of particles, while others were certain it was composed of waves. Isaac Newton was one of the advocates of the ‘corpuscular’ theory, and performed experiments on light towards the end of the 17th century. Perhaps the most famous was his experiment with sunlight and prisms where he showed that white light is composed of many colors, and that each individual color could not be used to re-create white light or be broken down further. He also performed rather frightening experiments on himself to study the perception of light by his eyes.
Alongside Newton’s ideas, the idea that light was a wave had been proposed by people such as Christiaan Huyghens and Newton’s rival, Robert Hooke. But it was not until a century later, in 1800, that the experiments of Thomas Young showed that light can exhibit interference (e.g.., the crests and troughs of the waves can add or subtract to give bright and dark regions).
He also proposed that light of different colors has different wavelengths, and that we see these colors with sets of three detectors in our eyes for the three primary colors.
The camera obscura - or the projector as we know it today - has a long history dating back to 400 BC. Mo-ti, Chinese philosopher and founder of Mohism, is attributed with the first known mention of the camera obscura concept (then called a pinhole camera). His basic observations of light developed into a minor theory of optics. In 350, Aristotle further proved Mo-ti’s theory that light travels in straight lines by observing that light traveling through even the smallest holes in objects will still create a circle of light on the ground.
The year 2015 marks the 1000th anniversary since the appearance of the remarkable seven volume treatise on optics Kitab al-Manazir written by the Arab scientist Ibn al-Haytham. Born around a thousand years ago in present day Iraq, Al-Hasan Ibn al-Haytham (known in the West by the Latinised form of his first name, initially “Alhacen” and later “Alhazen”) was a pioneering scientific thinker who made important contributions to the understanding of vision, optics and light.