Walking between Briggs and the Science Atrium in the afternoon and early evening may solicit an unwanted lesson in optics in the form of a blinding reflection. Light from the sun strikes the glass of the atrium and reflects off in the direction of Briggs.This is not in itself remarkable; we have all seen sunlight reflect off of glass. However, during the right time in the afternoon, look around at the ground and snow banks near Briggs, and you may observe a single very bright spot about the size of a dinner plate.
Why does this mysterious spot appear only at some hours of the day, happily searing innocent passers-by? It would seem that one of the panes of glass on the Atrium is bowed ever so slightly, such that it focuses light rays.
The other panes are flat and don’t focus down the light, thus no spot is observed. Now optics will tell us that the window’s curve would have to be very slight in order to produce a spot so far away, but this makes sense as a window is, of course, normally flat.
In essence, the window is acting as a concave mirror, focusing light rays towards a point near Briggs for the malignant purpose of blinding poor students and adding insult to injury, as if the four flights of stairs, bitter cold, and tuition weren’t enough.
Of course, now that this phenomenon is explained by science we can harness it to our purpose! The focused beam of light provides a toasty spot for the passing student to warm up in the cold winter.
All of the sunlight that hits the window is redirected into a much smaller area, so naturally the light in the spot has significantly more intensity than simply standing in direct sunlight. The result of being bombarded by all these extra photons? Heat!
Stand in the beam and you will feel the warmth in just a few seconds. A number of us actually tried this yesterday, and it worked quiet well. As each of us stepped into the spot to immediately squint dumbly and shield our faces against the intense bright, we realized that this pleasant warmth came at the price of our dignity.
In case you were wondering, glass (in air) reflects light more at glancing angles and transmits it more when it is hit squarely, which is why you see through glass looking straight at it, while when you look at the atrium at a steep angle you see reflections.
Special thanks to Leroy Frahm and Professor Pickett of the physics department for noticing and pointing out this local phenomenon to us.