Question

(A) What is Olber's paradox?
(B) Explain how Olber's paradox supports the Big Bang theory.
(C) Name the properties of the Cosmic Background Radiation observed from the Earth.
Also, discuss the connection between the Cosmic Background Radiation and the Big Bang theory.
(D) Predict how Cosmic Background Radiation will change in the future.

Answer 1

A] In 1823 a German Astronomer by the name Heinrich Wilhelm Matthias Olbers first talked about the Idea of Dark Nights. Hence Olbers Paradox is also called the Dark Night Sky Paradox. At those times the Universe war considered to be Infinite , Static and Uniform which lead to an interesting proposal my Olbers which read as

" If stars are distributed evenly throughout an infinite universe, the sky should be as bright by night as by day, since more distant stars would be fainter but more numerous"

B] The darkness of the night sky is one of the pieces of evidence for a dynamic universe, such as the Big Bang model. That model explains the observed non-uniformity of brightness by invoking spacetime's expansion, which lengthens the light originating from the Big Bang to microwave levels via a process known as redshift; this microwave radiation background has wavelengths much longer than those of visible light, so appears dark to the naked eye.

This perhaps was the defining theory which was able to support the Big Bang Theory properly.

C] Properties Of Cosmic Background Radiation:

1) The cosmic microwave background radiation is an emission of uniform, black body thermal energy coming from all parts of the sky.

2) The radiation is isotropic to roughly one part in 100,000.

3) Density of energy for CMB is 0.25 eV/cm3 (4.005×10−14 J/m3) or (400–500 photons/cm3 )

Connection between the Cosmic Background Radiation(CBR) and the Big Bang theory:

The Cosmic Background Radiation is the leftover radiation from the Big Bang or the start of the Universe as predicted by scientists. About 380,000 years after the Big Bang, the universe was cool enough that hydrogen could form. Because the CMB photons are barely affected by hitting hydrogen, the photons travel in straight lines. Cosmologists refer to a "surface of last scattering" when the CMB photons last hit matter; after that, the universe was too big. So when we map the CMB, we are looking back in time to 380,000 years after the Big Bang, just after the universe was opaque to radiation.

D] The Future of Cosmic Background Radiation?

Well we have to understand that CBR is a product of something that took place more than 13 billion years ago. The very future of CBR is that it will disappear in the future. This relic radiation left over from the Big Bang is being increasingly redshifted as the Universe expands. So its energy is being constantly diluted. In another few trillion years later the CBR would become completely undedectable.

Hope you find this useful!!!