Weekly Online Lesson Online Lesson Archive Grade Level: 8-12 Subject: Physics

Lighting Our Way

Light has been both an elusive and necessary driving force in our biotic world since life began. Some organisms, like plants, use light simply for basic growth, but humans have looked at how light behaves in ways that have allowed us to move beyond a primitive state.

During the last two weeks of January 2001, for example, scientists have published research results showing that they essentially stopped light and then restarted it. The experiments mirror the testing of an on/off switch for a light bulb, but the implications of the results are one more step in the evolution of human technology to create applications only dreamed about by Star Trek fans, and hoped for by those who have become impatient with the limitations of today's technological devices. In this week's lesson you will explore the history of human understanding of light and find out how this week's news may push our future lifestyles into "light speed."

Illuminating History

Although light has apparently existed even before life on Earth, and even thought humans have been studying this natural "phenomenon" for many years, we are still learning new things about it. To start off this week's lesson, read A History of Light and Lighting. Here, you will discover how light and its various sources, like the sun, burning fuels, and bioluminescence, have helped humans create the lifestyle most of us experience daily. Note that human fascination and study of light has influenced how we lived, the religions and philosophies we created, and how our increasing knowledge of light — its properties, predictabilities and our manipulations of it — has been the keystone of our evolving technologies. What were some experiments or discoveries directly related to the behavior of light or use of light-emitting sources? What were some of the experiments or discoveries NOT directly related to light but influenced our use or understanding of light?

Sparking the Human Mind

Humans, like plants and animals, have used light to live by for thousands of years. Modern humans have used their primitive knowledge and their higher intellectual capacities (their science smarts) to delve deeper into the mysteries of light, testing theories and quantifying the results. Visit the Discovery School's A-to-Z Science page on Light, and read about what light is and how it can be measured. How is light produced? How does it behave under different circumstances (e.g., through lenses, slits, etc.)? Do different sources emit light differently? In what ways is light quantified? How did our understanding of light change over time?

Einstein Gets Some Bright Ideas

Albert Einstein was a physicist who rocked the scientific world with his theories, particularly those related to the properties and behaviors of light. One important concept to understand from Einstein's era is how light interacts with atoms, which eventually led to the creation of lasers. Check-out Physics 2000, and in the menu under Einstein's Legacy click on Lasers. Read through the dialogue, which continues on the "Atom-Light Interactions," "Population Inversions," and "Creating a Laser" pages, and experiment with the Java Applets to find out how and why lasers are different from natural and average electrical light sources. What makes light energy "flow"? Why is a laser different from a light bulb? In what ways do we use lasers that we couldn't with an average light source? Explore some of the related sections if you have time.

Stopping Light, Starting a Revolution

On January 18, scientists announced that, in two different and independent experimental studies, they can essentially stop light and capture the information of that moment. Read the MSNBC's article, Scientists put a light wave on hold to learn more. Based on what you've already learned about human exploration of light, what kinds of previous knowledge did the scientists use to create this experiment? Why were lasers the best light sources to use?

Find out more about the implications of their discovery by going to the MSNBC Interactive site, Cats and qubits. This special section explains what quantum computing is and provides hints about why it would change how we live technologically. Based on the recent scientific news, do you think this kind of application will be possible anytime soon? If we such computers were common today, in what specific ways do you think they would affect your life?

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