can we get more info on glass refraction

[acc24ex]

What exactly is going on with glass.. wikipedia says 1.5 or 1.6 refractive index.. so around that.. but still how much does it depend on the thickness of an object? Mind you, there is no thickness in 3d, the thickness is always like double glazing windows there is (virtual) air in between so what is going on there, the refraction is counted twice? But still you don't get much refraction when you put stuff in behind windows in real world and octane is always breaking up light..
I'm getting a bit confused and running refractive indices up and down all the time, depending on the shot..
It always bends the light.. but it doesn't seem like it should bend it that much all the time..
It's like I should set it at almost zero to get the more real effect of ordinary glass window, or a thin glass object..
So.. some glass explanations and pictures would come in handy right here.. or a physics 101

[ROUBAL]

there is no thickness in 3d, the thickness is always like double glazing windows there is (virtual) air in between so what is going on there, the refraction is counted twice?

Wrong, in 3D thickness is important, but in actual Optic laws, IOR has nothing to do with thickness.

The difference in Octane and some other render engines is that if you use an open object or a single surface instead of a closed volume, the space behind the surface will be considered as a volume with same IOR as the last encountered surface. I recently spoke about that in a other topic : if you model a car and use simple planes for the windows, all the inside volume will be considered as glass, and you will see through the car like through a big lens.

So, when you create windows, you have to extrude the glass planes to get an actual thickness (5 to 10 mm) and set an IOR near 1.45, or you can also cheat with physics and use simple planes, with a very low IOR very close to 1 (1.01 or something like that), to avoid the lens effect.

[acc24ex]

thanks, that is information I've been looking for, I was making a small glass vase and it seemed like it's a big lens at 1.45 .. but I did make the thickness maybe the geometry was broken, so what happens if the geometry is slightly broken, like if there is a space in the edges..