Quantum mechanics represented a revolution in physics with implications in many other fields like chemistry and biology. It also conducted changes on some of the main scientific lines of thought, including a farewell to determinism. In the science before quantum mechanics probability was accepted only as a lack of knowledge from the system being studied […]
It is likely that you have read somewhere that gravity is much weaker than the electromagnetic interaction. And it is true: for the electron and the proton gravity is 39 orders of magnitude weaker. Still what governs the movement of moons, planets, stars and galaxies is gravity; even the existence of dark matter is deduced […]
As we have discussed in our previous post, there is an important debate in the scientific community regarding the existence of negative absolute temperatures. The debate is not over, and both sides have valuable arguments, but in any case, one thing has already been proved. If negative absolute temperatures are real, the requirement to achieve […]
Graphene is a material with outstanding electronic characteristics. Many of them arise from the cone-like dispersion of charge carriers near the Fermi level (at which the occupation probability of energy levels is 0.5), where electrons behave as relativistic Dirac fermions, i.e., as if they had no mass. This excellent video from toutestquantique.fr summarizes them very […]
In an electromagnetic wave, the direction of the electric field is perpendicular to the direction of propagation of the wave. We say the wave is circularly polarized if the tip of the vector that represents the electric field describes a circular helix (thus circular polarization is sometimes called helicity) about the direction of propagation. Waves […]
An electric current can be visualized as a flow of electrons through a conducting piece of material. The less the resistance the material structure opposes to the flow of electrons the better a conductor it is. A part of this resistance appears at the surface of the material, where the electrons first encounter it; as […]
This is the second of the series of articles on the geometry of String Theory compactifications. Before reading this note, the interested reader may want to read the first note, where the concept of compactification background is introduced in the context of String Theory and M-Theory compactifications. As it is well known, to be well-defined […]
Mechanics and thermodynamics are two of the main pillars of physics. Mechanics, the branch of physics that studies movement, is considered to be well established since the publication of Isaac Newton’s Philosophiæ Naturalis Principia Mathematica (1687). Thermodynamics, the science dealing with heat and temperature, enjoyed its golden age in the 19th century, and was the […]
Imagine that you enter a room full of a poisonous gas wearing a mask that is not good enough to prevent the gas reaching your lungs and killing you. The mask is not good enough because it would allow the gas to diffuse through the fabric it is made of, eventually reaching your nose and […]
This is first of a series of notes on the geometry of String Theory compactifications. The space-time in String Theory is often described by means of a mathematical object called manifold . Manifolds are very important objects from the mathematical and the physics point of view, not only in String Theory. For example, differential geometry […]