Light

“Remember, No matter where you go, there you are” Buckaroo Bonzai

Light

Light; Its a form of energy, it shows us color and brightness. It travels in space and time. It

can show us what stars are made of. It interacts with matter. It is probably one of the most important

and interesting things we have learned about so far in class. I am amazed at all the information that is

contained within “light”. There are many forms other than just visible light. I learned about the electromagnetic spectrum of light that include radio waves, infrared, visible light, ultraviolet,

X rays and gamma rays. A misconception I had was that I thought radio waves were a form of sound.

Radio waves are the longest wavelength of light. Therefore radio waves are a form of light. Microwave

cooking is an example of using electromagnetic radiation as energy. We see blue skies and red sunsets

because of absorption, transmission and reflection of visible light. Another interesting thing we learned

is how light behaves differently. Sound waves have to move through

some form of medium. Light does

not. It can travel through a vacuum. In a vacuum light travels at the same speed (300,000 kilometers

per second) regardless of its wavelength or frequency! The shorter the wavelength the higher the

frequency and the higher its energy. Light behaves as both a wave and a particle.

What I find most impressive about light is, as we look out into space, the farther out we look, the further back in time we see. This is because of the time it takes light to travel to us. So we are seeing into the past. I myself have looked through a telescope and saw the Andromeda galaxy.

(that was pretty cool in itself) It is approximately 2.5 million light years away. So the light I saw looking through the telescope that night actually traveled a great distance. At the time I didn’t realize that what I was seeing was a vision of the Andromeda galaxy how it looked about the time humans first appeared on Earth. It’s very hard to imagine. It makes me wonder what it looks like right now? How much has it changed since that time so long ago? It’s incredible that every sunrise or every sunset we see actually happens eight minutes earlier because that’s how long it takes the light to reach Earth.

I also thought it was very interesting that light contains information about motion.

Specifically the Doppler effect and how it causes shifts in the wavelengths of light. If an object is

moving toward us, its entire spectrum is shifted to shorter wavelengths, which are toward the blue end

of the spectrum of light, otherwise known as blueshift. If an object is moving away from us, its entire

spectrum is shifted to longer wavelengths, which are toward the red end of the spectrum, known as

redshift. The lab that we did was very interesting in the fact that we could see the patterns of elements

in the emission spectrum. Each element has a unique pattern. Using the example of hydrogen we looked at the emission lines and could identify the pattern, then we looked at a spectrum of a bright star in a distant galaxy and saw the same pattern of hydrogen. What was really interesting was the pattern of hydrogen in the line spectra was shifted to the left toward the red end of the spectrum (longer waves) and that told us that the star was moving away from us or redshifted. The Doppler effect can also tell us about the motion within an object. By studying spectra we can tell how fast stars rotate by measuring the width of their spectral lines. There is so many exciting ways Doppler shifts can be used to give us information in the field of astronomy and also