by S. Prasad Ganti

A recent article in the journal “Nature” intrigued me. It stated that the accelerated expansion of the Universe, attributed to dark energy currently, could be happening due to merger with other Universes. A very thought provoking idea indeed, although very difficult to prove. It made me think and come up with my 2 cents. 

Our Universe was born from a super giant explosion called “The Big Bang”. From a very humble beginning a small dense and hot dot grew rapidly – a phenomenon called “inflation”. It led to the Universe we know today. The expansion still continues. This expansion pales in comparison with the initial inflation which expanded the space twenty orders of magnitude (10 followed by 20 zeroes) in a very tiny fraction of a second. Given below is the picture from Wikipedia  depicting the growth of our universe since the big bang. The vertical rise to the left is the period of rapid inflation. 

The current expansion which is accelerating (right portion of the picture) is supposed to be caused by Dark energy. Also known as the energy of the vacuum, wherein virtual particles come into existence and get annihilated, not much is known about it,  There has been no light shed on the “dark” yet. In the middle of such a situation comes in an explanation based on Multiverses or Multiple Universes. While the Multiverse is only a mathematical theory, it is also being used to explain what happened before the Big Bang. Very well explained in the book “Before the Big Bang” by Laura Mersini-Houghton. It is posited that multiple Universes float in a higher dimension. Universes are born and not everyone of them matures to become one like ours. 

Given this background, it is not much of a stretch to say that we are absorbing other Universes from higher dimensions. In fact it is being said that we did absorb a lot of other Universes during the initial inflation phase. Collisions and mergers amongst astronomical objects are very common in our Universe too. Black holes merge into other black holes, neutron stars merge into black holes and also into other neutron stars. Galaxies merge too. In fact, our neighboring Andromeda galaxy is on a collision path with our Milky Way galaxy to happen in about two million years. After the merger, things will settle down into a bigger merged galaxy. Our galaxy, in effect, would be expanded to more than double its size.   

Multiverse may sound like science fiction. But then about a century ago, our Universe was just confined to our galaxy, Edwin Hubble made a shattering discovery that  a nebula in the Orion belt called Andromeda is a separate galaxy and is about 2 million light years away. Since then a lot of galaxies have been found and the span of our Universe and its age and history were discovered as well. A century from now, multiple universes may be in the same state as multiple galaxies are today. And another dimension would have been added to our lexicon.

For now, the question is how to find evidence. Most of the evidence in astronomy is indirect. It is only remote measurements anyway. Analyzing the spectrum of the radiation coming in, to infer what elements or molecules have emitted that radiation. And to look at pictures and infer the properties of the object. After all, no human being has gone beyond our moon and none of our spacecraft has ventured beyond the confines of our solar system.  

Studying the pattern of CMB (Cosmic Microwave Background) radiation can give us some clues. Like the book “Before the Big Bang” mentioned that a patch of the pattern in CMB was possibly related to interaction with our neighboring Universes (picture shown below has a circled patch in the right lower corner, by the Planck satellite, courtesy Physics World). There could be other hidden messages in the CMB patterns. CMB could tell us about possible mergers with other Universes. I am letting my imagination fly here. Someday we might find out there is no dark matter at all. The gravitational effects we see may be due to the tug of our neighboring Universe ! Both the “darks’ ‘ which are not well understood – dark energy and dark matter may be due to a common cause of the multiverse.

CMB detectors will become more granular in the future.  And AI (Artificial Intelligence) may come to the fore to detect patterns that our minds cannot imagine. Hoping it would be a groundbreaking discovery.