Universe bounded.

• Author: Gardner, Gary
• Position: Evaluating second law of thermodynamics - Column

Normally we link Groundwork columns to specific articles using the icon at left, but this column and this special issue on Katrina are entirely about limits, so we have omitted the link this time.

Here's a happy thought: the Second Law of Thermodynamics, the entropy law, says that the universe is running down, that energy and materials are moving from concentrated, useful states to diffuse, unusable ones, as when a pile of coal is combusted and disperses as carbon dioxide and heat. The Second Law tells us that energy and materials tend to be transformed in one direction: toward disintegration. But if the physics of entropy are depressing, the metaphysical implications of a universe of tightening limits are much more hopeful, and even inspiring, because limits seem to be central to the sustainable development of our universe and everything in it.

First, the physics. Admittedly, the entropy law seems only partially to accord with our experience. Burned coal or wood is degraded to ash, gas, and heat, it's true, but buildings and mountains are not collapsing around us. On the whole, our world seems far more stable than not. In fact, we see regular evidence of movement toward greater complexity, not less: each spring lesser materials like sugars and water are transformed into greater ones such as new buds and leaves, through the wonder of photosynthesis. And minerals, metals, and other materials, fueled by energy and human ingenuity, are regularly transformed into complex office buildings, homes, and freeways. A disintegrating universe? That's not what the building boom in Shanghai seems to suggest.

But don't be fooled. While humans can create new uses of energy and materials, we cannot create new sources. Nobel Prize-winning physicist Erwin Schrodinger once wrote that "the device by which an organism maintains itself at a fairly high level of orderliness ... really consists in continually sucking orderliness from its environment." Shanghai's skyscrapers signal a temporary increase in complexity that actually increases the entropy of materials and energy sources faster than if they had been left alone. And the complex creativity that nature produces each spring is possible because of the steady inflow of solar energy to our planet.

So the entropy law is real. And it has implications for our economies. Spent energy and materials can be recaptured or recycled, but with steadily diminishing efficiency--and at some point it's simply not worth it...