Question

#1 There are two classes of explanations for the two major observations concerning Dark Matter. The first class explains Dark Matter as some heretofore unknown massive stuff that we have not been able to detect prior to these observations. The second class of explanations suggests that the current theory of gravity is not true at the scale of galaxies, opening the way for an alternative theory of gravity (Modified Newtonian Dynamics or MOND). In your textbook there is a section about The Bullet Cluster of galaxies being used as a test concerning these two classes. Which class is supported by the evidence as explained in your textbook?

a. Dark Matter

b. MOND

#2 How did the evidence support your answer for Question 2?

a. Dark matter caused the first galaxy to move closer to the black hole.

b. Gravitational Lensing appeared where the galaxies would have been had they continued on their path.

c. The combined mass of the two galaxies combined caused the lensing effects to increase.

d. Gravity needed to be redefined at every point in order to explain the motion of the galaxies.

Answer 1

solution;

By study of the Bullet Cluster of galaxies and use of experimental techniques known by the name of gravitational lensing it was ascertained that dark matter was the reason for light to be bent while escaping from the stars and gas clouds which formed part of the Bullet Cluster. Thus the first class of observations which postulated the presence of Dark Matter was a plausible explanation of the gravitational effects behind the formation of Bullet Clusters.