Text of a lecture by the physicist Stephen Hawking, in which he discusses the connection between black holes and entropy, the quantitative measure of the relative disorder of a system.
 
Answers to questions such as 'how big is a black hole', 'what is a wormhole' and 'what is a white hole'.
 
Text from a series of educational leaflets covering a wide range of topics in astronomy and cosmology. Educational use of the information by private individuals or schools is encouraged.