International Year of Light

Here in Switzerland the weather tends to be bad and we have a Zwinglian/Calvinistic Leitkultur, which might explain our tendency towards pessimism and feeling more unlucky than lucky: it is customary to first look at the negative side of things and then to let us be surprised and feel lucky when things turn out to be positive. In this context, nobody is surprised when the newspapers announce the new year by listing negative anniversaries: 700 years Morgarten, 500 years Marignano, 70 years end of World War II.

Today's Zürich is home to many computer science labs and the city has as many nerds as gnomes (the equivalent persona in banking). They may see 2015 as the year of the palindrome, because 2015₁₀ = 11111011111₂. Or the many mathematicians in Zürich will see 2015 as a Japanese cube, because in the Japanese calendar it is 平成２７年 or Heisei 27 = 3³. For movie buffs, this year is MMXV.

For color scientists, 2015 is the International Year of Light and Light-based Technologies, a United Nation observance that aims to raise awareness of the achievements of light science and its applications, and its importance to humankind. The IYL 2015 will launch at the UNESCO headquarters in Paris on 19 January 2015, with the unveiling of 1001 Inventions and the World of Ibn Al-Haytham.

Indeed, 2015 marks the anniversaries of several events related to light, optics, and vision:

• 1015, a millennium ago, the Iraqi scientist Ibn Al-Haytham published his Book of Optics
• 1815 Augustin-Jean Fresnel proposed the notion of light as a wave
• 1865 James Clerk Maxwell proposed the electromagnetic theory of light propagation
• 1915 Albert Einstein embedded his 1905 theory of the photoelectric effect into cosmology through general relativity
• 1965 Arno Penzias and Robert Woodrow Wilson discovered the cosmic microwave background
• 1965 Charles Kao theorized and proposed to use glass fibers to implement optical broadband communication

In ancient Greece, there where two competing theories of vision. One theory was called the emission theory (Euclid, Ptolemy) and claimed that vision worked by little flame exiting the eye, traveling on rays, scanning the objects in the visual field, and traveling back to the eye reporting what they detected. In the intromission theory (Aristotle), when an object is looked at, it replicates itself and the replica travels along a ray into the viewer's eye, where it is seen.

For a millennium, there was a raging discussion of whether the emission theory or the intromission theory was the correct one. This discussion was based purely on theoretical considerations and heuristics. In his 1015 book, Ibn Al-Haytham introduced the modern concept of scientific research based on experimentation and controlled testing that we still use today: a hypothesis is formulated, an experiment is conducted varying the parameters, the results of the experiment are discussed, and the conclusions are drawn. Because of this, Ibn Al-Haytham is often referred to as the first scientist.

Using the scientific method, Ibn Al-Haytham developed the first plausible theory of vision. Among other contributions, he also explained the camera obscura and catoptrics. He has strongly influenced later scientists like Averroes, Leonardo da Vinci, Galileo Galilei, Christian Huygens, René Descartes, and Johannes Kepler.

Ibn Al-Haytham's full name was Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham. His Latinized name was originally Alhacen; since 1572, when Friedrich Risner misspelled his name, in the West he has been known as Alhazen. He was born and raised in Basra, where he initially worked. Later he worked in Baghdad and Cairo.

For more information on the International Year of Light see here.