Can anything in the (S.W.) Galaxy penetrate the light of a saber?

Perhaps it's impossible to do so..or not.

It's pure energy, you can't penetrate it. It can be dissipated though...i.e Cortosis.

there can be nothing canon about this thread

EU

Here's a question. We all know why some lightsabers are blue and some are red and so on. But why are some blaster bolts red and others are blue and green?

Probably because George Lucas wanted to make it easier for you to tell what team was killing who

Probably.