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EPJ Plus Focus Point on Tensions in Cosmology from Early to Late Universe: The Value of the Hubble Constant and the Question of Dark Energy
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- Published on 03 March 2023
Guest editors: S. Capozziello, V.G. Gurzadyan
The papers included in this Focus Point collection are devoted to one of the hot topics in modern cosmology - the Hubble constant tension – claimed as a discrepancy between the descriptions of the early and late Universe. A broad range of topics are involved in the Hubble tension issue, from the sophisticated methods of observational data analysis up to dark energy models dealing with modifications of the standard cosmological model and related to the extensions of the General Relativity. The papers included in the collection are authored by known experts and groups, and reflect the diversity of approaches, both, aiming in solving the tension improving measurements and datasets and in searching for new physics capable of addressing the problem.
All articles are available here and are freely accessible until 3 May 2023. For further information, read the Editorial.
EPJ ST Highlight - Tracking how magnetism affects animal behaviour
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- Published on 23 February 2023
We still know little about how animal behaviour changes in response to magnetic fields. A new review provides a tutorial introduction to the study of this fascinating and potentially useful phenomenon.
For over 50 years, scientists have observed that the behaviour of a wide variety of animals can be influenced by the Earth’s magnetic field. However, despite decades of research, the exact nature of this ‘magnetic sense’ remains elusive. Will Schneider and Richard Holland from Bangor University in Wales and their co-worker Oliver Lindecke from the Institute for Biology, Oldenburg, Germany have now written a comprehensive overview of this cross-disciplinary field, with an emphasis on the methodology involved. This work is now published in EPJ ST.
EPJ B Highlight - 2D Janus materials could harvest abundant hydrogen fuel
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- Published on 23 February 2023
A new group of asymmetric 2D materials can readily catalyse the splitting of water into hydrogen and oxygen – providing a reliable source of hydrogen fuel.
Several studies have predicted that the water splitting reaction could be catalysed by certain groups of 2D materials – each measuring just a few atoms thick. One particularly promising group are named 2D Janus materials, whose two sides each feature a different molecular composition. Through new calculations detailed in EPJ B, Junfeng Ren and colleagues at Shandong Normal University in China present a new group of four 2D Janus materials, which could be especially well suited to the task.
EPJ B Highlight - Examining heat transfer in granular materials
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- Published on 22 February 2023
Heat transfer through granular materials in a humid atmosphere occurs mainly through the air in the case of larger particles, and via water capillary bridges for smaller particles.
Granular materials contain large numbers of small, discrete particles, which collectively behave like uniform media. Their thermal conductivity is crucial to understanding their overall behaviour – but so far, researchers haven’t considered how this value is affected by the surface roughness of their constituent particles. Through new analysis published in EPJ B, Bo Persson at the Peter Grünberg Institute, part of the Jülich Research Centre in Germany, has discovered that when this roughness is considered, thermal conductivity in granular materials is heavily influenced by particle sizes. These findings could help physicists to better describe a wide array of granular materials: from sand and snow, to piles of rice, coffee beans, and fertilizer.
EPJ Plus Highlight - Building a computer with a single atom
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- Published on 15 February 2023
New research opens the horizons regarding what a “computer” can be and how small a computational unit can get
Considering a “computer” as anything that processes information by taking an input and producing an output leads to the obvious questions, what kind of objects could perform computations? And how small can a computer be? As transistors approach the limit of miniaturisation, these questions are more than mere curiosities, their answers could form the basis of a new computing paradigm.
In a new paper in EPJ Plus by Tulane University, New Orleans, Louisiana, researcher Gerard McCaul, and his co-authors demonstrate that even one of the more basic constituents of matter — atoms — can act as a reservoir for computing where all input-output processing is optical.
EPJ E Highlight - Shear ultrasound shaking lowers friction between solids
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- Published on 15 February 2023
A simple new experiment shows how tiny ultrasound shaking at the interfaces between two objects will lower the friction between them – and in some cases, can induce sudden, large jerky motions
When high-frequency shaking occurs at an interface between two solids, recent experiments have revealed that the frictional forces between the objects can be weakened. Through a simple new experiment detailed in EPJ E, Julien Léopoldès at Université Gustave Eiffel, Marne la Vallée (formerly at ESPCI Paris) has discovered that mechanical vibrations also enhance structural aging in these systems, and can sometimes trigger sudden, jerking motions. The results could lead to a better understanding of how buildings are weakened by ambient vibrations, and may also help geologists to draw new insights into the mechanisms responsible for triggering earthquakes and landslides.
EPJA Topical Collection: CompOSE: a repository for Neutron Star Equations of State and Transport Properties
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- Published on 14 February 2023
Guest Editors: Danai Antonopoulou, Enrico Bozzo, Chikako Ishizuka, Ian Jones, Micaela Oertel, Constança Providencia, Laura Tolos and Stefan Typel
The CompOSE Topical Collection is a compendium of several works on neutron star equations of state (EoS) and transport properties related to the online repository CompOSE (CompStar Online Supernovae Equations of State).
EPJ D Highlight - Atoms slow down more within colder blackbody radiation
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- Published on 10 February 2023
New analysis shows that atoms will encounter high frictional forces in the presence of blackbody radiation at lower temperatures. Accounting for this effect could help researchers to improve the accuracy of high-precision experiments.
Blackbody radiation (BBR) contains electromagnetic waves with characteristic spectra, which changes shape depending on the temperature of the body. When moving atoms encounter these fields, they experience a repulsive force which slows down their movement towards the source of the radiation. Through new analysis published in EPJ D, Vipul Badhan and colleagues at Guru Nanak Dev University, India, show that the influence of this ‘blackbody friction force’ (BBFF) is particularly strong at lower temperatures.
EPJ H Highlight - Quarks and gluons: The JADE experiment at DESY
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- Published on 10 February 2023
A new paper in EPJ H describes the JADE experiment at DESY in Hamburg, in which high-energy electron-positron collisions led to the discovery of the particle that holds quarks together to form protons and neutrons: the gluon.
The DESY research centre in Hamburg has been at the centre of German physical science research since the 1960s, leading to important discoveries about the fundamental structure of matter. One experiment at DESY, known as JADE, recorded data on electron-positron collisions between 1979 and 1986. Siggi Bethke from the Max Planck Institute of Physics in Munich and Albrecht Wagner from DESY have now reviewed the history of JADE in the journal EPJ H: Historical Perspectives on Contemporary Physics.
EPJ B Highlight - Finely-tuned quantum dots enhance nonlinear optics
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- Published on 10 February 2023
Quantum dots with finely-tuned spherical defects could display advanced ‘nonlinear’ optical properties, new calculations have suggested. Adjusting the sizes of these defects could enable researchers to tightly control the brightness and frequency of the light they produce when illuminated.
Quantum dots are semiconductor particles measuring just a few nanometres across, which are now widely studied for their intriguing electrical and optical properties. Through new research published in EPJ B, Kobra Hasanirokh at Azarbaijan Shahid Madani University in Iran, together with Luay Hashem Abbud at Al-Mustaqbal University College, Iraq, show how quantum dots containing spherical defects can significantly enhance their nonlinear optical properties. By fine-tuning these defects, researchers could tightly control the frequency and brightness of the light emitted by quantum dots.
