What is Cosmic Microwave Background Radiation?

Cosmic Microwave Background Radiation (CMBR) is thought to be the left-over radiation from the Big Bang. CMBR cannot be seen with the human eye but it is everywhere in the Universe. It is invisible to humans because it is so cold, just 2.725 degrees above what is known as absolute zero (-2725 degrees). This means its radiation is mostly visible in the microwave part of the electromagnetic spectrum, hence the name Cosmic Microwave Background Radiation. The temperature of deep space has been measured as around 3 Kelvin, not absolute zero, due to the remaining energy from the Big Bang (CMBR).

What is Cosmic Microwave Background Radiation used for?

CMBR can now be used to map the universe, the image below shows that the CMBR was not evenly distributed and because of this it can be used as a way to navigate the universe.

When were images like this taken?

The first full sky map came from NASA’s Cosmic Background Explorer mission which launched in 1989 and ended operations in 1993. The image that NASA obtained confirmed the Big Bang theory predications and also showed scientists cosmic structures that had not been previously discovered. In 2003, a more detailed map was produced by the Wilkinson Microwave Anisotropy Probe, they launched operations in 2001, and the project was ended in 2010. It was the WMAP that came to the conclusion that the universe began 13.7 billion years ago.

What is Olber’s Paradox?

Olber’s Paradox questions why the sky is dark at night. If the universe is endless and populated with light emitting stars, then every line of sight must be met with the surface of a star. Opposing observations, this argument suggests that the night sky should be bright everywhere without dark spaces between stars. This paradox was first discussed in 1823 and still does not have a solidified solution. However, the simplest resolution is that the average luminous lifetime of stars is too short for light to have reached Earth from very distant stars. Plus, considering that it is believed that the Universe is expanding, it can be argued that the Universe is too young for light to have reached the Earth from extremely distant stars.