Question

Pase No.:
Date :
1
7
© How did the Big Bang
occurred ?​

Answer 1

Answer:

The universe began, scientists believe, with every speck of its energy jammed into a very tiny point. This extremely dense point exploded with unimaginable force, creating matter and propelling it outward to make the billions of galaxies of our vast universe. Astrophysicists dubbed this titanic explosion the Big Bang.

Answer 2

Answer:

Virtually all astronomers and cosmologists agree the universe began with a “big bang” — a tremendously powerful genesis of space-time that sent matter and energy reeling.

The evidence is clear, ranging from the underpinnings of Albert Einstein’s general theory of relativity, to the detection of the cosmic microwave background by Arno Penzias and Robert Wilson in the 1960s, to the confirmation of ripples in the fabric of ancient space-time from the Cosmic Background Explorer (COBE) satellite in 1992. But the devil is in the details, and that’s where figuring out how Big Bang cosmology really works gets interesting.

The Big Bang model is typically broken down into a few key eras and events. Standard cosmology, the set of ideas that are most reliable in helping decipher the universe’s history, applies from the present time back to about a hundredth of second after the Big Bang. But before then, particle physics and quantum cosmology ruled the universe.

When the Big Bang occurred, matter, energy, space, and time were all formed, and the universe was infinitely dense and incredibly hot. The often-asked question “What came before the Big Bang?” is outside the realm of science because it can’t be answered by scientific means. In fact, science says little about the way the universe behaved until some 10–43 second after the Big Bang, when the Grand Unification Epoch began (and lasted only until about 10–35 second). Matter and energy were interchangeable and in equilibrium during this period, and the weak and strong nuclear forces and electromagnetism were all equivalent.

The universe cooled rapidly as it blew outward, however, and by 10–35 second after the Big Bang, the epoch of inflation occurred, enlarging the universe by a factor of 1050 in only 10–34 second. During this wild period, cosmic strings, monopoles, and other exotic species likely came to be. As sensational as inflation sounds, it explains several observations that would otherwise be difficult to reconcile. After inflating, the universe slowed down its expansion rate but continued to grow, as it does still. It also cooled significantly, allowing for the formation of matter — first neutrinos, electrons, quarks, and photons, followed by protons and neutrons. Likewise, antiparticles were produced in abundance, carrying the opposite charge of their corresponding particles (positrons along with electrons, for example).

As time went on and particles’ rest-mass energy was greater than the thermal energy of the universe, many were annihilated with their partners, producing gamma rays in the process. As more time crept by, these annihilations left an excess of ordinary matter over antimatter.

Chemistry has its roots deep in the history of the universe. At a key moment about one second after the Big Bang, nucleosynthesis took place and created deuterium along with the light elements helium and lithium. After some 10,000 years, the temperature of the universe cooled to the point where massive particles contributed more to the universe’s overall energy density than light and other radiation, which had dominated until then. This turned on gravity as a key player, and the little irregularities in the density of matter were magnified into structures as the universe expanded.

The relic radiation of the Big Bang decoupled (picture heavy traffic suddenly clearing) nearly 400,000 years later, creating the resonant echo of radiation observed by Penzias and Wilson with their radio telescope. This decoupling moment witnessed the universe changing from opaque to transparent. Matter and radiation were finally separate.