Wednesday, September 14, 2005


I have always found it very interesting and amusing that Einstein could produce a marvel of counter-intuitive brilliance; the theory of relativity, and yet could not come to terms with another paradigm of brilliance- quantum theory. The reason also seems to be interesting, and while an extrapolation to the matters of daily life might seem more philosophical then plausible, it does seem to lead to an tempting interpretation of life. Here's the way I think about it:

While the framework of relativity is definitely counter-intuitive, the laws governing the framework are nonetheless, definite. Just as in Isaac Newton's universe, in Einstein's universe, if you know the position and velocity of every particle in the present, then you could predict its future condition, no matter how strange a game of nature that particle's attributes may seem to play. Even though the properties of matter and the universe as dictated by the mandates of relativity are strange, they nonetheless are predictable.
But in quantum mechanics, you simply cannot know the future; in fact, you cannot also know the present for sure. There, the game is one of probabilities, and no matter how accurately you may try to measure attributes of a particle, the uncertainty principle and the basic probabilistic nature of the laws that govern the microscopic, forbid you from being sure about anything.Within the framework of probabilities, there is exquisite certainty, but only within that framework.

It seems that what Einstein wanted was security and predictability, just like many of us do in daily life. We are prepared to accept a bizarre existence (if not too easily) provided it is certain. Bizarre certainty is preferable to normal uncertainty. If I know that everytime I fly to India, I have to swim the English channel, over time I will accept this weird notion, no matter how preposterous it sounds like, because it is certain. It obeys a law that has been ordained, no matter how ridiculous (not to mention possibly fatally arduous for me). In fact, many of us accept many things in our life, not because they logically make sense, but because centuries of convention have dictated that they be done a particular way. Relativity is just like that. Strange, but largely certain and predictable.

However, what we cannot come to terms with is uncertainty, even in simple matters. We can accept the notion that that we will meet our sweetheart only after four years of separation, no matter how painful the feeling may be, but it is much harder to accept the uncertainty that maybe we will meet her the next moment, or maybe in two months, or maybe she will show up at our doorstep only when we are seventy...or maybe not at all. That is a much harder pill to swallow. But that is exactly the fluid landscape of quantum mechanics. We can never predict even the simplest thing such as the trajectory of an electron. We can only talk about probabilistic estimates of that attribute. Einstein could never accept this; hence he said 'God does not play dice', a pithy statement that has been overinterpreted and turned into a cliche over the years. He could bear the thought of a certain version of even an outlandishly fantastic reality, but not the thought of an uncertain version of everyday, mundane reality.

Interestingly, if we think about it, the ability to come to terms with uncertainty is usually considered as one of the important signs of human maturity. It is only a small child who insists that everything be certain in the world. Long before physics, human beings have already known that uncertainty is a painful but essential ingredient of our existence. Einstein was a visionary with an acutely sensitive awareness of nature. What distinguished him apart from every other scientist of his time? Many answers, in no ways certain, have been touted, but his own reply seems convincing. He said that he had the same sense of wonder that a five year old has, and in fact all of us have this sense at that age. But fortunately or unfortunately, we lose that sense of wonder and curiosity as we grow up. Einstein, however, never lost that magical sense. He retained it throughout his life, and it proselytized into a powerful way of probing the most fundamental features of the universe. In that sense, Einstein says, he never grew up. Was his inability to accept quantum mechanics and its uncertainty also a manifestation of his state of being a child forever? Did the immaturity of a five year old also, along with the sense of wonder, outgrow his age? It's an interesting thought.

But there's also a twist, because it is precisely a drive to find certainty among uncertainty that makes revolutionary discoveries possible, and this drive is the essential condition for a scientist to probe the edge of the unknown, to search for order in a world of fuzzy correlations. In case of quantum theory, it was ironically this very search for certainty that led Werner Heisenberg to abandon models of the atom altogether, and work purely with the mathematics, with a brave foray into the unknown. The startling feature that he discovered; the existence of classical attributes like momentum and position that do not commute, that directly gave birth to the edifice of modern quantum theory. Like many others, Heisenberg also was trying to look for certainty in uncertainty. Paradoxically, he found out the sine quo non of physical laws, that the only thing that is certain is uncertainty. I believe that this once and for all, destroyed the feeling of exalted assurance that we had, in a way a feeling of hubris that we could know everything. This, along with Kurt Godel's extraordinary discovery of the so-called 'Incompleteness Theorem'- the fact that there are certain statements even in the most pristine of mathematical systems whose truth value cannot be ascertained- were two defining moments for our human existence. I like to think that this was the time when scientists truly matured, when they really became ensconced in the same kind of existence that all of us have always lived, seamless integrating the vagaries of nature with those of life. We grew up at last. But one does get the feeling that Einstein did get left behind, although mavericks frequently face that fate. Only time can tell whether he truly was behind, or just like he was before, way ahead of us to be beyond recognition...


Blogger Vivek Gupta said...

The problems quantum mechanics poses to us are deeply unsettling. Human intuition breaks down completely in the realm of quantum mechanics. Feynman had famously said ," Nobody understands quantum mechanics" which is as true as it can get because quantum mechanics is just not compatible with human intuition. You either take it or leave it. Einstein could not take it, he was just not prepared to accept the fact that nature would play a game of chance with us thats why he termed quantum physics as an incomplete theory. Lesser physicists were satisfied with treating quantum mechanics as a black box which would yield startingly accurate answers, but Einstein forever a "child" was disturbed deeply because try as he might he could never grasp quantum mechanics at an intuitive level (just like everybody else). I will tend to side with Einstein, there must exist a more complete theory of nature bereft of those strange notions of probabilities even though it may very much be beyond the realm of human conciousness.

1:10 PM  
Blogger Ashutosh said...

Yes, I can completely sympathize with that feeling. But I also totally trust the hundreds of accurate experiments that have proved that qm is really weird and bizarre. Especially the experiments cited in Greene's book which prove that particles separated even by light years can instantaneously affect each other...but yes, the issue is still not completely decided yet, but I suspect it may never be, because in the end, it just might be limited by our powers of perception and our inability to see the world in an 'objective' way and only from our POV as human beings.

1:17 PM  
Blogger Vivek Gupta said...

One thing-which I am sure has been noticed by better minds and pondered upon greatly- of note is the fact that probabilities on which the whole edifice of quantum mechanics rests is a very artificial concept in mathematics in the sense that there is no physical meaning one can give to them. Being a student of probability, I know well that the concept is a very useful device to deal with our ignorance (or laziness!), nothing more. We attribute a probabilistic distribution to some phenomenon just because we do not know any better. One person's perception of the chance of an event could be entirely different from another person's depending upon their personality or availability of information to them. The suggestion that an artificial concept like that could have such a fundamental importance towards the fabric of reality is a very hard one to accept.

6:16 PM  

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