Physicists have proposed several theories to explain why Λ is so small. One of the most popular -- the "anthropic principle" -- states that Λ is randomly set and has very different values in different parts of the universe (figure 1). We happen to live in a rare region, or "bubble", where Λ has the value we observe. This value has allowed stars, planets and therefore life to develop. However, this theory is also unsatisfactory for many scientists because it would be better to be able to calculate Λ from first principles.
We understand where strings reside in terms of "microseconds" and the "arrow of time?"
Once we know that there is one de Sitter solution, it is easy to find many more of them by just changing the values of the fluxes. Sujay Ashok and Michael Douglas of Rutgers University have recently estimated the number of different solutions to be at least 10100, which indicates an extremely rich landscape with many mountains, valleys, oceans and even volcanoes. Each minimum-energy point represents a different universe, and the height of that point is the value of the cosmological constant for that universe. Viewing the solution this way, the probability that one of these universes has a cosmological constant that is as small as is indicated by current experiments is actually non-zero.
Hmmmm..... remember Higgins?