The first book on Astronomy that I read was very old. The author praised Einstein for his work, but he was skeptical about the expansion thing. His opinion was that even a slight unknown effect in how light travels between galaxies for millions of years could explain the red shift that's usually attributed to expansion.

I don't even understand the maths that justify it, so I won't dare to even have an opinion. But I find it strange how can "we" know so much about objects at monstruous distances. Most of this knowledge is based in a chain of facts that could be invalidated if only one of the links breaks.