by Shane L. Larson
My wife and I just bought a new couch and when we flipped the old one over to carry it downstairs, a quarter fell out. When I was in high school, arcades were the rage and a quarter was a ticket to a nice half-hour playing Xenophobe or Blasteroids. These days, it goes in my pocket and gets spent on parking. Despite the sad evolution of my life into adulthood, the appearance of the quarter sparked an interesting thought: I don’t remember dropping a quarter in my couch, and probably no one else would either, so that must mean almost everyone’s couch likely has a loose quarter in it! That observation, sparked an interesting question: how much money in quarters is hidden in couches?

(L) How I used to spend quarters. (R) How I spend quarters now. If the place on the left still existed, I could feed the the thing on the right with my phone and put those quarters to good use! 🙂
Because you and I live in the future, information is at our fingertips. I pulled my phone out of my pocket and was quickly at the US Census site, which told me there are approximately 116,000,000 households in the United States (this page is where I landed). So if they all have a couch, and each couch has a quarter in it, that amounts to:
$0.25 * 116,000,000 = $29,000,000
There are 29 MILLION dollars in quarters hiding in couches! This observation has sparked some interesting discussions with friends that are wide ranging and varied: is there really only 1 quarter per couch? How much money disappears from circulation every year? Is there some way we could collect all that money? What could we do with $29 million?
This little exercise is something known as a “Fermi Problem,” — taking something you know (my couch has a quarter in it) and figuring out the implications based on other things you know (the number of households in the United States). Scientists use the method all the time to understand what the Universe is all about, particularly in astronomy where we don’t know much. But the interesting bit about the quarter question is not the number, it is the discussions that ensue afterward.

Just a few observations I have made and shared with friends, found on my smartphone. You most likely have a similar set!
You make observations of the world around you all the time, and share those observations on social media or over coffee with friends. I know you do, because I see jillions of people everyday taking pictures of flower bushes and posting them to social media, asking friends over coffee if they noticed they way the clouds were streaked over the city that day, speculating on why the traffic was heavy or light today, or simply enjoying the spectacle of the brilliant turquoise color of the lake on a sunny day. You see the world around you and record it and talk about it, every single day.
Given our social connectedness in modern life, this week’s exhortations from the #AdlerWall are ones that might not seem totally incongruous: “Share Interesting Observations” and “Ask Questions.” We are all good at this to some varying degree, but kids are masters. Children ask incessant questions of their parents:
“How do airplanes fly?”
“Where do frogs go in the winter?”
“Why do we say ‘bark’ to mean the sound dogs make and the skin of a tree?”
They also share interesting observations:
“Look how you can make a loud sound by squishing your hand in your armpit!”
“If I hit my spoon right here, it flips oatmeal WAY over there!”
“The shadows from this tree look like an octopus!”
But sadly, somewhere along the pathway to adulthood, many of us lose that unbridled enthusiasm we had as children for exploring the world around us, and declaring our discoveries to the world. Sure, I’ve wondered how many gummy bears I can fit in my mouth and figured out the answer (37) — who hasn’t? It’s not that we don’t know how to ask questions and share our observations. It has just become the societal norm to squelch the unbridled enthusiasm.
Yes, that’s right: squelch, not kill. Because in the quiet moments, we all give into the most basic impulse to ask a question, to look at the world around us and see what is going on. You might not always post a picture of the weather radar during a torrential thunderstorm, but you still made a screen capture. You have stayed up too late at night because you went to Wikipedia to find out about The Great Platte River Archway and two hours later found yourself still on your tablet, having randomly navigated through clicks until you were reading about the Toledo War. You’ve almost certainly been hanging out with your friends, when someone has asked some esoteric question about the difference between fountain pens and calligraphy pens, igniting a debate that was only resolved by asking Google or Wikipedia.
For most of us, making interesting observations and asking questions of our friends and the internet are diversions to everyday life, something we do for the sheer enjoyment of learning. But lurking just below the surface of those questions and observations is always a myriad of important ideas and applications, some of which we understand and some of which we may not. Irrespective, it points a simple and inescapable fact: we are all close to being scientists, simply by doing what we do — asking questions and making observations.
Let me illustrate with a curious observation I just made the other day. I have a vertical glass shower door; the glass is maybe 10 mm thick. If you put your eye right up against the edge of the door, and look into the glass (not through the glass), you a mesmerizing collection of reflections inside the glass door!
I’m sure I could work out the physics of the all the reflections as to why it happens (and could probably subject some future students to the analysis of that problem), but instead I’ll just share that observation with you. The next time you walk through a glass door, take a moment and peer in through the edge, looking longways into the glass — you’ll be treated to the same awesome spectacle I discovered. Maybe you’ll show it to a friend, or you’ll sketch it in your pocket notebook, or you’ll create a new glass sculpture inspired by the sight. Irrespective, I’ve shared my observation with you, and hopefully shown you something you haven’t see before! You should share what you see too.
So what does that have to do with anything? Peering into the glass of your shower door produces a spectacle that is fun and pleasing to behold, like a piece of symmetric art or a kaleidoscope. But the basic physics, called internal reflection, led to many, many modern applications, not the least of which are fiber optics, and the heart of most high-speed communications networks that are likely streaming internet and movies into your home right now. Binoculars have a pair of prisms that use internal reflection to gather the images of distant objects and route them through the binoculars to make a correct, right-side up image at your eye. Internal reflection of light in a raindrop takes the light from the Sun behind you, and directs it back at you to make a rainbow. And perhaps last, but not least, internal reflection is the basic physical principle behind infinity mirrors (IMHO, one of the coolest pieces of home decor you can have — your spouse may or may not disagree…).
![Everyday examples of internal reflection. (Top L) Binoculars. (Top R) Rainbow creation by raindrops. (Bottom) Light propagating through a fiber. [All images from Wikimedia Commons]](https://writescience.files.wordpress.com/2016/09/reflectionapplications.jpg?w=500&h=398)
Everyday examples of internal reflection. (Top L) Binoculars. (Top R) Rainbow creation by raindrops. (Bottom) Light propagating through a fiber. [All images from Wikimedia Commons]
So I’ll see you out in the world — I’m the guy blocking the entrance to the coffee shop as I try to snap a picture looking longways into their glass door. 🙂
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This post is part of an ongoing series about the #AdlerWall. I encourage you to follow along with the activities, and post your adventures, questions and discoveries on social media using the hashtag #AdlerWall. Links to the entire series are here at the first post of the #AdlerWall Series.