Is the multiverse physics, philosophy, or something else entirely?
The idea of the multiverse, or the theoretical possibility of infinite parallel universes, straddles a strange world between science fiction and a plausible hypothesis.
Though scientists have no direct evidence for the multiverse’s existence, some theoretical models suggest the multiverse could solve some key riddles in physics, such as why the parameters of our universe have values that are exactly in the small range required for life to exist.
Perhaps, some scientists posit in one version of the multiverse theory, there are billions of other universes out there with all different possible values of these parameters—ours just happens to be the one with the right values for life.
But how credible is a scientific theory that might not be testable? Scientists are constantly pushing the boundaries of our knowledge, which includes developing ideas in areas where evidence is scarce.
However, theories like the multiverse have drawn criticism from some scientists, who warn of the danger of speculation beyond what data can tell us.
Testable Theories of the Multiverse
But what if the concept of the multiverse were testable?
We have two ideas which can prove experimentally the Multiverse concept.
1. One is “Cold Spot”. The cold spot was first observed by NASA’s WMAP (Wilkinson Microwave Anisotropy Probe) satellite in 2004, and then confirmed by ESA’s Planck mission in 2013. It is extremely enigmatic.The cold spot is about 70 µK colder than the average temperature (2.7 K ) of the Universe.
A study showed it to be a “supervoid” in which the density of galaxies is much lower than it is in the rest of the universe.
There are many scientists claiming that the cold spot is a collision spot of the Parallel Universes, which supports the concept of Multiverse but now we don’t have any experimental evidence with us.
2.The Second one is String Theory. According to the String Theory everything in the Universe made up of strings.
These could be open ended and closed strings. An open ended string will be attached to our 3D Universe (4D with Time) but a closed string can escape from our 4D Universe to any other dimension/ Universe.
The weakness of Gravity compared to the other forces in the Universe could be explained with the String Theory. The explanation follows, the string theory modeled Gravity is the resultant of the exchange of hypothetical particles called Gravitons.
These are Bosons of Spin 2 , and it is a “closed string” could escape to the other dimensions and making the Gravity is weak in our Universe compared to its counterparts.
The scientists at the CERN carrying-out various high energy experiments which may possibly produce the Gravitons. If we discover with 100% accuracy that there is an energy difference before and after the experiment, then we can assure that these closed strings shifted from our 4D Universe to the other Universe.
Then we can say our Universe is one of the many Universes i.e Multiverse.