When an object radiates heat, the strength of this radiation far from the object decreases when distance from the source increases as shown in the graph below:
That is, radiated heat is much stronger near its source.
The universe is full of heat that was radiated by a source that no longer exists. This heat is known as cosmic background radiation. Cosmic background radiation is not stronger in any one direction or part of the universe than in others.
The following image is a map of the cosmic background radiation. Red areas are only 0.0002 K hotter than the blue areas. The overall temperature of the radiation is 2.725 K.
Image by the WMAP team, courtesy of the Legacy Archive
for Microwave Background Data Analysis (LAMBDA) supported by NASA
What does the uniformity of this radiation imply about its source?
A.
The source of cosmic background radiation existed for a very long time.
B.
The source of cosmic background radiation filled the entire universe.
C.
The source of cosmic background radiation moved randomly.
D.
The source of cosmic background radiation existed for a very short time.