Category archives: Physics

The properties of bismuth have long defied classification, placing it in a category of its own. Now, as if it was not enough, it turns out its electronic structure has higher-order topology. This has been shown by an international team with the participation of Maia G. Vergniory (DIPC, Ikerbasque, UPV/EHU) and coordinated by Titus Neupert […]

Most of the theories describing dynamical processes at surfaces rely on the validity of the adiabatic Born-Oppenheimer approximation. What does this mean? We have already seen that adsorption commonly is understood as the reversible binding of molecules and atoms from the gaseous or liquid phase on surfaces, mostly of highly porous adsorbent media. In chemisorption […]

The concept of moduli space is of utmost relevance in theoretical physics and mathematics, especially in geometry, topology and string theory. A moduli space is, roughly speaking, a space that classifies a given class of objects modulo an equivalence relation # which identifies the objects in that we want to consider as equivalent or, more […]

Since the discovery that graphene, the two dimensional carbon allotrope, can be isolated and incorporated into electronic devices intense research efforts have been triggered. Driving forces usually mentioned behind the experimental and theoretical studies of graphene are the exceptional electronic properties, in particular the high electron mobilities, the long spin coherence lengths and the possibility […]

The electronic wave function of an n-electron molecule depends on 3n spatial and n spin coordinates. In a sense, the wave function of a many-electron molecule contains more information than is needed and is lacking in direct physical significance. This has prompted the search for methods that involve fewer variables than the wave function and […]

Topological insulators are materials with special universal properties, which are protected against perturbations. Such properties are theoretically described by topology, a branch of mathematics concerned with the properties of geometrical objects that are unchanged by continuous deformations. Concretely, topological insulators are electronic materials that have a bulk band gap like an ordinary insulator but have […]

The wave–particle dualism is a fundamental aspect of quantum mechanics. But, in order to explore this dualism properly and what it means for our image of atoms, it is necessary to review some ideas of probability. In some situations, no single event can be predicted with certainty. But it may still be possible to predict […]

You may have read somewhere that atoms are actually made up mostly of empty space. The usual description goes more or less as follows. At the centre of each atom there is a very tiny nucleus, which carries all of the positive charge and nearly all of the mass of the atom. Surrounding the nucleus […]

In the previous post, Family unification 1, we reviewed the historical development of Grand Unified Theories (GUT) of force and matter, i.e. Comprehensive Unification. We saw how the SO(18) spinor, 256, is able to accomodate the Standard Model (SM) family structure, however it contains too many families and, also, phenomenologically dangerous mirror families. During the […]

How long does it take a photon to split a molecule? It is apparent that the answer must be well bellow a second, but, how much bellow? Attoscience focuses on these kind of phenomena that occur at the attosecond time-scale using pulses of electrons or photons. The prefix ‘atto-‘, symbol a, means 10-18, hence an […]