I'm sort of glib. Glad for some help here!
I think she may be referring to the varying theories about the directionality of time, like this;
" In 2004 Carroll and a graduate student of his, Jennifer Chen, came up with a much different answer (pdf) to the problem of before. In his view, time’s arrow and time’s beginning cannot be treated separately: There is no way to address what came before the Big Bang until we understand why the before precedes the after. Like Steinhardt and Turok, Carroll thinks that finding the answer requires rethinking the full extent of the universe, but Carroll is not satisfied with adding more dimensions." http://discovermagazine.com/2008/apr/25-3-theories-that-might-blow-up-the-big-bang And because we live perceiving time as a one way thing it is hard for us to consider or even imagine that under different circumstances it may not, limiting the number of theories one might come up with.