[dventimi]

"problematic" is a matter of degree, and is relative. Inflation is less problematic than some theories (e.g. "magic"). Are there any alternative theories that are less problematic than inflation, and yet also solve the same problems that inflation solves?

[hwillis]

Cosmic inflation is the observation, not the explanation. The expectation is that cosmic inflation should be much, much larger based on what we understand about quantum mechanics: that vacuum is practically boiling with energy, and should be forcing stars away from each other. Instead we observe that it is very small.

I was being somewhat tongue in cheek responding to OP, who was not specific about what they find problematic. The vacuum catastrophe is the area in physics where our explanations explain the smallest amount of our observations. We're very confident in our measurements and understanding at both the large and small scale, and there is essentially no explanation that anyone has any confidence in.

By comparison, observations of dark energy/matter are practically perfectly accurate. It's a single order of magnitude difference from expected observations. We have some half-decent candidates to explain them. Unlike magic, inflation is not a theory in search of an observation. The fact that we don't see inflation is what is so desperately confusing.

[dventimi]

I don't consider cosmic inflation to be an observation. I consider it theory.