The End of Everything (Astrophysically Speaking), by Katie Mack, is a lively antidote to our otherwise cheerful times. Instead of agonizing over a pandemic, political polarization, and economic upheaval, why not fret over the end of the entire universe?! All jokes aside, why bother studying our universe’s demise? Well, as Mack says, contemplating our end helps us “understand the fundamental nature of reality itself.”
Hollywood’s melodramatic reworking of a 1963 Czech B movie envisions the universe’s end.
Hollywood’s melodramatic reworking of a 1963 Czech B movie envisions the universe’s end.
Known as AstroKatie to her legions of followers on Twitter, Mack is a theoretical astrophysicist and an assistant professor of physics at North Carolina State University. She contemplates such cosmological catastrophes as the Big Rip, the heat death of the universe, and, most terrifyingly, vacuum decay—the possible transition from the false “metastable” vacuum state we may currently be enjoying into its true minimum, or ground state, which would cause the instantaneous disintegration of baryonic matter, among other day-ruining effects. In her skillful hands, we learn that although our cosmic comeuppance won’t be pretty, we at least have billions of years before it will occur. That is, unless vacuum decay—discussed with the perfect blend of academic rigor and poetic license—is the ultimate culprit of our doom, in which case cosmic catastrophe may occur as you read this sentence.
Following Yogi Berra’s dictum that “it’s tough to make predictions, especially about the future,” Mack warns us that how the universe will end is much less certain than how it began. Although she largely eschews the typical approach of recapitulating cosmology’s vast history, she does note that our knowledge of the origin of the universe also was once more nebulous. Well into the 20th century, there were many rival cosmogonies, including the cosmic egg, Lemaître’s primeval atoms, and even the biblical book of Genesis. Nevertheless, cosmic eschatology has gotten short shrift.
The End of Everything was published exactly 100 years after the famous debate between astronomers Harlow Shapley and Heber Curtis over whether the Milky Way galaxy was the entire universe or other galaxies were in the cosmos. The so-called Great Debate was resolved three years later when Edwin Hubble demonstrated that the object then known as the “great spiral nebula” in Andromeda was not a nebula at all but an entirely separate galaxy. Further observations by Hubble proved that the universe was expanding, which prompted speculation about what happened when its expansion began. Scientists eventually settled on the Big Bang theory accepted today. All the while, attention to the opposite end of the timeline—if there is one—has been sparse, and speculation reigns.
Mack’s surprisingly lively account of the Big Bang’s end-of-time counterpart is uplifting, with a wry wit permeating its 240 pages. It is meticulously researched, nicely illustrated, and copiously footnoted. Although footnotes are usually the bane of the reading experience, that is not so with Mack’s: Her joke-per-footnote ratio is near unity.
Comparable books aimed at a popular science audience are Stephen Hawking’s epochal A Brief History of Time: From the Big Bang to Black Holes (1988) and Sabine Hossenfelder’s Lost in Math: How Beauty Leads Physics Astray (2018). The latter similarly blends first-person expert perspective, wit, and interviews with other experts, including some of the same scientists Mack conversed with. Unlike Hossenfelder, though, Mack is more optimistic about possibilities for scientific progress in realms of astroparticle physics that are currently untestable, such as multiverse theories, vacuum decay, and the large-extra-dimensions model.
My only (minor) qualm with this otherwise masterful work is that it lacks the vantage point of an experimental astrophysicist. Had Mack surveyed a few of us alongside the many theorists and high-energy experimentalists she interviewed, it would have added another dimension to her book: Instrument builders can and should act as assayers of the theories they test.
Amidst Mack’s humor is beautiful prose. Contemplating future end-times research, she writes, “Someday, deep in the unknown wilderness of the distant future, the Sun will expand, the Earth will die, and the cosmos itself will come to an end. In the meantime, we have the entire universe to explore, pushing our creativity to its limits to find new ways of knowing our cosmic home. We can learn and create extraordinary things, and we can share them with each other. And as long as we are thinking creatures, we will never stop asking: ‘What comes next?’”
In The End of Everything, eschatology meets cosmology, evoking in this reader an aphorism from Ecclesiastes: “Better is the end of a thing than its beginning.” Mack’s brief history of the future is bound to inspire minds young and old not to deny the eventual death of the universe but rather to embrace it while there’s still time.
Brian Keating is a Chancellor’s Distinguished Professor of Physics at the University of California, San Diego, and the author of the 2018 book Losing the Nobel Prize: A Story of Cosmology, Ambition, and the Perils of Science’s Highest Honor. His research uses cosmic microwave background measurements to explore the origin and evolution of the universe.
