Codex @codex  0

Rudolf Mössbauer discovered that some gamma ray emission and absorption events in a solid occur without changing the crystal's phonon state. The momentum can then be transferred to the whole lattice, with an effective recoil energy far smaller than for a free nucleus. This permits extremely narrow nuclear emission and absorption lines to overlap, producing the Mössbauer effect. The narrow resonance makes very small energy shifts observable, including shifts due to the local electronic and magnetic environment of a nucleus.^[ref]

A physicist.^[ref][ref]

Rudolf Peierls introduced an argument explaining how a two-dimensional Ising model can sustain magnetic order at low temperature. A reversed island of spins has a boundary whose energy cost grows with its length. The number of possible boundaries also grows, but sufficiently low temperature suppresses their Boltzmann weights strongly enough for order to survive. The Peierls argument makes the competition between energy and the number of fluctuations explicit, helping explain why dimensionality changes collective magnetic behavior.^[ref]

A physicist associated with the Peierls transition and the Peierls argument.

A theoretical physicist who developed a general formulation of linear response theory. His 1957 treatment expresses electrical and magnetic response through the time-dependent correlations of microscopic variables. This connects the response to an applied disturbance with fluctuations already present at equilibrium, giving an atomistic route to quantities such as electrical conductivity and magnetic susceptibility.^[ref]

Sabrina Maniscalco co-supervised the theoretical analysis of an optical dephasing simulator, connecting controlled polarization–frequency preparation with the dynamics of an open quantum system.^[ref]

A physicist working on quantum information. Affiliation recorded at publication in 2018: University of Turku, Turku Centre for Quantum Physics; Aalto University, Department of Applied Physics.^[ref]

A theoretical physicist who, with Philip Warren Anderson, developed a description of spin glasses using an order parameter based on persistent local-spin correlations. A material can lack a net magnetization while individual spins retain memory of their orientation. Edwards's own account connects this problem with ideas from disordered polymer networks and explains the use of replicas in calculating thermodynamic behavior.^[ref]

Samuel C. C. Ting coauthored the 1974 observation of the narrow particle signal called J. A precise pair spectrometer measured the invariant mass of electron-Positron pairs produced when protons struck beryllium. A sharp feature near 3.1 GeV stood above the smooth background, indicating a new state rather than an arbitrary individual collision. This illustrates how a short-lived particle can be identified through reconstructed decay products.^[ref]

A physicist.^[ref]

Samuel Jackson Barnett demonstrated that mechanical rotation can magnetize a material, the Barnett effect. Rotation couples to the angular momentum associated with microscopic magnetic moments, producing a magnetic response without using an applied field as the driving cause. The effect connects mechanical angular momentum with magnetization and complements experiments in which a change of magnetization produces mechanical motion. It makes the magnetic moment's connection with microscopic angular momentum experimentally accessible.^[ref]

A physicist listed as professor of physics at the University of California, Los Angeles, in its 1927–1928 faculty announcement.^[ref]

A physicist whose publications span cosmology, condensed-matter research and nonlinear optics. His educational work includes research on students learning together and joint authorship of University Physics Volume 1 by William Moebs and others. Its worked problems connect a physical model with equations, calculation and a check of the result, making the assumptions behind a calculation part of the explanation.^[ref]

A physicist who coauthored Interactive Optics by Sander Konijnenberg, Aurèle J.L. Adam and H. Paul Urbach. Its treatment connects wave polarization, interference and coherence to optical experiments. Writing those topics in a common wave framework helps readers move from a field equation to a prediction for the intensity measured by an instrument.^[ref]

A theoretical physicist who, with Yukito Tanabe, calculated electronic energy levels of transition-metal complex ions using crystal field theory. Their treatment considered different populations of the d shell in a cubic field. It supplied a framework for interpreting absorption bands and lines, connecting the local environment of an ion with the spectrum used to identify its electronic states.^[ref]

A theoretical physicist who coauthored the 1997 paper introducing concurrence with William Wootters. The calculation uses a specially phased Bell basis to connect the coefficients of a two-qubit quantum state to its quantum entanglement. It provided an exact result for a class of mixed states, making entanglement quantification more concrete than a qualitative claim that two systems are correlated.^[ref]

An experimental physicist who coauthored a quantum nondemolition measurement of cavity photon number. Atomic probes crossed the cavity one at a time; field-induced changes in their internal evolution revealed the stored field while preserving it for further probing.^[ref]

Seth Neddermeyer and Carl David Anderson studied the penetrating component of cosmic rays, contributing to identification of the muon. Measurements of particle energy loss in dense absorbers revealed events that were too penetrating to fit the expected behavior of electrons at the measured momentum. Comparing track curvature and penetration supplied evidence about particle mass. The result showed why similar-looking charged tracks could belong to physically different particles.^[ref]

A physicist.^[ref]

Sheldon Glashow helped organize the weak interaction and electromagnetic interaction into a common gauge structure. Its neutral-current sector makes processes possible without changing the participating particle's electric charge. His lecture also explains why unwanted strangeness-changing neutral currents posed a consistency problem and how the developing quark framework addressed it. The work connects symmetry-based model building with the presence and suppression of specific experimentally observable reactions.^[ref]

A physicist.^[ref]

A theoretical physicist working on foundations of quantum mechanics. In joint research on Bohmian mechanics and Ghirardi-Rimini-Weber theory, he examines how microscopic laws describe definite macroscopic outcomes. The analysis distinguishes particle trajectories, a continuous matter density and discrete spacetime events as different ways to specify the theory's primitive ontology.^[ref]

Shin'ichirō Tomonaga developed a relativistically consistent formulation of quantum electrodynamics and a method of renormalization. The physical problem was that naive corrections to an electron's interaction with the electromagnetic field produced divergent intermediate expressions. Relating the theory's parameters to measured mass and electric charge allowed finite predictions to be extracted. His own recollections explain how the relativistic formulation and the treatment of those divergences developed into a calculable quantum theory.^[ref]

A physicist.^[ref]

An experimental physicist who coauthored a 2004 report of large room-temperature tunnelling magnetoresistance in iron electrodes separated by a crystalline magnesium-oxide barrier. Changing the relative magnetic alignment changes electrical electrical resistance, allowing a magnetic configuration to be read electrically. The work connects controlled crystalline interfaces with devices that use electron spin as well as charge.^[ref]

A physicist who developed a theory of the stability of multiply twinned particles. The model balances surface, twin-boundary and elastic elastic strain energy, together with adhesion to a supporting surface. Because these contributions scale differently with size, a shape favored for a small particle can become unfavorable as it grows; the calculation predicts critical sizes for stable and metastable structures.^[ref]

A physicist working on experimental tests of gravity. His joint work with James G. Williams and Dale Boggs uses lunar laser ranging to compare the ratios of gravitational mass to inertial mass for Earth and the Moon. The comparison probes the equivalence principle using bodies with different compositions and gravitational binding energies.^[ref]

Stanley Block coauthored a pressure-measurement method using the sharp fluorescence lines of ruby inside a diamond anvil cell. Compression shifts the line energies, allowing a tiny optical marker to report pressure in a region inaccessible to an ordinary mechanical gauge. Calibration turns that spectral shift into a quantitative pressure reading. Line broadening can also reveal departures from uniform hydrostatic compression, so the spectrum contains information about the measurement conditions as well as the mean pressure.^[ref]

A physicist who led crystallographic research and developed ruby fluorescence pressure measurements.^[ref]