Physics Without Physics

David Finkelstein was very fond of the new information-theoretic paradigm of physics advocated by John Archibald Wheeler and Richard Feynman. Only recently, however, the paradigm has concretely shown its full power, with the derivation of quantum theory (Chiribella et al., Phys. Rev. A 84:012311, 2011; D’Ariano et al., 2017) and of free quantum field theory (D’Ariano and Perinotti, Phys. Rev. A 90:062106, 2014; Bisio et al., Phys. Rev. A 88:032301, 2013; Bisio et al., Ann. Phys. 354:244, 2015; Bisio et al., Ann. Phys. 368:177, 2016) from informational principles. The paradigm has opened for the first time the possibility of avoiding physical primitives in the axioms of the physical theory, allowing a re-foundation of the whole physics over logically solid grounds. In addition to such methodological value, the new information-theoretic derivation of quantum field theory is particularly interesting for establishing a theoretical framework for quantum gravity, with the idea of obtaining gravity itself as emergent from the quantum information processing, as also suggested by the role played by information in the holographic principle (Susskind, J. Math. Phys. 36:6377, 1995; Bousso, Rev. Mod. Phys. 74:825, 2002). In this paper I review how free quantum field theory is derived without using mechanical primitives, including space-time, special relativity, Hamiltonians, and quantization rules. The theory is simply provided by the simplest quantum algorithm encompassing a countable set of quantum systems whose network of interactions satisfies the three following simple principles: homogeneity, locality, and isotropy. The inherent discrete nature of the informational derivation leads to an extension of quantum field theory in terms of a quantum cellular automata and quantum walks. A simple heuristic argument sets the scale to the Planck one, and the currently observed regime where discreteness is not visible is the so-called “relativistic regime” of small wavevectors, which holds for all energies ever tested (and even much larger), where the usual free quantum field theory is perfectly recovered. In the present quantum discrete theory Einstein relativity principle can be restated without using space-time in terms of invariance of the eigenvalue equation of the automaton/walk under change of representations. Distortions of the Poincaré group emerge at the Planck scale, whereas special relativity is perfectly recovered in the relativistic regime. Discreteness, on the other hand, has some plus compared to the continuum theory: 1) it contains it as a special regime; 2) it leads to some additional features with GR flavor: the existence of an upper bound for the particle mass (with physical interpretation as the Planck mass), and a global De Sitter invariance; 3) it provides its own physical standards for space, time, and mass within a purely mathematical adimensional context. The paper ends with the future perspectives of this project, and with an Appendix containing biographic notes about my friendship with David Finkelstein, to whom this paper is dedicated.     

物理竞赛中的物理图象

图象处理法是物理竞赛中常用的处理方法,主要表现在图象的"面积"与图象的交点两个方面.     

Chinese Physics C(Formerly High Energy Physics and Nuclear Physics)

<正>Monthly,founded in 1977Published monthly in hard copy by Science Press and online by the Institute of High Energy Physics of the Chinese Academy of Sciences(domestic)and by IOP Publishing,Temple Circus,Temple Way,Bristol BS1 6HG,UK(international).     

Physics Needs Philosophy. Philosophy Needs Physics

Contrary to claims about the irrelevance of philosophy for science, I argue that philosophy has had, and still has, far more influence on physics than is commonly assumed. I maintain that the current anti-philosophical ideology has had damaging effects on the fertility of science. I also suggest that recent important empirical results, such as the detection of the Higgs particle and gravitational waves, and the failure to detect supersymmetry where many expected to find it, question the validity of certain philosophical assumptions common among theoretical physicists, inviting us to engage in a clearer philosophical reflection on scientific method.     

物理新闻和动态

中国物理学会2006年秋季学术会议简讯9月15日上午,中国物理学会2006年秋季学术会议(CPS2006FallMeeting)在清华大学礼堂拉开帷幕.来自中国大陆和香港的上百个科研单位和高等院校的千余名代表参加了大会开幕式暨特邀学术报告会.开幕式上,2006年秋季学术会议地方组委会主席,清华大学物理系王青教授首先代表清华大学物理系向各位代表表示了真诚欢迎.秋季学术会议大会组委会主席、中科院基础科学局局长张杰院士向与会代表介绍了秋季会议的发展概况,对2006年秋季会议的筹备工作进行了简要介绍并给予了充分肯定.清华大学校长、中国物理学会费米…     

Fundamental Physics

A survey is given of the elegant physics of N-particle systems, both classical and quantal, non-relativistic (NR) and relativistic, non-gravitational (SR) and gravitational (GR). Chapter 1 deals exclusively with NR systems; the correspondence between classical and quantal systems is highlighted and summarized in two tables of Sec. 1.3. Chapter 2 generalizes Chapter 1 to the relativistic regime, including Maxwell’s theory of electromagnetism. Chapter 3 follows Einstein in allowing gravity to curve the spacetime arena; its Sec. 3.2 is devoted to the yet missing theory of elementary particles, which should determine their properties and interactions. If completed, it would replace QFT; promising is the ‘metron’ approach.