Optics 101

Regretfully, I haven't touched this blog in about a month. I acted the Emperor in my friends' Star Wars Musical, so I had rather limited access to the various activities since the beginning of rehearsals the day school started. However, now that we completed the show...I'M BACK!!!

Today, I'd like to share something I noticed a while back. A couple of days before school started, I underwent an oral operation to fix the growth of my wisdom teeth. The operation took its toll on my mouth, so my dentist prescribed two painkillers. One of them were/was these blue pills (grammatical error, I know).

 
Interestingly, the pills inside the bottle look green when viewed from the outside.

However, that should not be possible! If anything, the pills should look a bit white.

In nature, an object is a certain color because the thing reflects that color (or part of the electromagnetic spectrum--ie, light) when shined upon (which is , as my physics teacher pointed out, why the Rebels in Star Wars should have painted their ships green to reflect the TIE Fighter's green lasers). Thus, physically, I should see my pills as white, but that was not the case. In a quest for the truth, I asked my physics teacher.

He pointed out that the orange dye of the bottle is imperfect--it doesn't allow all blue light to pass through. Furthermore, he pointed out that the bottle-maker most likely designed the bottle to behave that way on purpose. Reminding me of the altering effects* of Ultraviolet light on chemical substances, which lies just beyond blue/violet in the EM spectrum, my teacher explained that the blue-reflecting property of the bottle protected the pills from degradation. Ergo, the bottle reflected a lot of red and green light, while letting through some blue light. Most of the blue light then got reflected by the light blue pills, only to get absorbed once more in small amounts by the bottle on its way back to my eyes. At the same time, the reflected green and red light combined with the blue light the create the blue/green light I see as the pills.

And that's optics for you.

*If I remember correctly,  UV light's high frequency (energy) and penetrability helped it break through Earth's atmosphere and supply the energy for the formation of the planet's first organic molecules. The same properties cause skin cancer in humans.