The long and the short of it
Time in its broad sweep and minutest detail is at the core of two illuminating titles.
Mammals such as ourselves had to cope with a number of global catastrophes before they could take over the Earth. A 15kmwide asteroid that smashed into Mexico’s Yucatán Peninsula saw off the dinosaurs about 66 million years ago, and the animals that did survive took full advantage, growing rapidly in size and number. Then the PaleoceneEocene Thermal Maximum (PETM) came about 10 million years later. It’s of particular interest to scientists because, though the overall picture is complicated, it is the most recent period of rapid global warming until now. The amounts of carbon released into the atmosphere, perhaps as a result of volcanic activity and the release of polar methane deposits, were similar to those being spewed out today from the burning of fossil fuels, though possibly much less.
Over 10,000 years, an eye blink in geological time, average global temperatures rose between 5°C and 9°C. The planet was largely ice-free. Many animal and plant species disappeared. The climatic spike lasted about 200,000 years before carbon dioxide levels slowly began to fall.
Australian history professor David Christian arrives at PETM about halfway through his thoroughly rewarding “Big History” of the world from the Big Bang to our future, uncertain though it may be. Accounts of our planet have become so siloed into specialised areas of science that the overall picture is not usually grasped. Or the unparalleled role of humans, ushering in the so-called anthropocene epoch. Many of the plain-language explanations of the author – he’s co-founder of the Big History Project with Bill Gates – of aspects of the likes of physics, chemistry and genetics, and how they fit together, I’ve not read elsewhere. My one reservation: although his passion for the subject is welcome, the exuberant tone of a TED talk can’t and shouldn’t be sustained across 300 pages.
One of Christian’s fascinations is entropy, nature’s tendency towards disorder, a “dissolute, lurking” character in the story of the universe, which also features in theoretical physicist Carlo Rovelli’s elegant philosophical investigation of time. Entropy appears in the book’s only equation, that for time’s arrow. “It is the only equation of fundamental physics that knows any difference between past and future.”
After reading this fascinating, confounding book, you can still believe old concepts about
A 15km-wide asteroid that smashed into the Earth saw off the dinosaurs about 66 million years ago.
time if you wish, such as that it is universal, has a direction, is measurable. But once you’ve grasped some of the ideas here, that would be just nostalgia. The opening sentence may decide whether you even pick it up. “Let’s begin with a simple fact: time passes faster in the mountains than at sea level.”
In fact, he writes, modern physics tells us that “there is no single time; there is a different duration for every trajectory; and time passes at different rhythms according to place and according to speed. It is not directional: the difference between past and future does not exist in the elementary equations of the world; its orientation is merely a contingent aspect that appears when we look at things and neglect the details.”
ORIGIN STORY, by David Christian (Allen Lane/ PRH, $40) THE ORDER OF TIME, by Carlo Rovelli (Allen Lane/PRH, $35)