🌐EnglishEnglishDeutschEspañolPortuguêsSvenskaРусскийالعربية中文日本語EntityQ906378· pop 15homogeneous systemnotion in physicsAvailable in 15 languagesEspañolDeutschРусскийPortuguêsالعربيةAzerbaijaniBelarusianEstonianGeorgianHebrew