Newton suggested that the apparent colours of natural objects depend on which colour is most strongly reflected or scattered to the viewer by the object. In general, there is no simple way of predicting from the surface structure, chemical composition, etc., what colours a substance will reflect or scatter. However, the blue colour of the […]
We now refer to light as the form electromagnetic radiation to which the human eye is sensitive and on which our visual awareness of the universe and its contents relies. If we want to go a step forward we could say that its macroscopic behaviour is best explained by a set of differential equations proposed […]
We know that incident light can provoke a strong optical response in metallic nanostructures due to the excitation of resonant plasmonic modes, i.e, the electrons in the metal become excited by the photons in the incident light and oscillate collectively. One of the most interesting properties of plasmon resonances is their associated enhancement and confinement […]
In the previous articles (I, II), we have characterized the simplest class of supersymmetric heterotic compactification backgrounds. In particular, we have finished the second article with the following result: There is a class of admissible Heterotic internal manifolds characterized as being six-dimensional, oriented, spin, Riemannian compact manifolds admitting a parallel spinor respect to the Levi-Civita […]
With “many-body problem” we usually make reference to one that is very difficult to obtain exact solutions for, because the system involves interactions between more than two bodies. This kind of problem appears both in classical and quantum systems. In order to understand the physics of many-body systems, it is necessary to make use of […]
Imagine you want to study the biology of an animal that no one has been able to capture. First, you devise a way of trapping it, then a method of calming it down so that you can manipulate it. This is exactly what David Wineland did, but his long-sought prey was not an animal, but […]
Chemistry • Condensed matter • Energy • Materials • Physics
The German mineralogist Gustav Rose (1798 – 1873) made important contributions in the fields of petrology and crystallography. He was the first to use a reflective goniometer in Germany and developed a particular interest in the relationship between the crystalline form and the physical properties of minerals. As a consequence, he contributed significantly to the […]
Anyone who has studied, even superficially, some thermodynamics has encountered the word adiabatic very early. This is because adiabatic processes are extremely useful to understand the basics of the field. An adiabatic process is any process that occurs without heat (or matter) entering or leaving a system. In general, an adiabatic change involves a fall […]
Our universe is not stable according to the currently measured values of the top quark and Higgs particle masses. There is a non-null probability that at any instant in the next billions of years the present “false vacuum” will change to a “true vacuum” by quantum tunneling, destroying all matter, energy and spacetime without any […]
Usually, the concept of exciton is linked to that of nonmetallic crystal: an electron-hole pair in a crystal that is bound in a manner analogous to the electron and proton of a hydrogen atom. It behaves like an atomic excitation (hence the name) that passes from atom to another and may be long-lived. Exciton behaviour […]