Saturday, July 16, 2016

The Big Picture II

In the end I found The Big Picture quite useful as a summary of how an informed person might view the world in light of modern physics. Carroll makes a strong case for physicalism and eschews superstition, theism and references to phenomena other than those detected by scientific methods. There remain conceptual challenges to combining the standard model of particle physics with general relativity, but together they provide a complete picture of the universe:

...we don't live inside a black hole, and the Big Bang was quite a few years ago. We live in a world where gravity is relatively weak. And as long as the force is weak, quantum field theory has no trouble whatsoever describing how gravity works. That's why we're confident in the existence of gravitons; they are the inescapable consequence of the basic features of general relativity and quantum field theory, even if we lack a complete theory of quantum gravity. 

The domain of applicability of our present understanding of quantum gravity includes everything we experience in our everyday lives. There is, therefore, no reason to keep the standard model and general relativity separate from each other. As far as the physics of the stuff you see in front of you right now is concerned, it is all very well described by one big quantum field theory. Nobel Laureate Frank Wilczek has dubbed it Core Theory. It's the quantum field theory of quarks, electrons, neutrinos, all the families of fermions, electromagnetism, gravity, the nuclear forces, and the Higgs....The Core Theory is not the most elegant concoction that has ever been dreamed up in the mind of a physicist, but it's been spectacularly successful at accounting for every experiment ever performed in a laboratory here on Earth....

We can be confident that the Core Theory, accounting for the substances and processes we experience in our everyday life, is correct....The laws of physics underlying everyday life are completely known. 

The picture that Carroll paints is of a deterministic universe that runs from the Big Bang up to the present. From one moment to the next, physics is theoretically capable of predicting exactly what will happen, but as a practical matter it is computationally impossible due to the complexity of the existing world.

Core Theory is at the center of the book, and Carroll makes an impressive effort to relate it to a broad array of topics. There are fifty chapters, covering everything from the existence of the universe, the Big Bang, probability theory, entropy, quantum mechanics, general relativity, string theory, evolution, biochemistry, neuroscience and artificial intelligence to minds, souls, consciousness and free will. In general he is a typical scientific skeptic-atheist, and I agree with his positions there, though some of his views are so obvious to me and so much has been written about them already that I don't see the point of repeating them. In some respects he seems to be attempting to be a kinder, gentler physicist, leaving room for alternative theories as long as they are internally consistent and are not contradicted by empirical evidence. He has an uncommon interest in philosophy, which puts him at odds with one of his idols, Richard Feynman, who, like many physicists of that generation, thought of academic philosophy as complete nonsense. Physicist Freeman Dyson, who knew Feynman, recently described contemporary philosophers as follows:

Compared with the giants of the past, they are a sorry bunch of dwarfs. They are thinking deep thoughts and giving scholarly lectures to academic audiences, but hardly anybody in the world outside is listening. They are historically insignificant. At some time toward the end of the nineteenth century, philosophers faded from public life. Like the snark in Lewis Carroll's poem, they suddenly vanished. So far as the general public was concerned, philosophers became invisible.

Although some regard Dyson, who is ninety-two, as a crank, I think he has a legitimate criticism and writes clearly on this topic. I couldn't agree with him more and think that Sean Carroll has been taken in by the philosophy establishment. To my way of thinking, most of the philosophers he mentions concern themselves with made-up problems that are of little or no intrinsic interest. They take old questions and dress them up with new terminology such as "qualia." In philosophical circles it is still popular to pretend that there is an unfathomable split between the mind and the body, that machines can't be conscious and that self-awareness is a unique feature of the universe. In my view all they're really talking about is the reality of subjective experience, which is simply a function of having a brain. If you remove the nonsense from the language of contemporary philosophy, the questions become simple and obvious: "Does Bob have a headache?" or "Is Jane angry?" We all have subjective experiences, including consciousness and self-awareness, which may be hidden from others, and they don't bring into question the nature of the universe. While Carroll tends to be unruffled by the so-called dualism and paradoxes cooked up by philosophers, he does his readers a disservice by bringing them up in the first place.

Rather than wasting all of that space on philosophy, I would have liked to see more on evolution and AI. Instead of providing a comprehensive view of our place in the universe, Carroll gets sidetracked and finishes up the book with a laundry list of platitudes. I find the big picture offered by E.O. Wilson more compelling, because it includes much more about our Earth-evolved predispositions and provides the right backdrop for all that we find meaningful. Regarding AI, Carroll only discusses it in relation to the issues manufactured by philosophers and says nothing about its potential role in our future. The book discusses ad hoc theories that Carroll believes will eventually gel into one final theory, and the feeling of human intellectual limits is palpable, yet Carroll does not go on to speculate that AI may in the near future be able to surpass our feeble little brains.

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