Why Is the Cosmic Microwave Background (CMB) So Cold If

question 47

Multiple Choice

Why is the cosmic microwave background (CMB) so cold if the early Universe was so hot

• A)Enough time has passed for matter in the universe to release enough heat to cool down.
• B)The CMB constantly interacts with atoms, which effectively cool down the photons.
• C)The expansion of the Universe has redshifted those photons to an effectively cooler temperature.
• D)Misleading; The big bang was initially hot but the CMB was released from cold material much later on.

---

Definitions:

Trade

The exchange of goods and services between individuals or entities, often in different countries or economies.

Production Possibilities

The various combinations of goods and services an economy can produce given its available resources and technology.

Opportunity Cost

The price paid for not selecting the second-best choice when deciding between options.

Rancher

An individual who owns or manages a large farm, especially one used for raising cattle, sheep, or other livestock.