Field of Science

Alice underground: the door, the quaternion and the relativity

Alice underground is the first version of Aline in the wonderland by Lewis Carroll. The original manuscript, illustrated by Carroll himself, was given to the little Alice Liddell for Christmas in 1864 and picked up the story that he had told to Alice and her sisters Lorina and Edith during a summer's afternoon, precisely on July the 4th, 1862. This first version of the carrollian fantasy novel is, ultimately, a restricted version of Alice, where various characters and episodes completely absent in Underground are added, such as the Duchess or the team composed by the Mad Hatter, the March Hare and the Dormouse.
The intial, interesting considerations about underground is about the importance of the trees and the doors: following the suggestion by Adele Cammarata(3), we can assume that the tree and the door that Alice cross to enter the garden of the Queen of Hearts, completely absent in Wonderland, is linked with the Celtic tradition. Indeed the oak is one of the sacred trees of the druids, symbolizing a link between heaven and earth(1). In this way the oak, which in Celtic was called duir, is a real door that connects people with the gods, but also ourselves with our inner part. So, from an etymological point of view, a carved door in a tree trunk is a Celtic symbol used to identify the Alice's passage towards a more stable phase after the size's changes of the previous scenes.
These changes in size, alluding both to the transition to adulthood, in perfect connection with the Druidic symbolism, and with the more classic homothetic transformations, i.e. the transformations which, without changing the proportions of a geometric figure, change its size. All these changes remain unchanged in the transition to the second version, including the meeting with the Caterpillar, who continues to ask Alice:
Who are you?

Doubt like a salmon

An happy #towelday to all readers!
If you has ready and appreciate also one book by Douglas Adams, I think that you could have a little idea of what the people who knew him proved after his death. So, Peter Guzzardi composed The Salmond of Doubt with the idea to make an hearthful tribute to the writer of the Hitchhiker's Guide using unpublished articles, interviews and the third unfinished novel of the series of Dirk Gently, which also gives its name to collection.

from the italian cover of the book, by Franco Brambilla

Transit of Mercury

We speak about astronomical transit or simply a transit when an astronomical body move between the observer and the celestial body that he observes. In particular the transit was used by Planck to discover exolpanets, but we can use also to observe some events that occur in our solar system. And between 9th and 10th May it occurs the transit of Mercury between Sun and Earth.
In the figure below (via EclipseWise) you can see the visibility of the transit:
More details on: NASA | NakedEyePlanets.com

How to become a superhero


from Amazing Fantasy by Stan Lee and Steve Ditko
We analyze a collaboration network based on the Marvel Universe comic books. First, we consider the system as a binary network, where two characters are connected if they appear in the same publication. The analysis of degree correlations reveals that, in contrast to most real social networks, the Marvel Universe presents a disassortative mixing on the degree. Then, we use a weight measure to study the system as a weighted network. This allows us to find and characterize well defined communities. Through the analysis of the community structure and the clustering as a function of the degree we show that the network presents a hierarchical structure. Finally, we comment on possible mechanisms responsible for the particular motifs observed.
Gleiser, P. (2007). How to become a superhero Journal of Statistical Mechanics: Theory and Experiment, 2007 (09) DOI: 10.1088/1742-5468/2007/09/P09020 (arXiv)

A mathematical theory of communication

A mathematical theory of communication is a paper by Claude Shannon published in two part in July and October 1948. The paper posed the basis for the modern information theory and the basi elements of communication:
  • An information source that produces a message
  • A transmitter that operates on the message to create a signal which can be sent through a channel
  • A channel, which is the medium over which the signal, carrying the information that composes the message, is sent
  • A receiver, which transforms the signal back into the message intended for delivery
  • A destination, which can be a person or a machine, for whom or which the message is intended


Shannon, C. (1948). A Mathematical Theory of Communication Bell System Technical Journal, 27 (3), 379-423 DOI: 10.1002/j.1538-7305.1948.tb01338.x (pdf)
Shannon, C. (1948). A Mathematical Theory of Communication Bell System Technical Journal, 27 (4), 623-656 DOI: 10.1002/j.1538-7305.1948.tb00917.x (pdf)

The Marvel Universe as a real social network


Cover of the first number of Marvel Team-Up, comic book dedicated to the collaborations between Marvel heroes
We investigate the structure of the Marvel Universe collaboration network, where two Marvel characters are considered linked if they jointly appear in the same Marvel comic book. We show that this network is clearly not a random network, and that it has most, but not all, characteristics of "real-life" collaboration networks, such as movie actors or scientific collaboration networks. The study of this artificial universe that tries to look like a real one, helps to understand that there are underlying principles that make real-life networks have definite characteristics.
R. Alberich, J. Miro-Julia, & F. Rossello (2002). Marvel Universe looks almost like a real social network arXiv arXiv: cond-mat/0202174v1

Postcards from Pluto

The New Horizons mission has provided a lot of observations about Pluto, the farthermost known celestial object in our Solar System. Thanks to these observations, astronomers can now describe some interesting Pluto's characteristics.
The Pluto system is surprisingly complex, comprising six objects that orbit their common center of mass in approximately a single plane and in nearly circular orbits. (...)
All four of Pluto's small moons are highly elongated objects with surprisingly high surface reflectances (albedos) suggestive of a water-ice surface composition. Kerberos appears to have a double-lobed shape, possibly formed by the merger of two smaller bodies. Crater counts for Nix and Hydra imply surface ages of at least 4 billion years. Nix and Hydra have mostly neutral (i.e., gray) colors, but an apparent crater on Nix's surface is redder than the rest of the surface; this finding suggests either that the impacting body had a different composition or that material with a different composition was excavated from below Nix's surface. All four small moons have rotational periods much shorter than their orbital periods, and their rotational poles are clustered nearly orthogonal to the direction of the common rotational poles of Pluto and Charon.