why no negitive or close to zero refraction?
help?
I have some ideas I need to model, that involve thermal distortion, as well as modeling a shockwave,
1.0 is no refraction, not 0. Negative refraction is whole different can of worms:
Well, I know that the atmosphere barley bends light with temp/pressure diffrence, so, to achieve this I need a refraction closer to like .05,
I doubt that you need .05, a perfect vacuum is considered to have an IOR of 1.0 and doesn’t bend light at all.
What people commonly call “air” has an IOR of 1,000292
But J already said that.
I see, I was thinking that the refraction was too high, when it was to low, I have some stuff to test, thank you
I am still learning, and don’t fully understand ray-tracing yet I guess
You should brush up on physics 
That issue is simply optics and a ray-trace is a simulation of that.
I know greater the change in density, the greater the diffraction, and the greater the energy the more a wave is bent, but i have not studied refraction beyond that, o and angle of Incidence=angle or reflection…
Actually it is the greater the density the greater the refraction, or deviation from the surface normal dependent upon the incidence angle of the incoming ray, and the more energy a ray has the less it will bend, thus the reason why x-rays (as well as gamma rays) cannot be “lensed”, at least through a material. Diffraction is the separation of light into it’s constituent parts, like an acrylic prism separating white light into the familiar ROYGBIV spectrum.
That’s dispersion. Diffraction is a wave effect that is generally not simulated directly in raytracing. See:
Nope.
Like BPR said, it’s the greater the change in density.
The IOR depends on the optical density of a material alright.
The refraction on the other hand depends on the density of the materials between it migrates.
The IOR is defined only by the density, but by the optical density.
The IOR:
It is the relation of the speed light travels in vacuum to the speed it travels in the medium.
IOR = c_vaccumm / c_medium
The refraction:
IOR_m1 * sin (incoming_angle) = IOR_m2 * sin (outgoing_angle)
If you have a refraction between Glass and Ruby you’ll have 1.45 against 1.76. There’ll be not much refraction.
If you have air against ruby you got ~1.0 vs. 1.76. There’ll be a lot of refraction.
All dispersion and physical optics aside.
Most render engines use geometrical optics anyways.