Fascinating Facts About Photons1/08/2008 5:44 AM Eastern
Fascinating Facts About Photons
- Any light you see is made up of a collection of one or more photons propagating through space as electromagnetic waves.
- A photon, or quantum, of light is produced whenever an electron in a higher-than-normal orbit falls back to its normal orbit, emitting a packet of energy with very specific characteristics.
- The photon has a frequency, or color, that exactly matches the distance the electron falls.
- The photoelectric effect was discovered in 1887 by Heinrich Hertz and explained by Albert Einstein in work for which he received the Nobel Prize.
- The energies of photons range from high-energy gamma rays and X-rays to low-energy infrared and radio waves, though all travel at the speed of light.
- In 1900, Max Planck, a German theoretical physicist, found that heat radiation is emitted and absorbed in distinct units, which he called quanta. He received the 1918 Nobel Prize in physics.
- The energy of a photon equals the frequency of the radiation multiplied by Planck's constant, a value of 6.626 x 10-34 joule-seconds, represented by the symbol “h” and equal to the energy of a quantum of electromagnetic radiation divided by the radiation frequency.
- Electromagnetic radiation can be described in terms of a stream of photons.
- Photons are the smallest unit of light/electromagnetic energy and generally regarded as particles with zero mass and no electric charge.
- Sometimes the amount of energy a photon has makes it behave more like a wave than a particle. This is called the “wave-particle duality” of light.
- There are three types of photons: shadow photons, global photons, and caustic photons.
- Gilbert Lewis coined the term photon in 1926.
- In the 1800s, the wave properties of light became glaringly obvious and scientists essentially threw the particle theory of light out the window. It wasn't until Albert Einstein explained the photoelectric effect and realized that light energy had to be quantized that the particle theory returned.
- A photon cannot decay on its own, although its energy can transfer (or be created) upon interaction with other particles.
- The photon torpedo of Star Trek is a self-propelled missile consisting of a small quantity of matter and antimatter bound together in a magnetic container.
SOURCE: HOWSTUFFWORKS.COM; BRITANNICA CONCISE ENCYCLOPEDIA; WORLD ENCYCLOPEDIA; NASA'S IMAGINE THE UNIVERSE!; THE INSTITUTE OF COMPUTER GRAPHICS AND KNOWLEDGE VISUALIZATION, GRAZ UNIVERSITY OF TECHNOLOGY; ABOUT.COM; STARTREK.COM