Slender Galaxies

The tradition of horror stories is full of hooded characters, but the great success of creepy pasta, short stories, but also animations and illustrations spread online, has led to the success of a particularly disturbing character, Eric Knudsen's Slender Man. And the above shot taken by the Hubble Space Telescope on June 19, 2019 is somewhat reminiscent of that disturbing kidnapper of children. From an astronomical point of view, the image captured a particularly advanced collision of two galaxies.
But as a fan of superhero comics I find that also Mr. Bloom, a Batman's villain recently introduced (2015), could be a very good alter ego of Arp-Madore 2026-424.

Maths in Europe: Seven cosmic messengers

Let us suppose we travel from Earth to the furthest observable point in the universe. We have seven satellites on our spacecraft, used to keep communications between us and the Earth. Let’s suppose that the speed of the satellites coincides with that of light, or in any case equal to a speed whose difference with c is negligible, while the speed of the spacecraft is $v = 2 / 3c$. The satellite, once it reaches Earth orbit, transmits the information we have loaded into its memory, then heads back to us to collect the new information. Meanwhile, within 24 hours of each other, we launch all the satellites.
The time each probe takes will be given by the formula \[t = \frac{y_1+y_0}{c}\] where $y_0$ is the distance traveled on the outward journey (or if you prefer the relative position of the spacecraft respect to the Earth at the time the first probe was launched), $y_1$ the distance of the return (or the position of the spacecraft when the first probe returns) and c is the speed of the probe.
(continue on Mathematics in Europe)

Great number

The Large Numbers hypothesis asserts that all the large dimensionless numbers occurring in Nature are connected with the present epoch, expressed in atomic units, and thus vary with time. It requires that the gravitational constant G shall vary, and also that there shall be continuous creation of matter. The consistent following out of the hypothesis leads to the possibility of only two cosmological models. One of them, which occurs if one assumes that the continuous creation is a multiplication of existing matter, is Einstein’s cylindrical closed Universe. The other, which occurs if one assumes the continuous creation takes place uniformly through the whole of space, involves an approximately flat Minkowski space with a point of origin where the Big Bang occurred.
Dirac, P. A. M. (1974). Cosmological models and the large numbers hypothesis. Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences, 338(1615), 439-446. doi:10.1098/rspa.1974.0095


Evaluating Beneficio is by no means trivial. The narrative is all concentrated around a woman in search of herself, remembering her missing grandmother.
There is not only this, however. The protagonist's journey takes her to Beneficio, a valley near the Spanish village of Orgiva where there is a community that lives in contact with nature in self-built tents, tepees and shelters.
In this environment the woman begins to reflect on her life and then passes, without any solution of continuity, to the universe and the divine, mixing fantastic, almost religious ideas, with the great scientific questions still unanswered. All within a valley surrounded by large mountains, wild and peaceful.
The narrative itself fits the theme: the story is diluted and rarefied, the pages with the minimum number of vignettes (rarely more than three or four), while the drawings now look like travel sketches, at other times particularly detailed.
Overall, both from a narrative and an aesthetic point of view, Beneficio by Michał Kalicki and Krzysztof Gawronkiewicz is almost a land version of Daisuke Igarashi's Children of the sea.

Supermassive web hole

With the help of ESO’s Very Large Telescope (VLT), astronomers have found six galaxies lying around a supermassive black hole when the Universe was less than a billion years old. This is the first time such a close grouping has been seen so soon after the Big Bang and the finding helps us better understand how supermassive black holes, one of which exists at the centre of our Milky Way, formed and grew to their enormous sizes so quickly. It supports the theory that black holes can grow rapidly within large, web-like structures which contain plenty of gas to fuel them.
The location of the supermassive black hole is in the Sextans' constellation.
Sextans is a small and dark constellation straddling the celestial equator and located near Leo. Introduced in 1687 by Johannes Hevelius, thanks to its equatorial position, the Sextant is visible from most of the Earth's surface.
The main stars are not particularly bright, but with a particularly clean sky it is possible to identify them even with the naked eye, in particular Alpha Sextantis, a blue-white giant with a magnitude of 4.48, and 35 Sextantis, an orange double star, the whose main star has a magnitude of 5.79. Also noteworthy there are the white Gamma Sextantis (magnitude 5.07) and the blue Beta Sextantis (magnitude 5.08).
(via ESO)

John Barrow: Some Generalities About Generality

John D. Barrow - via commons
On 1 December 2014 I had the pleasure of attending a lecture by John David Barrow at the "Enriques" Department of Mathematics in Milano. Very kind person, when I approached him to be able to shake his hand and take a picture of him, he granted me both honors with great simplicity. Unfortunately that photo has now been lost among smartphone changes, perhaps kept in some hard disk stored somewhere, nor did I publish it on one of my social networks, but I still wanted to pay homage to it by offering you the abstract of an article from 2015, the fifth chapter of the book The Philosophy of Cosmology (arXiv):
We survey a variety of cosmological problems where the issue of generality has arisen. This is aimed at providing a wider context for many claims and deductions made when philosophers of science choose cosmological problems for investigation. We show how simple counting arguments can be used to characterise parts of the general solution of Einstein's equations when various matter fields are present and with different spatial topologies. Applications are described to the problem of singularities, static cosmological models, cosmic no hair theorems, the late-time isotropisation of cosmological models, and the number of parameters needed to describe a general astronomical universe.

The flying Batman

Comics' authors, and more generally those who write about fiction (but not only them), are the modern Scheherazade of One Thousand and One Nights. This comparison is very fitting for Detective Comics #1027 which celebrates at the same time #27, where Bob Kane and Bill Finger's Batman made his debut, and the 1001th issue of the magazine dedicated to the Caped Crusader, so you understand the initial comparison.
I'm not here, though, to write you why Detective Comics's 1001 releases with Batman (if you want to, follow note(1)), but to seize the opportunity and talk about Batman's physics.