Most active galactic nuclei are found at large distances from us, with relatively few nearby. What does this imply?
A) Supermassive black holes existed only when the universe was young, and no longer exist today.
B) Active galactic nuclei can form only at large distances from the Milky Way.
C) Active galactic nuclei exist tend to become less active as they age.
D) The jets seen in many active galactic nuclei must cause them to move far away from us.
Question 2
From the 1970s to the present, the accepted value of H has almost doubled, so
A) the age of the universe is twice as old as we originally believed.
B) the age of the Universe is half what we believed.
C) the Copernican principle is not valid beyond our solar system.
D) the ages of the oldest globular clusters are invalid.
E) the critical density must also be halved.
An ecological puzzle: the cicada, Diceroprocta apache, is active when air temperatures would appear
Small and large intestines
Active site of rubisco
Amino sugars are found in many polysaccharides