People and the Cosmos: Constructor Theory

Note–this was originally published with Areo Magazine.

It seems that as soon as our ancestors could afford to do so, they forged a spiritual dimension into their existence. Human burial practices are at least 100,000 years old, and religious ceremonies date back at least 50,000 years. Though interpretations vary, it is thought that the famous archeological site called Gobekli Tepeis the oldest ritual site ever discovered. This Turkish site is thought to have been constructed starting in roughly 10,000 BC, not by city-dwellers, nor even by settled agriculturalists, but by nomadic hunter-gatherers. This would imply that people satisfied their spiritual needs before settling down and building those great early civilizations of Mesopotamia. The Biblical Matthew, in his famous “Upon this Rock I will build my Church” line, may have gotten things exactly backwards.

Between cave paintings that reveal a reverence for Nature’s beasts, and the divine constellations of the Greeks, our forebears lacked the explicit distinctions between the sky above their heads, the fauna that roamed the Earth beside their nascent civilizations, and themselves that we take for granted today; it is only after centuries of scientific investigation that the fundamental differences between these realms becomes obvious. To our prescientific ancestors, the terrestrial, the celestial, and people intertwined in the magical stories that they told themselves. 

In humanity’s earliest theories of the world, then, people played a fundamental role.

But with the dawn of the Scientific Revolution in the sixteenth century, such anthropocentrism grew less plausible—first in 1543 with Copernicus’s overthrow of the geocentric model of our Solar System, and culminating in 1687 with Isaac Newton’s epoch-defining work, Principia Mathematica. Newton offered a bold new worldview, in which the motions of objects from pebbles to planets could be both explained and predicted—you tell me the current position and velocity of an object, along with the forces acting on it, and I’ll tell you its position and velocity at any later point in time. Copernicus, and later the much more strident Galileo, struck at humanity’s naivety by demonstrating that the Earth was not at the center of the Solar System. Newton further robbed our ancestors of their innocence with the first-ever universal theory, one that explained phenomena across all of time and space in purely physical terms—magical, religious thinking was banished from his predictable, clockwork universe. Humans, it seemed, played no special role in this new understanding of Reality.

But it was not obvious how Newton’s theory (called classical mechanics) applied to living things. After all, predicting the trajectory of a cannonball was far easier than predicting the flight pattern of a bird. Moreover, none of this new physics had anything to say about the intricate design of living creatures. So people could still take refuge in the fact that humans were created in God’s image—there was still no explanation for our apparent design, let alone our ability to comprehend the cosmos.

But then along came Darwin with his 1859 book, On the Origin of Species, and our ancestors took another steep into adulthood. In Darwin’s theory of evolution by natural selection, all of the apparent design in the biosphere had emerged through a long, long chain of slight modifications that passed down from generation to generation. Those changes, which we now understand as due to mutations in the genetic code, were more likely to be passed on if they increased the organism’s fecundity, its ability to yield offspring. The organism’s environment was a selector, a ruthless arbiter that determined which organisms were more likely to reproduce, and which were more likely to be tossed into the dustbin of extinction*. String together enough of these cycles of random-changes-nonrandom-selection, and the result was all of the elegant design and order in the biosphere. 

There was no getting around it—this process explained the evolution of humans, too. Apparently, the story behind the emergence of algae and cattle was also behind our entry onto the world stage. There was no room for exceptional status of our species that many had hoped biology would preserve. 

And so, after only a few centuries of modern science, the role of people had been cast out on all fronts. We were not at the physical center of our Solar System, nor of our galaxy. We were not mentioned in any of our deepest physical theories, which presented a world that conformed to exact laws of motion and could be predicted with certainty. And even our best theory of life implied that we came about by the same naturalistic process that brought about every other apish creature. Anthropocentrism, it seemed, was a thing of the past, a relic of a less mature people.

But then came a new theory of Reality, one that cannot be readily dismissed. Only a few years ago, physicist David Deutsch published a foundational paper on what he calls ‘constructor theory’. Since Newton, our best theories in physics have followed the paradigm he’d established—given the state of a system, a theory ought to predict its state at any future time. The details of what a ‘state’ is depends on the particular theory, but the point is that this had been the prevailing conception—to borrow a phrase by Deutsch himself—since Newton’s first great universal theory. 

 Constructor theory’s fundamental principle is that the laws of physics can instead be cast in terms of transformations that are either possible or impossible. So, if Newton’s theory tells you the trajectory of a projectile given some initial position and velocity, constructor theory asks what trajectories are possible in principle according to Newton’s theory.

The switch from thinking about a system’s particular transformation from one state into another to asking what transformations are possible in principle is a radical shift in perspective. This new, deeper worldview goads us into asking questions that wouldn’t have been conceivable in the previous, Newtonian framework. If we may describe the world in terms of possible transformations, rather than particular trajectories, then which objects may cause such transformations, and which can’t, and why?

People have converted rocks into cathedrals. They’ve mixed the fiery energy of the Sun with the guts of Earth itself to produce the orderly, purposeful devices that prevail in our Digital Age. They’ve turned wolves into dogs and and trees into books and metal into vehicles that fly through space.

None of the aforementioned transformations happen spontaneously in the Universe. They require the presence of people—entities capable of rendering any transformation that’s allowed by the laws of Nature, so long as they know how achieve it. In describing Reality, then, one cannot help but mention people in answering a fundamental question about how it works.

*The modern version of Darwin’s theory, called the neo-Darwinian Synthesis, holds that genes are the fundamental unit of biological evolution, not organisms.

2 Replies to “People and the Cosmos: Constructor Theory”

  1. I’ve read a lot of books by preeminent scientists that seriously try to make the case that the “Copernicus Principle” (the idea that science will always devalue humans) is an integral aspect of science and anything that violates that principle must not be scientific.

    This was one of the main things that drew me to Deutsch’s views, that he showed it was completely wrong-headed.

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