Does the Multiverse Help Naturalism?

Perhaps our universe isn’t as finely tuned as we thought! We know that life requires stars and planets to form. Overly rapid expansion of the universe would prevent this from happening and a larger amount of dark energy means that the universe expands more rapidly. Yet a recent paper shows that the amount of dark energy in the universe could be hundreds of times larger and yet still permit stars and planets to form. This result seems to reduce the role of fine-tuning, right? Sort of, but not really. In fact, this discovery makes multiverse explanations for the intricate balances that life requires even more difficult to accept—if you demand a purely naturalistic multiverse.

How Does the Multiverse Attempt to Explain Fine-Tuning?

Countless scientific results show that our universe looks designed to support life, and most scientists affirm this conclusion. The real question for many scientists is not if our universe appears designed, but whether it actually is designed. The multiverse currently provides a popular explanation for many who answer “no” to this question. Basically, the argument follows this line of reasoning:

1. Yes, our universe looks fine-tuned for life.
2. However, inflation (or any other multiverse-producing mechanism) produces an enormous number of universes and our best models say that the observed laws of physics exhibit great variability over those universes.
3. Since life demands a rather specific set of conditions in order to exist, we must observe what appears to be a finely tuned universe.
4. It is a mistake to conclude that our universe is designed because our universe naturally fits into the distribution produced by the multiverse.

In other words, although our universe appears atypical (because of the fine-tuning for life), in truth our universe is typical (given the multiverse and the fact that we exist).

Does This Explanation Work?

In order for the explanation to work one must ask, Does our universe appear typical? At first glance, the notion that it could have hundreds of times more dark energy and still support life seems to make our universe more typical. But it doesn’t for two reasons.

First, we must put the “hundreds of times more dark energy” in context. Some people will say that the dark energy must be fine-tuned to one part in 10¹²⁰, but that is not a correct statement from a physics perspective. Rather, given our theoretical understanding of the earliest moments of the universe, scientists predict that the amount of dark energy should be 10¹²⁰ times larger than we observe. Adjusting that statement to reflect recent discoveries means that theoretically typical amounts of dark energy exceed the maximum amount possible in a habitable universe by a factor of 10¹¹⁷. Yes, the factor is smaller, but not in any significant way.

Second, and perhaps more importantly, a larger range of habitable universes makes our universe more atypical. Remember, we observe a much smaller amount of dark energy than expected from our best models. Additionally, the farther something gets from the expected value, the rarer that condition becomes.

Consider going out to see one (and only one) shooting star. The majority of shooting stars arise from particles around the size of a sand grain. Many more particles smaller than that hit Earth’s atmosphere, but they don’t meet the requirements necessary to produce a streak of light visible to the naked eye. So, the vast majority of particles are incredibly small (think size of a proton) but the typical size of particles that produce shooting stars are like sand grains. To reach the ground, the “particle” must be the size of a small rock (a few kilograms). Armed with this knowledge, you go out to observe your one shooting star. As you settle in and wait, a bright light appears overhead, persists for a brief time, and then a small pebble strikes you on the head. Given your knowledge, you must conclude that you witnessed a remarkable, or atypical, shooting star.

Let’s assume that a vast multiverse exists and that this multiverse produces a wide enough variety of universes to account for ours. We now know that our universe could contain much more dark energy and still form stars and planets. Yet, we observe much less dark energy than expected. Our universe is atypical. As Luke Barnes, one of the paper’s authors, states, “Our work shows that our ticket seems a little too lucky, so to speak. It’s more special than it needs to be for life. This is a problem for the Multiverse.”

Our ticket may be too lucky for the naturalist’s multiverse, but it makes perfect sense if God created our universe for us to observe and marvel at his handiwork!