- 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.>
- Published on 11 July 2018
Quantum secret-sharing scheme for noisy environments
To protect the confidentiality of a message during its transmission, people encrypt it. However, noise in the transmission channels can be a source of concern regarding how faithful the message transmission may be after it has been decrypted. This is particularly important for secrets shared using quantum scale messengers. For example, a classical secret takes the shape of a string of zeros and ones, whereas a quantum secret is akin to an unknown quantum state of two entangled particles carrying the secret. This is because no two quantum particles can be in the same state at any given time. In a new study published in EPJ D, Chen-Ming Bai from Shaanxi Normal University, Xi’an, China, and colleagues calculate the degree of fidelity of the quantum secret once transmitted and explore how to avoid eavesdropping.
- Published on 10 July 2018
The publishers of The European Physical Journal C – Particles and Fields are pleased to announce the appointment of Professor Kostas Skenderis as new Editor-in-Chief for Theoretical Physics II: Gravitation, Astroparticle Physics and Cosmology, General Aspects of Quantum Field Theories, and Alternatives, replacing Professor Ignatios Antoniadis.
Kostas Skenderis is Director of the Southampton Theory Astrophysics and Gravity (STAG) Research Centre and a Professor in Mathematical Sciences at the University of Southampton. His research interests are in high energy theoretical physics and string theory, and in particular in the study of holographic dualities, their foundations and their applications.
- Published on 04 July 2018
A new study investigates the extremely rapid changes in the density of electrons in specific sites of the caffeine molecules thanks to an ultra-fast laser pulse that persists long enough to be observed
Caffeine keeps physicists up at night. Particularly those concerned with the capacity of electrons to absorb energy. In a new study published in EPJ B, a Franco-Japanese team of physicists have used the caffeine molecule as a playground to test the effect of ionising radiation on its electrons as they approach excited states. Their model accounts for the ionisation phenomenon in electrons, which are in a site-specific, localised orbit in the caffeine molecule. The electron excitation leaves the door open to positive charge progression along a molecular backbone. Thomas Niehaus from Claude Bernard Lyon 1 University, France, and colleagues have now developed a method for quantifying this positive charge migration in line with the ultra-short laser impulse. The observed charge motion happens on an attosecond time scale charge rearrangements driven by nuclear motion.
- Published on 26 June 2018
New study of Bitcoin transactions reveals hidden owner communities and a high-concentration of wealth distributed between a few people
Cryptocurrencies like Bitcoin can be analysed because every transaction is traceable. This means that they are an attractive system for physicists to study. In a paper published in EPJ B, Leonardo Ermann from the National Commission for Atomic Energy in Buenos Aires, Argentina, and colleagues from the University of Toulouse, France, have examined the structure of the Bitcoin-owner community by looking at the transactions of this cryptocurrency between 2009 and 2013. The team’s findings reveal that Bitcoin owners are close to an oligarchy with hidden communities whose members are highly interconnected. This research has implications for our understanding of these emerging cryptocurrency communities in our society - as usual bank transactions are typically deeply hidden from the public eye. They could also be helpful to computer scientists, economists and politicians who could better understand handle them.
- Published on 26 June 2018
Mobile data can be (and has been) used to study a vast number of subjects related to human behavior. One of its potential applications is on epidemics, a complex field that is informed not only by healthcare, but also social interactions and human mobility. In this blog post, Stefania Rubrichi explains the context in which her team used a real mobile phone dataset in an attempt to better understand and tackle the spread of diseases. Their study was just published in the journal EPJ Data Science.
(Guest post by Stefania Rubrichi, originally published on the SpringerOpen blog)
- Published on 26 June 2018
New study of how positive and negative electrical charge disorder at the ends of polymers acts like a green or red light for proteins to pass through biological membranes
Nature’s way of allowing proteins across its gates, through porous biological membranes, depends, among others, on their electrical charge. For a protein to cross this type of membrane, it needs to be stimulated by an electrical field. A new study focuses on a particular kind of proteins that have multiple functions - dubbed Intrinsically Disordered Proteins - because the electric charge disorder on their surface makes it possible for them to take multiple shapes. In the work, recently published in EPJ E, Albert Johner from the Charles Sadron Institute (part of the CNRS) in Strasbourg, France and Jean-Francois Joanny from Paris reveal how the mixed electrical charge at the ends of the proteins influences biological membrane crossing. This has potential implications for our understanding of how proteins travel across the body, and of disease mechanisms.
EPJ B Highlight - Futuristic data storage based on controlling the interactions between nanodots magnetic ‘mood’ twirls
- Published on 18 June 2018
Better understanding of the changing magnetic state of nanometric squares in an array could be the basis for future ultrahigh density data storage
The magnetisation of nanometric square material is not fixed. It moves around in a helical motion. This is caused by the electron whose degree of freedom, referred to as spin, which follows a precession motion centred on the middle of a square nano-magnet. To study the magnetisation of such material, physicists can rely on two-dimensional arrays of square nanomagnets. In a paper published in EPJ B, P. Kim from the Kirensky Institute of Physics, associated with the Russian Academy of Sciences, in Krasnoyarsk, Siberia, Russia, and colleagues have devised a new model taking into account the factors affecting the magnetic interaction between individual nanomagnets. Better controlling such nanomagnets arrays could have applications in ultrahigh density data storage,in an electronic application called spintronics exploiting electron spins and its magnetism, and in micro- and nanosurgery controlled by magnets.
- Published on 14 June 2018
New model examines the relative role of random interactions between individuals in a crowd compared to interactions stemming from their eagerness to be on their way
Ever found yourself crushed in a metro station at rush hour? The mathematician Carlo Bianca and physicist Caterina Mogno, both from the engineering research lab ECAM-EPMI in Cergy-Pontoise, France, have developed a new model to study the movement of crowds exiting a metro station. In a recent study published in EPJ Plus, they have for the first time employed models typically used to study gases consisting of a large number of molecules that collide at random (known as thermostatted kinetic theory) to study the consequences of the different interactions occurring among pedestrians in a crowd while exiting a metro station.
- Published on 12 June 2018
New study reveals theoretical calculation of new possible state for quantum particles which have received a photon
Quantum particles behave in mysterious ways. They are governed by laws of physics designed to reflect what is happening at smaller scales through quantum mechanics. Quantum state properties are generally very different to those of classical states. However, particles finding themselves in a coherent state are in a kind of quantum state which behaves like a classical state. Since their introduction by Erwin Schrödinger in 1926, coherent states of particles have found many applications in mathematical physics and quantum optics.
Now, for the first time, a team of mathematical physicists from Togo and Benin, call upon supersymmetry - a sub-discipline of quantum mechanics - to explain the behaviour of particles that have received a photon. These particles are subjected to particular potential energies known as shape-invariant potentials.
In a paper published in EPJ D, Komi Sodoga and colleagues affiliated with both the University of Lomé, Togo, and the University of Abomey-Calavi, in Cotonou, Benin, outline the details of their theory. These findings are relevant to scientists working on solving quantum optics and quantum mechanics applications.