In 2013, it was announced by the United Nations that 2015 would be the “International Year of Light and Light-based Technologies”, a year-long celebration aiming to bring worldwide attention to light science and how it can improve lives and develop society. With over 13,000 events organised around the world, and hundreds of partners and collaborations, it proved to be successful. To continue this work, an annual International Day of Light event now takes place each year, on 16^th May.

Light is a crucial aspect of life on Earth. Whilst solar light is fundamentally responsible for providing the energy for all biological life through photosynthesis, the advent of information technologies that use light has facilitated the third industrial revolution, enabling the sharing of information and knowledge on a global scale. Maintaining awareness of the remarkable power of light is essential if we are to continue the life-altering innovations that have allowed humankind to progress in the modern age.

International Day of Light

For the International Day of Light, 16th May was chosen in honour of the American engineer Theodore Maiman, who on 16^th May 1960, successfully fired a laser for the first time. The history of light science actually extends back much further than this, to ancient Greece, when many philosophers, such as Pythagoras and Ptolemy, had different theories about how light was perceived by the human eye. Later, these theories were expanded with the development of geometrical optics, as Arab mathematician Ibn al-Haytham (965–1040) consequently described the process of seeing objects with light accurately.

The most modern discoveries came in the 17^th century and beyond, when Christiaan Huygens and Isaac Newton created their own theories on the properties of light. Albert Einstein then asserted in 1905 that light is in fact a photon, allowing light scientists to better harness light for useful purposes. Since then, continuous advancements have been made in the field. As well as the invention of the laser, the study of quantum optics has become a recent hot topic. In 2018, physicists discovered a new form of light that could enable quantum computing. Discoveries and innovations in light and the way in which it is used continue to be relevant as technology develops and the world becomes accustomed to relying on light more than ever before.

Light sciences research

As an innovator in light sciences research, MDPI hosts a high calibre of light-related research in its many journals. For example, Dr. Silvia Romano and Dr. Gianluigi Zito guest-edited the Special Issue “Frontiers of Light Science: Novel Concepts, Nanomaterials, Nanostructures, and Applications”, a compilation of research on novel imaging techniques and light manipulation in Nanomaterials. Furthermore, in the paper “The LED Paradox: How Light Pollution Challenges Experts to Reconsider Sustainable Lighting”, the authors investigate the sustainability and suitability of LED lighting in urban, public areas.

As well as the development of sustainable light, other innovations in light technology include a method to sanitise rooms using ultraviolet light, and photodynamic therapy, a targeted light treatment which selectively destroys cancer cells. Needless to say, these advances have the potential to benefit the health and lives of infinite numbers of people in the future. Research and discoveries such as these are part of the reason why the International Day of Light is so important. See the Nanomaterials journal homepage for more.