No, light is a form of energy and the shadow is the place where there is absence of light.

Absence of Light or Energy.

They are similar, in that one is the absence of the other. However, they are not opposites, so they could not be considered 'alike'.

Synonyms are words with similar meanings.

Absence refers to the complete lack or nonexistence of something, while near absence implies that there is a very small amount or almost none of that thing present. In other words, absence means something is not there at all, whereas near absence suggests that there might be a small trace or amount.