Although the Closer to Truth podcast (6:48 min) that aired last week is called “Alan Guth – Must the Universe Contain Consciousness?”, it actually doesn’t address consciousness. Rather, MIT cosmologist Alan Guth, originator of the widely accepted inflationary universe theory, mainly talks about alternatives to the Anthropic Principle in the study of our universe.

As described in the podcast, the Anthropic Principle means the “apparent fine-tuning of some of the critical values in particle physics and cosmology,” which enables life on Earth, among other things. Readers may recall that in January, cosmologist Alexander Vilenkin told host Robert Lawrence Kuhn that if the universe were really fine-tuned, the cosmological constant should equal zero, not the currently accepted value of something slightly above zero. The trouble is, cosmologists are unclear even about what the cosmological constant is. So it’s not clear why it should equal zero.

Guth takes a stab at explaining away fine-tuning via inflationary cosmology and string theory — although he seems surprisingly uncertain about all that:

Robert Lawrence Kuhn: [0:00] Alan, in dealing with the majesty and mystery of what you and your colleagues discover in cosmology and particle physics a whole new area of thinking has developed because there’s such so-called apparent fine-tuning of some of the critical values in particle physics and cosmology, and some have invoked what’s been called the Anthropic Principle to try to explain that. How do you view, as a cosmologist, the Anthropic Principle?

Alan Guth: [0:39] Yeah, I guess I’m kind of a fence-sitter still on that issue. I used to hate the Anthropic Principle when it was first proposed. It sounded very religious and there didn’t really seem to be a scientific context to it.

Kuhn: [0:48] How so?

Guth: [0:53] Well, when it was first proposed in the earliest days, there was just no explanation as to what mechanism implemented the Anthropic Principle. One had the feeling that somehow behind it all there had to be some intelligent designer who was trying to design the universe for life. And I think some versions of the Anthropic Principle were really pretty explicit about that.

—

So what does he propose?

—

Guth: [1:16] I think we do now have a fully scientific framework for the Anthropic Principle. In the modern setting, it consists of, first of all, ideas coming out of string theory that there are many, many kinds of vacua [vacuums] in string theory — no unique ground state, no unique vacuum. So instead of string theory predicting uniquely that if things wait long enough, they’ll settle into this state, instead, there are many different states they could settle into.

—

Theorists, Guth goes on to say, estimate that there could be 10⁵⁰⁰ such states [2:19], each of which could be a vacuum for a universe. Inflation would produce more and more “pocket universes,” creating “a natural setting for the Anthropic Principle.”

Inflationary cosmology is widely accepted but string theory, which “attempts to merge quantum mechanics with Albert Einstein’s general theory of relativity,” is generally regarded as much more doubtful. The numbers that suggest fine-tuning are, by contrast, not in doubt. An approach that depends on doubtful string theory to explain undoubted numbers sounds a bit risky.

Guth somehow senses the problem, perhaps with a teensy nudge from Kuhn:

—

Kuhn: [4:30] … some people have said that we’re maybe even less confident of finding absolute one-way-only physical law to account for this, which gives credence to the need for the Anthropic Principle.

Guth: [5:03] That’s right, that’s right. Certainly, the energy density of the vacua has, I think, had a lot to do with driving the consideration that physicists had given to the Anthropic idea. Before that, it seemed like there was almost certainly a better explanation for anything.

We have not found any sensible explanation for why there should be a cosmological constant or an energy density of dark energy, as we sometimes call it. [5:28] The magnitude that we see is vastly smaller than what we would expect. We used to think it was really zero and we didn’t understand that. But zero we were willing to accept as something that we might be able to calculate someday soon [5:39]. Now that we think it’s a small number but nonzero — and by small I don’t mean kind of small — I mean extremely small. The energy density of this dark energy is about 120 orders of magnitude less than what particle physicists would naturally guess it ought to be. [5:55]

Kuhn: [5:57] I don’t think there’s another number like that in all of science.

Guth: [6:02] There probably is not. It’s a standalone.

—

Guth brings up the suggestion of Nobelist Steven Weinberg (1933– 2021) that a multiverse might take care of the problem. But he doesn’t seem enthusiastic about that, possibly because we know of only one universe, which appears fine-tuned. We know of no other universes, fine-tuned or not. Then he says:

—

Guth: The Anthropic explanation I think is a valid explanation. (6:37) And so far, I think it’s our only sensible explanation.[6:42] I still hope that we’ll find a better explanation ,and by better I just mean one that’s more predictive.

—

The segment ends without further information about what Guth is trying to predict. The viewer is left with the impression that cosmologists are finding it harder than ever to rule out intelligent design of the universe.