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Big Bang Theory
The prevailing cosmological model that describes the early development of the universe.
Formation and Timeline
The universe began as a hot, dense singularity.
It underwent rapid expansion during the inflationary epoch, within the first fraction of a second.
Cooling allowed the formation of subatomic particles and later atoms.
Cosmic Microwave Background (CMB)
A remnant of the Big Bang, the CMB is faint radiation detected across the universe, providing evidence for this theory.
Evidence for the Big Bang
Redshift of Galaxies: Edwin Hubble discovered that galaxies are moving away, indicating expansion.
CMB Radiation: Discovered by Arno Penzias and Robert Wilson, it supports the idea of a hot, dense early universe.
Abundance of Light Elements: Hydrogen, helium, and lithium in the cosmos align with predictions from Big Bang nucleosynthesis.
Mathematical and Scientific Foundations
Hubble's Law:
v=H0dv = H_0 dv=H0d
Where vvv is the velocity of a galaxy, H0H_0H0 is the Hubble constant, and ddd is the distance.
Critical Density: Determines the geometry of the universe.
ρc=3H028πG\rho_c = \frac{3H_0^2}{8\pi G}ρc=8πG3H02
Case Studies
Observation of the CMB by the Wilkinson Microwave Anisotropy Probe (WMAP) and Planck satellites.
Comparisons
How the Big Bang differs from steady-state or cyclic universe theories.
What came before the Big Bang? This remains an open question.
Dark Matter and Dark Energy: What roles did they play in the early universe?
Inflation: The exact mechanism behind the rapid expansion is not fully understood.
Expansion of the universe, Age of the universe, Formation of galaxies and large-scale structure
The term "Big Bang" was coined by Fred Hoyle as a dismissive remark during a radio broadcast!
If you could rewind time, all galaxies would converge to a single point.
Quiz: Test Your Knowledge!
What year was the CMB discovered?
What is the Hubble constant?
Books: "The First Three Minutes" by Steven Weinberg.
Websites: NASA’s page on CMB and ESA’s Planck mission insights.
Papers: Original works by Georges Lemaître and Edwin Hubble.