Field of Science

The cosmological un-constant

Just a couple of abstract:
A general line element and a general metric tensor are defined as functions of two parameters $\alpha$ and $\alpha'$. The related Einstein's field equations of a gravitational potential field in a vacuum, including parameter $\Lambda$, have been derived. The parameters $\alpha$ and $\alpha'$ are identified in a gravitational field by the solution of the Einstein's field equations. Parallel with this, it has been find out that the so‐called cosmological constant $\Lambda$, is not really constant, but a function of gravitational radius, $\Lambda = f(r)$. This discovery is very important, among the others, for cosmology. One of the consequences is the new form of the acceleration equation of the universe motion that can be attractive (negative) or repulsive (positive). According to the observations, the repulsive acceleration gives rise to accelerating expansion of the universe at the present time. The obtained solution of the diagonal line element can be applied in a very strong gravitational field. Besides, this solution gives the Ricci scalar equal to zero, $R=0$. This is in an agreement with the current observation that our universe is flat.
from Novakovic B.M., Novakovic D.B. & Novakovic A.B. (2004). The Cosmological Constant $\Lambda$ is not Really Constant but the Function of a Gravitational Radius, AIP Conference Proceedings, 718 133. DOI:


pic via @astroperinaldo

Pluto's Panorama with the Sun far far away imagined in the documentary Universe - via @astroperinaldo

Quarks of power

about @LHCbExperiment #pentaquark discovery
Once upon a time, there was a controversy in particle physics. There were some physicists who denied the existence of structures more elementary than hadrons, and searched for a self-consistent interpretation wherein all hadron states, stable or resonant, were equally elementary. Others, appalled by the teeming democracy of hadrons, insisted on the existence of a small number of fundamental constituents and a simple underlying force law. In terms of these more fundamental things, hadron spectroscopy should be qualitatively described and essentially understood just as are atomic and nuclear physics.(11)
The need of the partons
When we descrive the collisions between particles, we calculate the cross section, the area of the distribution of the collisions' products. The mathematical object used to calculate the cross section are the structure functions, that mathematically describes the inner structure of the particle. In 1969 studying the deep inelastic scattering J. D. Bjorken(4, 18), in order to explain the experimental results, proposed a particular property for the hadronic structure function in the cross section called scaling. In the same year Richard Feynman(5, 18) suggested the necessity to adopt a new description of hadrons: they had to be made by smaller components, more elementary than the hadrons themselves. These components are called partons.
The Feynman's thesys was immediatly verified by Bjorken and Paschos(6, 7, 18), in this way starting a great discussion about the parton models, described in the paper by De Rújula, Georgi and Glashow quoted at the beginning of the post(11) (an interesting review of the parton model and its story is in Greenberg(18)).
Probably the most strong motivation to adopt the parton model to describe hadrons is the great production of particles in the ring particles accelerators(5). So, theoretical physicists produced a lot of model, but the most succesfull is the quarks model, developed by Murray Gell-Mann(1) and Georg Zweig(2, 3), that introduced a new quantum number, the flavor. The first formulation involved three type of quarks (and so three flavors): up, down and strange. To this first set of elementary particles in 1970 the quark charm was added by Glashow, Iliopulos and Maiani(8) and finally in 1973 Kobayashi and Maskawa(9) completed the family with the two last quark, top and bottom, named by Harari(10) in 1975.
Three quarks for Muster Mark!
Sure he has not got much of a bark
And sure any he has it's all beside the mark.
from Finnegan's Wake by James Joyce

The telescopic view of the Moon

John Philipps Emslie (1839–1913) was a British topographical artist and folklorist.
From 1854, Emslie studied at The Working Men's College, and was a student of Dante Gabriel Rossetti. He became a topographical artist, and illustrated The Illustrated topical record of London vol. 9. in 1900. He wrote and illustrated the New Canterbury Tales (Griffith, Farran, Okeden & Welsh) ca.1887.
Emslie was an original member of The Folklore Society and was a council member for that Society. He gathered local folklore from around England, making notes and topographical drawings.
He also realized a lot of scientific illustration, something like the modern infographics. For example the map of the Moon (via core77) at the beginning of the post. The caption of the map was a quotation by William Scoresby about his observation of the Moon at the Lord Rosse's telescope between 1847-48:
It appeared like a Globe of Molten Silver, and every object of the extent of a hundred yards was quite visible. Edifices, therefore of the size of York Minster might be early perceived if they had existed. But there was no appearance of anything of that nature neither was there any in diction of the existence of water or of an atmosphere. There was a vast number of extinct volcanoes, several miles in the breadth through one of them there was a line in continuance of one about 160 miles in length, which ran in a straight direction on like a railway. The general appearance however was like one vast ruin of nature.

Lovecraft and the discovery of Pluto

about #Lovecraft, #Pluto, #Lowell and #Tombaugh
The story of the Pluto's discovery started with Urban Le Verrier, a French mathematician that he was interested in celestial mechanics: performing some newtonian calculation, on on 31 August 1846, he announced the prediction of a planet beyond Uranus. This planet, Neptune, was discovered one month later by the astronomer Johann Gottfried Galle about 1° of the position predicted by Le Verrier. From further observation, astronomers supposed that there was another planet that perturbed Uranus' orbit.
Meanwhile in Providence a young boy growing with the passion of astronomy: Howard Phillips Lovecraft, in a letter to Rheinhart Kleiner on 16 November 1916, wrote:
In the summer of 1903 my mother presented me with a 2-1/2" astronomical telescope, and thenceforward my gaze was ever upward at night. The late Prof. Upton of Brown, a friend of the family, gave me the freedom of the college observatory, (Ladd Observatory) & I came & went there at will on my bicycle. Ladd Observatory tops a considerable eminence about a mile from the house. I used to walk up Doyle Avenue hill with my wheel, but when returning would have a glorious coast down it. So constant were my observations, that my neck became much affected by the strain of peering at a difficult angle. It gave me much pain, & resulted in a permanent curvature perceptible today to a close observer.(1)
Thanks to this passion for cosmos, Lovecraft starting to write The Rhode Island Journal of Astronomy:
In January, 1903, astronomy began to engross me completely. I procured a small telescope, and surveyed the heavens constantly. Not one clear night passed without long observation on my part, and the practical, first-hand knowledge thus acquired has ever since been of the highest utility to me in my astronomical writing. In August 1903 (though I knew nothing of the press associations) I commenced to publish an amateur paper called The R.I. Journal of Astronomy, writing it by hand, and duplicating it on a hectograph. This I continued for four years, first as a weekly, later as a monthly.(1)
he wrote in a letter to Maurice W. Moe, on 1 January 1915.
In this way he could perform a lot of observations and he also supposed the possible existence of a new planet beyond Neptune, like he wrote on a letter to the Scientific American:

Balloon, art and mathematics

After (or before?) @StartsWithABang's balloon animals' post?
A couple of week ago Ethan Siegel published a post about ballon animals, so I decide to repost an old piece that I wrote in 2011 for my italian blog: the english version is lost, but it is magically reposted here!

Two one-balloon constructions and their associated graphs
I recently discovered this interesting site, vihart. In the site there are some interesting paper and today I want to write something about Computational Balloon Twisting: The Theory of Balloon Polyhedra by Erik and Martin Demaine and Vi Hart (the paper was reported in 2010 by the Improbable Research blog).
The interest about ballon twisting was motivated by...
Balloon twisting is fun: the activity can both entertain and engage children of all ages. Thus balloon twisting can be a vehicle for teaching mathematical concepts inherent in balloons. As we will see, these topics include graph theory, graph algorithms, Euler tours, Chinese postman tours, polyhedra (both 3D and 4D), coloring, symmetry, and even NP-completeness. Even the models alone are useful for education, e.g., in illustrating molecules in chemistry.
There's also a second motivation: building architectural structures with air beams (Army blows up building, Center manages technology of inflatable composite structures).
Our approach suggests that one long, low-pressure tube enables the temporary construction of inflatable shelters, domes, and many other polyhedral structures, which can be later reconfigured into different shapes and re-used at different sites. In contrast to previous work, which designs a different inflatable shape specifically for each desired structure, we show the versatility of a single tube.

Twisting baloons
The problem of the researchers is to determine the twistable graphs. Referring to a phisical balloon like a bloon, we have the following definitions:
(...) a bloon is a (line) segment which can be twisted at arbitrary points to form vertices at which the bloon can be bent like a hinge. The endpoints of a bloon are also vertices. Two vertices can be tied to form permanent point connections. A twisted bloon is stable if every vertex is either tied to another vertex or held at a nonzero bending angle.
The three researchers also defined two models

The chirality at the beginning of the universe

A new clue about the #quarkgluonplasma from @RHIC_STAR at @BrookhavenLab
Within the particles that constitute atomic nuclei, protons and neutrons, there are the quarks, the elementary particles with fractional charges, linked to each other thanks to the gluons, bosons that carry the nuclear interaction. Thanks to the gluons it is impossible to observe, at present, free quarks, but it is expected that in the very first stage of the universe, matter was in a state called quark-gluon plasma. Thanks to the observation of so-called quark jets we know, indirectly, that the interior of the accelerators RHIC and LHC, in particular in heavy ion collisions, this kind of plasmas were created and, according to the theory, in the presence of axial anomalies, dued by the presence of strong electromagnetic fields, we can create two special effects: the Chiral Magnetic Effect (CME) and the Chiral Separation Effect (CSE).
The CME is the phenomenon of electric charge separation along the axis of the applied magnetic field in the presence of fluctuating topological charge.
The Chiral Separation Effect (CSE) refers to the separation of chiral charge along the axis of external magnetic field at finite density of vector charge (e.g. at finite baryon number density)(5)
These two effects are generated by the topology of the system: indeed, within the theory(1, 2, 3) is contemplated the existence of some numbers (called topological invariants, or winding number(4)) that, while not associated with an observable, still generate effects physically relevant because of their link with the fundamental symmetries of the system.