Cosmic Microwave Background Radiation

The cosmic microwave background radiation (CMB) is electromagnetic radiation that fills the universe and is a remnant of the Big Bang. It is the oldest light in the universe, dating back to about 380,000 years after the Big Bang when the first atoms formed. The CMB is now observed as microwave radiation with a temperature of about 2.7 Kelvin.

Origin

The CMB is believed to have originated from the moment when the universe cooled down enough for protons and electrons to combine and form neutral hydrogen atoms. This allowed photons to travel freely through space, creating the CMB radiation that we observe today.

Discovery

The CMB was accidentally discovered in 1965 by Arno Penzias and Robert Wilson, who were using a microwave antenna at the Bell Telephone Laboratories. They found a faint, mysterious noise that seemed to be coming from all directions in the sky, and after eliminating all possible sources of interference, they concluded that the noise was the CMB.

Significance

The discovery of the CMB provided strong evidence for the Big Bang theory, as its existence and characteristics align with the predictions of the theory. It also offers valuable insights into the early universe, including its composition, age, and evolution.

Study Guide

1. What is cosmic microwave background radiation and how does it relate to the Big Bang theory?
2. Explain the significance of the discovery of the CMB.
3. How do scientists study the CMB, and what have they learned from it?
4. Discuss the temperature and characteristics of the CMB.
5. Describe the contributions of Arno Penzias and Robert Wilson to the discovery of the CMB.