Brief reminders
I was reminded of something tonight. The son who picks up information like a hoover, asks me all sorts of questions about science (”Why did people know that if a helicopter had just a main rotor, the helicopter would spin round?”) and often has his nose in a book is also the lad who is still the right age to occasionally want to make a bed specially for his teddy bear and tuck it in goodnight.
I was reminded of something else this afternoon. We were walking back from town, it was very sunny and K had a green balloon which was casting a green shadow on the floor, even though our bodies were all casting normal black/dark ones. K asked “Why is the shadow green?” and we said that the sun shines on the path but our bodies get in the way and act like a wall because they don’t let any light through. The sun shines on another bit of the path and the balloon gets in the way… K immediately piped up “It only lets the green light through” 
J then asked the very sensible question “Why are our shadows not completely black?” and I was still a bit staggered by K’s understanding that I fluffed describing light bouncing off other things like walls to get to the path. I was reminded that I have two sons with a brain.
I wasn’t reminded as such, more learned, yesterday that L throws as well as her brothers. Very impressive.
August 6th, 2006 at 10:43 am
Oh that is a really nice post. Thank you
Didn’t know that about shadows either!
August 11th, 2006 at 12:06 pm
[...] We were discussing why shadows aren’t completely black and I didn’t come up with a good explanation beyond the fact that light usually gets to a particular point e.g. the floor via many routes, bouncing off other things or going direct from the sun or lightbulb, and usually the thing casting the shadow only blocks off one of the routes. I then found a video showing the effects of radiosity, which is the term (in computer graphics, at least) for light bouncing off things and going on other things. Most of the video is showing how whizzy some product is because it works out the radiosity instantly, but towards the end it shows what happens if you do computer graphics to show a room without worrying about radiosity. [...]