- Published on 08 February 2023
Guest editors: L. Cifarelli, F. Noferini, G. C. Righini
The celebration of the International Year of Glass in 2022 is at the origin of this Focus Point. Glass is a complex material with unique properties, that make it ubiquitous and indispensable in everyday life. Natural glass exists on the Earth since millions of years. The discovery of how to make glass was probably made towards the end of the third millennium B.C. From then on, in a way that at times has had something magic, glass objects have been an important part of human life and in the last centuries they have also been essential for the development of modern science. Microscopy, astronomy and, more recently, particle physics, data communications and optoelectronics are examples of academic and industrial research fields whose progress has been made possible thanks to the availability of special glasses. In this Focus Point, various different aspects in the development and use of glass will be addressed.
EPJ Plus Focus Point Issue: Focus Point on Higher Derivatives in Quantum Gravity: Theory, Tests, Phenomenology
- Published on 07 April 2022
The quantization of General Relativity via standard perturbative quantum field theory results in a quantum theory of gravity which is perturbatively non-renormalizable. This caused a proliferation of approaches to quantum gravity, based on different assumptions, ideas, and quantization methods. However, within many of these approaches the Einstein-Hilbert action is expected to be complemented by higher-derivative operators. In the framework of quadratic gravity, these higher-order terms are crucial to make gravity renormalizable and asymptotically free; in string theory infinitely many of these arise in the form of “corrections”; in non-local gravity infinitely many derivatives are introduced at the level of the bare action to achieve both renormalizability and perturbative unitarity; in asymptotically safe gravity and in the spin-foam approach to quantum gravity a similar structure is expected to emerge at the level of the quantum effective action. Higher derivatives are also key in the framework of effective field theory, whose results ought to be matched by all approaches to quantum gravity. Last but not least, higher derivatives could impact the phenomenology of black holes, the wave form of gravitational waves, and the early-universe cosmology.
EPJ Plus Focus Point Issue: Citizen science for physics: From Education and Outreach to Crowdsourcing fundamental research
- Published on 31 January 2022
Citizen Science encompasses a broad range of activities, from science education and outreach to the actual harnessing of crowdsourcing to conduct state-of-the-art research in all sciences.
The present focus point is intended as both a review and advancement of current and future such activities in the field of core physics and related disciplines, as covered in the journal’s aims-and-scope. In particular, this article collection wishes to thoroughly explore - and act as incentive to foster - the contribution of citizen science to advancing science and how to design ongoing and future research projects to this aim.