Several physicists posit the existence of a multiverse, but foundational mathematical assumptions may be flawed

One of the most remarkable scientific revelations in recent decades is the apparent fine-tuning of physics for life. This entails that specific numbers in physics had to align within an extremely narrow range to make life feasible. Among the perplexing instances of fine-tuning is the strength of dark energy, the force propelling the universe’s accelerating expansion. If this force were slightly stronger, matter wouldn’t coalesce, preventing the formation of stars, planets, and structural complexity necessary for life.

Conversely, if the force were significantly weaker, it would be unable to counteract gravity, causing the universe to collapse rapidly, again negating the possibility of life. The strength of dark energy had to be, in essence, “just right” to permit the emergence of life. This example is just one among many illustrating fine-tuning. The prevailing explanation for this fine-tuning posits the existence of a multiverse, suggesting that our universe is just one among many.

Much like the probability of winning a lottery increases with more tickets purchased, the multiverse hypothesis suggests that with numerous universes, each with different physics, the likelihood of one having the right conditions for life becomes plausible. While this explanation has long been considered plausible, experts in probability mathematics have identified a fallacy in the reasoning from fine-tuning to a multiverse—a point explored in my new book, “Why? The Purpose of the Universe.” Specifically, critics argue that proponents of the multiverse commit the inverse gambler’s fallacy.

Let’s consider Betty, who finds herself alone in her local bingo hall one night and experiences an extraordinary stroke of luck as all her numbers are called in the first minute. Betty’s reasoning involves an assumption: if numerous people are playing bingo across the country, it becomes less improbable that someone would achieve such a swift success. However, this line of thinking represents the inverse gambler’s fallacy.

Regardless of the number of people participating in bingo elsewhere, probability theory indicates that Betty herself is no more likely to have this run of luck. Drawing a parallel to dice, when we witness multiple consecutive sixes, there is an erroneous belief that subsequent throws are less likely to yield sixes. Conversely, if no sixes appear for a while, the misconception arises that there must have been numerous sixes in the past. In reality, each dice throw has an equal and specific probability of one in six for obtaining a particular number. Multiverse proponents commit a similar fallacy.

They contemplate the apparent improbability of our universe possessing the necessary conditions for life and deduce that there must be many other universes with unsuitable conditions. This parallels Betty assuming she can explain her luck based on others playing bingo. However, when our universe originated, akin to a dice throw, it still had a specific, low probability of aligning with the right conditions. At this juncture, multiverse advocates introduce the anthropic principle, asserting that our existence limits our observations to a universe compatible with life.

Yet, this doesn’t negate the possibility of other universes with incompatible conditions. Consider a scenario where a sniper lurks in the bingo hall, prepared to shoot Betty if a number not on her card is called. Now, the situation mirrors real-world fine-tuning, as Betty cannot observe anything other than the right numbers for victory—similarly, we cannot observe a universe with the wrong conditions for life. Despite these parallels, Betty would be mistaken to conclude that many people are playing bingo. Analogously, multiverse theorists err in inferring the existence of many universes solely from the fine-tuning argument.

What about the multiverse?

Doesn’t scientific evidence support the existence of a multiverse? The answer is nuanced. In my book, I delve into the interplay between the inverse gambler’s fallacy and the scientific argument for the multiverse—an exploration surprisingly absent in previous discussions.

The scientific concept of inflation, positing that the early universe underwent significant expansion, lends support to the multiverse. If inflation occurs once, it is likely to transpire in various spatial regions, generating distinct universes. While this offers tentative backing for a multiverse, there is no evidence that these diverse universes exhibit different numerical values in their local physics.

However, a more profound reason underlies the failure of the multiverse explanation. Probabilistic reasoning adheres to the principle of total evidence, compelling us to base our assessments on the most specific evidence available. Concerning fine-tuning, advocates of the multiverse rely on the most specific evidence not merely stating that “a” universe is fine-tuned but asserting that “this” universe is fine-tuned. If we accept that the constants of our universe were shaped by probabilistic processes, as multiverse hypotheses propose, the likelihood of this specific universe, among countless others, being fine-tuned becomes exceedingly improbable. Once we accurately frame the evidence, the multiverse theory falters in providing a satisfactory explanation.

The prevailing scientific consensus suggests that these fundamental constants have remained unaltered since the inception of the Big Bang. If this assertion holds true, a critical decision looms. It becomes a choice between attributing the rightness of these numbers to an astonishing coincidence or positing that these numerical values exist as they do because nature is inherently guided or compelled by some unseen, intrinsic principle to foster complexity and life.

In my perspective, the former option appears too improbable to warrant serious consideration. My book introduces and expounds on a theory aligning with the second option—cosmic purpose—and delves into its repercussions on human meaning and purpose. This divergence from anticipated scientific outcomes parallels historical moments, such as the 16th century when evidence emerged challenging the notion of Earth occupying a central position in the universe. Accepting that the familiar understanding of reality no longer aligns with the emerging data proved challenging for many during that era.

I contend that a similar situation unfolds with fine-tuning today. There may come a time when we look back with surprise, questioning why we overlooked what was plainly evident—that the universe exhibits a predisposition toward the existence of life.

This article is republished from PhysORG under a Creative Commons license. Read the original article.