Thermodynamics, entropy and environmentalism

Everyone I know can tell you about thermodynamics, even non-scientists. It’s one of those things that have been cited in newspapers, books and movies so much that everyone knows at least a couple of things. Maybe you don’t think you know about it, but if I say “energy cannot be created nor destroyed, only transformed” or “the universe tends to a state of disorder” you know what I’m talking about.

Hubble Directly Observes a Planet Orbiting Another Star

Energy, matter and entropy in the universe (Photo by NASA)

Those two sentences are ways of explaining in words the first two laws of thermodynamics, but they have often been misinterpreted or not properly quoted. Both laws don’t actually refer to the universe but to a closed system, any group of particles/elements that is isolated from everything else and, thus, doesn’t exchange matter or energy with the external world. The universe, as defined in physics, is the largest closed system there is.

With the first law of thermodynamics what is implied, after Einstein, is that the amount of energy and matter in the universe is constant, you can only transform one type of energy into another type and the same applies to matter. People accept this law very easily, it’s almost common sense, but the second law is more problematic. If the universe is getting more and more disordered, why do we see new patterns arise everyday? How can we still breed and build instead of slowly dying, dissolving and fading away?

The answer is simple: the earth is not a closed system. Disorder is measured using the concept of entropy, and the second law says it increases if the system is completely isolated. Also, entropy is a measure of the whole system, not individual parts or sections. For order to appear in some part of the system (decreasing the entropy of the system), disorder must be created in another part (increasing the entropy). Given enough time, and we are talking billion of years, the universe will become a system with all the matter and energy sorted uniformly, every section of it will have the same amount of matter and energy and this state will be of maximum entropy.

And what does this have to do with environmentalism? The video above explains the cycle of life. The earth is an open system, it gets energy from the sun, uses this energy to maintain its structure, and dissipates energy into space. Energy should not be a problem as long as the sun is still there, but the earth doesn’t get much matter from space and we cannot create matter, only transform it. Even if we consider the possibility of transforming energy into matter, the amount of energy needed makes it inviable (CERN’s LHC takes a lot of energy to produce only subatomic particles, not even atoms!).

So, we have an unlimited (in our time frame) source of energy but a limited amount of matter. Even if we don’t tamper with the cycle, the earth is getting rid of some matter in the form of heat, life on earth has a limited time. But we are transforming some matter into washing machines, cars and computers, losing some of it as heat in the production stages and unable, in many cases, of reusing this newly created materials. If we transform one type of matter into another type (for example burning coal to produce ashes, smoke and heat) and we are unable to reverse this transformation we are reducing our stock of that type of matter.

It’s not only that we are killing other species, animals or plants, or that we are destroying mountains and rivers. It’s not that we are contaminating the air and the water, making them toxic for ourselves. It’s that even if we adapt and survive these changes, there will be no matter for us to use, not to breed and not to build.

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