International Day of Light

International Day of Light is May 16th

Light is something we are constantly surrounded by - we wake up to light, plants grow from light, we use it to see things, measure things, technology, and art etc. International Day of Light is a day that aims to raise awareness about the important role light-based technologies play in things such as science, culture and art, education, sustainable development, and in fields as diverse as medicine, communications and energy.

International Day of Light and Light-based Technologies is a day that the United Nations observe in order to raise global awareness of the achievements of light science and its applications and its importance. Later in 2016, International Day of Light was adopted by the United Nations Educational, Scientific and Cultural Organization (UNESCO) Executive Board.

UNESCO Goals

• Improve the public understanding of how light and light-based technologies touch the daily lives of everybody and are central to the future development of the global society.
• Build worldwide educational capacity through activities targeted on science for young people, addressing issues of gender balance, and focusing especially on developing countries and emerging economies.
• Highlight and explain the intimate link between light and art and culture, enhancing the role of optical technology to preserve cultural heritage.
• Enhance international cooperation by acting as a central information resource for activities coordinated by learned societies, NGOs, government agencies, educational establishments, industry, and other partners.
• Emphasize the importance of basic research in the fundamental science of light, the need for investment in light-based technology to develop new applications, and the global necessity to promote careers in science and engineering in these fields.
• Promote the importance of lighting technology and the need for access to light and energy infrastructure in sustainable development, and for improving quality of life in the developing world.
• Raise awareness that technologies and design can play an important role in the achievement of greater energy efficiency, in particular by limiting energy waste, and in the reduction of light pollution, which is key to the preservation of dark skies.

History of Light

There is a long history about the creation of light, to the discoveries and the things we have learned about light in the past. However, all these discoveries and experiments are the reason we have the technologies we do today.

• The creation of the sun 4 billion BCE
• Socrates (469-399 B.C.), Plato (427-347 B.C.), and Aristotle (384-322 B.C.) established the foundations of astronomy, biology, mathematics, politics and philosophy, etc. Then Euclid (330-275 B.C.) summarized the fundamental knowledge of optics, such as reflection, diffusion, and vision, into a book called “Optics”.
• Ibn al-Haytham (Alhazen) (965-1040) created historical works including the “Book of Optics” that covers experiments and observation on light reflection and refraction through the use of lenses and mirrors. He also authored treatises on reflection from concave mirrors, refraction from glass spheres, visual perception, light from the moon and stars, and the structure of space.
• Sir Isaac Newton (1643-1727) presented a paper in 1672, announcing his “New Theory on Light and Color” in which he proclaimed that “light is a mixture of various colors having different refractivity” rather than “the pure white (sunlight)” proposed by Aristotle, and demonstrated his theory in the famous prism experiment. In 1704, he authored the book “Opticks” where he reveals his “Light Particle Theory.”
• Christiaan Huygens (1629-1695) in 1690 published a paper on light advocating his theory that light is a wave or wavefront. Utilizing his theory of light as a wave to explain light reflection and refraction.
• Thomas Young (1773-1829) in 1807 presented an experiment showing when light comes from a point light source is shined into two pinholes, interference fringes can be observed on a screen an appropriate distance away and advocated his theory that light behaves like a wave.
• James Clerk Maxwell (1831-1879) established the field of classical electrodynamics based on his famous equations known as the “Jewel of Physics” in 1864 that became the foundation for modern electromagnetism. He predicted the existence of electromagnetic waves, the fact that electromagnetic waves propagate at the same speed as light, and as horizontal waves. He is further well known for his research on the composition of Saturn’s rings and the Kinetic theory of gases (Maxwell-Boltzmann distribution).
• Albert Einstein (1879-1955) in 1905 presented three papers on the photoelectric effect theory where light is made up of particles called photons, the theory of Brownian motion utilizing kinetic theory of molecules and the theory of special relativity. The theory of relativity in particular was a discovery about space and time expressed in the relativity principle of electromagnetism and which resolved the ether problem in 19th century physics. Later in 1921 he received the Nobel Peace Prize.

Facts About Light

There are many things to learn about light - what it can do, how it is measured, how we use it or control it etc. Here are a few facts that you may have been unaware of:

• Light is measured in ‘waves’ and the light that we can see is only a small portion of the types of light. They are measured in the ‘electromagnetic spectrum’. The human eye sees specific areas of the spectrum, but other animals and insects can actually see parts of the spectrum that we can’t.
• The process is called ‘photosynthesis’ and converts carbon dioxide through the energy of the light.
• Isaac Newton studied light as it hit a glass prism. When he saw the light expand into the different colors (ROYGBIV): Red, Orange, Yellow, Green, Blue, Indigo, Violet. He realized that light refracts and each color traveled through glass (or other materials) at varying speeds.
• Light travels in a vacuum at 300,000 km per second (186,000 miles per second).
• A camera can control the amount of light that comes into the camera lens. We also use light in televisions, medical systems, copy machines, telescopes, and satellites.

Ways to Celebrate International Day of Light

Be a part of your own student chapter of light-based technologies, conduct your own light experiments, research more about light and light-based technologies, and volunteer and donate to communities that support the continuation of research about light and light-based technologies.

This day is a chance to learn something new, but also do some good when it comes to advocating about safe light-based technology use, for promoting peace and equality and overall just goodness.