In all the talk of the multiverse that gets tossed around these days, there's a subtle but important point that is often lost: there are really two completely different notions of a multiverse. What one thinks of when someone utters the word "multiverse" likely depends on whether one is most influenced by cosmology or by quantum physics. To the latter, the multiverse is typically viewed in the context of the Everett-DeWitt interpretation of quantum mechanics in which every process that includes more than one possible outcome, leads to a bifurcation of the universe in which the process occurred, into multiple universes, one for each possible outcome of the process. In such a multiverse (whose core idea is due more to DeWitt than Everett), everything that can happen, will happen.
In the inflationary multiverse, each "universe" is really a patch of space that becomes isolated due to eternal inflation. This is subtly different than the Everett-DeWitt model which suggests an actual bifurcation of reality. As it turns out, the difference could also have ethical and moral implications, some of which are discussed in Zeeya Merali's new book A Big Bang in a Little Room: The Quest to Create New Universes (Basic Books, 2017; $27.99).
Merali's book explores the quest by some physicists to produce new, "baby" universes in a lab. As preposterous as it sounds, the idea is largely grounded in accepted physics, though does remain highly speculative. In an Everett-DeWitt model, new universes are constantly being created ad infinitum as we blithely go about our day. There appears to be little we could do to affect change in any branching universe within this multiverse model. On the other hand, the inflationary universe model of the multiverse holds the promise of intentionally planning the creation of a baby universe which raises the thorny question of whether we would be responsible for the suffering of any living beings produced in that universe. We would, to some extent, be playing God.
These and other issues are tackled head-on in Merali's book, but in an engaging and subtle manner. The book is largely constructed from a series of interviews with physicists around the globe who are either actively thinking about how to create baby universes or who played a role in the development of inflationary theory. As someone who has been interviewed by Merali multiple times, I can personally attest to her ability to make the interviewee feel at ease and this sense clearly comes across in the book. Interviews are more like discussions with Zeeya.
One get's the sense, though, that this project was less about writing a book and more about her own quest to more fully understand the universe. At times, one gets the impression that she is wrestling with some deeply personal questions. Far from detracting from the narrative, however, I think it adds to the human aspect of the story.
I did have a few minor quibbles here and there, but Merali is an accomplished scientist herself having received her PhD in physics from Brown University under noted cosmologist Robert Brandenberger, and so some of my quibbles might be considered "professional differences." In all, it was an enjoyable book that addressed an exciting area of modern physics research in a thought-provoking way. For anyone interested in the "big questions," this book is essential reading since it deals with perhaps the biggest question of all: can we--should we--humble human beings create a universe?
A Big Bang in a Little Room: The Quest to Create New Universes is available to buy here.