I’ve gotten a reply from a well-known Democrat in these parts that shows that the true believes in Global Warming really don’t understand what temperature and heat really are. (link)
As a favor to that particular reader, and readers everywhere, I will take some time to explain some very difficult concepts. These concepts are critical to understanding why the Greenhouse Effect is nonsense. (link)
I’m drawing this lesson from a brief reading of Wikipedia’s entry on entropy. You’re certainly welcome—and encouraged—to read the article, as well as find a good textbook on Thermodynamics that should contain several great examples and exercises to help you learn the concept.
Don’t be surprised if this concept is difficult to understand! In terms of physics, it’s still a relatively new idea, being discovered in the mid-19th Century. However, if you think carefully, you will come to understand the concept quite well.
In physics, we talk a lot about energy. Energy comes in different forms, and energy is transferred from one object to another. We know that energy is conserved, except in tiny edge cases that don’t matter in the big world (as opposed to the quantum world of particles and photons.) We can measure the energy before, and measure the energy after, and know that the two quantities must equate each other. What happens in between is irrelevant.
I want you to imagine a bag of marbles. Now, if I tightly tie the bag of marbles together so that they can’t move around, and throw them at a target of some sort, the kinetic energy of those marbles will almost completely be transferred to the target. This is because the marbles don’t “lose” any of the energy in plastic deformation (as long as they don’t crack or break up). The marbles can’t shuffle around in the bag very much, so we don’t see much energy being lost there either.
If you took the same bag of marbles, and allowed them to move around freely in the same bag, then threw it at the target, you’d notice that less energy was transferred. See, the marbles end up bouncing around in that bag during the collision, and a lot of energy is spent moving marbles back and forth rather than transferring energy to the target. This wasted energy is Entropy.
The problem with Entropy is that it’s useless. You can’t restore order to a disordered system. Well, not easily. It takes a lot of work applied in very smart ways to get in there are straighten things out. Even then, you can only straighten things out a little bit.
Temperature is almost an exact measurement of Entropy. All this bouncing around and moving around randomly is what it means to be warm. Cold systems have more order, while hot systems have less. It’s hard to picture this, but imagine a bunch of atoms bouncing around inside some chamber. If they are moving slowly, then the pressure they exert from bouncing off the sides of the chamber is small. If they move around quickly, then the pressure increases. This is how, ultimately, energy is measured—by watching for changes in volume and pressure to a substance. In mercury thermometers, you can see the mercury rise and fall. In other thermometers, like bi-metallic ones, the metal stretches or shortens. In resistive thermometers, the resistance of the substance increases or decreases.
Now, Entropy can be analyzed and interpreted in a variety of ways. What you will discover is that two properties of Entropy emerge:
- Entropy never decreases, unless outside work is applied. (When you include the external work in the system, entropy still increases.)
- “Hot” stuff transfers entropy to “cold” stuff, increasing the overall entropy WITHOUT changing the total energy of both systems. Or, another way to look at it is that “cold” stuff sucks entropy out of “hot” stuff.
Further mathematical and theoretical analysis will lead you to conclude that those two points are really two faces of the same physical law, the law we call the Second Law of Thermodynamics.
Those who “get” the Second Law understand that entropy is wasted energy and know how it behaves. Those who don’t “get” the Second Law don’t understand what entropy is or don’t believe that it is irreversible.
To draw this back to the Greenhouse Effect, too often people state that the CO2 layer “retains”, “reflects” or “absorbs” heat from the ground. When they discuss temperatures this way, they are not thinking of Entropy, and so their mental model of the system is patently absurd. When you treat heat transfer like energy transfer, then you will likely come to the wrong conclusion.
If you don’t trust what I have said, then you are free to either research for yourself or find the closest physicist and see what they have to say about it. Science isn’t politics, and trying to mix the two destroys science.