A Cosmic Archipelago: Multiverse Scenarios in the History of Modern Cosmology

TL;DR

This paper reviews the historical development of multiverse theories in cosmology, highlighting their diversity, foundational issues, and how they reflect evolving physical understanding over time.

Contribution

It provides a comprehensive historical analysis of multiverse scenarios, emphasizing their conceptual diversity and the deepening of fundamental cosmological questions.

Findings

Multiverse ideas have evolved through various stages in cosmology.

Fundamental issues in multiverse theories become more profound with advancing physics.

There is no unified model of the multiverse, only diverse, often incompatible proposals.

Abstract

Multiverse scenarios are common place in contemporary high energy physics and cosmology, although many consider them simply as bold speculations. In any case there is nothing like a single theory or a unified model of the multiverse. Instead, there are innumerable theoretical proposals often reciprocally incompatible. What is common to all these scenarios is the postulated existence of many causally disjointed regions of space/time (if not completely separated space-times) and the consideration of the observable universe as atypical in a global perspective. This paper examines the history of modern cosmology focusing on the forerunners of current ideas, and shows how some fundamental issues tend to present themselves on increasingly deeper levels of physical knowledge.