Cosmic Microwave Background: A fossil of our beginning

Figure 1. Cosmic Microwave Background radiation: Thermal image as captured by Planck

Source: Figure reproduced from NASA (2013).

Soon after the rapid expansion of the universe, from a highly dense state - radiation was released (May and Howell, 2023). This radiation was the first light that moved freely all over the universe (ESA, n.d.). This light has since cooled down and now - can be detected in the microwave domain (ESA, n.d). And this cooled remnant is called the Cosmic Microwave Background radiation (CMB). Moreover, since CMB was released soon after the ‘Big Bang’ or the rapid expansion, it contains information about the early universe! Hence, this CMB functions as a fossil - a cooled remnant of the Big Bang (May and Howell, 2023).

This fossil radiation has been mapped most clearly by the Planck satellite launched in 2009. Planck's mission was to map the fossil radiation and was held by the European Space Agency and assisted by NASA (Planck, 2013). This mission revealed that the universe is actually 13.82 billion years older than what was previously estimated from the other satellite -WMAP (Plait, 2013)!

References

ESA. (n.d.). Cosmic Microwave Background (CMB) radiation. The European Space Agency.https://www.esa.int/Science_Exploration/Space_Science/Herschel/Cosmic_Microwave_Background_CMB_radiation#:~:text=The%20Cosmic%20Microwave%20Background%20(CMB,shockwave%27%20of%20the%20Big%20Bang.

May, A. & Howell, E. (2023, May 12). What is the Big Bang Theory? Space. https://www.space.com/25126-big-bang-theory.html

Planck. (2013, March 26). The universe comes into sharper focus. NASA. https://www.nasa.gov/mission_pages/planck/multimedia/pia16874.html

Plait, P. (2013, March 21). The universe is 13.82 billion years old. Slate. https://slate.com/technology/2013/03/age-of-the-universe-planck-results-show-universe-is-13-82-billion-years-old.html#:~:text=Planck%20has%20found%20that%20the,age%20is%20120%20million%20years.