The band theory of metals has been subjected to experimental tests many times and is now the accepted model of the behaviour of conductors and insulators. But it has to be modified when it comes to superconductivity. Electrical resistance is due to collisions of the electrons (whether treated as particles or waves) with impurities, imperfections […]
In our previous post, we have discussed the importance of a loophole-free entanglement experiment. Now, we are going to discuss one of the most important loopholes for this kind of experiments, the locality (or communication) loophole . To understand the locality loophole we need to review the Bell’s inequalities experiments one more time. Alice and […]
In 1928, just two years after the formulation of quantum mechanics, the German physicist Arnold Sommerfeld modified the classical free-electron model by treating the electrons according to quantum mechanics. But the new theory still contained the unrealistic assumption that the electrons do not interact with the charged lattice ions except to collide with them. As […]
Electrical energy is now the dominant form of energy consumption in industrialized countries and is an essential element in the operation of many of the devices we use every day. For decades, one of the most poorly understood yet most practical properties of a piece of solid matter was its ability, or lack of ability […]
Recently, a new experiment has attracted a lot of attention. It was published in Nature and entitled as “Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometres ” . Many scientific and non-scientific media took account of the results of the experiment and published short news with fancy titles as Quantum ‘spookiness’ passes […]
One of the first recognized successes of the early quantum theory arose, not from the study of radiation, but from the theory of solids. Once again in the physics of the first half of the 20th century Albert Einstein was at the forefront; but this time the story is seldom told. After presenting the hypothesis […]
We finished our last article saying that it is one thing to accept this newly stated connection between electric and magnetic fields; but it is a little bit harder, and more interesting, to understand the physical necessity for such a connection. We will try to explain this necessity now avoiding the use of mathematics, step […]
We recently explored the concepts that Faraday introduced regarding the relationship between electricity and magnetism. In this article we focus on their treatment by Maxwell. The work of Oersted, Ampere, Henry, and finally Faraday had established two basic principles of electromagnetism: 1. An electric current in a conductor produces magnetic lines of force that circle […]
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 […]