# Outer Space. And real aliens.

##### October 10, 2006 mathematics

There are some questions about outer space that I would like to be able to answer. Some nice survey articles look to be [1] and also [2].

Here is a ridiculously simple question I have wondered about: given , say with , how can I tell if and are conjugate? I suspect Iām being stupid here.

In light of my recent comments on LINCOS and communicating with extraterristrials, I found the article [3].

Putnam also makes use of the idea of mathematicians from other planets, to more philosophical ends.

[1] M. Bestvina, The topology of , in: Proceedings of the International Congress of Mathematicians, Vol. II (Beijing, 2002), Higher Ed. Press, Beijing, 2002: pp. 373ā384.

[2] K. Vogtmann, Automorphisms of free groups and outer space, in: Proceedings of the Conference on Geometric and Combinatorial Group Theory, Part I (Haifa, 2000), 2002: pp. 1ā31. https://doi.org/10.1023/A:1020973910646.

[3] D. Ruelle, Conversations on mathematics with a visitor from outer space, in: Mathematics: Frontiers and Perspectives, Amer. Math. Soc., Providence, RI, 2000: pp. 251ā259.