¶ How reality is built from a few basic ingredients
As the story is usually told, science began when some deep thinkers in ancient Greece decided to reject the popular mythological explanations for various natural phenomena. Those early philosophers sought logical explanations for things like thunderstorms, rather than attributing them to Zeus throwing temper tantrums in the form of thunderbolts.
But early Greek scientific philosophy was not merely about replacing myth with logic. For the Greeks, explaining reality did not mean just devising a logical reason for each natural phenomenon in isolation — it was also about seeking a deep, coherent explanation for everything. And that meant identifying fundamental principles that explained a diversity of phenomena, encompassing the totality of physical reality. That’s the essence of science.
Science today is vastly more advanced, accurate and complex than it was in ancient times. Nevertheless, all of today’s sophisticated knowledge of physical reality is also rooted in a few fundamental principles, which physics Nobel laureate Frank Wilczek attempts to identify and explain in his latest book, Fundamentals: Ten Keys to Reality.
Wilczek’s fundamentals are framed as the “fundamental lessons we can learn from the study of the physical world,” as expressed by “the central messages of modern physics.” Each chapter assesses one of the “broad principles” he regards as fundamental. He explains their role in modern physical understanding and relates them to “how we humans fit into the big picture.”
He divides his account into two main parts: “What there is” and “Beginnings and ends.” He describes the fundamentals he identifies from the perspective of two themes: “abundance” and “born again.” (He does not mean “born again” in a religious sense, but rather as an expression of the need to realize that the view of the world based on ordinary human experience does not conform to the underlying reality that modern science reveals. As adults, we must be “born again,” without preconceptions formed in childhood, to appreciate the actual fundamentals of reality.)
What there is, Wilczek avers, includes plenty of space and plenty of time. Space, for instance, is vast no matter which way we look — compared with the universe, people are tiny; compared with the atom, people are huge. Similarly, the universe has existed for a very long time and has an even longer future ahead of it. Additional ingredients of this vast cosmos ultimately consist of a handful of subatomic particles, or more precisely, quantum fields responsible for those particles. And their behavior is governed by a small set of physical laws, as codified in the equations of general relativity and physicists’ “standard model” of particles and forces. Those ingredients, though limited in type, exist in abundant quantities. And the supply of energy in the cosmos needed to cook those ingredients into complex things is immense: A single star (the sun) emits thousands of times more than the total annual energy consumption of the Earth’s entire population.
Wilczek describes how all those ingredients came to be in the form we see today in his “Beginnings and ends” chapters. A key part of the story is the emergence of complexity despite the simplicity of the fundamentals — the very few ingredients governed by very few laws. It turns out that tiny differences in the distribution of the ingredients lead to a diversity of structure and composition found on all scales throughout the cosmos. Gas clouds in space that differ only slightly, for example, “can yield systems of stars and planets that differ drastically.”
Another key idea is Wilczek’s final fundamental, the physicist Niels Bohr’s principle of complementarity. Understanding the world requires the mind-expanding realization that one thing viewed “from different perspectives, can seem to have very different or even contradictory properties.” And that is why “the world is simple and complex, logical and weird, lawful and chaotic.”
Fundamentals is an engaging account of the history of humankind’s understanding of reality, told by one of the key contributors to recent parts of that story. Wilczek’s grasp on the physics he relates is comprehensive and authoritative; he conveys technicalities with a rare combination of accuracy and accessibility. He is a little sketchy on some of his history, though. He gives an incorrect date for the Geiger-Marsden experiment leading to the discovery of the atomic nucleus, for example. Also, Einstein did not base his original proposal of photons on Max Planck’s work, and Wolfgang Pauli did not say the neutrino could not be observed in the letter wherein he originally proposed it.
Such quibbles aside, Wilczek provides an exceptionally clear guide to the state of physical knowledge in the early 21st century, much in the spirit of the sort of explanation that the ancient Greeks desired. Of course, as Wilczek emphasizes, the story is not nearly over. Perhaps a century or more from now, someone else will have to take up the task again.
“We do understand many aspects of the physical world very deeply,” Wilczek writes. Yet “our understanding of the physical world is still growing and changing. It is a living thing.”
Source: ScienceNews