Blue light.

So, three time this week I have exposed my lack of knowledge about the physics of light in everyday things.

1)  The blood in veins is NOT blue.  I was taught this in public school and never questioned it.  In spite of the fact that I was a science major and worked as a medical tech for many years and drew blood samples.  Blood in veins does not turn blue because the oxygen has been used up.  Blood does not "immediately oxidise" when exposed to the atmosphere.

2) Swimming pools do not appear blue/turquoise because the pools are painted that colour.  That is the colour of large amounts of water.

3) Ice bergs do not have those beautiful blue areas because of Rayleigh scattering.  That explains why the sky is blue but not why ice is.

But, though I was ignorant of these things I am not anymore.  And that's good.