A Darling Theory
- Anwesha Sahu
- Mar 30, 2020
- 7 min read
Darlings. Darlings don’t enter our lives quietly all the time. Neither do they enter our lives with a bang. From my finite experience with life, they enter our lives memorably in ways that cannot be replicated by any other rambler in the fabric of space-time. They blow your mind and touch your soul the instant you come across them. They make you ponder why you did not know about them earlier. In a way, they seem to be the answer to a quest – a quest that you’ve been on since eternity but were oblivious to. My first introduction with one such darling was something like this. Unsuspecting. Unexpected. It wasn’t a jolt. It was a caress. A reassuring caress – one that gave me hope that science will not be overcome by internal bias and politics to satisfy egos.
Raised in Tanzania, I grew up under a star-filled sky while relishing a childhood in the arms of the Indian Ocean and an Orion rotated 90 degrees in the equatorial skies. The night sky was my playground. The stars were children whose eyes sparkled with curiosity. Inevitably, my inherent curiosity was touched by these celestial phenomena and I set off on an endless journey to uncover the science and mechanics behind their reason for existing. I was introduced to cosmology. I came across various leading theories attempting to explain the origin of the universe – an endeavour to explain perhaps the greatest unknown. Though mesmerising, the inflationary model failed to please me and I wanted something more convincing: something that would satiate my hunger. With the internet as my only tool, I was lost in a maze that always brought me back to square one.
In December 2015, the renowned cosmologist Dr Neil Turok (below) was visiting Tanzania. Dr Turok was born in South Africa and spent a portion of his childhood in the city that I call home, Dar es Salaam, Tanzania before moving to the UK with his family. Currently, he is the director of the Perimeter Institute for Theoretical Physics in Waterloo, Canada. His connection with Africa and its potential in the sciences led him to found a chain of advanced studies institutes across Africa called the African Institute for Mathematical Sciences, otherwise abbreviated as AIMS. The aim of this visit of Dr Turok was regarding the founding of a branch of this institute in Tanzania. With the assistance of Dr Jiwaji, a physics professor at the Open University, Dar es Salaam, I was able to organise a meeting with Dr Turok prior to his departure at the airport. For the most part, I was starstruck during the meeting. To my surprise, I was not being the chatterbox that I normally am. It was as though I was having a meeting with Einstein himself. I was dumbstruck. Simply dumbstruck. Dr Turok and I chatted about the history of science, string theory, the state of educational outreach in Africa, and several other enlightening topics regarding the reality of science and education in the 21st century. However, to that day, I hadn’t a clue about his ground-breaking theory – the Ekpyrotic theory. Countless times, I had wondered about the universe being cyclic and bouncing back and forth in a Big Bang followed by a crunch. Despite my Googles and reading books, I hadn’t come across a solid answer to my hypothesis. Yet here I was, sitting face to face with the founder of the Ekpyrotic theory, oblivious to this fact.
The following day, I spent the entire day researching his works, watching his talks and documentaries and I was mind-blown by his Ekpyrotic theory. Shocked at how ignorant I had been, I knew something. I had found my darling theory.
Before diving into the elements of the Ekpyrotic theory, it is crucial to understand some colossal ideologies in the scientific community that have the potential to cripple scientific development. I am talking about none other than the response to the inflationary theory. The inflationary theory was developed in the 1980s primarily by Dr Alan Guth (see below), in an attempt to explain the Big Bang singularity. I’d like to call this age the Golden Age of Cosmology (The Cosmic Background Explorer (COBE) was also launched in this decade and gave us our first detailed glimpse into the cosmic microwave background). Inflationary theory took us closer to the Big Bang. Simply put, it said that “Let’s say there was a Big Bang. Right when it banged, the universe was filled with an exotic form of energy called ‘inflationary energy’. We have no idea where this came from really, but it was there and it explains things pretty well, so it must make sense for it to exist. Inflationary energy is repulsive and it has the ability to cause the universe to expand quickly. Ridiculously quickly.” Observations matched what this fairy-tale theory had to say and inevitably, it gained popularity. A large number of people in the scientific community in fact accept this theory to be the correct theory. If someone recommended a restaurant to you, and you ate there and loved its food, you’d appreciate the recommendation because your observations matched the prediction. But wouldn’t you want to know how hygienically the food has been prepared? What if the food is packed with ridiculous amounts of carcinogenic ingredients and you found out that the restaurant had never been approved by the food safety bureau? Would you still be in favour of that restaurant? Ironically, nobody bothered about the cornerstone question. What caused the Bang?
The inflationary theory was a porcelain doll. Nudge it to extremes and it breaks apart. It is a treat to the eye but no one is bothered with what lies inside. This conundrum demanded a more robust theory and thus was born the ekpyrotic theory. The journey begins with the union of two fine intellects: Dr Neil Turok and Dr Stephen Hawking. Dr Hawking along with Dr James Hartle had developed a unique cosmological model. In layman’s words, their theory predicted that if the universe started with nothing, it should have nothing today and that simply does not match the observations. Dr Turok’s quest for a unified theory took a boost at this stage. In an interview, he wisely elaborated that theoretical physics has an inherent beauty that allows one to introduce fancy gadgets and tools to make theories work but if it doesn’t work in the long-run, it is futile. Similarly, introducing such tweaks can breach special symmetries that are crucial to the framework of the entire theory. After about five years of trying to fix Dr Hawking’s theory this way, Dr Turok came to the realisation that perhaps this science demanded a radically different theory – something developed from a grass-root level. It seemed impossible for our universe to bang and be brimming with inflationary energy at the same time.
After an intoxicating workshop organized by Dr Turok himself and Dr Paul Steinhardt at the Isaac Newton Institute, Cambridge, Dr Steinhardt and Dr Turok formulated their ground-breaking theory. This conference was a medley of some of the brightest minds in theoretical physics ranging from M-theorists to string theorists to cosmologists.
The ekpyrotic theory uses string theory as its cornerstone. String theory suggests that at the fundamental level, everything is made up of tiny loops called strings. It is the way that these strings vibrate or stretch that gives matter its properties. Another idea it brings forth is the concept of branes – this is a higher dimensional version of a string. The theory emerged from these branes. Our universe’s three dimensions of space could be dimensions along one such brane. Thus, there could be two parallel branes separated by an infinitesimally small distance as predicted by the mathematical models. To that day, no one had considered the idea of these branes moving and colliding despite the fact that theory allowed these branes to move and bang. The Big Bang wasn’t the beginning of time. It was an event – an event in time that can neatly be described by theoretical physics. The bang would be just as powerful as that predicted by established cosmological models and would emit bursts of radiation precisely as predicted by previous models. This radiation was neatly explainable as there was radiation that permeated the previous universes and this radiation ‘carried forward’ into the current set of universes. The universe may have existed for an eternity – infinitely in the past, infinitely into the future.
The ekpyrotic theory is able to explain the simple features of the universe such as its flatness and density variations by the brane-collision model, just as well as the inflationary model. Such nail-biting competition healthily allows physicists to assess flaws and strengths in theories. The ekpyrotic theory also possesses some blaring voids. Can all the precise details of the brane collisions be calculated? Can rough arguments be converted into precise mathematical formulations? Similarly, in the case of inflation, we are left questioning whether inflation occurred in every region of space. Or what happened before inflation?
At such a crossroad, the best way out is experimentation. With LIGO’s successful detection of gravitational waves, cosmology has a major tool to look out for. Though the two contenders have remarkably similar predictions for countless observations, they do in fact disagree in a certain realm – the formation of gravitational waves at the Big Bang. Colliding branes predict no gravitational waves forming while inflation works the other way round. So, essentially, either theory could be proved wrong by experiment. I know which theory I’m wishing on.
To conclude, we will address what I feel is the most humorous yet frustrating perspective I have come across in all of physics. We will take the string theory approach to this. String theory allows space time to have multiple dimensions that can be curled up in literally an infinite number of ways. Different universes have different ways of curling and thus was born the multiverse. So, which one do we call home? Well, here’s where things get interesting. Some people choose to say that the Big Bang was simply a game of dice and things are the way they are simply because, well, that’s the way they are! Most of these physicists are physicists who are primarily not in favour of the ekpyrotic theory and thus lack a model of the Big Bang itself. So, they resort to probability as an explanation why the dimensions are curled up the way they are. They resort to the anthropic principle. Don’t get me wrong. I appreciate this theory and I truly respect its deep foundations in philosophy. There are scenarios when I’m forced to accept the anthropic perspective. However, there are certain circumstances where the human mind resorts to this theory simply to escape from the harsh reality of extra work to answer the real question. Or sometimes, it’s just a game of ego.
I agree with Dr Turok. He said that, “the best way to approach the cosmological puzzles, is to begin by understanding how the Big Bang works”.
“If you can't understand the dynamics, you really can't do much, except give up and resort to the anthropic argument. It's an obvious point, but strangely enough it's a minority view. In our subject, the majority view at the moment is this rather bizarre landscape picture where somebody, or some random process, and no one knows how it happens, chooses for us to be in one of these universes.”
The choice is up to you.
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