Photon decoupling time

Definition

Photon decoupling time is the epoch in the early universe when photons stopped interacting frequently with matter and began to travel freely through space. This event led to the formation of the Cosmic Microwave Background radiation.

5 Must Know Facts For Your Next Test

1. Photon decoupling occurred approximately 380,000 years after the Big Bang.
2. Before photon decoupling, the universe was opaque because photons were constantly scattered by electrons.
3. The temperature of the universe dropped to around 3000 Kelvin during photon decoupling.
4. Photon decoupling marks the moment when atoms first formed, allowing photons to travel unimpeded.
5. The evidence of photon decoupling is observed today as the Cosmic Microwave Background radiation.

Review Questions

Related terms

Big Bang:

The initial explosion that created the universe approximately 13.8 billion years ago

Cosmic Microwave Background (CMB): The remnant radiation from the Big Bang, visible today as a faint glow permeating all of space

Recombination:

The process during which electrons combined with protons to form neutral hydrogen atoms, leading to photon decoupling