fr en es pt
Contact the author rss astronoo
 Automatic translation  Automatic translation Category: light and photons
Updated January 29, 2015
  2015 declared International Year of Light (AIL)

Image: In this image, we see a bubble expanding debris called SNR 0519-69.0. This massive star exploded in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. These star debris are gas at very high temperatures, several million degrees, observable (in blue) in the X-rays with Chandra. The outer edge of the explosion (red) and the stars in the field of view are seen in visible light by the Hubble Space Telescope. Credit: NASA.

  Birth of Light

Image: The first light of the observable universe seen by the Planck mission (March 2013). This picture shows traces of the first moments of creation about 380,000 years after the Big Bang. Image Credit: ESA Planck collaboration.

The electromagnetic force much superior to the force of gravity, acts only on particles in charge of particles loaded, either positively as protons, or negatively as electrons. It forms atoms by attaching electrons to pits, but it does not stop there. It welds atoms by obliging them to share their electrons to form molecules. It still urges molecules to harmonize in turn in long chains, the highest expression of these chains is the DNA which allows the life. The gravitational force was discovered to the XVII th century by Newton, this attractive force acts on any masses. The weakest of four forces of the nature, but also the one who has the biggest reach, she acts on the whole universe, she is the glue of the cosmos. The intensity it this force depends on the mass of the object. It is that in the astronomical scale which the gravity really is felt, in enormous masses as that of the Earth (6x10e27 grams, in the Sun (10e33 grams), of a galaxy (10e44 grams), of a heap of galaxies (10e47 grams) or of the whole universe. The strong nuclear force is the one who cements nucleons in pits. It is too who associates quarks 3 by 3 inside nucleons and give birth to the nuclear energy. 1 gram of nuclear fuel = 1 ton of dynamite. She acts on a distance of 10e-13 cm, she is 100 times as strong as the electromagnetic force and acts only on massive particles as the proton and the neutron 10e-24 grams weighty. The mass of a proton is equal to 1836 times the mass of the electron. The weak nuclear force is one that allows neutrons to turn into protons and vice versa when the conditions are met. It does not act on the particles as the electron immortal, the photon and neutrino. Although stronger than gravity, it is 1000 times lower than the electromagnetic force. It has influence only over a distance of 10-16 cm. In 1896, for chance that the French physicist Henri Becquerel discovered the process of disintegration, on a photographic plate.

1997 © − Astronomy, Astrophysics, Evolution and Earth science.