The subtitle of this book could be: a physicist, who is extremely knowledgable with the general sciences, tries to explain life, the universe, and other big questions using empirics and without resorting to metaphysics or mysticism. Carroll sets out to explain the “big picture” in short chapters that each deal with a small part of science, gradually building in theme, to tackle life’s biggest mysteries. He sees the world through the lens of poetic naturalism. “Poetic naturalism is “poetic” because there are different stories we can tell about the world, many capturing some aspects of reality, and all useful in their appropriate context.” It is a filter to see the world on my levels- each correct in their own specific domain. A few themes run throughout the book. The first is that Core Theory can adequately and completely explain our physical world. “Almost all of human experience is accounted for by a very small number of ingredients. The various atomic nuclei that we find in the elements of the periodic table; the electrons that swirl around them; and two long-range forces through which they all interact, gravity and electromagnetism…. A field is kind of the opposite of a particle; while a particle has a specific location in space, a field is something that stretches all throughout space, taking on some particular value at every point… And what are the fields made of? There isn’t any such thing. The fields are the stuff that everything else is made of.” A second area which is at once the most confusing and most profound is quantum mechanics. He quotes the physicist Richard Feynman, “I think I can safely say that nobody understands quantum mechanics.” Carroll does his best in explaining to the layman. “The reason we observe only certain wavelengths in the emitted light is that the electrons are not gently spiraling inward but spontaneously leaping from one allowed orbit to another, emitting a packet of light to make up the difference in energy between them. The electron is doing “quantum jumps.”.… In quantum mechanics, the state of a system is a superposition of all the possible measurement outcomes, known as the “wave function” of the system. The wave function is a combination of every result you could get by doing an observation, with different weights for each possibility…. Quantum mechanics tells us the probability that, upon observing a quantum system with a specified wave function, we will see any particular outcome.” At the quantum level of analysis everything becomes so micro that macro phenomenon all become, in the end, wave functions. “Not only does the deepest layer of reality not consist of things like “oceans” and “mountains”; it doesn’t even consist of things like “electrons” and “photons.” It’s just the quantum wave function.” In all his speculations Carroll relies heavily on Bayesian reasoning to adjust his credences of likely outcomes based on his priors and any new available information. As such, he always believes “simple theories should be given larger priors than complicated ones” and “evidence that favors one alternative automatically disfavors others” and, therefore, “the credence we assign to a theory should go down every time we make observations that are more probable in competing theories.” Using these tools, Carroll systematically tackles the origins of the universe, entropy and the arrow of time, the nature of memories, what is reality, the limits of knowledge, evolution, the existence of God, and the nature of the self- including free will, the boundaries of life and death, consciousness, the existence of the soul, and mental versus physical properties. This is an amazing book that uses all of the available tools of modern science to demystify some of life’s biggest challenges that have stumped scientists, philosophers, and theologians alike.
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