Spectral Speculation

Originally featured in The Salty Fish Bowl - May 2010

Recently, whilst frolicking amidst the mist of a public lawn moistener, I was struck by the innate beauty of the Rainbow. As I darted from one water spout to the next, I encountered a perfect circle of colour hovering before me, moving as I moved, like a spectral specter. It was breathtaking. I stood wondering where its end may be, and what might be there if I could find it; but circles have no end, and there is more to rainbows than mere beauty and the promise of gold. Rainbows are more unique, and full of more hidden treasures, than you might think.

I think it’s fair to say that most of us, at least once in our lives, have uttered something along the lines of, “Look at that rainbow,” and in most instances everybody did, but did you know that not a single one of you saw the same rainbow? It’s all about angles of perception. Light from the sun travels toward us through Space at the speed of light, until it hits something solid or is slowed down passing through an alternate medium (like a prism, or in this case moisture in our atmosphere) causing refraction. Light refraction is the result of the longer wavelengths (red) travelling faster through the moisture than the shorter wavelengths (indigo). This “bends” the light and separates the different wavelengths causing the spectrum you see in the sky. But why do we all see different rainbows? Picture yourself with a laser. If you aim it at a mirror the beam will bounce off at the same angle and hit whatever happens to be in that direction (hopefully not a somebody). Now, trying to keep your laser pointed just so, take a step to the left. Your beam should be hitting something else. Now imagine the same scenario outside, except the sun is the laser, moisture is the mirror, and you are the something. In summary, the sunlight that ends its journey in your eyes is different than that which hits your friends’ eyes, due to the angular discrepancies between yourselves and the sun. The next time you’re out with friends and see a rainbow, you can keep it to yourself, because they won’t be able to see it anyway. Be content in the knowledge that you are the only thing in existence that saw that particular rainbow.

The building blocks of the Universe. It has been theorized that the elements that make up everything we see, including you and me, originally came from stars. Stars are thought to be “Crucibles of Life,” where the necessary ingredients are brought to a boil and then blasted out into the Cosmos to become anything from planets, to people, to jalapeno poppers. How though, do scientists know what is inside a star? Quite simply, by reading rainbows. Light reacts differently when it interacts with different elements, and this can be seen in its wavelengths. With a (very) large telescope astronomers can pinpoint the light from individual stars, and with the application of a spectrograph (I’m not going to pretend I know how they work), they can determine exactly what elements reside inside. Spectrography can be used to determine types of stars, helping astronomers estimate things like age and life expectancy. It’s also used, perhaps most notably, to locate other Sun-like stars in the search for Earth-like planets, and may one day result in scientists finding somewhere else for us to live once we’ve F’ed up our own planet beyond repair.
Spectra of stars and galaxies are even used to observe the expansion of the Universe. The light from distant galaxies, has been found to be “red-shifted”, which means as the “fabric of Space” has stretched out, so have the wavelengths of the light travelling over that time. In fact it is widely believed that light from the Big Bang (approximately 13.7 billion light years ago) has red-shifted so much in getting to us that it is now actually radio waves. And we know all of this simply from looking at rainbows.

So the next time you see a rainbow, while you’re admiring it all to yourself, think on its Cosmic significance. Imagine how far the light had to travel, and all that it’s been through, only to be bent by some raindrops and splashed across the sky. Imagine what it’s trying to tell you about its beginnings, and perhaps even your own Fate.