Monday, September 5, 2016

The Known Unknowns

Statutory warning: This blog is scientific in nature. If you hate anything to do with science and math (majority of us do), now is the time to close this tab in your browser. If you have slightest of curiosity about our universe, this blog will be a good 5 minutes read.

The idea of this blog had been drifting around in my thinking apparatus (dwelling in the upper most part of the body through which I think I think) for a while. Somewhere I read that the amount of information that was consumable by a man just 200 years ago in his whole life time is now available to us in just a day! This fact has led us to believe that we know it all. Yes, we surely know a lot but do we really know all that is to know? Have we been able to span the whole gamut of knowledge that’s potentially available to us to know/explore? I would like to think of it at 2 different levels – we certainly know a great deal to know whats there is to know? In other words, I believe we know what questions to ask when we want to fathom everything that’s fathomable. This is indeed a great start. The natural follow up to any questions is of course its answer – this is where things start getting interesting. To put it simply, do we know the answer to all the questions that we have asked? To take it to 3rd level (if I am permitted to be adventurous), do we know the truth, and not just the answer!!

The quest to get answers to our questions is in fact a distinguishing characteristic of mankind, something that sets us apart from say animals and other living species. So what kind questions and their answers am I talking about? I don’t mean to refer to questions such as what I am going to have in dinner tonight!! Though I can safely tell you that’s a billion dollar question for me that I am challenged with every day and gets complicated further with the fact that my better half generously gives me 30 seconds to record my answer – failing which I might not be able to ask any question!! Coming back to our train of thoughts, I am referring to the questions that are scientific in nature and beg simple answers. I will skip bigger ones like why we exist or what exists beyond universe or how we came into existence to ask these questions in the first place. These questions certainly have their own merits and while probing them, I realized we need to start with more basic questions to reach to the answers to these literally out of the world questions. So I scaled down to something simpler – what is space, time, gravity et all? What governs them? Do we have full understanding of these basic building blocks of the universe to understand more complex structures? In this quest, I was guided by a simple principle we were taught in the school – that the more you learn, the more you become learned!! This corollary came crashing unfortunately – because the more I read about these phenomenon, the more I realize how little we know about things around us.

Let’s start with the most fundamental thing we all recognize since the time we are born – notice the word ‘time’ in the previous line – yes that’s the 1st thing I wanted to study about, followed by another fundamental concept called space – in theoretical physics (I am emphasizing the word theoretical because believe me these concepts are practically incomprehensible!), the concept of space and time is dubbed as 4 dimensions of the universe where we live. They say there are more complex higher dimensions but as I said earlier, let’s start with the basics. So if I am allowed to jump to the conclusion directly (it would spawn a 1000 page book if we were to go in detail), I can safely say that we don’t understand both time and space completely – what we do know are their characteristics - they are not absolute and change relative to the observer (Einstein’s famous theory of relativity – first 500 leaves in that 1000 page book would be filled up by this one theory alone!). It’s quite counter intuitive to imagine how time can be different for different observers and how space can change its length basis the speed at which you are travelling. This is to say that if I am travelling in a plane, time slows down for me – I am ageing slower than my friend who is at work – wow I get to live more years for doing nothing – just keep flying. Indeed this is true as per special theory of relativity. The more the speed at which you move, the slower the time for you. If you think about it for a moment, there comes a point when you have reached the speed of light (which is the upper limit set on anything that can move in our universe) and theoretically speaking – time should slow down to being still/ frozen in moment – so if we ever are able to fly in a rocket at the speed of light, we would be able to immortalize ourselves! All these are not science fiction stuff but actual facts – though there are severe physical limits on achieving even a fraction of the speed of light – let alone the speed of light. This explanation leads to one edge case – the photons that comprise light are travelling at the speed of light – so is the ‘time’ thing not happening at all for light? Sounds very strange indeed.

After having discovered mutating behavior of time and space (read ‘Trespassing on Einstein's Lawn’ by Amanda Gefter for complete low down on variant/invariant universal quantities), the theory of relativity mercifully introduced an immutable constant in universe ‘the speed of light’ – an absolute quantity which to me sounded more like compensation for the variant space and time quantities. One might be tempted to think about light being fully understood entity – sorry to disappoint here too – rather it’s the most confusing and least understood entity which lies between 2 big chasms to begin with – one of them called wave nature of light and the other its particle nature. When you talk about dual nature of light, there is no way you can skip the most esoteric world called the quantum world or quantum theory. I remember in high school days, I participated in a seemingly boring experiment called ‘Double Slit’ experiment. Our education system is such that we are taught with the sole objective to clear the exam, never for the purpose of acquiring true knowledge we are supposed to learn. So the double slit experiment never registered anything significant in me when I first studied it in school days. Then I laid my hand on a book called ‘In search of Schrodinger’s cat’ by John Gribbin, this book changed my view about our world forever. This book introduces the quantum world, the paradoxes and the contradictions and the intuitively opposite things that happen in it just because of us observing something– leading us to believe that we live in a surreal world, a world where reality is observer dependent! The double slit experiment basically describes how light can behave like a wave or a particle merely by the act of us observing/ or not observing it. The experiment throws a mysterious aspect when it shows that light behaves as a particle the moment we try to 'observe' it - yes, somehow light behaves as if it has the intelligence and consciousness to understand what we are upto!! Spooky and creepy totally!! This experiment has multiple variations – one of them is called ‘delayed choice experiment’ while another one called ‘delayed choice quantum eraser’ experiment, do google them and be ready to get your mind blown away with the consequences these experiments throw at us, especially the ‘Quantum Entanglement’ phenomenon which tells us that the speed of light is not the ultimate barrier and that universe can play out very differently if we were to consider full implication of quantum entanglement at that scale.

Another fundamental component that I want to throw in here is what we call as ‘matter’ or more common concept called mass. We thought we knew mass well, I read recently that the recent discovery of Higg’s Boson has completely solved the question about matter/mass. What was left unsaid in a hushed voice was the fact that Higg’s Boson is only proven until its proven wrong – in other words, while there is substantial proof in favor of its existence – doesn’t negate the probability that the scale can tilt the other way in future – so I am forced to think that we don’t have full confidence in the understanding of mass as yet! When we talk about mass, one can not not mention its compliment called ‘energy’ – these 2 are convertible and are represented by the most recognizable physics equation e=mc2. Again thanks to the ‘amazing’ education I received during school days, I never knew the true beauty of this equation till I read a book called ‘Why does E=mc2?’ by Brian Cox and Jeff Foreshaw – this is a book written in lay man language and takes herculean effort to drive home the immense contribution this equation has in our day to day life. So far we have declared space, time, light and matter as not completely understood phenomenon. Well the party has just about started.

Let’s move on to the fundamental forces of nature – scientists have made us to believe that there are 4 fundamental types of forces – weak nuclear, strong nuclear (these 2 are responsible for all the nuclear bombs/ reactors we hear about), electromagnetic (almost everything around you utilizes this force to make our day to day life simpler) and gravity (the reason I am not levitating while writing this article). My knowledge about the first 3 forces is limited to their basic definitions and their practical applications. My curiosity in knowing more about the force of gravity led me to read a lot of material available on net – but soon I found out that we are yet to identify gravity’s parallel of Higg’s Boson (the particle which provides mass to matter) called graviton. In simple terms, we don’t know yet why gravity exerts force on any object/matter.

There are a couple of more universal entities that I want to write about to elaborate more about the ‘less’ we know about – dark energy and dark matter. Funny they have been named that way, we might as well have named them ‘i-don’t-know-energy’ and ‘i-don’t-know-matter’!! Yes these are 2 phenomenon which we are still grappling to even witness in the first place, lest understand them completely. So one might ask – how do we know about something which we haven’t seen. Let’s talk about dark energy first – it seems we have figured out that we all are speeding away from each other – well in terms of heavenly bodies I mean. So a galaxy is moving away from another galaxy, a star is moving away from a distant planet and so on. However it seems that this should not have been the case – the universe was supposed to expand with big bang and then contract subsequently – well that’s what scientists believed till Hubble (the actual guy, not the telescope) discovered the exact opposite. But when the scientists tried to find a reason as to why the universe is expanding so rapidly, they didn’t find any reason – yes we drew absolute blank. Let’s take a step back and talk about what we called ‘Hypothesis’. Oxford defines ‘hypothesis as “a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation”. In the day to day slang, it’s called ‘WTF-I don’t know a shit!!’. So to reconcile for this unknown phenomenon contributing to the expansion of universe, scientists introduced the concept called ‘dark energy – an energy which is making all the celestial bodies in the universe repel each other. One will be tempted to think that as a corollary, dark matter must be actual content of dark energy – how I wish life was that simple. Dark matter hypothesis is slightly different but equally interesting – hang on tight there. In simplest terms, when you see a ‘merry go round’ – it’s possible to estimate the mass of that giant wheel depending on its rotating speed. Taking this analogy at galactic scale, scientists can estimate the mass of a galaxy depending on its orbital speed. Things threw weird results when scientists could measure both for an observable galaxy – turns out the mass they estimated basis its speed was way too less to account for that speed – thus the hypothesis of dark matter was born! Again the point to note here is – both dark matter and dark energy have never been found till date – and guess what – they constitute a whopping 95% of all the universe that we know of. In other words, we bloody know only 5% of universe, rest is all guessing game!!!

This discussion will be incomplete if we don't touch upon the enigmatic topic of big bang, the phenomenon describing how this whole story started. Its interesting to note how scientists deduced (
ala Sherlock Holmes' style) from the fact that universe is acceleratingly expanding - that the expansion must have had a 'starting point' - they call it the 'initial singularity' - the point when all of universe and space and time was contained in one singularity - and some unknown trigger (again please note this is completely unknown, a guess) led to big bang and thus us. Recently (2015/16), scientists have discovered a phenomenon called gravitational waves (its like guitar string vibration in universe to put simply - guitar strings being space/time). This is very useful to understand big bang - why? Because, for about 380,000 years since big bang, light could not emit outside and hence not seen by us today in any form (we are able to get the 'light' relics post 380,000 years from big bang through a phenomenon called 'Cosmic Microwave Background - CMB') - so what exactly was happening in those 380,000 years? We don't yet know - but the gravitational waves from those times called 'Gravitational Wave Background - GMB' can help us 'see' what exactly happened immediately after big bang (this might sound  crazy but it turns out the 1st second from big bang was the most crucial period - its like saying that a 3 hours movie had the most important scene in the very 1st second!!). GMB might help us one day to know what that most important scene was in this 'universal' movie! 

In all the unknown hoopla I have mentioned above, there is one thing that has astonished me to no end - the fact that nature allows itself to be dictated by mathematics literally. What I mean is - we know (or don't know) so much of physics, so much about our universe, all the laws that the universe obeys and the equations it follows - be it e=mc2 or the thermodynamic equations or the equations governing known particles called 'Standard model of particle physics' or the equations that govern force, energy, mass, gravity and every thing that we have discovered so far. In other words, equations or simply put the math that governs these phenomenons doesn't change and is able to predict the physical phenomenon - and mind you - math is abstract quantification of the physical processes/laws that govern universe. This to me sounds very intriguing - how can abstract (mathematics) predict universe (physical in nature)? To quote from the book why e=mc2 - "...this is unreasonable effectiveness of mathematics. Why should the natural world not be far more complex? Why do we have a right to condense so much physics into one equation like that? Nobody really knows why nature allows itself to be summarized in this way, and it is certainly true that this apparent underlying elegance and simplicity is one of the reasons why many physicists do what they do. While reminding ourselves that nature may not continue to submit itself to this wonderful simplification, we can at least for the moment marvel at the underlying beauty..." 

In the above write-up, I have to confess that I haven’t even peeled the upper most layer of a healthy onion, so to speak. There are bigger follow up questions that are yet unanswered – where did life come from? Are we the only ones to ask this question – if the universe is so big, then there should be many more intelligent lives - where are they, it would be so boring to know that we are absolutely alone in such a widely available real estate – seriously ‘god’ (if he exists) didn’t utilize the available resources optimally. Fermi’s paradox talks about this anomaly in great depth. There are many variations to this theory – some say that we might be living in a simulation where we are programed to behave certain way with a few fuzzy rules thrown in in the form of societal/ ethical norms. Others have propounded the theory that we might be time travelers and that we have already advanced so much in technology that we can keep travelling back and forth in time at our will. Then the concept of parallel universe completely throws all of these in disarray – this theory says that we exist in different worlds and that earth happens to be just one of those worlds! If that be the case, I might have completed this blog already in a different world or I might have died already – just one of the myriad probabilities of my existence in those worlds. The multiverse theory is at times tied to black hole – they say that the black holes (inside which we don’t know what exists) are the entry points to other universes (read ‘Black holes and baby universes by Stephen Hawking).

I want to come back to the basic question I started this blog with – are we asking the right questions, getting their answers seems to be secondary priority – one such thing which has made me wonder often is – our universe see

ms to be only ~14 billion years old. When I look at other ‘universe’ scale such as trillions of stars, zillion of celestial bodies, this seems to be awfully small. Did we miss something? Is it possible that the universe always existed, it’s just that we have been able to trace things back only till ~14 billion years in the past – we don’t know yet. A highly recommended book ‘A brief history of time’ by the legendary Stephen Hawking is a must read to understand some of the above and more.

While I am aware about the negative connotation of this article, I didn’t mean to downplay tremendous strides made by the humans in our quest to find the ultimate truth. After all just a few hundred years before, we thought that the earth was the center of the universe and that sun revolved around us. In other words, we have come a long way – but it’s still day one in the realm of infinite knowledge that awaits to be uncovered and revealed.

If you are intrigued with these known unknowns (the things we know we dont know about), the below recommended books will do a great help to understand the riddle called Universe better (also gets mentioned in the blog at different places) –
  1. In search of Schrodinger’s cat by John Gribbin
  2. A brief history of time by Stephen Hawking
  3. Trespassing on Einstein's Lawn by Amanda Gefter
  4. Black holes and baby universes by Stephen Hawking
  5. Why does E=mc2? by Brian Cox and Jeff Foreshaw
  6. One, Two, Three...Infinity by George Gamow
  7. Surely You're Joking, Mr. Feynman! Ralph Leighton and Richard Feynman
  8. The Fabric of the Cosmos by Brian Greene
  9. The Elegant Universe by Brian Greene
  10. Hyperspace by Michio Kaku
  11. Quantum: A guide for the perplexed by Jim Al-Khalili
  12. Billions & Billions: Thoughts on Life and Death at the Brink of the Millennium by Carl Sagan
  13. God and the New Physics by Paul Davies
  14. A Short History of Nearly Everything by Bill Bryson
  15. For the Love of Physics by Walter Lewin