If you are able to see an object, how can you be sure that it is not at absolute zero?
a.
objects are never actually at absolute zero
c.
objects at absolute zero are too small to see
b.
as soon as light hits the object, it gives the object energy and it will no longer be at absolute zero
d.
if an object is visible, there can be no heat present.

What would occur if the index of refraction of a material was less than n=1? the speed of light would increase to a speed larger than the maximum speed of light in a vacuum. the light wave would not bend at all though the material. the light wave would not be able to refract and would instead reflect off of the material. the speed of light would reduce to values close to 0 m/s.