MU-6: Theoretical Physics

As maths became the only way to talk about physics, it led to the rise of theoretical physics. After all, you could work out the maths and its implications in your armchair without doing any experiments yourself! As Walter Isaacson wrote in his book titled Einstein:
“(Theoretical physics) pioneer practitioners – such as Max Planck, Hendrik Loretz and Lutwig Boltzmann - combined physics with math to suggest paths where experimentalists had yet to tread.”
But of course, physics needs the experimentalists too. As Mark Jackson wrote:
“Without theorists, experimentalists would not have anything to test. Without experimentalists, theorists would not have anything to explain.”

Yet over the last century or so, all the rock stars of the physics world are theoretical ones, from Albert Einstein to Heisenberg and Schrodinger to Feynman to Stephen Hawking. Such is that dominance that Richard Feynman once remarked:
“Theoretical physics is a human endeavour, one of the higher developments of human beings.”

You may have heard of the “tension between general relativity and quantum mechanics”, as Brian Greene calls it in his book, The Fabric of the Cosmos. So what is it exactly? Well, the two theories are used (mostly) in mutually exclusive areas but a few topics “fall squarely in the demilitarized zone” (again, Greene’s choice of words), topics where the two theories clash. These demilitarized zone topics, by the way, are known even to most laymen: black holes and the Big Bang! The problem? The maths produces infinities when applied in those topics: and if you get infinities, it means the maths (and hence the theories) has broken down!

One proposed solution to this impasse is something called string theory. That too, unsurprisingly, is built on maths. The maths of string theory is consistent and avoids the infinities of the other theories; hence may be right! But is it right? The experiments to check it are impossible today; and may remain that way for the foreseeable future. But since the maths works, it may be true. After all, maths has an uncanny ability to prove to be right, no matter how weird or outlandish it may seem. If that sounds crazy, remember this: the famous Higgs Boson that made headlines a few years back was “just a theory” until that point too!

And so the march of theoretical physics looks like something that will continue.

Comments

  1. KumarJune 22, 2015 at 12:34 PM

    Historically speaking, what you say namely "As maths became the only way to talk about physics, it led to the rise of theoretical physics", needs some factual course correction. From Newton onward, the embedding of mathematics into physics was the only direction no doubt. But segregation between theoretical and experimental physics got more and more concrete due to the extremely complex experimental setups tilting the scale in favor of experimenters on the one side, and, due to the uncanny ability of juggling mathematics with known results/data to explain them away tilting the scale in favor of theoretical people on the other. We need to note that both Newton and Faraday managed theoretical and experimental things pretty well. Those days physics experimentation was relatively simple - not today.

    Now about your concluding remark: "And so the march of theoretical physics looks like something that will continue". Perhaps it will continue forever, or, at least as long as mankind exists and continues with interest in physics! Who knows physics may get junked by mankind one day in preference to something we cannot predict today. :-) or maybe :-(

    While many people are pinning their hope on string theory for want of something better available, we must know that string theory is working against terrible odds actually. Some physicist with an unbelievably uncanny knack is the need of the hour because what we need is about 5 multi-dimensional vibrating strings out several billion different (i.e possibilities) vibrating strings. It is like hoping to get 5 bricks of greater than 2 kilogram diamond nuggets in the gold mine spread over 100 kilometers. Gold mines usually offer only mud and sand for any searcher most of the time. Even small diamonds are hard finds. Yielding anything greater than a kilogram nugget once in a rare century, so to say. So, good luck physicists!

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