In The Animate and the Inanimate (1925), Sidis predicted the existence of regions of space where the second law of thermodynamics operated in reverse to the temporal direction that we experience in our local area. Everything outside of what we would today call a galaxy would be such a region. Sidis claimed that the matter in this region would not generate light. (These dark areas of the universe are not properly dark matter or black holes as they are used in contemporary cosmology.) This work on cosmology, based on his theory of reversibility of the second law of thermodynamics was the only book published under his name.