Sep 12, 2023, 06:28AM

Perspectives on Time

Reading about physics while turning 58.

1.jpg?ixlib=rails 2.1

In the run-up to my recent 58th birthday, I read advance copies of two books involving physics, by authors born in 1965, like me, and who were influenced in their youth by astronomer Carl Sagan, also like me. Both books got me thinking about time, albeit in different ways, reflecting what a vast subject physics is, and how it relates to matters ranging from the pressing and practical, to the exotic and bizarre.

The books are Our Fragile Moment: How Lessons from Earth’s Past Can Help Us Survive the Climate Crisis (PublicAffairs, Sept. 26), by Michael Mann, climatologist at the University of Pennsylvania and director of its Center for Science, Sustainability and the Media; and Putting Ourselves Back in the Equation: Why Physicists Are Studying Human Consciousness and AI to Unravel the Mysteries of the Universe (Farrar, Straus and Giroux, Nov. 7), by George Musser, science journalist and contributing editor to Scientific American (and a friend and colleague through my work as an editorial contractor for the magazine).

Mann was inspired to pursue a science career by watching Sagan’s 1980 Cosmos series while a freshman in high school, and he was an undergrad physics student at Berkeley a few years later when Sagan became embroiled in a debate about “nuclear winter” with Edward Teller, Berkeley faculty member and hydrogen-bomb inventor, who had a reserved parking space at the physics building, “an honor that was otherwise granted only to Nobel Prize winners.”

Mann’s career in geophysics and climatology has shown a style reminiscent of Sagan, in emphasizing communication with the public, and in gravitating toward contentious issues where science and politics intersect. Over two decades ago, Mann and colleagues published papers with “hockey stick” graphs showing temperatures spiking upward in recent decades compared to baselines over centuries and millennia. This brought criticism from right-wing think tanks and fossil-fuel interests, but contrary to claims that the hockey stick’s been debunked, it’s held up well as more data’s been collected.

In Our Fragile Moment, Mann seeks lessons about current and prospective warming through examining vast climate fluctuations that have occurred over the eons. Such episodes include the Paleocene-Eocene Thermal Maximum, or PETM, 56 million years ago, or 10 million years after the asteroid that brought the dinosaurs’ downfall. The PETM, starting from a baseline already far warmer than today, produced additional warming of some five degrees Celsius; this happened over thousands of years and was likely caused by carbon spewed from volcanic eruptions (though the alternative “Silurian hypothesis,” involving pollution by an ancient reptile civilization, may appeal to some).

The PETM, in Mann’s view, offers a mixed lesson for our own time. “Even when the planet was hotter than a worst-case fossil fuel emission scenario can plausibly make it, there was no runaway warming,” he writes. Fortunately, a massive methane belch from the seabed appears unlikely. But the news is not all good, Mann points out: “Even if PETM-level warmth is out of reach, a policy of total climate inaction could warm the planet up to the point where substantial regions would become uninhabitably hot for human beings—a hotter, more crowded planet with less food and drinkable water.”

Aided by the perspective of deep time, Mann, who’s long fought against denialists of human-caused climate change, cogently emphasizes that “the truth is bad enough” and shouldn’t be exaggerated. After noting positive developments such as the election of an Australian government pledged to emissions reduction, Mann writes: “Ironically, it is at this very moment of promise that a new obstacle has emerged. The greatest threat is no longer denialism—which is frankly untenable given the impacts that we can all see playing out in real time—but rather doomism, the notion that it is too late to act.”

Musser’s Putting Ourselves Back in the Equation gives much to think about regarding humanity’s role in the physical world, including fundamental questions about space, time, energy and matter. Increasingly, as Musser shows, physicists have veered toward possibilities that fields such as particle physics and cosmology may have interconnections with studies of the human mind, and of artificial intelligence. He writes, for example, about how physicists played a key role in the development of neural networks, how Roger Penrose pushed the physics profession to consider possible quantum effects in the brain, and whether there might be “quantum aliens,” as Heinrich Päs refers to beings with a radically different take on reality, like the Heptapods in the movie Arrival who seem to perceive past, present and future.

Knowing that Musser started his career in the astronomy department at Cornell when Sagan was there, I asked about any interactions. It turned out Musser got encouragement from Sagan in his early career, but in an idiosyncratic way. Located just above the famous astronomer’s corner office, he went to ask about projects, and Sagan advised him to do what Musser calls “a fairly boring literature survey on tholins,” organic compounds of the outer solar system that Sagan had named, “so I ended up doing other things.” Later, Musser took a job editing an astronomical journal called Mercury and again asked advice from Sagan, who “said it was a forgettable magazine,” which Musser took as license to make changes, “and a year or so later he wrote to say how much he liked it. That was shortly before he died.”

Similar to Sagan, Musser’s an optimist about humanity’s capacity to probe the universe’s mysteries. “Is It Really So Hard?” he titles an epilogue, referring to how the relation of consciousness to the physical world has been dubbed “the hard problem.” Perhaps such matters are beyond human cognitive ability, much like how calculus is unknowable to a cat. However, while cats don’t care about calculus, there’s an open-ended quality to human curiosity. “Our minds evolved to understand the world, which requires that the world be understandable,” Musser writes. “And we are of this world.”

—Kenneth Silber is author of In DeWitt’s Footsteps: Seeing History on the Erie Canal, and posts at Post.News.


Register or Login to leave a comment