Edward Mills Purcell, Henry Cutler Torrey and Robert Vivian Pound observed nuclear magnetic resonance through absorption in a bulk solid. A static magnetic field separates nuclear magnetic energy levels, and an applied radiofrequency field drives resonant transitions. Measuring the absorbed signal connects a microscopic nuclear moment with a laboratory electromagnetic circuit. The experiment helped make nuclear-spin behavior accessible in ordinary condensed samples.^[ref]

A physicist.^[ref]

Percy Williams Bridgman developed apparatus that made very high pressures useful as a controlled experimental variable. A pressure-assisted seal tightens as the load increases, helping contain conditions that would defeat a simple fixed gasket. Measuring changes of volume, phases and other properties under pressure reveals how strongly compressed matter differs from its ordinary state. His account connects the mechanical design of the pressure vessel with the reliability and range of the resulting physical measurements.^[ref]

A physicist.^[ref]

Edward Victor Appleton investigated the ionosphere by measuring how radio signals return from the upper atmosphere. Comparing direct and returning radio waves makes their path difference experimentally accessible and constrains the effective height of the reflecting region.

The response changes with frequency because the atmosphere's free electrons alter electromagnetic propagation. Scanning frequency and observing the returning signals helps distinguish ionized layers and their changing conditions. His Nobel lecture connects these measurements with the physical basis of long-distance radio propagation.^[ref]

A physicist whose work with Edward Victor Appleton tested the return of radio waves from the upper atmosphere. Their experiments supplied evidence for reflecting ionized layers and distinguished returns from different heights. The Appleton-Barnett radio interference experiment thus connects an observed ground-level interference signal to the structure of the ionosphere, explaining how radio communication can reach beyond the direct line of sight.^[ref]

Hideki Yukawa proposed explaining the short range of the nuclear interaction through exchange of a massive field quantum. A schematic static Yukawa potential has the form $V(r)\propto e^{-mcr/\hslash }/r$: the exponential introduces a range of order $\hslash /(mc)$, linking an inferred force range with a predicted particle mass. His 1935 proposal made the observed nuclear scale a clue to a new particle, while the later distinction between muons and pions was an experimental question.^[ref]

A physicist.^[ref][ref]

An experimental particle physicist who coauthored observations of nuclear disintegration in photographic emulsions with Hertha Wambacher. A cluster of charged-particle tracks sharing one origin provided evidence for an interaction induced by cosmic rays. Recording such events photographically made rare nuclear processes available for repeated microscopic examination and measurement.^[ref]

An experimental particle physicist who, with Marietta Blau, studied nuclear disintegrations recorded in photographic emulsions exposed to cosmic rays. Several heavy charged tracks emerging from a common point identified a nuclear event. The emulsion served simultaneously as target and persistent track detector, allowing the geometry of a rare interaction to be examined after exposure.^[ref]

John Cockcroft and Ernest Walton used accelerated protons to produce the disintegration of lithium in 1932. A high-voltage accelerator supplied the projectile beam, while the energetic alpha particles leaving the target provided the reaction signal. The reaction $p+{}^7\mathrm{Li}\to 2\alpha$ releases nuclear binding energy, so the outgoing particles can carry far more kinetic energy than the incident proton. This connected a controlled electrical accelerator with a quantitative nuclear reaction.^[ref]

A physicist.^[ref][ref]

Ernest Walton and John Cockcroft produced nuclear reactions with a controlled beam of electrically accelerated protons. Their 1932 lithium experiment detected energetic alpha particles from the target. The apparatus made both the incident proton energy and the outgoing reaction products experimentally accessible, replacing reliance on naturally emitted projectiles alone. The result demonstrated how accelerator control could be used to investigate the binding and transformation of atomic nuclei.^[ref]

A physicist.^[ref][ref]

An experimental physicist who coauthored the Bloch nuclear induction experiment measurements of Felix Bloch and Martin Packard. A sample's precessing nuclear magnetization induces a radiofrequency signal in a pickup coil. Detecting that signal connects the collective motion of nuclear magnetic moments to nuclear magnetic resonance, making the same sample's magnetic dynamics repeatedly observable.^[ref]

An experimental physicist who coauthored Felix Bloch's nuclear-induction experiments. Precessing nuclear magnetization generated a radiofrequency signal in a coil surrounding the sample. Detecting the induced signal made collective nuclear motion directly measurable and helped establish bulk nuclear magnetic resonance as a laboratory technique.^[ref]

An experimental physicist who coauthored observation of nuclear magnetic resonance in a solid with Edward Mills Purcell and Robert Vivian Pound. A radiofrequency field drives transitions of nuclear magnetic moments in an applied magnetic field; resonance appears as enhanced absorption. The method provided access to nuclear properties without requiring a freely traveling atomic beam.^[ref]

An experimental physicist who, with Glen Rebka, measured the gravitational redshift of gamma radiation over a laboratory height difference. Narrow nuclear resonance and a controlled Doppler shift made an extremely small gravitational frequency change accessible. The experiment linked a prediction of general relativity to resonant absorption in an apparatus on Earth.^[ref]

An experimental atomic physicist who, with Willis Eugene Lamb Jr., measured the Lamb shift in 1947. Their microwave method distinguished hydrogen levels that the simplest relativistic theory placed at the same energy. The experiment made a small spectral discrepancy into a precise test, helping motivate improved calculations in quantum electrodynamics.^[ref]

Frits Zernike developed phase-contrast microscopy, making transparent structures visible through changes in wave phase. A weakly absorbing specimen may change the wave phase of transmitted light without producing much ordinary intensity contrast. Shifting the relative wave phase of the direct and diffracted components lets their wave interference convert that information into visible brightness differences. His discovery began with imperfections in diffraction gratings, before becoming a method for observing transparent specimens.^[ref]

A physicist.^[ref]

Cecil Frank Powell developed nuclear emulsion methods for studying cosmic rays. A charged particle leaves a microscopic sequence of developed grains; track length, scattering and grain density can then constrain its energy and mass. His work with colleagues on connected stopping tracks helped identify the pion and its decay into a muon. The method combined long exposures with repeated microscope measurements, turning rare cosmic events into quantitative evidence.^[ref]

A physicist.^[ref]

Hugh Muirhead coauthored the 1947 observations that distinguished charged pions from their lighter decay products. In a nuclear emulsion, one stopping particle track was followed by another emerging from its endpoint. Track ranges and ionization provided evidence for a two-stage process involving different masses. The recorded geometry made a decay recognizable even though neither particle was directly followed in real time.^[ref]

A physicist.^[ref]

A theoretical nuclear physicist who develops descriptions of nuclear forces through effective field theory. His joint review relates the allowed low-energy interactions of nucleons to symmetries of quantum chromodynamics. Organizing interactions systematically makes it possible to improve a nuclear calculation in stages and compare few-body predictions with measured nuclear properties.^[ref]

A theoretical nuclear physicist working on effective field theory descriptions of nuclear forces. His review with Evgeny Epelbaum and Ulf-G. Meißner compares descriptions at different resolution scales. Selecting the relevant low-energy degrees of freedom permits controlled calculations of few-nucleon systems while retaining constraints from quantum chromodynamics.^[ref]

A theoretical nuclear physicist who studies nuclear forces using effective field theory. His joint review with Evgeny Epelbaum and Hans-Werner Hammer explains how the symmetries of quantum chromodynamics constrain low-energy interactions between nucleons. The approach organizes increasingly accurate calculations without treating a nucleus directly as a collection of interacting quarks.^[ref]