It is generally accepted that, at the very
early stage of its evolution, the Universe has
undergone a period of rapid, almost exponential
growth, christened inflation. The details of
this process are largely unknown, and there are
lots of diverse theoretical models on the
market, with some of them stemming from string
theory. However, one common feature in all this
plentitude is a special scalar field (inflaton)
which slowly rolls down its potential and
provides a dynamical mechanism of accelerated
expansion. Unfortunately, there are serious
stumbling blocks in the way of any attempt to
employ non-zero spin fields for this purpose.
First of all, one faces a break-down of the
slow-roll conditions and also a strong unwanted
anisotropy of expansion. In this talk we will
present an original attempt to overcome the
problems and make a model with massive vector
inflatons. Approximate isotropy is achieved by
use of multiple vector fields, while the
slow-roll conditions can be satisfied due to
non-minimal interaction with gravity. Then we
will also reveal the fatal stability issues
which, contrary to some other opinions, do not
allow us to deem this attempt a successful model
of non-scalar inflation.