Replies

Lot's of folks have the common misconception that the processes of life that they see about them here on good ol' Earth somehow violate the 2nd law of Thermodynamics. On several occasions I try to come in and clear things up for folks, to help them understand, in plain, ordinary English. I have not done that in few months, so here we go again:

In "layman's" terms, the 2nd Law of Thermodynamics states that over time, things "run down" and become more disordered. Water runs downhill. Clocks unwind and stop. Shiny polished metal rusts and pits away. Batteries lose their juice and go dead.

Since people rewind clocks, pump water uphill, recharge batteries, reproduce and have children, smelt and process metal, then gee, aren't we INCREASING the order of our environment around us? Are we not violating the 2nd Law?

At first glance, this might appear to be so. All the organisms on this planet are directing their energies to making a more orderly and more complex environment about them, even if it is by the mindless act of bacteria reproducing. How is this possible? Where does the energy for all this activity come from?

If we follow the food chain backwards, we find that all life on Earth depends initially upon plants for a food source. Even meat eaters, since they usually eat animals that have in turn eaten plants. Where then, do the plants get their energy?

Plants create their own food by assembling sugars in a process called Photosynthesis. Energy from the Sun's light is used to drive the production of sugar molecules. OK, so where does the Sun get its energy?

The Sun produces energy from the fusion of Hydrogen Atoms into Helium Atoms. The Sun has been doing this for a VERRRY long time (billions of years). The Sun is likely to continue to do this for a VERRRY long time (billions of years). However, the amount of Hydrogen in the Sun is FINITE. The Sun WILL EVENTUALLY run out of fuel. When that happens, there will no longer be a steady stream of inflowing energy to planet Earth. Earth will cool off (after an initial baking, but that is another story), things will run down, and there will be nobody to "wind things back up".

It makes no difference if we consider only our local solar system, or the known observable universe. Virtually all the order and energy we see generated stems from the conversion of Hydrogen into Helium. Eventually, the stars will cease to shine, and the remorseless 2nd Law will have the last say. Life offers no contradiction.