What force to scientist think was responsible for clumping matter together to form the first stars after the big bang?

Answer : Gravity

Explanation :  Matter comes together to form stars under the force of gravity. Gravity is a force that causes all object to attract each other . This force dependent on their masses and their distance.

So, we can say that scientist know the force of gravity is responsible for clumping matter together to form the first stars after the big bang.

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.