Tuesday, 23 December 2014

Is String Theory Correct?

The following is a very old blog post that was posted in an old blog. The post was written on 2nd of January, 2012. I am posting it unedited.

The modern world of particle physics is having a very good time now with the experiments going on at the Large Hadron Collider in CERN. Newer and newer results are being generated from the experiments as we speak. So, what will these results predict? Will they finally put an authorative stamp on the Standard Model that has been doing the rounds since the 1970s, or will it by some twist of fate prove the almost 'unprovable' theory called “String Theory” correct? These are questions that are best left to the experts. Today, I would just write about something else.

I first heard about this strange theory called “String Theory” when I was in high school. The only accompanying explanation to it (I forgot where I first got the reference) was that the theory uses very advanced mathematical tools which are not comprehensible even to experts. So, I thought maybe later when I had some ammunition in my armour I would battle with that theory. Later I found out that the theory indeed works in mysterious ways, interplaying a rich bridge of mathematics and physics. Breaking the shackles of conventional scientific knowhow this theory uses more than 3 dimensions. Now I was really intrigued, how can such a theory have a validity in the conceivable universe where everything we see is 3-dimensional. I found out that the primary tenet of this theory is what are called 'strings' that replace the concept of 'particles'. These 'strings' are so tiny that they appear to be like particles, but in reality are much stranger.

Ever since I had that knowledge, I always wanted to know more about this strange theory. The last time I visited the Tata Book House at IIT Madras, I had to drag my feet out of there to keep myself from buying a highly technical book on the subject and which was very expensive. Then I came across the excellent blog by Peter Woit called “Not Even Wrong”. There he writes mainly about mathematics and physics and their connections. He also had a very popular book called “Not Even Wrong: The Failure of String Theory and the Search for Unity in Physical Law”. The International editions of that book were horribly expensive and with no allowances it was really difficult to get hold of it. Even the University library didn't have it. Fortunately there was Flipkart, and just when I had been mulling over when to buy the book, I happened to visit the recently held bookfair at Guwahati. Luckily for me, I found a copy of the book that was much cheaper than any of the other copies I saw online. Needless to say, there was no stopping me, and I bought it. Right now, I have read the Introduction and the first chapter, and I think I am going to like it.

Let me explain what the title refers to, then the title of this post will also become clear. “Not Even Wrong” is a phrase attributed to the great physicist Pauli, who was very much critical of third rate works. His most insulting phrase was to say that the work was not even wrong to comment upon it. This is the attitude that Woit takes in his book, for String Theory has till now not provided any concrete proof for its corectness neither has it prophesized any falsifiable statements. So in a sense, we cannot tell whether string theory is even wrong or not. Lets see what I feel about it after I read the book. Maybe that will come in a later post.

I have had the chance to listen to some popular and some technical talks about string theory in my visits to the Chennai Mathematical Institute and The Institute of Mathematical Sciences at Chennai. Last year in January I have had the immense pleasure of listening to Prof. David Gross, one of the living giants of particle physics and a Nobel Laureate. He spoke about string theory at length in his almost one and half hour talk, and concluded by saying that whatever he had told in his talk might be proven incorrect by some mathematician! By the way, I was really surprised to see that Woit begins the first chapter of his book by quoting none other than Gross himself. That reminded me of the talk.

As for now, I am not sure whether string theory as a coherent physical theory is correct or not. Let me read Woit's book. After that I plan to also read “The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and what comes next” by Lee Smolin, also bought at the bookfair. Maybe then I will have some idea about this whole affair. But this much is clear to me now that the mathematics developed as a result of string theory is of the highest order. Whether or not there is any use of string theory, I am not certain but definitely it has been a boon for mathematics. I am sure Edward Witten will agree to this statement. :)