Arnold Theodore Nordsieck (5 January 1911 – 18 January 1971) was an American theoretical physicist. He is best known for his work with Felix Bloch on the infrared problem in quantum electrodynamics. He developed the inertial electrostatic gyroscope (ESG) used as part of the inertial navigation system of nuclear submarines that allows them to remain underwater without having to surface to ascertain their location.
https://en.wikipedia.org/wiki/Arnold_Nordsieck

https://en.wikipedia.org/wiki/Victor_Weisskopf

Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong static magnetic field are perturbed by a weak oscillating magnetic field (in the near field and therefore not involving electromagnetic waves) and respond by producing an electromagnetic signal with a frequency characteristic of the magnetic field at the nucleus. This process occurs near resonance, when the oscillation frequency matches the intrinsic frequency of the nuclei, which depends on the strength of the static magnetic field, the chemical environment, and the magnetic properties of the isotope involved; in practical applications with static magnetic fields up to ca. 20 tesla, the frequency is similar to VHF and UHF television broadcasts (60–1000 MHz). NMR results from specific magnetic properties of certain atomic nuclei. Nuclear magnetic resonance spectroscopy is widely used to determine the structure of organic molecules in solution and study molecular physics, crystals as well as non-crystalline materials. NMR is also routinely used in advanced medical imaging techniques, such as in magnetic resonance imaging (MRI).

All isotopes that contain an odd number of protons and/or neutrons (see Isotope) have an intrinsic nuclear magnetic moment and angular momentum, in other words a nonzero nuclear spin, while all nuclides with even numbers of both have a total spin of zero. The most commonly used nuclei are 1
H
 and 13
C
, although isotopes of many other elements (e.g. 2
H
, 6
Li
, 10
B
, 11
B
, 14
N
, 15
N
, 17
O
, 19
F
, 23
Na
, 29
Si
, 31
P
, 35
Cl
, 113
Cd
, 129
Xe
, 195
Pt
) have been studied by high-field NMR spectroscopy as well.

A key feature of NMR is that the resonance frequency of a particular simple substance is usually directly proportional to the strength of the applied magnetic field. It is this feature that is exploited in imaging techniques; if a sample is placed in a non-uniform magnetic field then the resonance frequencies of the sample’s nuclei depend on where in the field they are located. Since the resolution of the imaging technique depends on the magnitude of the magnetic field gradient, many efforts are made to develop increased gradient field strength.

The principle of NMR usually involves three sequential steps:

• The alignment (polarization) of the magnetic nuclear spins in an applied, constant magnetic field B₀.
• The perturbation of this alignment of the nuclear spins by a weak oscillating magnetic field, usually referred to as a radio-frequency (RF) pulse. The oscillation frequency required for significant perturbation is dependent upon the static magnetic field (B₀) and the nuclei of observation.
• The detection of the NMR signal during or after the RF pulse, due to the voltage induced in a detection coil by precession of the nuclear spins around B₀. After a RF pulse, precession usually occurs with the nuclei’s intrinsic Larmor frequency and, in itself, does not involve transitions between spin states or energy levels.

The two magnetic fields are usually chosen to be perpendicular to each other as this maximizes the NMR signal strength. The frequencies of the time-signal response by the total magnetization (M) of the nuclear spins are analyzed in NMR spectroscopy and magnetic resonance imaging. Both use applied magnetic fields (B₀) of great strength, often produced by large currents in superconducting coils, in order to achieve dispersion of response frequencies and of very high homogeneity and stability in order to deliver spectral resolution, the details of which are described by chemical shifts, the Zeeman effect, and Knight shifts (in metals). The information provided by NMR can also be increased using hyperpolarization, and/or using two-dimensional, three-dimensional and higher-dimensional techniques.

NMR phenomena are also utilized in low-field NMR, NMR spectroscopy and MRI in the Earth’s magnetic field (referred to as Earth’s field NMR), and in several types of magnetometers.

https://en.wikipedia.org/wiki/Nuclear_magnetic_resonance

The first Shelter Island Conference on the Foundations of Quantum Mechanics was held from June 2–4, 1947 at the Ram’s Head Inn in Shelter Island, New York. Shelter Island was the first major opportunity since Pearl Harbor and the Manhattan Project for the leaders of the American physics community to gather after the war. As Julian Schwinger would later recall, “It was the first time that people who had all this physics pent up in them for five years could talk to each other without somebody peering over their shoulders and saying, ‘Is this cleared?'”

The conference, which cost $850, was followed by the Pocono Conference of 1948 and the Oldstone Conference of 1949. They were arranged with the assistance of J. Robert Oppenheimer and the National Academy of Sciences (NAS). Later Oppenheimer deemed Shelter Island the most successful scientific meeting he had ever attended; and as Richard Feynman recalled to Jagdish Mehra in April 1970: “There have been many conferences in the world since, but I’ve never felt any to be as important as this…. The Shelter Island Conference was my first conference with the big men…. I had never gone to one like this in peacetime.

https://en.wikipedia.org/wiki/Shelter_Island_Conference

https://en.wikipedia.org/wiki/George_Kistiakowsky

https://en.wikipedia.org/wiki/Seth_Neddermeyer

https://en.wikipedia.org/wiki/Little_Boy

Ross Lomanitz (1921–2003) was an American physicist. He was born in Bryan, Texas and grew up in Oklahoma. His father was an agricultural chemist and named his son after the Italian socialist Giovanni Rossi, who had founded an agricultural commune in Brazil in the 1890s. Lomanitz graduated from high school at age 14 and went on to earn his bachelor of science degree in physics from the University of Oklahoma and his doctorate in theoretical physics from Cornell University under Richard Feynman.

Source: Giovanni Rossi Lomanitz – Wikipedia