For the crisis, go here. For the “challenges,” see Anna Ijjas, Paul J. Steinhardt, and Abraham Loeb at Scientific American:
The latest astrophysical measurements, combined with theoretical problems, cast doubt on the long-cherished inflationary theory of the early cosmos and suggest we need new ideas. (paywall) More.
We remember when inflation was beyond dispute. It promised naturalists a multiverse. But science is now merely one expression of naturalism, so we can be sure that doubts about inflation will not cause doubts about the multiverse.
See also: Crisis in cosmology: Universe expanding too fast?
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