On April 10 th 2019, the Event Horizon Telescope project released the first image ever of a black hole. Five simultaneous press conferences, in Brussels, Taipei, Santiago de Chile, Tokyo and Washington were broadcast live, staging a global media event for astrophysics. Besides the inevitable memes in the so-called social media, more serious press outlets […]
Black holes are vacuum solutions of the Einstein equation. Hence, the energy-momentum tensor for a black hole is null at every point of space. The only place where its mass can be located is where there is no space, i.e., at the singularity. Hence, for a Schwarzschild black hole, the mass is located at the […]
I remember very well my physics professor during my first year at university. She stressed the importance of having clear intuitions of what physical terms mean before any mathematics was invoked. ‘Imagine someone drops an 100-gram apple 1 metre above your head’, she would say; ‘the pain you feel is the equivalent of a joule […]
It is commonly said that Astronomy is an observational science. We cannot create and study stars or galaxies in our laboratories and, thus all the information we have from the Universe comes from observations. However, there is another approach: simulations. Astronomers use complex algorithms and computational techniques, in combination with the laws of physics, to […]
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 […]
Superconductors are a particularly strange kind of metal. What makes them different is their behavior at very low temperatures – extremely low, that is, close to absolute zero. Basic thermodynamics dictates that in this regime we should expect all motion to cease, the constituents of the material being frozen at fixed positions. And with no […]
Black holes are not only gravitationally attractive: they also capture people’s attention. Just mention these two words in a course of elementary astronomy or in a public conference and you will find most eyes wide open. Even though they are common in observational astronomy, their singular physics and their fantastic dimensions makes them earn a […]
During the last year, a longtime forgotten controversy was reactivated by a very interesting paper written by J. Polchinski and his collaborators, in which they questioned whether the so called black hole complementarity principle is a good solution to the apparent information paradox of quantum gravity. This is a question that attracted a lot of […]
NGC1365 is a beatiful galaxy. It is big and bright enough to be observed with a medium-sized amateur telescope. Sometimes mis-located at the southern constellation of Eridanus, it is indeed located in the smaller Fornax constellation and it is one of the most notable peers in a famous galaxy cluster. Being one third of the […]
The idea sounds almost like science fiction: two tiny particles that are quantum mechanically linked might also be connected by microscopic shortcuts through spacetime itself, tiny wormholes. This possibility, known as the ER = EPR conjecture, has become a serious topic at the frontier where quantum mechanics meets gravity. The entanglement-is-just-a-wormhole idea The initials point […]