Light takes on many forms – including radio waves, ultraviolet, X-rays, and more – that are invisible to us and largely undetectable without modern technology. Since scientists began discovering there were “other” types of light at the start of the 19th century, they have been working to figure out ways to harness its potential. Today, it’s hard to overestimate how much we rely on light and how it plays a key role in the development of the world’s economies.
Credits: Data-AVHRR, NDVI, Seawifs, MODIS, NCEP, DMSP and Sky2000 star catalog; AVHRR and Seawifs texture-Reto Stockli; Visualization-Marit Jentoft-Nils
Light can play a pivotal role in developing nations. Through radio and microwaves, light has helped to open up communications with remote regions through Internet, GPS, and cellular services. Harnessing light from the Sun can provide clean, renewable power for the planet’s growing population. Lower-cost X-rays, MRIs, CT scans and other imaging (which use different forms of high-energy light) can improve medical care for those in locations where non-invasive techniques are too expensive, or unavailable.
Because of these and many other reasons, organizations around the world worked with the United Nations to proclaim 2015 as the International Year of Light and Light-based Technologies (IYL 2015). The hope is this global effort will help people around the world recognize the importance of how light-based technologies can promote sustainable development while also providing solutions for global challenges in energy, agriculture, health, and education. The following images from one project for IYL 2015 known as “Light: Beyond the Bulb” provide a brief look at key areas of light and development.
When we think of our Sun from the perspective of Earth, we might think it is a simple yellow sphere. However, if we observe the Sun in the "other" types of light that it emits, we find an entirely different looking object, such as in ultraviolet light as shown in this image. Much of the energy from our Sun comes in the form of infrared, ultraviolet and other types of light. These varieties of light are responsible for life on Earth, the ability to communicate over long distances, and the potential to explore beyond our own planet.
Perhaps one of the most remarkable light-based phenomena on Earth is photosynthesis. This is the process that allows plants, bacteria, and algae to convert light from our Sun into chemical energy. Photosynthesis uses light to transform carbon dioxide and water into carbohydrates and oxygen. Since all animal life, including humans, eats plants–either directly or indirectly through animals–and uses oxygen to breathe, light from our Sun is the fuel that allows us to exist.
Credit: Dennis Schroeder/NREL
The Sun is also important for providing us with power for electricity. Solar panels allow us to harness some of the vast energy that is provided to us every day from the Sun. Photovoltaic cells within the solar panels generate electrical power by converting light from the Sun into electricity using semiconducting material such as silicon. Solar panels may be used on individual homes or buildings or in large "farms" of networked panels that can provide electricity for large numbers of people and businesses. Many people consider solar power as one of the most promising sources of renewable energy.
Credit: U.S. Navy photo by Cmdr. Ed Thompson
Once our Sun sets, it can mean either darkness or the dim glow of sooty kerosene lamps or candles for more than 1.5 billion people over the globe. Poor or non-existent lighting can dramatically impact human health, as well as educational and economic opportunities. One aim of the International Year of Light in 2015 is the promotion of bright and portable solar-powered LED lanterns for areas with few lighting options, or less reliable energy sources.
Credit: National Institute of General Medical Sciences (NIGMS)
Light is one of the most important—and non-invasive—tools that doctors and scientists have to learn about the way the body works. By being able to view the internal structures of the brain and eye, as seen in these images, it allows researchers to learn about how these critical parts function as well as what happens when things go wrong. The image shown here is from a laser-scanning microscope of a mouse retina, where the cells have been stained with fluorescent dye to show different features. By studying the microscopic structure of both diseased and normal retina and optic nerves, scientists hope to develop therapeutic interventions.
Credit: NASA/JSC/Mike Trenchard
Images taken from satellites in space in different types of light help us better predict weather and understand the science that drives it. For example, infrared light reveals detail in cloud structures that would otherwise be invisible. Doppler radar, which measures the direction and speed of a moving precipitation, uses microwave light to tell us when to expect rain or snow. Astronaut Ed Luca captured this image in visible light of the eye of Hurricane Isabel as he passed overhead on the International Space Station on September 15, 2013. Details of a hurricane's structure can help meteorologists determine just how powerful such a storm may be as well as determine the path it may take.
Credit: ESO/B. Tafreshi
From applications in fields of manufacturing, to medicine, to the military, lasers are an important use of light. Lasers are based on controlling the way that energized atoms release photons, or packets of light. Lasers emit light coherently allowing it to be focused to a tight spot up close or over long distances. This image shows one innovative use of lasers. By beaming a laser into the sky, astronomers can measure and then compensate for the blurring effects of the Earth's atmosphere, allowing for clearer images of distant cosmic objects.
Credit: NASA/Johnson Space Center
There are many different ways cities produce light. Streetlights provide light when it is needed through high-pressure sodium lamps or by newer and more efficient downward focused light-emitting diodes (a.k.a., LEDs). Headlights in cars use sophisticated lamps that shine their light directly ahead yet are diffused enough to not interfere with the vision of oncoming drivers. Through the collisions of electrons and atoms, neon signs emit colored light by fluorescence. Taken together, light defines developed cities in many ways, as seen here in this photograph of Salt Lake City, Utah taken from astronauts aboard the International Space Station.
While artificial lighting has brought many benefits to humanity, it can also have negative consequences. The term “light pollution” refers to light that is wasteful or excessive and disrupts ecosystems, wastes energy, and disconnects us with the night sky. There are many people worldwide who are working to promote the issues around light pollution,
including improving the efficiency of lighting to keep the skies as dark as possible.
About one-fifth of the world’s population does not have reliable access to a power grid, and therefore, modern lighting solutions. Populations in developing countries who can connect to an established grid can experience common and unpredictable outages. Without reliable lighting (known as “light poverty”), they must illuminate their homes using unsafe means such as burning kerosene torches. A lack of consistent power can also make it difficult to provide government services and develop businesses.
Credit: X-ray: NASA/CXC/Univ. Potsdam/L. Oskinova et al.; Optical: NASA/STScI; Infrared: NASA/JPL-Caltech
The study of our Universe can play an important role in developing advanced technology, from inventing sophisticated detectors of light to making possible the increased speed of modern computers. Modern astrophysics requires sensitive electronics, extreme-precision adaptive optics, and advanced engineering. New optics, high-energy observatories and radio telescopes are among the most advanced instruments of human achievement and can also function as educational vehicles.
Credit: X-ray: NASA/CXC/SAO, Optical: NASA/STScI, Radio: NSF/NRAO/VLA
No matter where you live and under what circumstances, every human on our planet shares the same sky. Light is the way we learn about our place in the Universe, whether it is through looking at a starry night with our naked eye or using the world’s most sophisticated telescopes. The ancient light from distant stars, galaxies, and nebulas connects us as citizens of our planet.
Kimberly Arcand is the principal investigator for the IYL2015 project “Light: Beyond the Bulb” (http://lightexhibit.org/), an open-source exhibition program occurring in hundreds of locations across the globe. Megan Watzke is the co-creator of the Light: Beyond the Bulb project. Together, they are co-authors of the upcoming book "Light: The Visible Spectrum and Beyond" by Black Dog & Leventhal (November 2015).