Sheldon possesses a mastery (and extensive knowledge) of various subjects such as physics, spectroscopy, radiology, chemistry, pharmacology, both anatomy and physiology, zoology, microbiology, astronomy, cosmology, algebra, geometry, calculus, trigonometry, economics, computers, software engineering, robotics/cybernetics, artificial intelligence, nanotechnology, history, anthropology, geography, linguistics, cryptography, forensics, and railroad engineering (he is a well-known railfan and a fancier of model trains), and in addition to being fluent in Klingon, has some knowledge of Swedish, Finnish, Mandarin, and Hindi.