The Trouble With Physics

Title: The Trouble With Physics

Author: Lee Smolin

Publisher: Allen Lane 2006 (First)

ISBN: 978-0-713-99799-6

Pages: 355

This book is a distress report of the problems faced by physics communities around the world. It is rightly said that the 20^th century was the century of physics in light of the numerous inventions which changed the face of the world and the way we communicate with each other. Never before in the history of the world was so many inventions materialized in so short a period. The revolution began with the conceptualization of quantum by Max Planck in 1900, carried forward by Einstein in 1905 and 1913 with his special and general theories of relativity, matured with discovery of quantum mechanics from Heisenberg, Pauli and Dirac around 1925, explosion in electronics after the second world war, leaps in cosmology in the 1960s and last but greatest of all, the search for a unified theory of physics. The standard model of particles and forces, which is a catalogue of all known phenomena was finalised in 1973-74, with great expectations of winding up theoretical physics after a few more years. After the propositions of Steven Weinberg’s electroweak theory which integrated weak interaction and quantum chromodynamics which incorporated strong interaction, there was no forward going to include gravity also in the framework. All efforts to stitch the parameter into the common fabric has continued to evade victory for the last 40 years or so. Lee Smolin is worried about the prospect and asserts that never in the last two centuries of physics has such a peculiar phenomenon has occurred in which no new developments were arrived at.

The author discusses in detail about string theory which was put forward as a panacea to all ailments faced by theoretical physics. It was first proposed in the early 70s. Even though the theory is mathematically consistent, it has continuously failed to put forward some testable hypotheses. Some predictions made by the theory require enormous amount of energy that not even the biggest particle accelerators in service at present are not able to handle them. It is amazing to see the strength of the followers of the theory in academia. Almost all of the American universities hire exclusively among the supporters of string theory that a stage has reached where no alternative proposals would even be allowed to come to the fore. Inevitably, it makes research unidirectional and students are pressurised to follow the peers and senior professors who contributes only to string theory. Smolin claims that the adherents even demonstrate unscientific attitudes to propagate their points of view and wonder how a theory which can’t be falsifiable by experiment has bagged so many devotees and grant money! This is catalogued as a trouble with physics.

The author lists five great problems in theoretical physics.

1) Quantum mechanics and relativity are not reconciled as the former is yet to give a true understanding of nature. It even has traces which defy logic and reality as all results are obtained as result of some observer observing the experiment.

2) Resolve the problems with foundations of quantum mechanics such that either the postulates should be made sensible or invent a new theory right from the beginning.

3) Determine whether the various forces and particles can be expressed as manifestations of a single entity, the unified theory.

4) Explain why values of free constants like the Planck’s constant, gravitational constant, speed of light and such others have the values they presently possess.

5) Explain dark matter and dark energy

These five great problems represent the boundaries of present knowledge.

Attempts at unification was going on right from the advent of modern science with Galileo and Newton who unified absolute rest and motion. There is no way a body can distinguish whether it is at rest or is speeding at a uniform rate unless acceleration is not involved. This was a great intellectual leap for medieval science. James Clerk Maxwell unified electricity and magnetism with his electromagnetic theory in 19^th century. Einstein integrated space and time with his general theory of relativity which jolted traditional thinkers. Actually, it involved three unifications, a) all motion is equivalent if gravity is taken into account, b) effects of gravity is indistinguishable from acceleration and c) gravitational field is unified with the geometry of spacetime. Kaluza Klein theory unified electromagnetism with general relativity by adding an extra dimension to the universe in which electromagnetism popped out of the theory. However, no new predictions were made by the hypothesis and it went into disuse. A split in the physics community between classicals and quantum mechanists surfaced with the advance of quantum mechanics. Prominent scientists like Einstein continued the quest for a grand unified theory, but they were sidelined. Several theories, such as the SU(5) theory predicted quarks, of which nucleons are made of, failed to withstand when proton decay, which was one of the predictions failed to be observed. This was said to be the turning point when particle physics ceased to be exciting. Supersymmetry came along the way which unifies the forces and particles, with a superparticle suggested for every known particle. For the first time, it combined fermions and bosons and it is expected to come out successful when experiments are performed at full energy in the Large Hadron Collider.

String theory was born in this background. In 1968, Gabriele Veneziano of Italy proposed a formula to describe patterns of proton scattering. Scientists followed this up, particularly Yoichiro Nambu, Holger Nielsen and Leonard Susskind. They found that the equations don’t describe point particles which all theories held up to that time, and instead one dimensional strings which can be open-ended or forming loops. Vibrations in specific patterns along the string caused the manifestation of particles and forces. String theory was born from these considerations, but it included 25 dimensions of space and one of time. Tachyons, which travelled faster than light and massless particles were also included in the theory which put brakes on its acceptance. Also, it failed as a theory of strong interaction which was the motive of developing it in the first place. Researches by Pierre Ramond, Andrei Neveu and John Schwarz introduced supersymmetry into the theory and reduced the number of dimensions to 10 (9 of space, 1 of time). Photons and gravitons emerged spontaneously from the calculations and it was touted as the fundamental theory of everything, but not taken seriously by the academia. All of it was to change in 1984 with the first string revolution when Schwarz and Michael Green proved that the theory was consistent in 10 dimensions and unification indeed takes place. But again enthusiasm weakened when it was made clear that the theory had hundreds of thousands of solutions which can explain any observation. Proponents doubted the existence of a metatheory behind all these solutions and in 1996, Edward Witten and Joseph Polchinski proposed M-theory (mother, or membrane) which proposed membranes instead of strings and one more dimension was added to the picture.

Smolin says string theory satisfies only one out of the five criteria described above, that of unification. There is some progress in attempts to link gravity with quantum mechanics, but apart from that, in spite of the immense research, the theory still stands where it began vis-à-vis experimental verification. It is logical to search for alternative theories due to the dead end in mainstream physics. One such candidate is Mordehai Milgram’s MOND (modified Newtonian dynamics) proposed in 1983. An unknown kind of mass was seen to accelerate arms of spiral galaxies which couldn’t be accounted for by the amount of matter in the galaxy discernable by visible means, hence the name dark matter. This exotic substance was hypothesized to avoid facing the alternative, that Newton’s law of gravitation is either incomplete or wrong. MOND suggests that Newton’s law breaks down at very low accelerations of the order of 1.2 x 10^-8 cm/s² and proposed equations for correctly estimating the values. Another would-be groundbreaking theory was partnered by the author himself, which is called DSR II (Doubly special relativity). This tries to explain the smoothness or uniformity of universe whichever way we look. Since nothing can travel faster than light – according to special theory of relativity – this constituted a dilemma of how the uniformity information spread through the early universe. Alan Guth’s inflation theory solved this pesky problem by postulating that the early universe expanded in one great bounce causing the information to spread uniformly. However DSR II attempts to solve the issue without inflation. It says that in the early universe, the speed of light was considerably more than it is today. This settles the issue in one stroke, neatly. However, Smolin himself is not sure of its success.

After all these years of running the show without much success, Smolin considers that the present generation has bequeathed a set of ideas, some true, some only partially true with a cautionary tale of how even great scientists failed to make the story complete. We should not corner them by insisting that they work on them. Meanwhile, he takes stock of the shortcomings of string theorists who have become monolithic, tremendously self-confident, full of group identification, disregard for alternative ideas and interprets evidence optimistically without taking any risks. This runs contrary to the spirit of science and advises them to learn what is science. What the new students should inculcate is the courage and character to fight off orthodoxy, fashion, age and status. There are two kinds of scholars, the craftspeople who specializes in the technical running of the show and the seers who concentrate on basic philosophical problems and willing to face established ways and demolish them. Academia should take some risk in hiring people and should try to include more seers among their ranks.

The book is really heavy, both in its physical weight and the multitude of arguments it contains. This does not deal cutting edge science exactly, but that is to be expected when the author’s major intention was to do a dressing down of string theory. He highlights it only to announce later that the idea is not fully developed. String theorists should take a lesson or two from the points discussed in the book. But apart from that, I wonder whether an lay reader like me would benefit from this book. Lee Smolin is persuasive in his arguments, but he could equally have done it with half the number of pages the volume presently has! Many chapters are also uncharacteristically dry and boring. Unlike Smolin’s other works, this one is very tedious and is really an ordeal for the reader. There are several references to another book, ‘Life of Cosmos’, also from the same author and a promotional attitude is to be suspected.

The book is not recommended for the general reader.

Rating: 2 Star