h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Here it is! The meaning of life! Or pretty close anyway. For centuries people in the bath have been pondering that definative question 'why are soap bubbles so pretty?'
Warning: reading on will only disillusion you if you cling to the belief that they are so pretty because they are magical. If you want to retain this belief, click away quickly and you will leave with your spirit intact.

OK, when light hits a bubble some of it goes straight through, because it's clear. However, some of it is reflected off the bubble surface.
Now, the bubbles surface is extremely thin. We're talking tiny tiny tiny widths here, that's why they're so fragile.
However, it is a distance. Therefore the skin of the bubble has two surfaces, an inner and an outer.
Each time light hits a surface it has two options: to reflect or to pass through.
Both the inner and the outer surface reflect some light.

Now, light travels in the form of a wave. A wave has a peak and a trough(a high bit and a low bit)
When two peaks combine they make a bigger wave.
However, when a peak and a trough combine they cancel each other out, leaving no wave at all.

If the bubble width is a quarter of a wavelength thick the light leaving the inner layer will have half a wavelength further to travel than the light leaving the outer wavelength so it will be a wavelength behind. Consequently, where one has a peak the other has a trough, so that light will be cancelled out.

All colours of light have different wavelengths so at any given time the bubble thickness can only cancel a maximum of one colour out at a time. This however is enough to mean that white light is no longer reflected. Instead a mystical combination of the other colours appears- magic.

I didn't explain this very well, but at least I know what I mean. Perhaps somewhere out there someone else is on the same wavelenth and they can cancel me out. It's for the good of the country.