HowStuffWorks "How Light Works"

[http://www.howstuffworks.com/] SUBSCRIBE Adventure Animals Auto Culture Entertainment Health Home & Garden Lifestyle Money Science Tech Video Shows Quizzes Engineering Environmental Science Forces of Nature Innovation Life Science Military Physical Science Dictionary Science Vs. Myth Space Transportation Home / Science / Physical Science / Optics How Light Works by William Harris and Craig Freudenrich, Ph.D. Page 1 Introduction to How Light Works 2 What Is Light? 3 Light as Rays 4 Light as Waves As a citizen of sunny Earth, it's hard not to take light for granted. In this article, we salute you, light, for a lightless world would be a gloomy place indeed. Frank Krahmer/ Getty Images Related Links HowStuffWorks Forum: How close do you think humans will get to traveling at the speed of light? How Black Lights Work How Rainbows Work 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. Print Cite This! Close Please copy/paste the following text to properly cite this HowStuffWorks article: Harris, William, and Craig Freudenrich, Ph.D.. "How Light Works" 10 July 2000. HowStuffWorks.com. 14 August 2014. Citation & Date Feedback Page 1 Introduction to How Light Works 2 What Is Light? 3 Light as Rays 4 Light as Waves 5 Light Frequencies 6 Light as Particles 7 Wave-Particle Duality 8 Producing a Photon More To Explore All Things Science 10 Incredible Wind Power Facts 10 Remarkable Exoplanets Fact or Fiction: Earthquakes Top 10 Things That Women Invented Strange, Spooky, Scary: The Supernatural Quiz Watch 100 Greatest Discoveries videos » Most Popular Most Watched Most Popular 10 Reasons Why Tesla Is a Scientific God Strange, Spooky, Scary: The Supernatural Quiz 10 Heaviest Objects Mankind Has Ever Moved How Hydraulic Machines Work 10 Correlations That Are Not Causations Most Watched How to Make (Almost) Everything Understanding Bridges How do they do it? Why aren't the keys on my computer in alphabetical order? The Most Important Things So Far, Seriously Don't Miss Stuff You Should Know: Demystifying Your World Stuff Mom Never Told You: All Things Women and Gender Stuff You Missed in History Class: Fact or Fiction? CHECK OUT OUR PODCASTS HOWSTUFFWORKS NEWSLETTER THE LATEST AND GREATEST SUBSCRIBE HOWSTUFFWORKS Adventure Animals Auto Culture Entertainment Health Home & Garden Lifestyle Money Science Tech MORE STUFF Blogs HSW Tools RSS Maps Podcasts Quizzes Newsletters Video HSW Brazil HSW China STUFF WEBSITES BrainStuff CarStuff Fw:Thinking Stuff Mom Never Told You Stuff of Genius Stuff They Don't Want You to Know Stuff to Blow Your Mind Stuff You Missed in History Class Stuff You Should Know CUSTOMER SERVICE Advertising Contact Us Help CORPORATE About Us Careers @ HSW Privacy Policy Visitor Agreement TAKE US WITH YOU FOLLOW US Copyright © 1998-2014 HowStuffWorks, a division of InfoSpace LLC