Group items tagged

La commission avait alors statué qu'il n'était pas possible de prédire une éventuelle secousse plus forte. Le 6 avril 2009, un séisme de 6,3 sur l'échelle de Richter ravagea la ville de L'Aquila, dans les Abruzzes. Plus de 300 personnes ont trouvé la mort à la suite du tremblement de terre.

La tenue d'un procès et la condamnation à la prison de ces scientifiques ont provoqué une onde de choc dans le milieu scientifique international, où on estime qu'il est impossible, même pour les experts le plus aguerris, de prévoir les tremblements de terre.

« Dans une décision qui provoque une onde de choc dans la communauté de géophysique aux États-Unis, un tribunal italien a condamné six scientifiques à six ans de prison pour ne pas avoir prédit un séisme, ce qui est absurde et dangereux »,

Jusqu'en 1950, le magnétisme terrestre semblait être un heureux accident de la nature.  Beaucoup de facteurs devaient converger pour le maintenir : le noyau fluide de la Terre, sa conductivité électrique et ses mouvements, le tout doit obéir à des critères bien stricts de la théorie de la dynamo.  Nous savons maitenant que Vénus est la seule planète qui n'a pas de magnétisme. Les planètes diffèrent beaucoup entre elles en taille et en propriétés, ainsi que par leurs champs .  Les planètes ont toutes un champ magnétique ou en ont eu un dans le passé (tels Mars et la Lune). 

"Qu'est-ce-que cet objet brillant là-haut?" .  C'était Jupiter, le signal provenait de cette planète.  En publiant leurs résultats, les deux astronomes proposèrent que " la cause de cette radiation non-connue était sans doute dûe à des perturbations électriques dans l'atmosphère de Jupiter".

Ces quatre planètes ont un champ magnétique plus fort que la Terre

In the late 19th century, luminiferous aether, æther or ether, meaning light-bearing aether, was the postulated medium for the propagation of light.

Physicists confirm surprisingly small proton radius

In the experiment described in the newly published Science article, the energy shift was determined for another transition. This leads to a new measurement of the electric charge radius of the proton. Its value of 0.84087(39) femtometres (1 fm = 0.000 000 000 000 001 metre) is in good agreement with the one published in 2010, but 1.7 times as precise.

Planck Units

Planck units are largely based upon three fundamental units, h, G, and c.

The gravitational constant is given the symbol "G".   It is a measured value used in the force equation for gravity (see below). F = Gm1m2 / r2 The m units are masses of two bodies which are separated by a distance r.   By rearranging the equation, we have G (see below). G = Fr2 / m1m2 The gravitational force, F, was measured between two masses to arrive at G.   At various times, the laboratory equipment and methods were improved to arrive at more accurate values for G.   The physics texts were not usually updated for the new values because (1) the changes were not great enough to justify the added expense to the texts, and (2) the changes were happening frequently enough to make each text obsolete before it arrived in the hands of students.   Consequently, there are numerous variations of G to be found, but the differences between them are slight. There are many systems of weights and measures used in physics.   Fundamental constants such as G often have two values according to the measuring system used.   When two such units are mixed to arrive at subsidiary units such as the planck length, the result is a completely erroneous value along with units of measure which do not apply.   Consequently, it is important to convert the various units of the fundamental constants used to the same system of units.   In may instances of late, this has not been done. Finally, there is human error involved in copying from an old text to create a new next.   This means that it is wise to check various texts to see if they all agree (they usually don't), and decide what is correct and what is not correct.   For G, the following was discovered.

GE’s Brand New 100W Equivalent LED Bulb Illuminates the Future of Lighting May 7, 2012 Engineers at GE’s NELA Park in East Cleveland, Ohio, have spent a century building better light bulbs. When NELA opened in 1911, it became the world’s first industrial park, a distinction that earned it a place on the National Register of Historic Places. But now a new kind of history is taking place at NELA, the kind that will soon dispatch the incandescent light bulb down the same road traveled by the LP and the VCR. “This is an evolution,” says Glenn Kuenzler, a lighting engineer at NELA. He and his team of researchers are making sure that the GE bulb, whose legacy stretches back to Edison, is fit to survive.

Le joule (symbole : J) est une unité dérivée du système international (SI) pour quantifier l'énergie, le travail et la quantité de chaleur[1]. Le joule étant une très petite quantité d'énergie par rapport à celles mises en jeu dans certains domaines, on utilise plutôt les kilojoules (kJ) en nutrition et dans les tableaux de valeur nutritive. Cette mesure est de plus en plus utilisée au côté des calories et tend graduellement à les remplacer.

Un joule est approximativement égal à : 6,24150636309.1018 eV (électronvolts) ;

Un joule vaut exactement : 107 ergs ; 1 pascal-mètre cube.

Energy of Photon

A photon is characterized by either a wavelength, denoted by λ or equivalently an energy, denoted by E. There is an inverse relationship between the energy of a photon (E) and the wavelength of the light (λ) given by the equation:

Throughout the universe more than 99 percent of matter looks nothing like what's on Earth.

This material that pervades the universe, making up the stars and our sun, and also – far less densely, of course – the vast interstellar spaces in between, is called plasma. Plasmas are similar to gases, and indeed are made of familiar stuff such as hydrogen, helium, and even heavier elements like iron, but each particle carries electrical charge and the particles tend to move together as they do in a fluid.

"Which particles are moving, what is the source of energy for the motion, how does a moving wave interact with the particles themselves, do the wave fields rotate to the right or to the left – all of these get classified," says Lynn Wilson who is a space plasma physicist at NASA's Goddard Space Flight Center in Greenbelt, Md.