EPJ H Highlight - The coming of age of plasma physics
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- Published on 19 December 2018
The story of the generation of physicists involved in the development of a sustainable energy source, controlled fusion, using a method called magnetic confinement
Once upon a time, people thought that electrons and ions always stuck together, living happily ever after. However, under low density of matter or high temperatures, the components of matter are no longer bound together. Instead, they form plasma, a state of matter naturally occurring in our universe, which has since been harnessed for everyday applications such as TV screens, chip etching and torches, but also propulsion and even sustained energy production via controlled fusion.
In a fascinating editorial for a special plasma issue of EPJ H, called “Plasma physics in the 20th century as told by players”, three physicists share their perspectives on key events in the early history of plasma physics, in the first half of the 20th century. First, Patrick Diamond, from the University of California San Diego, USA, shares his recollections of the early days of wireless transmission and the description of the ‘Heavyside Layer’ (the electrically conducting layer of the upper atmosphere, which transmits radio waves). In turn, Yves Pomeau from the Ecole Polytechnique in Palaiseau, France, talks about the role of Irving Langmuir in the development of plasma physics theory, namely his calculation of the frequency of oscillation of electrons in a plasma environment with much heavier ions. Lastly, Uriel Frisch from the University Cote D’Azur in Nice, France, describes the birth of nuclear fusion theory.
EPJ H Highlight - Centenary of cosmological constant lambda
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- Published on 11 July 2018
Insights into its 100-year history reveal how the cosmological constant was marginalised by physicists before being reinstated by astronomers to explain the accelerated expansion of the universe
Physicists are now celebrating the 100th anniversary of the cosmological constant. On this occasion, two papers recently published in EPJ H highlight its role in modern physics and cosmology. Although the term was first introduced when the universe was thought to be static, today the cosmological constant has become the main candidate for representing the physical essence believed to be responsible for the accelerated expansion of our universe. Before becoming widely accepted, the cosmological constant was during decades the subject of many discussions about its necessity, its value and its physical essence. Today, there are still unresolved problems in understanding the deep physical nature of the phenomena associated with the cosmological constant.
EPJ H Highlight - From a model of fluids to the birth to a new field in computational physics
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- Published on 16 May 2018
Revisiting the roots of a physics field known as computational statistical mechanics
It may sound like the stuff of fairy tales, but in the 1950s two numerical models initially developed as a pet project by physicists led to the birth of an entirely new field of physics: computational statistical mechanics. This story has recently appeared in a paper published in EPJ H, authored by Michel Mareschal, an Emeritus Professor of Physics at the Free University of Brussels, Belgium. The article outlines the long journey leading to the acceptance of such models - namely Monte Carlo and Molecular Dynamics simulations - as reliable evidence for describing matter. This happened at a time when the computing power required to run simulations was scarce. Today, these techniques are used by thousands of researchers to model the behaviour of materials, in contexts ranging from fusion to biological systems.
EPJ H Highlight - Once upon a time, an exoplanet was discovered
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- Published on 16 April 2018
Personal recollections of an astrophysicist shed new light on the 1995 discovery on 51 Pegasi b
In recent history, a very important achievement was the discovery, in 1995, of 51 Pegasi b, the first extrasolar planet ever found around a normal star other than the Sun. In a paper published in EPJ H, Davide Cenadelli from the Aosta Valley Astronomical Observatory (Italy) interviews Michel Mayor from Geneva Observatory (Switzerland) about his personal recollections of discovering this exoplanet. They discuss how the development of better telescopes made the discovery possible. They also delve into how this discovery contributed to shaping a new community of scholars pursuing this new field of research. In closing, they reflect upon the cultural importance that the 51 Pegasi b discovery had in terms of changing our view of the cosmos.
EPJ H Highlight - Six decades of cosmology
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- Published on 27 February 2018
The personal memories of Jayant Narlikar point to the need for restoring cosmology as the flagship of astronomy
"Cosmologists are often wrong but never in doubt”, Russian physicist Lev Landau once said . In the early days, astronomers began by observing and modelling stars in different stages of evolution and comparing their findings with theoretical predictions. Stellar modelling uses well-tested physics, with concepts such as hydrostatic equilibrium, law of gravitation, thermodynamics, nuclear reactions etc. Yet in contrast, cosmology is based on a large number of untested physical assumptions, like nonbaryonic dark matter and dark energy whose physics has no proven link with the rest of physics. In a recent paper published in EPJ H, Jayant V. Narlikar, professor emeritus at the Inter-University Centre for Astronomy and Astrophysics in Pune, India, shares his personal reminiscences of the evolution of the subject of cosmology over six decades. He tells of the increase in our confidence in the standard model of cosmology to the extent that it has become a dogma.
EPJ H Highlight - How theoretical particle physicists made history with the Standard Model
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- Published on 05 December 2017
The personal recollections of a physicist involved in developing a reference model in particle physics, called the Standard Model, particularly in Italy
Understanding the Universe requires first understanding its building blocks, a field covered by particle physics. Over the years, an elegant model of particle physics, dubbed the Standard Model, has emerged as the main point of reference for describing the fundamental components of matter and their interactions. The Standard Model is not confined to particle physics; it also provides us a guide to understanding phenomena that take place in the Universe at large, down to the first moments of the Big Bang, and it sets the stage for a novel cosmic problem, namely the identification of dark matter. Placing the Standard Model in a historical context sheds valuable light on how the theory came to be. In a remarkable paper published in EPJ H, Luciano Maiani from the University of Rome and the National Institute of Nuclear Physics, Italy, shares his personal recollections with Luisa Bonolis from the Max Planck Institute for the History of Science, Berlin, Germany. During an interview recorded over several days in March 2016, Maiani outlines the role of those researchers who were instrumental in the evolution of theoretical particle physics in the years when the Standard Theory was developed.
EPJ H Highlight - How Einstein’s theory of gravitation experienced a Renaissance after World War II
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- Published on 26 June 2017
Journey into the post-war transformation leading to the return of General Relativity within physics
Einstein’s 1915 theory of gravitation, also known as General Relativity, is now considered one of the pillars of modern physics. It contributes to our understanding of cosmology and of fundamental interactions between particles. But that was not always the case. Between the mid-1920s and the mid-1950s, General Relativity underwent a period of stagnation, during which the theory was mostly considered as a stepping-stone for a superior theory. In a special issue of EPJ H just published, historians of science and physicists actively working on General Relativity and closely related fields share their views on the process, during the post-World War II era, in particular, which saw the “Renaissance” of General Relativity, following progressive transformation of the theory into a bona fidae physics theory.
EPJ H Highlight - Historical account of how donut-shaped fusion plasmas managed to decrease adverse turbulence
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- Published on 20 February 2017
Achieving fusion has become more realistic since plasma flow was identified as regulating turbulence in the 1980s
Fusion research has been dominated by the search for a suitable way of ensuring confinement as part of the research into using fusion to generate energy. In a recent paper published in EPJ H, Fritz Wagner from the Max Planck Institute for Plasma Physics in Germany, gives a historical perspective outlining how our gradual understanding of improved confinement regimes for what are referred to as toroidal fusion plasmas –- confined in a donut shape using strong magnetic fields-- have developed since the 1980s. He explains the extent to which physicists’ understanding of the mechanisms governing turbulent transport in such high-temperature plasmas has been critical in improving the advances towards harvesting fusion energy.
EPJ H Highlight - The 1950s: the decade in which gravity physics became experimental
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- Published on 12 October 2016
History shows experiments to be just as key as theory in gravity physics
In the 1950s and earlier, the gravity theory of Einstein's general relativity was largely a theoretical science. In a new paper published in EPJ H, Jim Peebles, a physicist and theoretical cosmologist who is currently the Albert Einstein Professor Emeritus of Science at Princeton University, New Jersey, USA, shares a historical account of how the experimental study of gravity evolved.
EPJ H Highlight - Timeless thoughts on the definition of time
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- Published on 22 March 2016
On the evolution of how we have defined time, time interval and frequency since antiquity
The earliest definitions of time and time-interval quantities were based on observed astronomical phenomena, such as apparent solar or lunar time, and as such, time as measured by clocks, and frequency, as measured by devices were derived quantities. In contrast, time is now based on the properties of atoms, making time and time intervals themselves derived quantities. Today’s definition of time uses a combination of atomic and astronomical time. However, their connection could be modified in the future to reconcile the divergence between the astronomic and atomic definitions. These are some of the observations made by Judah Levine, author of a riveting paper just published in EPJ H, which provides unprecedented insights into the nature of time and its historical evolution.
