a study of condensation and rarefaction phenomena in islamic natural philosophy (physics)

condensation (contraction) and rarefaction (expansion)are two terms in natural philosophy (physics) used inseveral different meanings. in this article the meanings ofthe two terms and their real and artificial kinds areintroduced and their differences with some terms such asgrowth, tumor, and, also, their opposite ones areexpressed. we have also evaluated the philosophical andexperimental arguments offered by islamic peripateticphilosophers for the real condensation and rarefactionfrom the perspective of modern science. finally we haveshown that although there are some criticisms against theirarguments, the islamic peripatetic philosophers have beenrealistic in describing these terms, and the opponents’words such as suhrawardi’s are not correct.