What did Stephen Douglass need for his train system to work?

"if i have seen farther than others," said newton, "it is because i have stood on the shoulders of giants." who were the giants to whom newton was referring? could this be said of any scientific accomplishment? explain.

Why is the supreme court decision in roe v. wade so controversial.

Why was galileo galilei brought before the inquisition? for insisting that earth stands still at the center of the universe for proving that planets move in elliptical orbits for putting forth evidence that earth moves around the sun for suggesting that the sun is a star