Tuesday, May 23, 2006

Physics fun with sunglasses

Yesterday was a public holiday (Victoria Day) in Canada, and (as opposed to last year, when I went to my windowless office at the university in blissful ignorance of the Canadian holiday schedule, wondered why it was so empty and the lights on the corridors were off, and only figured it out when I was unable to obtain any lunch in the food court) I got to enjoy the sunshine on a lovely day.

I had completely forgotten how much fun sunglasses could be: I have these sunglass things (I don't really know what the technical term for them is) that can be clipped to my glasses to turn them into sunglasses; what makes them so much fun is that they really are nothing but polarisation filters! Of course polarisation filters make great sunglasses because the sunlight is unpolarised, and because the polarisation filter does not introduce a colour bias like an old-fashioned green or brown filter would. But as everybody remembers from their undergraduate optics course, light reflected from surfaces is partially polarised, and the same is true for scattered light. Therefore, when wearing your polarisation filters/sunglasses, the brightness of the road surface and of the blue sky will vary as you tilt your head towards the right or the left, which is quite fascinating. Unfortunately, other people will probably consider you to be crazy if they see you tilting your head from side to side while stepping forward and backward trying to determine the Brewster angle, or turning around your own axis trying to precisely locate the spot of maximal polarisation in the sky (which is how bees detect the direction towards the sun even if the sun itself is behind a cloud) -- but a real physicist shouldn't mind, right?

So I got to feel like an experimentalist for a little while, while also taking a pleasant walk in the park, sipping lime juice on a terrace above Wascana Lake and generally enjoying myself, all thanks to great weather and Her Majesty's official birthday in Canada: God save the Queen!

Oh, and of course those sunglasses are real fun to use with LCDs, too...

3 comments:

Anonymous said...

They're called a clip. Marketing worked overtime picking out the name.

Joel said...

Driving can get quite distracting especially when you notice the patterns of violet light comming off of most tinted winshields...

fun stuff...

Ski Goggles said...

Yep, it's always suggested to buy the right sunglasses if you want to avoid distractions while driving.