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Reflections on the Past, Present, and Future of Condensed Matter Physics
... Science and technology have evolved over time on many scales and levels, so we now have the advantage to look at its historical developments more comprehensively and objectively than the pioneers. As Anthony Legget, a Nobel laureate, commented [3], "Mathematical convenience versus physical insight […] that theorists are far too fond of fancy formalisms which are mathematically streamlined but whose connection with physics is at best at several removes […] heartfully agreed with Philippe Nozieres that 'only simple qualitative arguments can reveal the fundamental physics'." In that regard, mostly physical and simple qualitative insights will be examined and emphasized here. ...
... The reversible Carnot cycle also comprises isothermal processes where heat is entirely (100%) converted to work (QH=WH) while increasing volume and entropy (process 1-2), or in reverse, where work is entirely (100%) converted to heat (WL=QL) while decreasing volume and entropy (process [3][4]. Note, that the isothermal ideal-gas heating is accompanied with the expansion work-out equal to heat-in, WH=QH), while the quantity of its internal energy is unchanged. ...
This comprehensive treatise is written for the special occasion of the author’s 70th birthday. It presents his lifelong endeavors and reflections with original reasoning and re-interpretations of the most critical and misleading issues in thermodynamics; since now, we have the advantage to look at the historical developments more comprehensively and objectively than the pioneers. Starting from Carnot (grand-father of thermodynamics-to-be) to Kelvin and Clausius (fathers of thermodynamics), and other followers, the most relevant issues are critically examined and put in historical and contemporary perspective. From original reasoning of energy forcing and displacement to logical-proofs of the fundamental laws, to ubiquity of thermal motion and heat, and indestructibility of entropy, including new concept of “thermal roughness” and inevitability of dissipative irreversibility, to “dissecting Carnot true reversible-equivalency” and critical concept of “Carnot-Clausius heat-work equivalency (CCHWE)” regarding interchangeability of heat and work, and to demonstrating “no hope” for the “challengers” of the Second Law of thermodynamics, among others, are offered. It is hoped that the novel contributions presented will enhance comprehension and resolve some of the fundamental issues, as well as promote collaboration and future progress.
... Many enduring questions of science and human society can be directly linked to our perception of energy and its transformation. Anthony J. Leggett classified the various levels of problems encountered in any discipline into the following three categories [14]: ...
We are accustomed to looking at matter, life and evolution from different viewpoints. In this article, we present a simple but unified theoretical framework inspired by classical mechanics and thermodynamics. Our framework generalizes Newton's third law of matter to encompass life and evolution. The generalized action–reaction relationship includes scale and temporal parameters. This generalization helps explain why life is a system out of equilibrium. Life can go beyond the action–reaction symmetry law of matter. We define life as an open system that is self-aware of the time trajectory of energy state and environment. The theoretical framework we propose for studying life in terms of power reduces to the science of matter as a limiting case.
This article is part of the theme issue 'Thermodynamics 2.0: Bridging the natural and social sciences (Part 1)'.
... If one follows the suggestions of Anthony J. Leggett, a 2003 Noble Laureate in physics, first distinguishing the various levels of the problems encountered in any discipline becomes important. As is the case with condensed matter physics (Leggett, 2018), the open problems in social science may also be classified under the following three categories (Poudel & McGowan, 2019): ...
... Therefore, on purpose, only phenomenological reasoning without any mathematics is presented here. As Anthony Legget, a Nobel laureate, recently commented [12], emphasizing "Mathematical convenience versus physical insight . . . that theorists are far too fond of fancy formalisms which are mathematically streamlined but whose connection with physics is at best at several removes . . . ...
The challenges and claims of hypothetical violations of the Second Law of thermodynamics have been a topic of many scientific, philosophical and social publications, even in the most prestigious scientific journals. Fascination with challenging the Second Law has further accelerated throughout the development of statistical and quantum physics, and information theory. It is phenomenologically reasoned here that non-equilibrium, useful work-energy potential is always dissipated to heat, and thus thermodynamic entropy (a measure of thermal disorder, not any other disorder) is generated always and everywhere, at any scale without exception, including life processes, open systems, micro-fluctuations, gravity or entanglement. Furthermore, entropy cannot be destroyed by any means at any scale (entropy is conserved in ideal, reversible processes and irreversibly generated in real processes), and thus, entropy cannot overall decrease, but only overall increase. Creation of ordered structures or live species always dissipate useful energy and generate entropy, without exception, and thus without Second Law violation. Entropy destruction would imply spontaneous increase in non-equilibrium, with mass-energy flux displacement against cause-and-effect, natural forces, as well as negate the reversible existence of the very equilibrium. In fact, all resolved challengers’ paradoxes and misleading violations of the Second Law to date have been resolved in favor of the Second Law and never against. We are still to witness a single, still open Second Law violation, to be confirmed.
... They remind us that unfathomed deep waters are out there; that for some problems we have no idea of ''Hamiltonian" or ''Lagrangian", the starting point of typical physical approaches. Despite of his busy schedule, Tony kindly responded to the request of writing down his lecture, the essay in same issue [6], which will certainly benefit us greatly. I also sincerely appreciate the invitation from Science Bulletin to publish his lecture: a favor for our scientific community has been done. ...
This comprehensive treatise is written for the special occasion of the author’s 70th birthday. It presents his lifelong endeavors and reflections with original reasoning and re-interpretations of the most critical and sometimes misleading issues in thermodynamics—since now, we have the advantage to look at the historical developments more comprehensively and objectively than the pioneers. Starting from Carnot (grand-father of thermodynamics to become) to Kelvin and Clausius (fathers of thermodynamics), and other followers, the most relevant issues are critically examined and put in historical and contemporary perspective. From the original reasoning of generalized “energy forcing and displacement” to the logical proofs of several fundamental laws, to the ubiquity of thermal motion and heat, and the indestructibility of entropy, including the new concept of “thermal roughness” and “inevitability of dissipative irreversibility,” to dissecting “Carnot true reversible-equivalency” and the critical concept of “thermal-transformer,” limited by the newly generalized “Carnot-Clausius heat-work reversible-equivalency (CCHWRE),” regarding the inter-complementarity of heat and work, and to demonstrating “No Hope” for the “Challengers” of the Second Law of thermodynamics, among others, are offered. It is hoped that the novel contributions presented here will enlighten better comprehension and resolve some of the fundamental issues, as well as promote collaboration and future progress.
1. Introduction.- 2. Ground State.- 2.1 Finite-Size Studies: Rectangular Geometry.- 2.2 Laughlin's Theory.- 2.3 Spherical Geometry.- 2.4 Monte Carlo Results.- 2.5 Reversed Spins in the Ground State.- 2.6 Finite Thickness Correction.- 2.7 Liquid-Solid Transition.- 3. Elementary Excitations.- 3.1 Quasiholes and Quasiparticles.- 3.2 Finite-Size Studies: Rectangular Geometry.- 3.3 Spin-Reversed Quasiparticles.- 3.4 Spherical Geometry.- 3.5 Monte Carlo Results.- 3.6 Experimental Investigations of the Energy Gap.- 3.7 The Hierarchy: Higher Order Fractions.- 4. Collective Modes: Intra-Landau Level.- 4.1 Finite-Size Studies: Spherical Geometry.- 4.2 Rectangular Geometry: Translational Symmetry.- 4.3 Spin Waves.- 4.4 Single Mode Approximation: Magnetorotons.- 5. Collective Modes: Inter-Landau Level.- 5.1 Filled Landau Level.- 5.2 Fractional Filling: Single Mode Approximation.- 5.3 Fractional Filling: Finite-Size Studies.- 6. Further Topics.- 6.1 Effect of Impurities.- 6.2 Higher Landau Levels.- 6.3 Even Denominator Filling Fractions.- 6.4 Half-Filled Landau Level in Multiple Layer Systems.- 7. Open Problems and New Directions.- Appendices.- A The Landau Wave Function in the Symmetric Gauge.- B The Hypernetted-Chain Primer.- C Repetition of the Intra-Mode in the Inter-Mode.- References.
A theory of superconductivity is presented, based on the fact that the interaction between electrons resulting from virtual exchange of phonons is attractive when the energy difference between the electrons states involved is less than the phonon energy, ℏω. It is favorable to form a superconducting phase when this attractive interaction dominates the repulsive screened Coulomb interaction. The normal phase is described by the Bloch individual-particle model. The ground state of a superconductor, formed from a linear combination of normal state configurations in which electrons are virtually excited in pairs of opposite spin and momentum, is lower in energy than the normal state by amount proportional to an average (ℏω)2, consistent with the isotope effect. A mutually orthogonal set of excited states in one-to-one correspondence with those of the normal phase is obtained by specifying occupation of certain Bloch states and by using the rest to form a linear combination of virtual pair configurations. The theory yields a second-order phase transition and a Meissner effect in the form suggested by Pippard. Calculated values of specific heats and penetration depths and their temperature variation are in good agreement with experiment. There is an energy gap for individual-particle excitations which decreases from about 3.5kTc at T=0°K to zero at Tc. Tables of matrix elements of single-particle operators between the excited-state superconducting wave functions, useful for perturbation expansions and calculations of transition probabilities, are given.
According to a commonly held view, the properties of condensed-matter systems are simply consequences of the properties of their atomic-level components, and all of theoretical research in condensed-matter physics consists essentially in deducing the former from the latter. I argue that this apparently plausible picture is totally misleading, and that condensed-matter physics is a discipline which is not only autonomous, but guaranteed in the long run to be fundamental.
He set directions for research in the quantum physics of macroscopic dissipative systems and use of condensed systems to test the foundations of quantum mechanics. He has been particularly interested in the possibility of using special condensed-matter systems
- J Anthony
Anthony J. Leggett is widely recognized as a world leader in the theory of low-temperature physics, and his
pioneering work on superfluidity was recognized by the
2003 Nobel Prize in Physics. He set directions for
research in the quantum physics of macroscopic dissipative systems and use of condensed systems to test the
foundations of quantum mechanics. He has been particularly interested in the possibility of using special
condensed-matter systems, such as Josephson devices,
to test the validity of the extrapolation of the quantum
formalism to the macroscopic level.