Mathematical Inference
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Faith-based theory?
"The Belgian astronomer and Catholic priest
Georges Lemaître proposed on theoretical grounds that the
universe is expanding, which was observationally confirmed soon afterwards by
Edwin Hubble.
[15][16] In 1927 in the
Annales de la Société Scientifique de Bruxelles (
Annals of the Scientific Society of Brussels) under the title "Un Univers homogène de masse constante et de rayon croissant rendant compte de la vitesse radiale des nébuleuses extragalactiques" ("A homogeneous Universe of constant mass and growing radius accounting for the radial velocity of extragalactic nebulae"),
[17] he presented his new idea that the universe is expanding and provided the first observational estimation of what is known as the
Hubble constant.
[18] What later will be known as the "Big Bang theory" of the origin of the
universe, he called his "hypothesis of the
primeval atom" or the "Cosmic Egg".
[19]
American astronomer Edwin Hubble observed that the distances to faraway galaxies were strongly correlated with their
redshifts. This was interpreted to mean that all distant galaxies and clusters are receding away from our vantage point with an apparent velocity proportional to their distance: that is, the farther they are, the faster they move away from us, regardless of direction.
[20] Assuming the
Copernican principle (that the Earth is not the center of the universe), the only remaining interpretation is that all observable regions of the universe are receding from all others. Since we know that the distance between galaxies increases today, it must mean that in the past galaxies were closer together. The continuous expansion of the universe implies that the universe was denser and hotter in the past.
Large
particle accelerators can replicate the conditions that prevailed after the early moments of the universe, resulting in confirmation and refinement of the details of the Big Bang model. However, these accelerators can only probe so far into
high energy regimes. Consequently, the state of the universe in the earliest instants of the Big Bang expansion is still poorly understood and an area of open investigation and speculation.
The first
subatomic particles to be formed included
protons,
neutrons, and
electrons. Though simple
atomic nuclei formed within the first three minutes after the Big Bang, thousands of years passed before the first
electrically neutral atoms formed. The majority of atoms produced by the Big Bang were
hydrogen, along with
helium and traces of
lithium. Giant clouds of these primordial elements later coalesced through
gravity to form
stars and galaxies, and the heavier elements were synthesized either
within stars or
during supernovae.
The Big Bang theory offers a comprehensive explanation for a broad range of observed phenomena, including the abundance of light elements, the
CMB,
large scale structure, and
Hubble's Law.
[9] The framework for the Big Bang model relies on
Albert Einstein's theory of
general relativity and on simplifying assumptions such as
homogeneity and
isotropy of space. The governing equations were formulated by
Alexander Friedmann, and similar solutions were worked on by
Willem de Sitter. Since then, astrophysicists have incorporated observational and theoretical additions into the Big Bang model, and its
parametrization as the
Lambda-CDM model serves as the framework for current investigations of theoretical cosmology. The Lambda-CDM model is the current "standard model" of Big Bang cosmology,
consensus is that it is the simplest model that can account for the various measurements and
observations relevant to cosmology."