Landscape

[S.M]

Hi,
Can anyone explain to me what the landscape is, and why there are so
many vacua in string theory?
Thanks

[Kris Kennaway]

On 2006-05-19, S.M <smetalman2006@yahoo.com> wrote:
> Hi,
> Can anyone explain to me what the landscape is, and why there are so
> many vacua in string theory?

It's a similar question to "why are there so many different consistent
quantum field theories that one may right down (different gauge
groups, matter content, cosmological constant, etc), but only one of
them gives the standard model?".

In string theory one obtains QFTs at low energies in some
compactification scheme (e.g. from a particular 10-dimensional
space-time geometry). Some kinds of QFTs apparently cannot be
obtained from string theory, but based on current knowledge this does
not seem to be very restrictive.

The extra thing is that in string theory these different QFTs are
embedded in a larger framework, so one may hope to obtain insight into
a selection mechanism on the space of QFTs (string theory vacua) that
may pick out the "right" one (or not). Most studies so far have
looked at frequency distribution of QFTs (gauge groups, matter
content, couplings, etc) in certain classes of string theory
compactifications, but one may hope to do more sophisticated things.

Kris