Field of Science

Magical modular furniture

#MIT #design #furniture #technology #Milano
Transform is a magical, modular furniture developed by MIT:
The work is comprised of three dynamic shape displays that move more than one thousand pins up and down in realtime to transform the tabletop into a dynamic tangible display. The kinetic energy of the viewers, captured by a sensor, drives the wave motion represented by the dynamic pins.
The motion design is inspired by the dynamic interactions among wind, water and sand in nature, Escher’s representations of perpetual motion, and the attributes of sand castles built at the seashore. TRANSFORM tells the story of the conflict between nature and machine, and its reconciliation, through the ever-changing tabletop landscape.
They came in Italy during the last design week, but I was busy at school, so I cannot go to see the exhibition and I had to settle with the videos:
It's a hard life...
(via Wired)

Jurij Gagarin: a dream during an orbit

by @ulaulaman about #YuriGagarin #space_esploration #Russia #ColdWar
He was born in Klušino on the 9th March, 1934; he died on the 27th March 1968, in a plane crash. His death and the controversy that followed and especially the pioneering gesture for which I remembered him today, make me pull over to Hal Jordan, a comic book superhero. In fact, Yuri Alekseevich Gagarin, when he returned home from his space mission, was celebrated as a hero, as a man who was raised on humanity in all its stature: the 12nd April 12 1961 he had become the first man to go in space, completing one orbit around the Earth.
Jurij Gagarin
Yuri has thus paved the way for space, marking a key point in the path toward the Moon: at that time Russia was very close to winning that race in space that characterized the Cold War, but thanks to Wernher von Braun, United States conquest the Moon before their opponents. In every case the importance of Gagarin and the Russian space school are now remembered for example with the movie First Orbit:

Waiting for the beginning

Following a draft published on arXiv a couple of weeks ago, the BICEP2's observations could be explained not only with the cosmic inflation, but also with another mechanism:
The recent claimed observation of primordial gravitational waves provides a dramatic new empirical window on the early universe. In particular, it provides the opportunity, in principle, to de nitively test the inflationary paradigm, and to explore the speci c physics of inflationary models. However, while there is little doubt that inflation at the Grand Unfi ed Scale is the best motivated source of such primordial waves, it is important to demonstrate that other possible sources cannot account for the current BICEP2 data before definitely claiming Inflation has been proved.
A possible contribution to BICEP2's signal could be given by a self ordering scalar field:
Finally we note that while current data cannot de nifitively rule out a SOSF transition as the source of gravitational waves, it nevertheless does imply that the source for such waves is at, or near the Grand Uni ed Scale. Thus, it allows an exploration of physics at a scale far larger than we can currently constrain at terrestrial experiments. This will be very important for constraining physics beyond the standard model, whether or not inflation is responsible for the entire BICEP2 signal, even though existing data from cosmology is strongly suggestive that it does.
About the SOSF I found some interesting paper on arXiv:
A Nearly Scale Invariant Spectrum of Gravitational Radiation from Global Phase Transitions, Probing the Gravitational Wave Signature from Cosmic Phase Transitions at Different Scales, and Gravitational waves from self-ordering scalar fields.
via AstronomicaMens, The Physics arXiv Blog

Orange Juice

about #RichardFeynman playing #bongo
Here, after a lecture, Richard Feynman plays his signature "Orange Juice" theme with his friend and fellow drum player, Ralph Leighton.

When gaming is NP-hard

by @ulaulaman about #candycrush #bejeweled #shariki #nphard #computerscience
Shariki is a puzzle game developed by the russian programmer Eugene Alemzhin in 1994. The rules are simple:
(...) matching three or more balls of the same color in line (vertical or horizontal). These balls then explode and a new ones appear in their place.
The first Shariki's clone is Tetris Attack, a fusion between Shariki and the most famous Tetris, also this developed in Soviet Union by Alexey Pajitnov. But the most famous clone is Bejeweled (2001) by PopCap Games, from which is derived the Candy Crush Saga. During this March, Toby Walsh and the italian team composed by Luciano Gualà, Stefano Leucci, Emanuele Natale proved that Candy Crush and other similar games are NP-hard:
The twentieth century has seen the rise of a new type of video games targeted at a mass audience of "casual" gamers. Many of these games require the player to swap items in order to form matches of three and are collectively known as tile-matching match-three games. Among these, the most influential one is arguably Bejeweled in which the matched items (gems) pop and the above gems fall in their place. Bejeweled has been ported to many different platforms and influenced an incredible number of similar games. Very recently one of them, named Candy Crush Saga enjoyed a huge popularity and quickly went viral on social networks. We generalize this kind of games by only parameterizing the size of the board, while all the other elements (such as the rules or the number of gems) remain unchanged. Then, we prove that answering many natural questions regarding such games is actually NP-Hard. These questions include determining if the player can reach a certain score, play for a certain number of turns, and others.
The italian team realized also a web-based implementation of their technique.
Toby Walsh (2014). Candy Crush is NP-hard, arXiv:
Luciano Gualà, Stefano Leucci & Emanuele Natale (2014). Bejeweled, Candy Crush and other Match-Three Games are (NP-)Hard, arXiv:

A blink of an eye

Almost 14 billion years ago, the universe we inhabit burst into existence in an extraordinary event that initiated the Big Bang. In the first fleeting fraction of a second, the universe expanded exponentially, stretching far beyond the view of our best telescopes. All this, of course, was just theory.
Researchers from the BICEP2 collaboration today announced the first direct evidence for this cosmic inflation. Their data also represent the first images of gravitational waves, or ripples in space-time. These waves have been described as the "first tremors of the Big Bang." Finally, the data confirm a deep connection between quantum mechanics and general relativity.
(from the press release)
In physics, gravitational waves are ripples in the curvature of spacetime that propagate as a wave, travelling outward from the source. Predicted in 1916 by Albert Einstein to exist on the basis of his theory of general relativity, gravitational waves theoretically transport energy as gravitational radiation. Sources of detectable gravitational waves could possibly include binary star systems composed of white dwarfs, neutron stars, or black holes. The existence of gravitational waves is a possible consequence of the Lorentz invariance of general relativity since it brings the concept of a limiting speed of propagation of the physical interactions with it. Gravitational waves cannot exist in the Newtonian theory of gravitation, in which physical interactions propagate at infinite speed.
(from Wikipedia) Cosmic inflation was introduced by Alan Guth and Andrei Linde in 1981:
One of the intriguing consequences of inflation is that quantum fluctuations in the early universe can be stretched to astronomical proportions, providing the seeds for the large scale structure of the universe. The predicted spectrum of these fluctuations was calculated by Guth and others in 1982. These fluctuations can be seen today as ripples in the cosmic background radiation, but the amplitude of these faint ripples is only about one part in 100,000. Nonetheless, these ripples were detected by the COBE satellite in 1992, and they have now been measured to much higher precision by the WMAP satellite and other experiments. The properties of the radiation are found to be in excellent agreement with the predictions of the simplest models of inflation.
(from MIT)
So our universe is born after a quantum blink of an eye, or like a solution of the equation of everything.
In the following a storify with a collection of link about one of the most important discovery of the... universe!

A brief history of pi: part 2

by @ulaulaman about #piday #pi #MachinFormula #EulerIdentity
Today is the pi day, so I continue the brief history of $\pi$
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After the introduction of $\pi$ in mathematics, one of the quest linked with the calculation of its digits is the research about its nature, or in other words what kind of number it is. Numbers classification is simple for all: we start with natural numbers (positive and negative), and so we can define rational numbers, as the numbers generated by the ratio between two natural numbers. Every rational number could be expressed like $\frac{a}{b}$, with $a$, $b$ natural and $b$ not null.
Johann Heinrich Lambert was the first to show the irrational nature of $\pi$ in 1761 in Mémoire sur quelques propriétés remarquables des quantités transcendantes circulaires et logarithmiques: that could be written in this way: \[\tan(x) = \cfrac{x}{1 - \cfrac{x^2}{3 - \cfrac{x^2}{5 - \cfrac{x^2}{7 - {}\ddots}}}}\] Lamberd proved that if $x$ is not null and rational, then the previous expression must be irrational. So the irrationality of $\pi$ follows from $\tan (\pi /4) = 1$. A good synthesis of Lambert's proof is on The world of $\pi$.
In 1997 Laczkovich proposed a simplification of this demonstration, while another variation was proposed in 2009 by Li Zhou, using the integral calculus. In particular the second demonstration is inspired by the proof that Charles Hermite written in two letters to Paul Gordan and Carl Borchardt in 1873. Following Harold Jeffreys in Scinetific interference (1973), a simplification of this proof, that used a reductio ab adsurdum is proposed by Mary Cartwright.
Another proof of one page about the irrationality of $\pi$ is dued by Ivan Niven in 1946.
At the other hand, the transcendence of $\pi$ is a direct consequence of the Lindemann-Weierstrass theorem:
If $\alpha_1$, $\cdots$, $\alpha_n$ are algebraic numbers that are linearly independent over rationals, then $e^{\alpha_1}$, $\cdots$, $e^{\alpha_n}$ are algebraically independent over rationals.
where an algebraic number is the solution of a polynomial equation with rational coefficients.
In 1882 Lindemann, using this theorem, showed that $e$ is transcendental, and, like a consequence of the Euler's identity, also $\pi$ is transcendental.