Stern-Gerlach Experiment’s Interpretations and Noether’s Theorem

In this paper we suggest that theories treating two interacting objects in a different manner (for instance electromagnetic field of a laser classically, and the interacting atom as a quantum object) should be called “mixed”. Mixed theories are not so rare in Physics. One just should look at the whole area of Atomic, Molecular and Optical Physics in which mixed theories are often used, and, also, theories including quantum object interacting with classical surroundings that are the subject of our present discussion: the field of Quantum decoherence, when applied to resolving the dilemma should classical trajectories be used in explaining the Stern-Gerlach experiment or not. Consequently we are proving one improved corollary to Noether’s theorem, stating that mixed theories are not supporting the law of conservation of angular momentum and spin, as they are not based on the isotropy of space-time.     

Minkowski’s tensor or Abraham’s tensor?

It is proved that the question in the article title has an unambiguous answer, i.e., Abraham’s tensor.     

Rovelli’s World

Carlo Rovelli’s inspiring “Relational Quantum Mechanics” serves several aims at once: it provides a new vision of what the world of quantum mechanics is like, and it offers a program to derive the theory’s formalism from a set of simple postulates pertaining to information processing. I propose here to concentrate entirely on the former, to explore the world of quantum mechanics as Rovelli depicts it. It is a fascinating world in part because of Rovelli’s reliance on the information-theory approach to the foundations of quantum mechanics, and in part because its presentation involves taking sides on a fundamental divide within philosophy itself.     

Stoney’s Electron

George Johstone Stony, th man who maned the electron, was led to the concept of a fundamental unit of electic charge by combining electro-chemistry with the kinetic theory of gases. But his understanding was incomplete (so the discovery of the electron is associated wit JJ Thomsons determination of its charge to mass ratio in October 1897)     

Rainbow’s stars

In recent years, a growing interest in the equilibrium of compact astrophysical objects like white dwarf and neutron stars has been manifested. In particular, various modifications due to Planck-scale energy effects have been considered. In this paper we analyze the modification induced by gravity’s rainbow on the equilibrium configurations described by the Tolman–Oppenheimer–Volkoff (TOV) equation. Our purpose is to explore the possibility that the rainbow Planck-scale deformation of space-time could support the existence of different compact stars.     

Relativistic generalization of Bell’s inequalities in Wigner’s form

A relativistic generalization of Bell’s inequalities in Wigner’s form was obtained for the decays of a pseudoscalar and a scalar particle to two particles having a nonzero spin (fermions and photons). Both inequalities involving a full anticorrelation of final-particle spins and having a nonrelativistic analog and inequalities involving a full correlation of spins are considered. It is shown that Bohr’s complementarity principle may be tested experimentally in the relativistic region.     

Newton’s Metaphysics of Space as God’s Emanative Effect

In several of his writings, Isaac Newton proposed that physical space is God’s “emanative effect” or “sensorium,” revealing something interesting about the metaphysics underlying his mathematical physics. Newton’s conjectures depart from Plato and Aristotle’s metaphysics of space and from classical and Cambridge Neoplatonism. Present-day philosophical concepts of supervenience clarify Newton’s ideas about space and offer a portrait of Newton not only as a mathematical physicist but an independent-minded rationalist philosopher.     

Anderson’s Orthogonality Catastrophe

We give an upper bound on the modulus of the ground-state overlap of two non-interacting fermionic quantum systems with N particles in a large but finite volume L ^d of d-dimensional Euclidean space. The underlying one-particle Hamiltonians of the two systems are standard Schrödinger operators that differ by a non-negative compactly supported scalar potential. In the thermodynamic limit, the bound exhibits an asymptotic power-law decay in the system size L, showing that the ground-state overlap vanishes for macroscopic systems. The decay exponent can be interpreted in terms of the total scattering cross section averaged over all incident directions. The result confirms and generalises P. W. Anderson’s informal computation (Phys. Rev. Lett. 18:1049–1051, 1967).     

Weyl’s Gauge Argument

The standard $\mathbb{U}(1)$ “gauge principle” or “gauge argument” produces an exact potential A=dλ and a vanishing field F=d ² λ=0. Weyl (in Z. Phys. 56:330–352, 1929; Rice Inst. Pam. 16:280–295, 1929) has his own gauge argument, which is sketchy, archaic and hard to follow; but at least it produces an inexact potential A and a nonvanishing field F=dA≠0. I attempt a reconstruction.     

Quantum Computing’s Classical Problem,Classical Computing’s Quantum Problem

Tasked with the challenge to build better and better computers, quantum computing and classical computing face the same conundrum: the success of classical computing systems. Small quantum computing systems have been demonstrated, and intermediate-scale systems are on the horizon, capable of calculating numeric results or simulating physical systems far beyond what humans can do by hand. However, to be commercially viable, they must surpass what our wildly successful, highly advanced classical computers can already do. At the same time, those classical computers continue to advance, but those advances are now constrained by thermodynamics, and will soon be limited by the discrete nature of atomic matter and ultimately quantum effects. Technological advances benefit both quantum and classical machinery, altering the competitive landscape. Can we build quantum computing systems that out-compute classical systems capable of some \(10^{30}\) logic gates per month? This article will discuss the interplay in these competing and cooperating technological trends.     

Experimentally testing Bell’s theorem based on Hardy’s nonlocal ladder proofs

Bell's theorem argues the existence of quantum nonlocality which goes basically against the hidden variable theory(HVT). Many experiments have been done via testing the violations of Bell's inequalities to statistically verify the Bell's theorem. Alternatively,by testing the Hardy's ladder proofs we experimentally demonstrate the deterministic violation of HVT and thus confirm the quantum nonlocality. Our tests are implemented with non-maximal entangled photon pairs generated by spontaneous parametric down conversions(SPDCs). We show that the degree freedom of photon entanglement could be significantly enhanced by using interference filters. As a consequence, the Hardy's ladder proofs could be tested and Bell's theorem is verified robustly. The probability of violating the locality reach to 41.9%, which is close to the expectably ideal value 46.4% for the photon pairs with degree of entanglement ε = 0.93. The higher violating probability is possible by further optimizing the experimental parameters.     

A Landau’s octagonal quasilattice

An Ammam-Beenker 2D octagonal quasilattice is derived from a Landau like method starting from an octagonal seed. The level of stability of this quasilattice, i.e. the level of difficulty in creating defects, is directly measured.Received: 28 November 2003, Published online: 28 May 2004PACS: 61.44.Br Quasicrystals     

The Steep Nekhoroshev’s Theorem

Revising Nekhoroshev’s geometry of resonances, we provide a fully constructive and quantitative proof of Nekhoroshev’s theorem for steep Hamiltonian systems proving, in particular, that the exponential stability exponent can be taken to be \({1/(2n\alpha_1\cdots\alpha_{n-2}}\)) (\({\alpha_i}\)’s being Nekhoroshev’s steepness indices and \({n \ge 3}\) the number of degrees of freedom). On the base of a heuristic argument, we conjecture that the new stability exponent is optimal.