In recent years, there has been a wealth of new science involving low-energy antimatter (ie,
positrons and antiprotons) at energies ranging from 10 2 to less than 10-3 eV. Much of this …

Einstein's general theory of relativity from 1915 1 remains the most successful description of
gravitation. From the 1919 solar eclipse 2 to the observation of gravitational waves 3, the …

Abstract The Antiproton Decelerator (AD) facility of CERN began operation in 1999 to serve
experiments for studies of CPT invariance by precision laser and microwave spectroscopy of …

In 1928, Dirac published an equation that combined quantum mechanics and special
relativity. Negative-energy solutions to this equation, rather than being unphysical as initially …

The spectrum of the hydrogen atom has played a central part in fundamental physics over
the past 200 years. Historical examples of its importance include the wavelength …

Antimatter was first predicted in 1931, by Dirac. Work with high-energy antiparticles is now
commonplace, and anti-electrons are used regularly in the medical technique of positron …

Atoms made of a particle and an antiparticle are unstable, usually surviving less than a
microsecond. Antihydrogen, made entirely of antiparticles, is believed to be stable, and it is …

The hydrogen atom is one of the most important and influential model systems in modern
physics. Attempts to understand its spectrum are inextricably linked to the early history and …

Abstract In 1906, Theodore Lyman discovered his eponymous series of transitions in the
extreme-ultraviolet region of the atomic hydrogen spectrum,. The patterns in the hydrogen …

The positron, the antiparticle of the electron, predicted by Dirac in 1931 and discovered by
Anderson in 1933, plays a key role in many scientific and everyday endeavours. Notably, the …