History and Philosophy of Physics
On June 5, 1905 Poincar\'e presented a Note to the Acad\'emie des Sciences entitled "Sur la dynamique de l'\'electron" ("On the Dynamics of the Electron"). After briefly recalling the context that led Poincar\'e to write this Note, we…
I give some personal reflections on Jacob Bekenstein's pioneering work on associating an entropy to a black hole proportional to its area and on the generalized second law of thermodynamics.
From its earliest days nearly a century ago, quantum mechanics has proven itself to be a tremendously accurate yet intellectually unsatisfying theory to many. Not the least of its problems is that it is a theory about the results of…
Theories of quantum gravity generically presuppose or predict that the reality underlying relativistic spacetimes they are describing is significantly non-spatiotemporal. On pain of empirical incoherence, approaches to quantum gravity must…
Here follow three reports covering different aspects of the early history from 1964 to 1980 of the Hipparcos satellite mission. The first report "Interviews about the creation of Hipparcos" contains interviews from 2017 with scientists…
We consider that the report by William Herschel on April 19 and 20, 1787, about an erupting volcano on the moon were really the observations of impact melt, produced by a meteorite from the Lyrid meteor shower. According to our…
SN 1572, also known as the Tycho's Nova, was a supernova largely reported and discussed in the literature of the time. Here we talk about this literature. In the latest texts, we find also mentioned the Kepler's Nova, today known as SN…
In De Impressionibus Elementorum, a treatise written by Grosseteste shortly after 1220, we can find a discussion of some phenomena involving the four classical elements (air, water, fire and earth), in the framework of an Aristotelian…
Here I am proposing a discussion of some parts of the De Generatione Sonorum, one of the short treatises written by Robert Grosseteste. The main subject of this treatise is the phonetics. However, sound and oscillations are shortly…
There is the Gibbs theorem in thermodynamics, according to which the entropy of the mixture of ideal gases is equal to the sum of the entropies of the components of the mixture. J. W. Gibbs proved this by a mathematical derivation from the…
Forty years ago I spent a year with my family at the Sacramento Peak Observatory in Sunspot, New Mexico. In August 2017 the U.S. National Solar Observatory ended its presence there with a Farewell Workshop. These reminiscences are in that…
There are relatively few antique photographs of the Sun compared to drawings of the solar disc. We want to highlight three solar photographs taken by Giorgio Roster in 1893. Roster (1843-1894) was a doctor, chemist, and photographer. The…
Who was Ulugh Beg? A prince who governed a province in the central Asian empire built by his grandfather Tamerlane. Above all, he was a scholar who founded the Samarkand astronomical observatory, whose work predated that of the best…
A possible way out of the conundrum of quantum gravity is the proposal that general relativity (GR) is not a fundamental theory but emerges from an underlying microscopic description. Despite recent interest in the emergent gravity program…
A brief history of the discovery of the expanding universe is presented, with an emphasis on the seminal contribution of VM Slipher. It is suggested that the well-known Hubble graph of 1929 could also be known as the Hubble-Slipher graph.…
The application of quantum theory to cosmology raises a number of conceptual questions, such as the role of the quantum-mechanical notion of "observer" or the absence of a time variable in the Wheeler-DeWitt equation. I point out that a…
This paper aims to recall some of the main contributions of Roberto Petronzio to physics, with a particular regard to the period we have been working together. His seminal contributions cover an extremely wide range of topics: the…
We present a centennial review of the history of the term known as the cosmological constant. First introduced to the general theory of relativity by Einstein in 1917 in order to describe a universe that was assumed to be static, the term…
There are well-known problems associated with the idea of (local) gravitational energy in general relativity. We offer a new perspective on those problems by comparison with Newtonian gravitation, and particularly geometrized Newtonian…
Robert Stirling's patent for what was essentially a new type of engine to create work from heat was submitted in 1816. Its reception was underwhelming and although the idea was sporadically developed, it was eclipsed by the steam engine…