This is probably our favorite essay in the series. Together with the next four essays, it contains the heart of our argument rejecting the multiverse and marks the conceptual turning point of this entire series.
This essay in particular has a strange objective - to thoroughly reject a naive version of multiverse theory that no serious scientist actually believes in. While this may sound strange, this exercise is actually quite important. First of all, while no serious scientist accepts a naive multiverse, many popular presentations of the multiverse do. So it’s good to see the problems with the popular, but naive, version of the multiverse. And more importantly, it turns out that understanding what a naive multiverse is, and where it goes wrong, is critical for appreciating the absolute necessity of the multiverse’s third premise - that our universe is typical.
But it should be clear that in this essay, we’ll be attacking a naive version of the multiverse. While the actual multiverse theory may seem absurd, many leading scientists believe that it’s a realistic possibility. The naive multiverse, on the other hand, is so completely ludicrous that no one serious can possibly believe in it. At least we hope not…
Highlights of this essay:
Introduction
In the previous essays, we presented multiverse scientists’ strongest supports for their first two premises. They base the first premise - that there exist an infinite number of universes - on eternal inflation, and the second premise - that the constants vary between universes - on the string theory landscape. While their supports are far from proofs, we’re willing, for the sake of argument, to grant them that theoretical considerations suggest the validity of these two premises.
Given these two premises alone, you might naively think that an infinite varied multiverse can solve the problem posed by fine tuning. The reasoning goes something like this: Since there are an infinite number of universes - each with different laws, constants, and initial conditions - every possible universe must exist somewhere in the multiverse - including a universe that’s as fine tuned, designed, and ordered as our own. And, of course, we shouldn’t be surprised to find ourselves in a universe hospitable to intelligent life, because there simply aren’t any observers in universes that aren’t hospitable to life.
Just so we’re all clear on the terminology, a naive multiverse theory like what we’re discussing here is the attempt to explain fine tuning and design by simply noting that in an infinite varied multiverse everything possible happens. We call it a naive multiverse if it doesn't also contain the all-important typical universe premise that we’ll explain in depth in the next essay.
While a naive multiverse is found in popular presentations of the multiverse, it has serious problems. In this essay, we’ll elucidate three such problems and show why no serious scientist actually believes in it.
Multiverse of the Gaps
The first serious problem that a naive multiverse encounters is that it’s a theory of the gaps. This is because by invoking an infinite number of randomly different universes, a naive multiverse is capable of “explaining” any possible observation we have ever made or ever will make. No matter what our actual universe was to look like (incredibly ordered, totally disordered, or anywhere in between), a theory of randomness coupled with an infinite number of attempts would provide an explanation.
To appreciate this problem, let’s review how multiverse relates to fine tuning. As we showed in our first series, fine tuning directly indicates that the constants have an intelligent cause. A naive multiverse theory argues that this implication is misleading because an infinite number of varied universes can also explain fine tuning. That is, in an infinite varied multiverse, at least one universe will happen to have fine tuned constants by pure chance.
The problem is that by the exact same logic, an infinite number of universes can explain any gap in knowledge. Whenever science reaches a difficult point or makes an observation that scientists can’t explain, one can simply reason that in an infinite multiverse, at least one universe will have this previously unexplained occurrence by pure chance.
Let's give an example of such a gap and show how an infinite multiverse would help explain it.
When scientists were trying to find an explanation for the diversity of life on Earth, there was no need for the theory of evolution. They could have just invoked an infinite multiverse, arguing that, by chance alone, one universe will contain Earth’s diversity of life.
The justification for a multiverse’s ability to explain everything is that an infinite varied multiverse truly contains every possible universe. The combination of chance with an infinite number of attempts naturally leads to any configuration of particles you can imagine. An infinite varied multiverse contains totally chaotic universes, highly ordered universes, universes with patterns that we recognize, universes with fire-breathing dragons, and everything in between.
The idea is that anything that could possibly exist, will exist. To see why, you need to realize that the fundamental laws of physics don’t intrinsically exclude far-fetched phenomena but only state that they are highly improbable. For instance, according to the laws of quantum mechanics, there’s a minuscule chance that all the atoms in a book will spontaneously fluctuate and reorder themselves into any other possible arrangement – a quantum fluctuation. Though such an occurrence is exceedingly unlikely – which is the reason you’ll never witness it – nevertheless, it remains a statistical possibility.
The main point is that while it would be highly improbable to get a quantum fluctuation of all life on Earth in one particular universe, if there truly are an infinite number of universes, at least one universe will, by chance alone, have the great diversity of life containing chickens, cats, dogs - even fire-breathing dragons.
In other words, every possible strange or bizarre occurrence will show up somewhere in the infinite multiverse. In fact, if it shows up once, it will show up an infinite number of times. We’re not saying this based on our personal speculations about multiverse theory; it necessarily follows from an infinite number of universes.
Many multiverse scientists explicitly state that every imaginable scenario that is physically possible must exist somewhere in an infinite multiverse. For instance, physicist Alan Guth, the originator of the theory of inflation, said as follows, “In an eternally inflating universe, anything that can happen will happen; in fact, it will happen an infinite number of times.”
This is a serious problem. Any theory that can be invoked to explain anything at all, in truth explains nothing at all. A naive multiverse is a wildcard theory that can plug any gap in knowledge and solve every single mystery. As such, it’s not a theory grounded in knowledge, but a desperate stopgap grounded in ignorance. If the extensive fine tuning, order, and design in our universe can be explained by an infinite varied multiverse, then anything can be explained by this trick. Therefore, a naive multiverse is truly a theory of the gaps.
See essay 5 of series one for a more in-depth analysis of a theory-of-the-gaps fallacy, and why the theory of an intelligent fine tuner doesn’t fall prey to this fatal flaw.
Intrinsically Irrefutable
The second problem that follows from a naive multiverse being able to explain anything and everything is that it’s intrinsically irrefutable; meaning, there’s no possible observation that could ever prove it false. The following humorous hypothetical story we’ve come up with will help illustrate how any evidence that would seem to completely contradict a naive multiverse can instead be used to confirm it.
It’s the year 2050 and the annual international physics conference Naive Multiverse is well underway. Everyone is having a grand time discussing their research papers about all the incredible wonders they have imagined, like fire-breathing dragons and unicorns, that actually exist somewhere in a parallel universe, when an amazing, shocking, event takes place. An immense voice, apparently coming from the heavens, thunders out the following:
I am the creator of the heavens and the earth! I perfectly designed the laws of nature, carefully chose exact values for the constants, and precisely arranged the initial conditions of the universe, all in order to bring about the one beautiful universe in which you are fortunate to live. I set the cosmological constant equal to 10^−122 because if it were smaller, the universe would have collapsed right after the big bang. On the other hand, if it were larger...You know what? You can just listen to the first series of the Physics to God podcast for more details.
I only created one universe. All multiverse theories are false, unfounded speculations that naive multiverse scientists have posited to avoid the manifest indications of my existence. As I will not appear to every generation of physicists, make sure to transmit this important message to your descendants to prevent them from wasting their time and energy pursuing a nonexistent multiverse, and to instead investigate the great wisdom and intelligence found throughout my one universe.
Now, one would think that this would be the ultimate proof in favor of an intelligent fine tuner and a complete falsification of the multiverse. But that’s not how the story goes. Let’s continue.
At first, all the naive multiverse theorists are filled with shock and despair. All the hours they wasted writing papers about fire-breathing dragons and unicorns have been wasted. Maybe they were wrong about an intelligent fine tuner being impossible all along. But then, one extremely clever young physicist emerges from the shadows, clears his throat, and begins to speak:
My fellow naive multiverse theorists. Let us not be moved by our emotions and overwhelmed by the strange soundwave from the sky. It is time to think clearly and coherently. Quantum mechanics shows that although the occurrence of that sound wave from a random fluctuation is highly improbable, it is certainly possible. Is it really any more unlikely than fire-breathing dragons? Granted, it would be quite puzzling for it to occur if there was only one universe. However, since we know there exists an infinite varied multiverse, this sound wave must occur by chance alone in at least one universe in the multiverse. Though we would never predict it in advance, our empirical observations tell us that we happen to be in such a rare universe. Come to think of it, not only is it not evidence for an intelligent cause, but since we all know that God is impossible this highly improbable sound wave is the clearest proof of all that we exist in but one universe in an infinite multiverse.
This sort of far-fetched explanation is a direct consequence of a naive multiverse. Random chance and an infinite number of universes can explain absolutely anything, including observations that should fully refute the theory. There is literally no observation or evidence that could disprove a naive multiverse. It’s intrinsically irrefutable, in that any apparent contradictory evidence can be dismissed by saying, "It has to occur in one universe in the multiverse, and apparently we’re in that universe.”
Being intrinsically irrefutable is worse than merely being practically irrefutable. To appreciate this distinction, consider a practically irrefutable theory like idolatry. The theory claims that bowing down to idols brings a person greater success than not bowing. Since one can never know what would have happened had the person not bowed, it is practically irrefutable; it can’t make any testable prediction. Nevertheless, if the creator of the heavens and earth produced a voice saying that bowing down to idols will never help a person but will lead people away from the truth, that would refute idolatry. While the mere possibility of such a voice doesn’t make it refutable in a practical sense, at least idolatry can be theoretically disproven by contradictory evidence.
Naive multiverse theory is worse than idolatry in this regard. A true believer in a naive multiverse would even reject the voice of the creator of heaven and earth, explaining it away using a naive multiverse. There can be no possible contradictory evidence whatsoever – even in theory. It’s an intrinsically irrefutable theory.
We want to mention that while our story was tongue-in-cheek, according to actual multiverse scientists, not just make-believe naive multiverse scientists, that story - including the young physicist - really does occur in an infinite number of universes in the multiverse. As Guth said, “In an eternally inflating universe, anything that can happen will happen; in fact, it will happen an infinite number of times.”
While that’s a bit of a side point for now, it does highlight the point that while a naive multiverse is completely ludicrous, the actual multiverse theory isn’t that much better. But we’re getting ahead of ourselves. Right now we’re just talking about a naive multiverse. We’ll talk about a complete multiverse and its problems in a later essay.
Let’s move to the third problem with a naive multiverse.
Self-Defeating
Not only does a naive multiverse’s ability to explain everything render it an intrinsically irrefutable theory of the gaps, but it also causes it to undermine itself. While this point is a bit subtle, we'll explain it slowly.
A naive multiverse is based upon the Infinite Multiverse Premise and the Varied Multiverse Premise. No scientist would simply posit these premises without any scientific basis whatsoever. Rather, multiverse scientists claim that they emerge from scientifically supported theories like inflation and string theory. The problem is that a naive multiverse undermines the scientific support for these theories.
Let’s see why. In an infinite varied multiverse, the results of any experiment will vary from universe to universe. Therefore, any possible experimental result will occur somewhere in the multiverse. If so, there is no meaning to the claim that a particular experimental result either confirms or contradicts a theory. Any theory will be confirmed in some universes and contradicted in others.
The problem is that the validity of the entire scientific method is based upon the premise that our observations will be determined by a fixed set of laws. This premise allows us to test whether our observations conform to the results predicted by our hypothesized laws.
However, if despite these fixed laws, naive multiverse scientists are willing to explain any observation by saying that in an infinite varied multiverse, anything that can happen will happen, then they could have never tested their theories in the first place. Whatever result an experiment gave, be it confirming or contradicting, they could have just chalked it up to the randomness of our particular universe in the infinite multiverse.
To understand this more clearly, let’s consider an example. Imagine we were testing the theory of gravity that in its simplified form says all things fall to the center of the Earth. Imagine we were to do a hundred experiments and they all confirmed the theory. You might think this would prove the theory of gravity.
However, if we truly existed in an infinite multiverse, maybe there is no law of gravity at all and instead, all motion is random. But we just happen to be in a universe where by chance alone all one hundred experiments we did resulted in things falling down. But since there is no actual law of gravity, there’s nothing to say that the next thing that goes up will fall back down.
The point is that if a naive multiverse is willing to explain observations like fine tuning based upon the fact that it happens somewhere in the infinite varied multiverse, then it can equally explain the one hundred experiments in this random manner.
But this would undermine the experimental confirmation of the theory of gravity and, more importantly, all the theories (like inflation) that led us to believe in a multiverse in the first place.
This is a significant problem indeed. The reason multiverse scientists allegedly accepted an infinite varied multiverse in the first place is because of their scientific theories - but a naive multiverse erodes the entire scientific basis for these theories!
The Three Problems with Naive Multiverse
Summing up, a naive multiverse that avoids an intelligent cause of our universe by explaining the fine tuning of the constants, design of the laws, and order of the initial conditions simply based upon the idea that everything must exist somewhere in an infinite varied multiverse, falls prey to three serious related problems:
1) It’s a theory of the gaps which can be used to explain anything, and therefore explains nothing at all;
2) It’s an intrinsically irrefutable theory that is even capable of explaining away blatantly contradictory evidence;
3) It’s a self-defeating theory that undermines the very scientific theories it’s based upon.
These three problems aren’t merely problems for a naive multiverse attempting to explain fine tuning, but are intrinsic problems with a naive multiverse trying to explain anything. Simply positing that in an infinite varied multiverse X happens somewhere and we just happen to be in the universe where X happens is bad science. That’s why no serious scientist actually believes in a naive multiverse.
You might be wondering: How do serious multiverse scientists avoid these problems and still explain fine tuning using an infinite varied multiverse?
If you’ll notice, all these problems derive from the fact that naive multiverse theory makes no concrete predictions. It just attempts to explain anything based on the fact that everything must happen somewhere in an infinite multiverse. Consequently, the basic solution to these three problems emerges by completing multiverse theory and including a prediction - the all-important third premise that our universe is a typical universe with intelligent observers.
In the next essay, we’ll clearly explain the typical universe premise using a marble analogy, and then show that once the multiverse’s explanatory power is limited to typical universes, all three problems are naturally avoided.-
Of course, their solution ultimately causes them to run into other problems that undermine their ability to avoid attributing the universe to an intelligent cause. The next few essays are going to be fun, so stay tuned.
Bình luận