"String Theory" and the Multiverse: New calculations suggest fewer parallel Universes.

String theory allows and maintains an almost infinite amount multiverses as a basis for its mathematical equations.  So, for the foundation of its theory to be significant it needs to add extra dimensions in Space-time as an equation, which in turn incorporates the expansive possibilities of millions of different Earths.  In simple terms, it is theory in physics which has attempted to meld Einstein's classical theory of relativity to the Quantum physics of the infinitesimal, theorized as ever changing vibrating membranes (strings) of infinite Universes and its parallel counterparts  - which, as mentioned, all align themselves as different versions of space-time.   But, it is still a theory of explaining that different aspects of dimensions and the space-time processes that could exists in parallel regions of space and time.  And as mathematical equations, which can look very correct and beautiful, even from the most simplistic calculations of the layman.   It still cannot answer to what is existence and our place in the Universe (within its beginning and end ad infinitum).  As it needs to solidify the factual (which will progressively be achieved through more advanced measurements via advanced space and land telescopes) rather than solely relying on the theory of numbers.    And it is dark matter and energy, within the Universe, that still mystifies the physicists to this day that will lead to more questions than answers.    So it is not a cut-and-dried theory.

However, I do like the idea that we are living in a expanding three dimensional bubble Universes that lie next to others.   And I personally believe in parallel Earth's - that may or may not harbor life, such as an alternative parallel 'human' worlds, that also could be dead-zones in a dead Universe.   As sometimes, in a speculative science (fiction) idea we, these cosmic Universes 'bubbles' knock into each other, causing a void or a massive bulging cold spot. 

This has been a topic of many of my stories and books.

From Scientific America 

"String theory is an attempt to describe the whole universe under a single “theory of everything” by adding extra dimensions of spacetime and thinking of particles as miniscule vibrating loops. Many string theorists contend it is still the most promising direction for pursuing Albert Einstein’s dream of uniting his general theory of relativity with the conflicting microscopic world of quantum mechanics. Yet the notion of a string theory landscape that predicts not just one universe but many has put some physicists off. “If it’s really the landscape, in my view it’s death for the theory because it loses all predictive value,” says Princeton University physicist Paul Steinhardt, who collaborated on one of the recent papers. “Literally anything is possible.” To Steinhardt and others, the newfound problems with dark energy offer string theory a way out. “This picture with a big multiverse could be mathematically wrong,” Danielsson says. “Paradoxically this makes things much more interesting because that means string theory is much more predictive than we thought it was...” 

"...Ultimately the debate going on in string theory centers on a deep question: What is the point of physics? Should a good theory be able to explain the particular characteristics of the universe around us or is that asking too much? And when a theory conflicts with the way we think our universe works, do we abandon the theory or the things we think we know?..."

"...String theory is incredibly appealing to many scientists because it is “beautiful”—its equations are satisfying and its proposed explanations elegant. But so far it lacks any experimental evidence supporting it—and even worse, any reasonable prospects for gathering such evidence. Yet even the suggestion string theory may not be able to accommodate the kind of dark energy we see in the cosmos around us does not dissuade some. “String theory is so rich and beautiful and so correct in almost all the things that it’s taught us that it’s hard to believe that the mistake is in string theory and not in us,” Sethi says. But perhaps chasing after beauty is not a good way to find the right theory of the universe..."