Lee Smolin — The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next — Mariner Books, 2006, 392 pp. ISBN 978-0-618-91868-3
In this book, the physicist Lee Smolin tries to explains us in what kind of predicament modern physics is today. He starts by enumerating the five great questions that modern physics must answer:
- Unify general relativity and quantum mechanics; that is, formulate the theory of quantum gravity
- Solve a number of problems within quantum mechanics
- Unify forces, that is, explain all of them within a coherent theory
- Explain the numerous natural constants, that is, explain why they have their specific values and not some other
- Explain weird cosmological phenomena such as “dark matter” and “dark energy”
He first describes a number of theories meant to solve these problems but that are ultimately shown to be defective. Either they conflict with experimental evidence (which instantly falsifies them) or they are so general and use so many parameters that they can be tweaked somehow to account for the new observation but fail in two important ways. First, they fail to have an explanatory function because the model can be extended to include just about anything; second they fail to have predictive properties, that is, they cannot be used to predict new phenomena. He explains how string theory (or more accurately the string theories) are meant to solve all of these problems but also how difficult it is to validate it. He then moves on to what the future may bring as challenges and solutions.
This book is very interesting but left me nonplussed; not being a physicist myself, it is very hard to judge accurately Smolin’s claims. There is obviously a vulgarisation part in the discourse, but it is also difficult to separate it from its editorial component; of course he wants to convince us that physics in a dire predicament, but it is difficult for the reader to decide whether what he exposes is objectively true or merely verisimilar. Still worth a read, if only to understand how to not do science.
This kind of assessment cannot be based on unrealized hypotheses or unproven conjectures, or on the hopes of the theory’s adherents. This is science, and the truth of a theory can be assessed based only on results that have been published in the scientific literature; thus we must be careful to distinguish between conjecture, evidence, and proof