Memories of a Theoretical Physicist

A groundbreaking theoretical physicist traces his career, reflecting on the successes and failures, triumphs and insecurities of a life cut short by cancer. The groundbreaking theoretical physicist Joseph Polchinski explained the genesis of his memoir this way: “Having only two bodies of knowledge, myself and physics, I decided to write an autobiography about my development as a theoretical physicist.” In this posthumously published account of his life and work, Polchinski (1954–2018) describes successes and failures, triumphs and insecurities, and the sheer persistence that led to his greatest discoveries. Writing engagingly and accessibly, with the wry humor for which he was known, Polchinski gives theoretical physics a very human face. Polchinski, famous for his contributions to string theory, may have changed the course of modern theoretical physics, but he was a late bloomer—doing most of his important work after the age of forty. His death from brain cancer at sixty-three cut short a career at its peak. Working on the memoir after his diagnosis, using a text-to-speech algorithm because he could no longer read words on a page, he was able to recapitulate his entire career, down to the details of problems he had worked on. For Polchinski, physics went deeper than words. This edition includes photographs from Polchinski's professional and family life, as well as physics explainer boxes, other technical edits, and bibliographic notes by his former student Ahmed Almheiri, a foreword by Andrew Strominger, and an afterword by his wife Dorothy Chun and sons Steven and Daniel

Claude Ambrose Rogers. 1 November 1920 — 5 December 2005

Claude Ambrose Rogers and his identical twin brother, Stephen Clifford, were born in Cambridge in 1920 and came from a long scientific heritage. Their great-great-grandfather, Davies Gilbert, was President of the Royal Society from 1827 to 1830; their father was a Fellow of the Society and distinguished for his work in tropical medicine. After attending boarding school at Berkhamsted with his twin brother from the age of 8 years, Ambrose, who had developed very different scientific interests from those of his father, entered University College London in 1938 to study mathematics. He completed the course in 1940 and graduated in 1941 with first-class honours, by which time the UK had been at war with Germany for two years. He joined the Applied Ballistics Branch of the Ministry of Supply in 1940, where he worked until 1945, apparently on calculations using radar data to direct anti-aircraft fire. However, this did not lead to research interests in applied mathematics, but rather to several areas of pure mathematics. Ambrose's PhD research was at Birkbeck College, London, under the supervision of L. S. Bosanquet and R. G. Cooke, his first paper being on the subject of geometry of numbers. Later, Rogers became known for his very wide interests in mathematics, including not only geometry of numbers but also Hausdorff measures, convexity and analytic sets, as described in this memoir. Ambrose was married in 1952 to Joan North, and they had two daughters, Jane and Petra, to form a happy family

Innovation management from fractal infinite paths integral point of view

While a mastery of management innovation is crucial for the future of the economy, to date, there is no theory able to base with objectivity the management of creativity and entrepreneurship. This absence is not due to the lack of methods but to ignorance of mathematical foundations which justify the paradigmatic transgression. These foundations exist nevertheless. It can be mentioned the fractal geometry and the role played by the singularities and correlations over long distances. In the set theory, let us mention Cohen's forcing methods and its engineering consequences through CK theory. In the categories theory, we can mention the principles of Kan extension herein applied by the mean of holomorphic analysis and the analytical extensions. All these methods are based on the recognition of the incompleteness of any structure axiomatically closed (Goedel). At the junction between the physics and the economy, the goal of the present work is to show that the lack of recognition of the role of singularities in this science must be searched in mental biases and the paradigms that affect our concept of equilibrium. We show that this concept must be generalized. If the criticism of the concept of equilibrium in economics is already known, it does not lead, quite as much, to a theory of innovation. We would like to address the issue of creativity by backing the reasoning by the questioning of the concept of equilibrium, using an analogy coming from the physics in fractal structures. The idea is to consider the equilibrium as some steady state limit of a fractional dynamics. The fractional dynamics is a dynamics controlled by non integer fractional equation. These equations will be considered in the Fourier space and by the means of their hyperbolic geodesics. Due to the intrinsic incompleteness of the fractality and of its cardinality, the thickening of the infinite will be used to show that there is no even physical balance but only pseudo-equilibria. The practical use of this observation leads to the design of a dynamic model of creativity, named DQPl (Dual Quality Planning), giving a topologic content to the innovation process. New principles of management of innovation emerge in naturally

The Fixed Point: A Review of John von Neumann’s Methodology

This paper gives an overview of John von Neumann’s methodology and provides a criticism of ’ordinary’ historical explanations concerning von Neumann’s writings. His broad multidisciplinary works are traditionally analysed within separate fields, completely detached from social and multidisciplinary context. This can often lead to oversimplified historical explanations. As an illustration of this I discuss one of his lesser-known articles which plays a central role in general economics in the postwar period. This is, however, the only one which concerns directly theoretical economics. I review the possible explanations behind his motivation for writing this article and propose a different historical approach to outlining his exceptional train of thoughts

Achilles And The Tortoise: Some Caveats To Mathematical Modeling In Biology

Mathematical modeling has recently become a much-lauded enterprise, and many funding agencies seek to prioritize this endeavor. However, there are certain dangers associated with mathematical modeling, and knowledge of these pitfalls should also be part of a biologist\u27s training in this set of techniques. (1) Mathematical models are limited by known science; (2) Mathematical models can tell what can happen, but not what did happen; (3) A model does not have to conform to reality, even if it is logically consistent; (4) Models abstract from reality, and sometimes what they eliminate is critically important; (5) Mathematics can present a Platonic ideal to which biologically organized matter strives, rather than a trial-and-error bumbling through evolutionary processes. This “Unity of Science” approach, which sees biology as the lowest physical science and mathematics as the highest science, is part of a Western belief system, often called the Great Chain of Being (or Scala Natura), that sees knowledge emerge as one passes from biology to chemistry to physics to mathematics, in an ascending progression of reason being purification from matter. This is also an informal model for the emergence of new life. There are now other informal models for integrating development and evolution, but each has its limitations

Parikh and Wittgenstein

A survey of Parikh’s philosophical appropriations of Wittgensteinian themes, placed into historical context against the backdrop of Turing’s famous paper, “On computable numbers, with an application to the Entscheidungsproblem” (Turing in Proc Lond Math Soc 2(42): 230–265, 1936/1937) and its connections with Wittgenstein and the foundations of mathematics. Characterizing Parikh’s contributions to the interaction between logic and philosophy at its foundations, we argue that his work gives the lie to recent presentations of Wittgenstein’s so-called metaphilosophy (e.g., Horwich in Wittgenstein’s metaphilosophy. Oxford University Press, Oxford, 2012) as a kind of “dead end” quietism. From early work on the idea of a feasibility in arithmetic (Parikh in J Symb Log 36(3):494–508, 1971) and vagueness (Parikh in Logic, language and method. Reidel, Boston, pp 241–261, 1983) to his more recent program in social software (Parikh in Advances in modal logic, vol 2. CSLI Publications, Stanford, pp 381–400, 2001a), Parikh’s work encompasses and touches upon many foundational issues in epistemology, philosophy of logic, philosophy of language, and value theory. But it expresses a unified philosophical point of view. In his most recent work, questions about public and private languages, opportunity spaces, strategic voting, non-monotonic inference and knowledge in literature provide a remarkable series of suggestions about how to present issues of fundamental importance in theoretical computer science as serious philosophical issues

Readings in the 'New Science': a selective annotated bilbiography

Die vorliegende kommentierte Bibliographie will hauptsächlich Historikern eine Orientierungshilfe für die Literaturfülle zum Thema 'New Science' geben. Die knapp besprochenen Arbeiten sind nach folgenden Themenkomplexen gruppiert: Unentscheidbarkeit, Ungewißheit und Komplexität; Makrostrukturen: Systeme und die humane Dimension; Dynamische Systeme (Spieltheorie, Katastrophentheorie, Chaos, Fraktale Geometrie, Antizipatorische Systeme, Lebende Systeme); Computer (Informationstheorie, Kognitionswisssenschaft und Künstliche Intelligenz); Die Mikro- und die Makrodimensionen; Zeit; Kultur und Erkenntnistheorie. (pmb