"You can think of the principle of increasing entropy this way. Under isolated conditions, the process by which energy turns from other forms into heat cannot be reversed. There's a line of argument that treats the universe as an isolated system too, and holds that the universe is also increasing in entropy without a stop, expanding without a stop, until in the end nothing is left but heat. That's called heat death theory."

Heat death is one of the predicted ends of the universe. Some number of years from now the entropy of the universe reaches its maximum, and everything falls silent. Nothing left but quanta. Energy is equally high everywhere, with no differences, no motion. Dead water without a ripple. Hence heat death.

The theory grew out of the study of the first and second laws of thermodynamics. The second law is the principle of increasing entropy.

Going from order to disorder is entropy increasing, and it is not only a principle in physics. It applies in the natural world too. Dirtying new clothes is a great deal easier than cleaning them. Smashing a television is easier than building one. The destruction of war is always simpler than building under a settled order.

The specialists explained it in plain terms, and Shen Cong got the gist of it.

"So does that mean the universe was going to reach heat death after however many years, by the principle of increasing entropy — and now that the principle is broken, the universe won't die that way? Isn't that a good thing?"

"How do I put this. Heat death theory has drawn a great deal of doubt to begin with. We human beings know too little about the universe to say." Tao Zhongyang sighed. "The principle of increasing entropy is one of the foundations of physics. It touches time, the universe, a great many systems. Now it's broken, and we old men are somewhat at a loss."

Another gray-haired academician offered some comfort. "New discoveries, new challenges. There's some pleasure in a world like this one."

At that a young researcher standing…