They believed that a centralized government would lead to tyranny and just having escaped the tyranny of England, they didn't want to run that risk. They believed that most of the power should be with the states.
In 1939, Albert Einstein wrote a letter to president Roosevelt alerting him to " a new and important source of energy" which was then developed by scientists in the United States.
Albert Einstein is the correct answer. Let me know if you have any more questions :)