Butterflies, hurricanes and... pools!

Chaos is nothing more than order seen from the opposite side.
This defintion by Fethry Duck in the italian story Il mobile caotico (The chaotic furniture) can be considered very centered on the heart of chaos. And the mathematical tool that we used to study it is the theory of chaos.
Flapping the wings
What best identifies chaos theory is the butterfly effect, which identifies in a simple and effective way the strong dependence of chaotic systems on initial conditions. The name was first used by Edward Lorentz, who published the first article on this effect in 1963(1).
The popular version of the butterfly effect goes something like this: The flapping of a butterfly's wings in Brazil causes a hurricane in New York and the use of the butterfly was probably suggested to Lorentz from Ray Bradbury's 1952 short story A sound of thunder in which an unwary time traveler, stepping out of the path set by the travel agency and thus stepping on a butterfly, even manages to change the result of the last US presidential elections, allowing a fascist to become the most powerful man on the planet!
From a scientific point of view, one of the most typically chaotic problems is that of weather forecasts, because of the large amount of variables that are present. The appearance of chaotic behaviors, however, would not be so scientifically interesting if it were not for one of their particular characteristics: the fundamental laws that govern, for example, time are deterministic and individually easily solved, but by combining together a large number of such equations, not only the resolution of the system is more complicated, so much so that it is necessary to use electronic calculators, but also the solution shows a chaotic behavior graphically well identified by the Lorentz attractors:

42: A family portrait

No, this is not the towel day, but what ESO released yesterday is undoubtedly something quite useful for any space tourist: a series of 42 detailed images of the largest asteroids in the solar system.
The main asteroid belt, located just beyond the orbit of Mars, is made up of rocky objects of various sizes, reaching up to 200 km in diameter, without forgetting the largest of all, Ceres and Vesta, respectively 940 and 520 kilometers in diameter. The family portrait of the 42 asteroids was made using the Very Large Telescope:

Nobel Prize in Chemistry 2021: A scent of Feynman

One of the most famous speech by Richard Feynman is There's plenty of room at the bottom:
Now comes the interesting question: How do we make such a tiny mechanism? I leave that to you. However, let me suggest one weird possibility. You know, in the atomic energy plants they have materials and machines that they can’t handle directly because they have become radioactive. To unscrew nuts and put on bolts and so on, they have a set of master and slave hands, so that by operating a set of levers here, you control the “hands” there, and can turn them this way and that so you can handle things quite nicely.
The idea is to manipulate molecules to build, for example, an electric engine, or a book, or something else. The most curious fact about the Nobel Prize in Chemistry 2021 is that Johan Jarnestad has illustrated the work of Benjamin List and David MacMillan using a couple of workers, an image that, in a particular way, is very similar to Feynman's idea.
Building molecules is a difficult art. Benjamin List and David MacMillan are awarded the Nobel Prize in Chemistry 2021 for their development of a precise new tool for molecular construction: organocatalysis. This has had a great impact on pharmaceutical research, and has made chemistry greener.
I hope to write soon an article about Feynman and miniaturization obviously from the physics point of view.
Stay tuned!

Giorgio Parisi: A Nobel for complex systems

The last time an italian was awarded the Nobel Prize in physics was in 2002: Roberto Giacconi for his pioneering research in the field of X-ray radiation from the universe. Another italian research that probably could win the Prize was Adalberto Giazotto, who designed the VIRGO interferometer, that with LIGOs shared the first observation of gravitational waves. The Swedish Academy decided to assign the Prize to three of the LIGO's founders, Rainer Weiss, Barry Barish and Kip Thorne. But this is not a great problem: after all, the Nobel Prize serves to emphasize personal contributions, but also to establish key points in the knowledge, and in this sense, the role of Italy had already been indicated as fundamental.
Today, however, a long-awaited award arrives: Giorgio Parisi, theoretical physicist, whose works have provided important contributions to field theory and statistical physics, won the Nobel Prize in physics
for the discovery of the interplay of disorder and fluctuations in physical systems from atomic to planetary scales

Dark scent


The hand of creation by John Byrne from Green Lantern: Ganthet's Tale
The XENON1T experiment at Gran Sasso's laboratories in Italy is a liquid xenon detector designed for serach of the mysterious dark matter. About one year ago researchers observed an excess of events: 53 more than the 232 predicted(1).
There are several explanations: an unexpected noise' source; the passage of some axions, an hypothetical particle predicted by Roberto Peccei and Helen Quinn in 1977; some neutrinos that interact with matter in a new way.
Or dark matter's traces(2). There are two new articles suggesting this; in particular the second suggests that the detected excess in XENON1T is dued by chameleons(3).
The chameleon is an(other) hypothetical particle proposed in 2003 by Justin Khoury and Amanda Weltman, that couples to matter more weakly than gravity, and so a candidate for dark matter. It has a variable mass, so the hypothetical fifth force mediated by the chameleons can evade the constraints deduced by experiments on the equivalence principle. In this way chameleons could drive the observed acceleration of the universe's expansion, but it's very difficult to verify experimentally.
  1. XENON collaboration. (2020). Excess electronic recoil events in XENON1T. Physical Review D, 102(7). doi:10.1103/PhysRevD.102.072004 ↩︎
  2. Aboubrahim, A., Klasen, M., & Nath, P. (2021). Xenon-1T excess as a possible signal of a sub-GeV hidden sector dark matter. Journal of High Energy Physics, 2021(2), 1-21. doi:10.1007/JHEP02(2021)229 ↩︎
  3. Vagnozzi, S., Visinelli, L., Brax, P., Davis, A. C., & Sakstein, J. (2021). Direct detection of dark energy: the XENON1T excess and future prospects. Physical Review D, 104(6). doi:10.1103/PhysRevD.104.063023 ↩︎

The Case for Dwarf K Stars

20210914-61-cygni
61 Cygni, a binary K-type star system - via commons
The stellar main-sequence is a strip that cuts diagonally the Hertzsprung-Russell diagram, a star's plot of stellar color versus brightness. The main feature of main-sequence stars is that they burn hydrogen. In this group the K dwarfs, or orange dwarfs, are intermediate stars in size between red M stars (red dwarfs) and yellow G stars. Their mass is between 0.5 and 0.8 times the Sun's mass and surface temperature is bewteen 3900 and 5200 K.
In the last few years these type of stars have become particularly interesting to astronomers, as they appear to have the characteristics to host life-as-we-know:

Uchuu: Universes' creator

If you are a superheroes' comics readers, you probably know All-Star Superman by Grant Morrison and Frank Quitely (if you want, I could publish a review of this comic). At some point in the story, Superman designs a small cubic universe to see what would happen on a planet like Earth without his presence. The development of intelligent life was also included in the Superman's simulation, but in essence even those of astronomers are structured in the same way: a cube of space of finite dimensions whose evolution is driven by a network of dark matter and dark energy.
At the end of the july 2021 it was realased Uchuu, presented as a suite of large high-resolution cosmological N-body simulations, in practice, a simulation that shows the evolution of dark matter structures in a cube of 9.63 billion light years on each side and made up of 2.1 trillion particles.
Uchuu's main goal is to shed light on the dark matter halos surrounding galaxies, but the researchers think that another field of use for their simulation is the study of gravitational lenses.
In any case, it is a tool that could be very useful for improving the algorithms generally used in astronomy to process the data collected by instruments such as satellites and telescopes.
Ishiyama, T., Prada, F., Klypin, A. A., Sinha, M., Metcalf, R. B., Jullo, E., ... & Vega-Martínez, C. A. (2021). The Uchuu simulations: Data Release 1 and dark matter halo concentrations. Monthly Notices of the Royal Astronomical Society, 506(3), 4210-4231. doi:10.1093/mnras/stab1755 (arXiv)
Read also:
Skies & Universes
Uchuu project on Git-Hub