From Columbia mathematician Peter Woit at Not Even Wrong:
New Scientist today has a feature article headlined
How to think about… The multiverse
The idea of an infinite multitude of universes is forced on us by physics.
It starts off quoting Sean Carroll:
“One of the most common misconceptions is that the multiverse is a hypothesis,” says Sean Carroll at the California Institute of Technology in Pasadena. In fact, it is forced upon us.”It is a prediction of theories we have good reason to think are correct.”
The problem with this claim is that it’s simply not true. There is no model that “we have good reason to think [is] correct” that predicts a multiverse of universes with different physics (i.e. fundamental constants). I’ve written about this many times, see for instance Theorists Without a Theory. More.
The problem is that the concept of a multiverse is not based in science and thus is immune to contradictions with evidence. It is based in a need to find an infinite variety of universes, such that none can seem to be fine-tuned. Science can wither and die but the multiverse will thrive among its adherents.
See also: Sabine Hossenfelder: The multiverse is “a fringe idea”
and
The multiverse is science’s assisted suicide