Talk:History of the World of Avatar/@comment-74.44.141.19-20101004231750/@comment-66.253.179.90-20110221000023

Read that law more carefully, it requires an isolated system. The Earth is not an isolated system and therefore application of those laws is technically theoretical but also practical (as we ignore the non-linear errors). Since the Sun (and the moon) exists in the world of Avatar, the same idea can be applied. But arguing this is pointless as the last person pointed out it's "avatar land"