Can anyone tell me why it is that Lie groups seem to have their second fundamental group $\pi\_2(G)$ equal to $0$, or provide me with a link to an article or a book reference?


I came across this fact reading an article where the author considers principal $G$ bundles with $G$ a simply connected simple group.


thank you



nullity of the second fundamental group of a Lie group
See: [Homotopy groups of Lie groups](https://mathoverflow.net/questions/8957/homotopy-groups-of-lie-groups)


