# Alternates of Big Bang Cosmology

There are several alternate models which contradicts Big Bang cosmology. Here we briefly discuss some alternate rival models.

1. de Sitter cosmology (1917)

• It models the universe as spatially flat and neglects ordinary matter. The universe is presumed to be entirely empty of matter.
• The density of matter in the universe is zero.
• Expands exponentially in time because of non-zero cosmological constant.
• Refutes nearly all observational facts now available.

2. Einstein’s static cosmology (1917)

• Einstein’s original cosmological model was a static (universe not expand), homogeneous with spherical geometry.
• The gravitational effect of matter caused an acceleration in this model which Einstein did not want, since at that time universe was not known to be expanding. Thus, Einstein introduced a cosmological constant into his equations of General Relativity. This term counteracts the gravitational pull of matter, and so it has been described as anti-gravity effect.
• The cosmological constant is precisely tuned to balance attractive tendency of matter.
• Like de sitter cosmology, it fails to agree with modern observations.

3. Lemaitre cosmology (1924)

• Universe started with a ‘Big bang’ with no cosmological constant.
• Initial state: Giant radioactive atom containing all the matter in the universe near absolute zero, called super atom.
• Agrees with observed expansion.
• Fails to explain existence of CMB radiation.
• Fails to explain the universal abundances of hydrogen, helium and deuterium because it requires the decay of a single massive ‘super atom’ at the instant of the Big Band.
• Lemaitre was a pioneer in applying Einstein theory of General Relativity to cosmology and predicting Hubble’s law theoretically.

4. Oscillatory Big Bang Cosmology (1930)

• Tolman proposed oscillatory or cyclic model.
• He proposed that universe would expand for a period of time before the gravitational attraction of matter causes it to collapse back in and undergo a bounce.
• Enough matter to make re-collapse expansion phase.
• Current observed expansion will be replaced by a collapse phase.
• No observational evidences.
• New cyclic model is brane cosmology (2001). According to this model, the process of matter to energy conversion in stars is fueling the cosmic expansion according to Mill’s theory.

• Developed by Fred Hoyle and Thomas Gold.
• Universe has no beginning and no end. In other words, it does not change its appearance over time. However, interestingly, this theory explains the reality of expanding universe.
• They proposed the existence of ‘C-field’, where C stands for creation. The c-field has negative pressure which enables it to drive the steady expansion of the cosmos whilst also creating new matter, keeping the large scale matter density approximately constant.
• According to this theory, new matter is continuously created as the space expands. However the average density of matter remain same over time.
• According to this cosmology, roughly one solar mass of baryons per cubic mega parsec per year is created from the c-field. (roughly one H-atom per cubic meter per billion years)
• New galaxies are created in the intergalactic space.
• Never able to explain Cosmic Microwave Background.
• Fails to explain universal abundance ratio for hydrogen, helium and deuterium.
• Opposed the existence of stellar nucleosynthesis. (PP chain / CNO cycle)

6. Brans-Dicke Cosmology (1955)

• Included a ‘scalar field’ in the Einstein’s field equation.
• This field causes the value of the ‘G’ to change slowly over billions of years.
• Failed to verify the existence of variable G.

7. Cold Big Bang Cosmology (1965)

• Big Bang occured
• Initial state was at absolute zero and consisted of a pure solid of hydrogen.
• This solid hydrogen fragmented into galaxy sized clouds as the universe expanded.
• No explanation of CMB radiation at all.

8. Hegedorn Cosmology (1968)

• Proposed all details of standard Big Bang Cosmology except the limiting temperature of early universe.
• Early temperature was assumed to be 1 trillion degrees.
• The structure of the matter has an infinite ladder of ‘fundamental particles’ out of which electrons, protons and neutrons are constructed.
• Refutes with the discovery that quark exists at nearly 1000 trillion degrees.
9. Big Bang Cosmology with Neutrino families (1970)
• Tried to explain ‘missing’ or ‘dark’ matter problem, new families of neutrinos have to be added to the universe.
• No experimental evidence that more than three types of neutrinos exist.

10. Old inflationary Big Bang Cosmology (1980)

• Developed by Alan Guth
• Inflationary era ended $10^{-34}$ seconds after the Big Bang.
• Bubbles of true vacuum formed.
• These bubbles merged to the matter and radiation in a very lumpy configuration.
• No evidence for such a turbulent lumpy transition era.