One of the most striking scientific discoveries of recent decades is that physics appears to be tuned for life. This means that certain numbers in physics must fall within a certain, very narrow range for life to be possible.

One of the examples of fine-tuning that has most baffled physicists is the power of dark energy, which is driving the rapid expansion of the universe. If this force were a little stronger, matter would not be able to stay together. No two particles will ever come together, which means there will be no stars, planets or any structural complexity, and therefore no life.

If this force were much weaker, it would not resist gravity. This means that the universe will collapse again in the first fraction of a second, without stars, planets and life. To make life possible, the power of dark energy had to be “just right,” like Goldilocks porridge.

This is just one example and there are many more. The most popular explanation for the fine-tuning of physics is that we live in one universe among many. If enough people buy lottery tickets, it’s likely that someone will have the right numbers to win. Similarly, if there are enough universes with different numbers in physics, it becomes possible that some universes have the right numbers for life.

For a long time this seemed to me the most plausible explanation for the fine-tuning. But probabilistic mathematicians have described multiverse fine-tuning inference as a case of fallacious reasoning; I explore this topic in my new book Why? The purpose of the universe. Specifically, the accusation is that multiverse theorists commit what is called the reverse actor fallacy.

Let’s say Betty is the only one playing at the local bingo hall one night, and by an incredible stroke of luck, all her numbers come up in the first minute. Betty thinks to herself, “Wow, there must be a lot of people playing bingo at other bingo halls tonight!” He reasons like this: if there are a lot of people playing all over the country, then it is unlikely that someone will get all their numbers in the first minute.

However, this is an example of a reverse player error. Regardless of how many people are playing at other bingo halls around the country, probability theory says that Betty herself is unlikely to be that lucky.

This looks like a dice game. If we get more than one six in a row, we make the mistake of assuming that we are less likely to get a six in the next few rolls. And if we don’t get a six for a while, we make the mistake of assuming there were plenty of sixes in the past. But in reality, each throw has an exact and equal probability of hitting a particular number (one in six).

Multiverse theorists make the same mistake. They think: “Wow, how improbable that our universe has the right numbers for life; There must be many other universes with the wrong numbers!” But it’s as if Betty thinks she can explain her luck by other people playing bingo. When this particular universe was created like a roll of dice, the chances of getting the numbers right were still very low.

At this point, multiverse theorists propose the “anthropic principle”; Since we exist, we cannot observe a universe that is incompatible with life. But this does not mean that there are no other such universes.

Let’s say there’s a crazy sniper lurking deep inside the bingo hall, waiting to shoot Betty when a number comes up that isn’t on her bingo card. Now the situation resembles real-world fine-tuning: Betty could not observe anything other than winning numbers, just as we cannot observe a universe with incorrect numbers in our lifetime. Even so, Betty, it would be wrong to assume that many people play bingo. Similarly, multiverse theorists are wrong to conclude that many universes are fine-tuned.

What about the multiverse?

Is there no scientific evidence for the existence of a multiverse? Yes and no. In my book, I explore the connections between the reverse actor fallacy and the scientific argument for the multiverse, which surprisingly has not been done before.

The scientific theory of inflation (the idea that the early universe exploded to enormous size) supports the multiverse. If inflation can ever occur, it will most likely occur by creating universes of their own in different regions of space. While this gives us preliminary evidence for the existence of a multiverse of some kind, there is no evidence that different universes have different numbers in their local physics.

There is a deeper reason why the multiverse explanation fails. Probabilistic reasoning is subject to a principle known as the cumulative evidence requirement, which forces us to work with the most specific evidence available.

From a fine-tuning perspective, this is not the only concrete evidence that people who believe in the multiverse have. Universe fully configured, but in this This The universe is finely tuned. If we believe that the constants of our universe are established by probabilistic processes (as suggested by multiverse explanations), then it is incredibly unlikely that this particular universe, unlike millions of other universes, is set up exactly. Once we get the evidence right, the theory cannot explain it.

Conventional scientific wisdom is that these numbers have not changed since the Big Bang. If this is true, then we have a choice. Or is it an incredible coincidence that our universe has the right numbers? Or the numbers are that way because nature is somehow driven or guided by an invisible, built-in principle to evolve complexity and life. In my opinion, the first option is unlikely to be taken seriously. My book presents a second alternative theory (cosmic purpose) and discusses its consequences for human meaning and purpose.

This is not what we expected from science. It’s a bit like the 16th century, when we started to get evidence that we weren’t at the center of the universe. Many found it difficult to accept that the picture of reality they were accustomed to no longer explained the data.

I think we’re in the same situation right now in terms of fine-tuning. One day we may be surprised that we ignored the fact that the universe supports life for so long. Source