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“The Current Crisis” in theoretical physics

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“Like spouses,” Mitch Stokes writes concerning quantum physics and general relativity, “each completes the other.” His new book How to be an Atheist explores the relationship between atheism and skepticism generally — arguing that atheists, though broadly skeptical, fail to employ their skepticism across the board into epistemology and ethics. If they did this, the atheist must reduce these fields to reject most of what atheistic leaders propose — namely, evolution by natural selection, M-theory, and moral values that do not originate from atheism, like equality, or justice.

One chapter stands out in particular. Can we use the scientific method to find out the fundamental nature of reality? No, Stokes argues, for various reasons over a few chapters. Moreover, in the outstanding chapter, he presents the case that even if science could answer these questions, we know anyway that “according to science itself, important aspects of our current physical theories are incorrect” (119).

Stokes writes,

General relativity and quantum mechanics shocked the world with their appearance in the first three decades of the 1900s, and together they account for the entire universe, including nature’s four fundamental forces and all the elementary particles out of which the universe is made — whether these particles are entirely at rest or approaching the speed of light. Although Newtonian mechanics is an excellent approximation for medium-sized dry goods at velocities far below the speed of light, when we address the most fundamental aspects of physical reality — when the universe “red lines” — physics becomes an extreme sport and we need quantum mechanics and general relativity (120).

Yes. Newton’s laws of motion did explain much more than Aristotle’s theories of motion, but they didn’t tell the whole story. We cannot blame Newton, of course, because the extremes of outer space and inner atoms had not been discovered. So he explained everything that had been discovered at the time. When those extreme phenomena were discovered, a more comprehensive theory came along to describe space (general relativity) and subatomic particles (quantum theory). But notice, these are two theories, not just one.

They need one another. Neither of them can account for physical reality alone, and so there’s a division of labor between them. Quantum mechanics takes care of the subatomic world; general relativity handles everything else. General relativity also treats gravity, which doesn’t exist in the eyes of quantum theory. Like spouses, each completes the other.

But the marriage has been rocky from the start. In fact, it began with a shotgun wedding. The division of labor, despite its practical success, was forced upon physicists, really. Our two pillars of physics are logically incompatible with one another, and so at least one of them is wrong. They tell different stories about the observable world (120-121).

The reason why these theories can coexist so well despite their underlying inconsistency is that physicists do not need to use both. What physicist uses both sets of tools, and how at once?

Rather inconveniently, there are scenarios that require both quantum mechanics and general relativity.

There are physical situations where physicists would really like to use both theories simultaneously. These are, as Greene points out, “extreme physical situations that are both massive and tiny.” Two such extreme cases are, he says, “the center of a black hole, in which an entire star has been crushed by its own weight to a minuscule point, and the big band, in which the entire observable universe is imagined to have been compressed to a nugget far smaller than a single atom.” Normally, in the quantum realm, the force of gravity is negligible because it’s so weak, being vastly overpowered by the other three (e.g., even a small magnet can overcome the force of gravity when it lifts a paper clip off the desk). But when the mass of a star or universe is packed into a volume smaller than an atom, we have to take gravity into account along with quantum effects. In other words, we need a theory of quantum gravity (121-122).

Nice. The two most important and empirically verified fields of science are incompatible and require some larger theory, perhaps we could call it a theory of everything?, that conatins both and synthesizes all the data into one explanatory framework. Man, people should really get on that, I bet it would make for a good life quest and —

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Oh yeah, never mind. Someone’s already been on that for a while.

But Stokes remains unimpressed by Hawking’s solution. String theory in general does not seem to be falsifiable: the versions of string theory we can test have been disproved, and the ones we cannot test are so numerous (as many as 10^500) that no experiment or set of experiments can disprove them all save the true one. M-theory in particular seems to be one step forward and two steps back: it is

a network of theories in which each theory is good at describing phenomena within a certain range. Or course, this sounds very much like our current situation, where general relativity and quantum mechanics each adequately deals with its respective domains, yet in some ways worse. Instead of merely two patches in the theoretical quilt, we now have five (124).

But, curiously, the same atheists who propose radical skepticism on the existence of God claim M-theory as the multiverse framework for the creation of a universe without a creator. Does that not also require non-skepticism? Stokes uses this point to support his claim that atheists are just not skeptical enough — and on precisely the issues that matter.

Why believe what false theories (allegedly) imply about topics even further removed from the topics they get wrong? Good skeptics will be wary of both.

So why aren’t they? (129).

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