Question of the Day: Why are bubbles always circles and why are they rainbow-colored?

My 4 year old son asked me this question as he was blowing bubbles in the car this morning. I told him that was a great question, and I didn't have the answer but I would look it up on the internet. Here is what I came up with (from www.askkids.com):

Bubbles and balloons have a lot in common! Scientists refer to them as "minimal surface structures." This means that they always hold the gas or liquid inside of them with the least possible surface area. The geometric form with the least surface area for any given volume is always a sphere, not a pyramid or a cube or any other form. An amazing exception to the rule! (Not really.) When a normally round bubble is surrounded by other bubbles, it can be made to take on a seemingly odd shape. Here, a bubble filled with smoke to make it more visable, is surrounded by six other bubbles, it appears to be a bubble cube! If the surrounding bubbles are popped, though, the bubble in the center reverts to its natural "round" shape.

Similar to the way we perceive the colors in a rainbow or an oil slick, we see the colors in a bubble through the reflection and the refraction of light waves off the inner and outer surfaces of the bubble wall. You can't color a bubble since its wall is only a few millionths of an inch thick. A bubble reflects color from its surroundings. When a light wave hits the surface of a bubble, part of the light is reflected back to a viewer's eye from the outer surface and part of the light is reflected from the inner surface which is a few millionths of an inch further. As the two waves of light travel back, they interfere with one another causing what we know as color. When the waves reinforce each other, the color is more intense. When the wave get close to canceling each other out, there is almost no color. As a bubble wall gets thinner, either from a weak solution or because gravity has pulled its chemical content to the bottom, the distance between the inner surface and the outer surface of the bubble becomes less and less until the two reflected waves of light start to coincide and cancel each other out. The result is that the bubble loses its color and can become nearly invisible.

Movie Box-Office Records

How the heck is it fair to keep saying "we had a record-breaking weekend for such and such movie" when ticket prices keep going up all the time? Of COURSE the newer movies are going to break records because it costs about $10 a ticket per person for each movie now when in times past, it was maybe $5 or $6. They make twice as much already for each movie ticket sold!