Proceedings

EPJ H Highlight - Centenary of cosmological constant lambda

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How history placed the cosmological constant at the heart of our understanding of the universe. Photo by Tbel Abuseridze on Unsplash https://unsplash.com/photos/0G1aF-yrlu8

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.

In his paper, Bohdan Novosyadlyj, affiliated with the National University of Lviv, Ukraine, explains how Albert Einstein introduced the cosmological constant in 1917 to make the model of static Universe, then accepted by most scientists, work. Its deep physical meaning, however, escaped Einstein. Following the discovery of evidence for a non-static universe in 1929, Einstein regretted introducing this constant into equations of general relativity. Meanwhile, other scientists tried for decades to understand its physical meaning and establish its magnitude. When evidence of dark energy was observed by Michael Turner in 1998, scientists began to consider alternatives of cosmological constant to model that dark energy.

In another paper, Cormac O'Raifeartaigh from Waterford Institute of Technology, Ireland, and colleagues present a detailed analysis of the 100-year history of the cosmological constant. Starting with static models of the universe, the paper explains how the constant became marginalised following the discovery of cosmic expansion. Subsequently, it was revived to address specific cosmic puzzles such as the timespan of expansion, the formation of galaxies and the red-shifts of quasars.

More recently, the constant has acquired greater physical meaning, as it has helped to the matching of further recent observations with theory. Specifically, it was helpful to reconcile current theory with the recently-observed phenomenon of dark energy as evidenced by the measurement of present cosmic expansion using the Hubble Space Telescope, the measurement of past expansion using supernova, and the measurement of cosmic microwave background by balloon and satellite.

“Century of Λ” by B. Novosyadlyj (2018), European Physical Journal H, DOI 10.1140/epjh/e2018-90007-y

“One hundred years of the cosmological constant: from ‘superfluous stunt’ to dark energy” by C. O'Raifeartaigh, M. O'Keeffe, W. Nahm, and S. Mitton (2018), European Physical Journal H, DOI 10.1140/epjh/e2017-80061-7

This year we decided to make the proceedings of the Workshop available to a wider scientific audience than in previous years. Choosing the media for publishing the papers we had two goals in mind. Firstly, we would like the papers to be in open access, and, secondly, to be indexed in major scientific databases (most notably in Scopus). Among the available choices, we opted for publication in EPJ Web of Conferences due to its international reputation and flexible policy in terms of papers format and publication pricing. The publishing procedure with EPJ was pleasant and smooth, all technical questions were solved in a fast and professional manner. Looking forwards to future collaborations with EPJ Web of Conferences.

Sergey Mishakin, Institute of Applied Physics, Russia
Scientific Secretary of the Workshop, EPJ Web of Conferences vol. 149 (2017)

ISSN: 2100-014X (Electronic Edition)

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