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Evolution of Universe

Facts for Prelims (FFP)


Source: TH

 Context:  As the universe ages, its future is shaped by fundamental laws of physics. Utilizing a logarithmic clock, cosmologists can trace the evolution of the universe from the Big Bang to the present.


Various stages in the evolution of the universe:

Initial SingularityThe universe begins as an extremely hot and dense point called a singularity. This marks the starting point of the Big Bang theory, where all matter and energy are concentrated in a tiny, infinitely dense space.
Inflationary EpochA brief period of exponential expansion, known as cosmic inflation, occurs within the first fractions of a second after the Big Bang. This rapid expansion helps explain the uniformity and large-scale structure observed in the present universe.
Quark EpochAs the universe cools further, quarks and gluons combine to form protons and neutrons. This transition occurs in a matter of microseconds.
Hadron EpochProtons and neutrons continue to form and combine, creating a “soup” of particles called hadrons. This epoch lasts for a few minutes and is crucial for the formation of light elements like helium and deuterium.
Lepton EpochThe universe becomes transparent as it cools, allowing photons to move freely. Electrons and positrons annihilate, leaving behind a small excess of electrons, which form the basis for the cosmic microwave background radiation.
Photon EpochPhotons dominate the universe, interacting with charged particles. As the universe expands and cools, it enters a phase where photons no longer interact frequently, marking the transition to the era of cosmic microwave background radiation.
Formation of StructureOver millions of years, gravitational instabilities lead to the formation of cosmic structures. Gas clouds collapse to form galaxies, stars, and other celestial structures, shaping the large-scale structure observed in the universe today.
Stellar EvolutionStars form from collapsing gas clouds, undergo fusion, and eventually exhaust their nuclear fuel. Depending on their mass, stars may end their lives as supernovae, neutron stars, black holes, or white dwarfs. Stellar evolution contributes heavy elements to the cosmos.
Galactic EvolutionGalaxies evolve through interactions, mergers, and the continuous formation of new stars. Over billions of years, galaxies take on various forms, influencing the distribution of matter and shaping the cosmic landscape.
Dark Energy DominanceIn late cosmic history, dark energy, a mysterious force driving the accelerated expansion of the universe, becomes more dominant. It counteracts the gravitational pull, leading to an ever-faster expansion.
Beginning of EndOver time, stars will exhaust fuel, galaxies collide, and new stars will form from merging brown dwarfs. Eventually, stars will be ejected from galaxies, and black holes will dominate, consuming rogue stars until their evaporation.