Assuming the conditions ripe for life and intelligence abound in ...

[hbsimmons88]

Assuming the conditions ripe for life and intelligence abound in the Galaxy, what factor limits the number of galactic civilizations currently in existence?
 
  A) the average survival time of the civilizations
  B) the lack of metals for technology
  C) the speed of technological development
  D) the expansion of the universe
  E) the number of supernova explosions

Question 2

Contrast the appearance of the H-R diagrams of a young open and old globular cluster.
 
  What will be an ideal response?

[jaykayy05]

Answer to Question 1

A

Answer to Question 2

In a young cluster, the main sequence is well defined, particularly to the top left, but as these massive stars evolved rapidly, in an old globular the top left portion is missing, and evolved red giants now populate the top right portion of the diagram.

[hbsimmons88]

Thank you!

[jaykayy05]

Always glad to help...