#SEETHELIGHT is a worldwide message for the International Day of Light on 16 May encouraging all to join a conversation and celebrate the importance of the science of light and light-based technologies in our lives.
The date of May 16 was chosen for the International Day of Light because it was the day that Theodore Maiman demonstrated the first laser in 1960. It recognizes the visible impact of science and engineering and their contributions like the laser. Today, there is a laser in practically every home – your humble CD or DVD player has one, for example.
The day of light is a global initiative that provides an annual focal point for the continued appreciation of light and the role it plays in science, culture, art, education, and sustainable development, as well as fields as diverse as medicine, communications, and energy.
Light plays a central role in our lives. On the most fundamental level, through photosynthesis, light is at the origin of life itself. The study of light has led to promising alternative energy sources, lifesaving medical advances in diagnostics technology and treatments, light-speed internet and many other discoveries that have revolutionized society and shaped our understanding of the universe. These technologies were developed through centuries of fundamental research on the properties of light – starting with Ibn Al-Haytham’s seminal work, Kitab al-Manazir (Book of Optics), published in 1015 and including Einstein’s work at the beginning of the 20th century, which changed the way we think about time and light.
The International Day of Light celebrates the role light plays in science, culture and art, education, and sustainable development, and in fields as diverse as medicine, communications, and energy. The celebration will allow many different sectors of society worldwide to participate in activities that demonstrates how science, technology, art and culture can help achieve the goals of UNESCO – building the foundation for peaceful societies.
This day is a call to strengthen scientific cooperation and harness its potential to foster peace and sustainable development.
Audrey Azoulay, Director-General of UNESCO, on the occasion of the International Day of Light 2019 stated: "From the birth of the universe to the creation of all kinds of new technologies, from X-rays to radio waves, in fields as diverse as medicine, agriculture, energy, optics, and countless others, light has shaped – and continues to shape – our world. By understanding light, we are able to achieve the greatest of scientific and technological progress.
All its natural benefits and its scientific and technological applications make light an essential part of the daily life of our societies; these benefits and applications make light an important issue for the Sustainable Development Goals of the 2030 Agenda."
Light is at once both obvious and mysterious. We are bathed in yellow warmth every day and stave off the darkness with incandescent and fluorescent bulbs. But what exactly is light? We catch glimpses of its nature when a sunbeam angles through a dust-filled room, when a rainbow appears after a storm or when a drinking straw in a glass of water looks disjointed. These glimpses, however, only lead to more questions. Does light travel as a wave, a ray or a stream of particles? Is it a single color or many colors mixed together? Does it have a frequency like sound? And what are some of the common properties of light, such as absorption, reflection, refraction and diffraction?
You might think scientists know all the answers, but light continues to surprise them. Here's an example: We've always taken for granted that light travels faster than anything in the universe. Then, in 1999, researchers at Harvard University were able to slow a beam of light down to 38 miles an hour (61 kilometers per hour) by passing it through a state of matter known as a Bose-Einstein condensate. That's almost 18 million times slower than normal! No one would have thought such a feat possible just a few years ago, yet this is the capricious way of light. Just when you think you have it figured out, it defies your efforts and seems to change its nature.
Still, we've come a long way in our understanding. Some of the brightest minds in the history of science have focused their powerful intellects on the subject. Albert Einstein tried to imagine what it would be like to ride on a beam of light. "What if one were to run after a ray of light?" he asked. "What if one were riding on the beam? … If one were to run fast enough, would it no longer move at all?"
Einstein, though, is getting ahead of the story. To appreciate how light works, we have to put it in its proper historical context. Our first stop is the ancient world, where some of the earliest scientists and philosophers pondered the true nature of this mysterious substance that stimulates sight and makes things visible. Over the centuries, our view of light has changed dramatically. Today, light dominates our lives every second of the day.
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