"Relative decline" is like saying, "my parents are half as tall as they were when I was eight."

How exactly are you measuring this decline?

Please provide these facts.

You could read a number of books on this subject. The China Dream, On China, or Destined for War: Can America and China Escape Thucydides’ Trap? The Economist is a good magazine, with almost weekly updates on this topic.

We've been surpassed in PPP, Global Trade, Industrial Output etc. China's steel production is 1 billion tons a year, the US 80 million tons. They poured as much concrete in the last 10 years as we poured in the 20th century. In just a few years we will be surpassed by GDP and witin 25 years China's GDP will be double the United States.

China's rise is not disputed.

Okay, that's not decline, and not all of those figures are facts. Also, you seem obsessed with quantity of infrastructure built, which isn't really a great metric for measuring what you're claiming is happening.

The other poster with the analogy about a child's height is 100% accurate.