Portrait of a Jovian satellite

The Jovian moon Io, imaged by SHARK-VIS@LBT on January 10, 2024. The red, green, and blue channels of this tri-color image show the I (infrared), R (red), and V (green) spectral bands, respectively (corresponding at wavelengths of 755, 620 and 550 nanometers). This is the highest resolution image of Io ever obtained from a ground-based telescope.

The breath of the ancestors

A research team led by the INAF (Istituto Nazionale di Astrofisica) and the University of Trieste has once again harnessed the very distant and energetic relativistic winds generated by a distant but decidedly active quasar (one of the brightest discovered so far). A study published in The Astrophysical Journal reports the first observation at different wavelengths of the interaction between the black hole and the quasar of the host galaxy J0923+0402 during the initial phases of the Universe, about 13 billion years ago (when the Universe was less than a billion years old). In addition to evidence of a gas storm generated by the black hole, experts have discovered for the first time a halo of gas extending well beyond the galaxy, suggesting the presence of material ejected from the galaxy itself via winds generated by the black hole.

Our study helps us understand how gas is expelled or captured by galaxies in the young Universe and how black holes grow and can impact the evolution of galaxies. We know that the fate of galaxies such as the Milky Way is closely linked to that of black holes, since these can generate galactic storms capable of extinguishing the formation of new stars. Studying the primordial eras allows us to understand the initial conditions of the Universe we see today. - Manuela Bischetti

Good bye, Arno Penzias

Unfortunately I heared of this news now through the Physics World newsletter, whose releases from the beginning of the year I am guilty of catching up with a guilty delay.
On January 22, 2024 Arno Penzias left us. He was 90 years old and had been awarded the Nobel Prize for Physics in 1978 for the discovery, together with Robert Wilson, of the cosmic microwave background radiation.
As the story goes, their discovery came by chance, while they were trying to eliminate background noise from the signals that the Bell Labs radio astronomy antenna was receiving.
In fact, another group of astronomers, headed by Robert Dicke, was also busy working on the question, and in the end he was "satisfied" with correctly interpreting the origin of the signal measured by the two researchers. The two articles, the observational one and the interpretative one, were published in the same issue of the Astrophysical Journal.
The story, as well as being told in the Physics World article linked at the beginning of this post, is also summarized in the video that you can see below:

Alan Turing and the sunflowers

Alan Turing was fascinated by mathematical patterns found in nature. In particular, he noticed that the Fibonacci sequence often occurred in sunflower seed heads. However, his theory that sunflower heads featured Fibonacci number sequences was left unfinished when he died in 1954, but some years ago a citizen science project led by the Museum of Science and Industry in Manchester and the Manchester Science Festival has found examples of Fibonacci sequences and other mathematical sequences in more than 500 sunflowers.
Inspired by this, I suggest a prompt to NightCafe, a text-to-image generator to celbrate Turing and his unstoppable mind:

The first extragalactic black hole

In the world of black hole researchers, there is a group led by Tomer Shenar that, so far, has mostly demonstrated the non-existence of black holes previously announced by other teams.
As Shenar himself recalled, however,

For the first time, our group has come together to discuss the discovery of a black hole, instead of eliminating one.

We are talking about a black hole found inside the Tarantula Nebula, which is part of the Large Magellanic Cloud, one of the satellite galaxies of the Milky Way.
In particular, this black hole, of stellar mass, is of the "dormant" type, that is, it emits very low levels of X radiation, which are the radiations with which black holes are generally discovered.
This happens because the black hole interacts very little with its surroundings.
Another interesting aspect of the discovery is the absence of any trace of the star that generated the black hole.

[It] appears to have completely collapsed, with no sign of a previous explosion.

This black hole, the first extragalactic, was discovered orbiting a massive star thanks to six years of observations at ESO's Very Large Telescope.

Fields Medals 2022

I hope to write something about the Ising model in the next weeks, but in the meanwhile you can read something about E8 group. Below you can find the mathematicians that awarded the Field Medals 2022:

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Hugo Duminil-Copin

For solving longstanding problems in the probabilistic theory of phase transitions in statistical physics, especially in dimensions three and four.

June Huh

For bringing the ideas of Hodge theory to combinatorics, the proof of the Dowling–Wilson conjecture for geometric lattices, the proof of the Heron–Rota–Welsh conjecture for matroids, the development of the theory of Lorentzian polynomials, and the proof of the strong Mason conjecture.

James Maynard

For contributions to analytic number theory, which have led to major advances in the understanding of the structure of prime numbers and in Diophantine approximation.

Maryna Viazovska

For the proof that the E8 lattice provides the densest packing of identical spheres in 8 dimensions, and further contributions to related extremal problems and interpolation problems in Fourier analysis.

Noether's theorem

The Noether's theorem, discovered by German mathematician Emmy Noether, is one of the most sophisticated theorems in physics, a way to see how group theory, a branch of mathematics believed by many to be abstract, can provide the basis for an important physical concept. The premises of the theory of groups, coupled with the calculus of variations, lead to the conclusions of the theorem: the existence, under certain conditions, of conserved quantities within physical systems.
First of all we start with symmetry, one of the most important concepts for physics, and also the subject og group theory studies. To realize, therefore, this close link, it is enough to have in mind the statement of the theorem:

If a physical system exhibits some continuous symmetry, then there are corresponding observables whose values are constant over time.

A more sophisticated formulation of the theorem, on the other hand, goes something like this:

To every differentiable symmetry generated by local actions there corresponds a conserved current.

This more technical statement links the theorem and the symmetries with some of the most important groups for physics, the Lie groups. In the abstract of the Noether's paper, Invariant Variationsprobleme, in fact, we can read:

The problems in variation here concerned are such as to admit a continuous group (in Lie's sense); the conclusions that emerge for the corresponding differential equations find their more general expression in the theorems formulated in Section I and proved in the following sections.

The Noether's theorem, therefore, ensures that, when a physical system is invariant under the action of the transformations belonging to a Lie group, that is a group in which we are able to differentiate functions, then it certainly exists at least one conserved quantity, and this quantity and its invariance are expressed in the following equation: \[\frac{\text{d}}{\text{d} t} \left ( \frac{\partial L}{\partial \dot x_k} \right ) = \frac{\text{d} p_k}{\text{d} t}\]

Emmy Noether (1918). Invariante Variationsprobleme. de.wikisource.
English translation by Mort Tavel on arXiv