Răspuns:
Big Bang
Th e Big Bang Model is a broadly accepted scientifi c theory for the
origin and evolution of our universe. According to this theory, the universe was created about 15 billion years ago from a cosmic explosion
that hurled matter in all directions.
Astronomers believe that once all the matter and energy in the
universe were concentrated in a single place. Th is place was extremely
hot and dense. Th en, sometime between 10 billion and 20 billion years
ago, an enormous and powerful explosion – the Big Bang – shot the
concentrated matter and energy in all directions. Aft er the initial Big
Bang, the force of gravity began to aff ect the matter racing outward in
every direction. Gravity caused some of the matter to come together to
form galaxies and stars. Th e clumps of matter around our own star, the
Sun, became planets. Some planets were large enough and had enough
gravity to attract matter that became moons or satellites.
In 1927, the Belgian priest George Lemaître was the fi rst to assume
that the universe began with the explosion of a primeval atom. Years
later, Edwin Hubble found experimental evidence that helped to justify
Lemaître's theory. He made observations, and stated that distant galaxies appeared to be moving away from us in every direction at a speed
proportional to their distance from the centre of the universe.
Since the Big Bang, the universe has been continuously expanding, and,
thus, the distance between clusters of galaxies has become much bigger
than it was before. Th is phenomenon is known as ‘the red shift ,. Th e stars
and galaxies were much closer to each other in the past than they are at
present. At the same time, the matter inside the galaxies continues to race
away from the area where the Big Bang had occurred.
Th e Big Bang theory also predicts the existence of cosmic background radiation (the glow left aft er the explosion itself). In 1964, this
radiation was discovered by Arno Penzias and Robert Wilson, who later
won the Nobel Prize for this discovery.
Although the Big Bang theory has been widely accepted, it will probably
never be proved. Th us it leaves a number of tough, unanswered questions.
eu ma apuc sa scriu ca tot asta am succes
