Automobiles were developed in the 19th century but became prevalent in the 20th century. Specifically the internal combustion powered auto. They clearly changed how and where we live, how we built our homes, shopping and businesses.
Is there anything that has changed the world’s more in the 20th century?
Is there anything we developed in the 20th century that will change how we live as the 21st century progresses? The transistor comes to mind. Atomic fusion is another. Thoughts?