Lee Smolin and The Trouble with Physics

These days I am reading the latest book of the theoretical physicist Lee Smolin , dubbed "The Trouble with Physics". It is a very provocative author, something that within science can be very healthy sometimes, and this might be one of the times when indeed it is welcome. The book is essentially an assesment of the current status of String Theory, in particular focusing on how well it does (based on proved results and not on conjectures and less even on expectations) in solving several of the most important problems of today theoretical physics, like unification of the forces, unification of general relativity and quantum gravity or the foundations of quantum theory.

I just finished the second part of the book, a rather string critique on string theory based on his lack of mathematical rigor, his absolute lack of testable predictions and the fact that it leads to the famous String Landscape, an almost infinite plethora of string theories, each of which lives on a different region of the multiverse. He complains that almost all academic positions and research funds are given to string theory and almost nothing to other approaches to quantum gravity, like loop quantum gravity.

Having studied a bit of string theory in my undergraduate years (see for example my paper on membranes ) and my more solid training on particle phenomenology, I tend to agree with the complain of the lack of predictions (a theory with so many parameters that they can be fine tuned to avoid always being falsified) but not the issue of mathematical rigor (this is physics not mathematics, I would rather believe more in the results of an experiment than on a "mathematical" proof that these actual results are not possible). My feeling is that we need to understand a lot better string theory. I would say that before we reach the stage in which we can obtain the sought-for Theory of Everything (if something like this really exists) we need much more input from reality, from experimental information. Human reason is a extremely powerful tool, but a careful observation of reality is sometimes more adequate to better understand our work. As Alexis Carrel used to say: Lots of reasoning and no observation lead to mistakes, lots of observation and few reasoning leads to the truth.

You can also read what a leading string theorist with Joe Polchinski thinks of
this issue in a recent review of this book for American Scientist ...