Can you summarize this excerpt?

"Multiverse

While commonly utilized and popular within science fiction media, cosmologically speaking, a "multiverse" is a hypothetical realm which contains our universe, as well as many, and possibly an infinite amount of, others. Many physicists, cosmologists, and astronomers do take multiverse theory kinda-sorta-seriously, including Andrei Linde, Alan Guth, Stephen Hawking, Michio Kaku, David Deutsch, Max Tegmark, Steven Weinberg, Hugh Everett, Raj Pathria, Arvin Borde, Alexander Vilenkin, and Brian Greene. It's plausible that there are an infinite amount of infinitely cyclic, infinitely large multiverses, all of which are apart of an infinite amount of infinitely cyclic, infinitely large higher-order verses, each having mirrored verses infinitely mirroring each other at all infinite levels, and that each brought forth an infinite amount of infinitely cyclic, infinitely large universes, each with infinite big bangs that each form an infinite amount of infinitely cyclic, infinitely large universes; thus each of them have infinite cyclic variations and infinite dimensions. Each universe, their infinite cycles, and infinite dimensions, thus, all have their own infinite varieties of fundamental forces, particles, chemical elements, planets, minerals, extraterrestrial genera, astronomical, physical, chemical, biological, and geoscientific phenomena. There are models and theories that can lead to a multiverse: eternal inflation, string theory, superstring theory, loop quantum cosmology, cyclic cosmology, black-hole cosmology, M-theory, Brane cosmology, the Holographic principle, and the many-worlds interpretation, and some of the physicists mentioned above as Max Tegmark have even attempted to classify the different types of Universe that range from his Level I (parts of the Universe very far beyond our observable one where — of course — physical laws would be the same as in our patch of space) to his Level IV (Universes that use different mathematics, not just physical laws, than ours). This is a philosophically satisfying interpretation of the fine-tuned universe problem. However, it's also completely stark-raving unfalsifiable:

For a start, how is the existence of the other universes to be tested? ... [I]nvoking an infinity of unseen universes to explain the unusual features of the one we do see is just as ad hoc as invoking an unseen Creator. The multiverse theory may be dressed up in scientific language, but in essence it requires the same leap of faith.

Until we develop instruments which can actually see outside of the universe, or create a universe in a jar that we can poke with scientific instruments (slightly more likely), this remains unfalsifiable.

Alternatives to the multiverse* are Ekpyrotic cyclical universe (Paul Steinhardt and Neil Turok), fecund universe or cosmological natural selection (Lee Smolin), conformal cyclic cosmology (Roger Penrose and Vahe Gurzadyan), cyclical Baum–Frampton model (Lauris Baum and Paul Frampton), loop quantum cosmology (Martin Bojowald, Abhay Ashtekar and Carlo Rovelli), eternal static universe, or the simulated universe (Nick Bostrom). And of course Goddidit. Depending on the theory, the multiverse have a finite size and age, as in eternal inflation, or be infinite and ageless, as in the cyclic multiverse model. Though some theories involve a finite but ageless multiverse, or an infinite but finitely-aged multiverse."

*Some of those theories also suggest either there was no cosmic inflation or that the Universe will go Big Crunch again, even if present data rules out that possibility, to re-boot in a new Big Bang.