Harvard professor Joseph Nye, an expert in the topic, wonders: "Is the American century over?" Simply by posing the question, we know that the answer in his new book of the same title is 'yes.' But who will occupy the top position? In polls conducted in 22 countries, respondents in 15 of the countries agreed that China has surpassed or is on the way to exceeding the United States. In 2014, 28 percent of Americans said that their country was on top, compared to 38 percent two years earlier.

When America gained independence from Britain in the 18th century, the British statesmen Horatio Walpole said that his country had become as insignificant as the island of Sardinia. It was, however, on the verge of becoming a great nation due to the Industrial Revolution. In 1985, a Harvard professor wondered, if the British Empire had lasted two centuries, why “are we slipping after about 50 years?" Soon after, however, the Soviet Union collapsed and America became the sole world power. When did the "American century" begin? One answer is that it began at the end of the 19th century, when the United States became the biggest industrial power in the world. At that time, the U.S. represented a quarter of the global economy and remained as such until the eve of World War II. Immediately after the war, however, the U.S. came to occupy half of the global economy because the war destroyed the economies of the other leading countries. But since the middle of the last century, that share has dropped, and China is expected to occupy the top economic position in a decade.

Until the beginning of the 20th century, however, America remained a small economic force, unimpressive politically or militarily. In the 1880s, the American navy was smaller than the Chilean navy. That changed at the end of the 19th century, when America seized Cuba, Puerto Rico, and the Philippines from deteriorating Spanish colonialism. After World War I, the U.S. decided to go out into the world.

After that, everything would change — for the United States and for the world. In 1941, Henry Luce, owner of Life magazine, wrote an article entitled "The American Century," a century which grew with the end of the war, the formation of NATO, the Marshall Plan, and the Korean War in 1950. From 1945 to 1991, the balance of world power was described as a duopoly: two giants competing for nuclear weapons and international blocs around the world, until the fall of the Berlin Wall in 1989 and the announcement of the fall of the Soviet Union in 1991.

The size of the American navy would come to equal the size of the next 17 navies put together, while the American military budget would equal the budgets of half the world's militaries put together, and the U.S. would vastly exceed other nations in space.

Nye believes that this great power is today starting to wane. Amitav Acharya sees a shift from the unilateral global structure to a multilateral structure [influenced by] China, Brazil, and India.