As Galileo discovers that the earth is not the center of the universe he tries to prove this point.  It is very difficult to do this because the people that he has to convince are not very open to discussion about this topic.  They are closed minded and they believe that the earth is the center of the universe.  Of course Galileo is a very well educated man is very well respected, but that is not enough to give him the power to actually enforce his thoughts.
         As the people already knew (or thought they knew) that the earth is the center of the universe, that is what their knowledge was.  Since Galileo was a well educated man he was intelligent enough to discover that it is not true.  But since his thoughts and ideas would challenge the construction of traditional knowledge, his ideas would not be accepted.  Of course Galileo knew that his ideas were true, he decided to give up the idea and let the ideas remain the same, even though they may not be true.  So Galileo stopped his studies from the public but really he was still continuing to work on his ideas.
         It is the same way in our world today if someone has a new idea or concept and it would be a threat to the way of knowing it would probably not be accepted.  We can see that our world can be very absent minded, and not everything that we learn is true.  It might be exactly opposite of what we learn just like in Galileo’s situation.