Worldship: Light of the Beginning.
Alkina: We call it the cosmic microwave background radiation.
Worldship: Just to be clear, these are photons from the beginning of the Universe which haven’t interacted with any matter since about 300,000 years after the Big Bang?
Alkina: Yes, that is correct.
Worldship: Why microwave?
Alkina: About 150 million years after the Big Bang, the first stars began to…
Worldship: Thank you. You have provided the required information.
Alkina: You mean we are free to go?
Worldship: Not quite yet.
What does it mean?
Cosmic Microwave Background (CMB) – This is the radiation left over from the big bang. It was produced early in the age of the universe, when the average density and temperature were much higher than today. The expansion of the universe has cooled the radiation to its current temperature of about 2.7 kelvin (The SI unit of temperature is the kelvin, symbol K. The name is to honor the 19th Century Scottish physicist William Thomson, who is more commonly known as Lord Kelvin).