The United States has failed to move forward because....
The United States has failed to move forward because Americans have failed to grasp and perpetuate a strong understanding of scientific principles that were established centuries ago. The proof is your complaining about "why" we haven't achieved this or that lofty ideal. You would know, if you'd learned. You might have even figured out what to do next. I could tell you, but you wouldn't understand the significance of what I say, or understand the logic of it. I predict that Americans will continue to cling to obsolete ideas.