The problem with inflation isn’t the idea per se, but the overproduction of useless inflationary models. There are literally hundreds of these models, and they are – as the philosophers say – severely underdetermined. This means if one extrapolates the models that fit current data to regimes which are still untested, the result is ambiguous. Different models lead to very different predictions for not-yet made observations. Presently, it is therefore utterly pointless to twiddle with the details of inflation because there are literally infinitely many models that one can think up, giving rise to infinitely many different “predictions.”
Rather than taking on this overproduction problem, however, Steinhardt et al. in their SciAm piece focus on inflation’s failure to solve the problems it was meant to solve. However, this criticism is off-target because the problems that inflation was meant to solve aren’t problems to begin with.
I’m serious. Let’s look at those one by one: More.
It feels odd listening to someone who thinks that cosmology needs more contact with evidence right now, not just another avalanche of bright ideas and great graphics.
See also: Cosmic inflation theory loses hangups about the scientific method