The Multiverse has no empirical or scientific evidence.

 

The Multiverse looks to be a flaw rather than a feature in scientific beliefs. We should put a stop to it.

These days, the Multiverse is everywhere. The notion that there is more than one Universe, or, better yet, that there are numerous parallel versions of our Universe, has become a popular fiction staple. It's an important part of the Marvel Cinematic Universe, for example, where an entire storey arc hinges on it (that is, Loki, Spiderman and Doctor Strange). Writers adore the Multiverse because it allows them to experiment with cause and effect, imagining how life and history may have changed if only a small modification in a timeline had been made. What kind of "you" may have emerged from a history devoid of that first love, or where a major victory was replaced by a major setback, or simply if you wore blue socks instead of black socks on September 17, 2012? Many fiction writers can't resist the concept that there are other universes out there, all existing at the same time and possibly even interacting.

Is there, however, any true empirical scientific support for it? Is there reason to assume that the Multiverse theory, which came from science's frontiers, is correct? Do you, in other words, live in a Multiverse?

For better or worse, the answer is no. There is no empirically supported scientific reason to assume that a Multiverse of alternative universes exists. In truth, the Multiverse is only mentioned in scientific theories as a flaw rather than a feature. If you have a Multiverse in your cosmological model, it's almost certainly a sign that it's failing in some manner.

Three ways the Multiverse appears

In modern physics and cosmology, the Multiverse can be found in three places: the many-worlds interpretation of quantum mechanics, string theory, and perpetual inflation. Let's take a look at each one individually.

If your best idea for explaining a gas cloud in the Andromeda galaxy requires the existence of 100 unobservable pink elephants in the vicinity of the star Vega, you may have a problem.

The many-worlds interpretation of quantum mechanics is an attempt to comprehend quantum physics' "collapse of the wave function." This is the entire Schrodinger's cat phenomenon, where a quantum system will be in two mutually incompatible states (like a dead cat and a live cat) at the same moment before a measurement is done. The system then "collapses" into one of two states when a measurement is taken (someone looks). For years, physicists have been pondering what this collapse signifies. The many-worlds view avoids the problem by asserting that no collapse occurs. When a measurement is taken, the Universe separates into two parallel versions, each of which evolves independently. Because every quantum event causes a splitting, the result is a quantum driven multiverse with an almost limitless number of parallel Universes.

The other type of Multiverse comes from inflationary cosmology, which claims that in the first minutes following the Big Bang, a tiny portion of the entire post-Big Bang spacetime expanded by 1060 times its original size. When inflation ceased, this minuscule piece of reality had grown to include the entire Universe. The rest of spacetime, on the other hand, continues to travel at a leisurely speed. As a result, additional slivers of it can go through their own inflationary episodes, forming their own realms of reality. So-called "pocket universes" appear inexorably in this "eternal inflation." They build a Multiverse when they get together.

String theory can also be useful in this situation. String theory was revealed roughly 20 years ago to be unable to forecast the one Universe we live in, instead yielding approximately 10500 Universes. If string theory is the correct Theory of Everything, it fits very perfectly with perpetual inflation and adds to the Multiverse prediction.

Cosmic buzzkill

Now, I'll grant that these are huge, cool, and intriguing ideas. The issue is that they are nothing more than concepts. There isn't a single shred of evidence that any of these Multiverses exist. There isn't a single shred. However, that absence is only the beginning. When you think about it, the Multiverse appears in these ideas primarily as a failure to address the underlying problem that they were interested in in the first place.

The many-worlds view appears to be overly generous in its creation of Universes. However, it bases this position solely on a metaphysical commitment to regard quantum mechanics equations as real and existing independently of us, rather than as tools we use to comprehend the world. I'm as interested in metaphysical debates as the next man, but creating an endless number of parallel universes to satisfy a philosophical commitment seems a little excessive.

String theory was marketed as a Theory of Everything that will provide us with a comprehensive description of the explicit Universe in which we live. When "the string landscape" was discovered, with its 10500 potential solutions (the Multiverse), it was interpreted by many as a sign that the theory was failing to deliver on its promises. Since then, string theory has only gotten worse, and the excitement it sparked 20 or 30 years ago has long since faded.

Inflationary cosmology has some empirical support, and it is now considered a conventional view of the Universe. However, inflation is more of a group of hypotheses than a single model, and perpetual inflation is a thorn in its side rather than a triumphant forecast. If they could, many theorists would be delighted to find a means to switch off all those other pocket Universes. After all, if your best idea for explaining a gas cloud in the Andromeda galaxy necessitates the existence of 100 unobservable pink elephants surrounding the star Vega, your theory may have a flaw.

So, when you add it all up, the Multiverse is mainly a bust from a scientific standpoint. It's a fix for flaws in existing theories, not an explanation for inexplicable facts or observations. That means we're trapped with the Universe we perceive and the past that has brought us to this point. However, given how lovely, wonderful, and incredible that one Universe and history are, I don't see this as an issue. I still enjoy the Multiverse as a work of fiction. Doctor Strange, I salute you!