When people argue about energy they almost always argue about quantity. How much do we have, how much is left, how much we burn. But from a physics point of view the amount is not really the interesting part. The quality is.
The Earth takes in a huge amount of energy from the Sun every second. About 340 watts per square meter reach the top of the atmosphere. Some of it bounces straight back, and around 240 watts get absorbed. The Earth warms up and radiates the same energy back out into space. So roughly speaking we return what we take. Or very nearly, since the Earth actually holds on to a tiny bit and slowly warms. So what actually changes?
The type changes. The energy from the Sun arrives as visible light, and each photon carries somewhere around 2 to 3 electronvolts. The Earth absorbs it, warms up, and sends it back out as infrared. But the outgoing photons are far weaker, closer to 0.1 electronvolt each. One incoming solar photon is roughly 20 times stronger than one outgoing Earth photon.
If the total energy is balanced but every photon leaving is 20 times weaker, then the Earth has to emit around 20 times as many photons as it takes in. We receive a few strong photons and give back a swarm of weak ones. The energy spreads out and flattens. In physics that spreading has a name, and it is entropy going up.
Everything on the surface of this planet runs on that quality gap. Photosynthesis, wind, rain, rivers, even the brain writing these sentences. All of it grabs the high quality energy from the Sun, does something with it, and lets it drain away as weak heat. So we do not really consume energy. We consume its quality.
A hydroelectric dam is a clean example. The dam does not create energy, it just catches part of the energy the water would lose on its way down anyway. Without the dam that same energy would still be spent, crashing against rocks and swirling into heat. And the thing that lifted the water up the mountain in the first place was the Sun. It evaporated the water, carried it up as vapor, and dropped it back as rain that fills the reservoir. So hydroelectric power is really stored sunlight, and we are just taking a toll as the water heads back down to the sea.
Now this is where I want to slow down, because the easy conclusion is a trap. It is tempting to say the point of all this is to catch that energy before it turns to heat, build the plant, put it to use, not let it go to waste. But wait. Waste according to whom?
That dam does catch energy, yes. It also drowns a valley, blocks the fish, stops the sediment that used to feed the land downstream. The river was not wasting anything, or at least it makes no sense to say it was. But I should be honest that this cuts both ways. Calling the river wasteful is a human frame, and calling the river innocent is also a human frame. The river is not trying to do anything, it just flows. Waste and purpose are both words we bring to it. What I can say is this. The moment I call the energy wasted, I smuggle in an assumption, that energy exists so we can turn it into something for us.
Maybe that assumption is worth questioning. There is a version of the story where the smart move is not to build more plants and capture more energy, but to simply need less of it, so we produce less in the first place. Less demand, less dammed river, less swirl of concrete and turbine. And yet that runs against something we often see in ourselves. We tend to want more. More comfort, more money, more reach. But I do not want to dress this up as fixed human nature, because I am not sure it is.
Plenty of societies have lived without that hunger, some even treat hoarding as shameful and sharing as a duty, so a lot of what looks like instinct might really be the particular system we grew up inside. Whether the wanting is something in the animal or something in the world we built around the animal, I honestly do not know. And either way it is not a life sentence. If it is partly the system, then it is partly a choice, which makes the question more interesting, not less.
So I am not going to pretend there is a clean answer here. When we call something a higher quality life, all that technology and growth and speed, are we sure that is actually good for us as living creatures, or is it just good at making more of itself? Good for whom, measured against what. Is the goal a planet that lasts longer, or more human generations living on it, or just this decade going well, or pushing technology as far as it will go? These do not point in the same direction, and I don’t think you can serve all of them at once.
The physics part I am fairly confident about. Entropy will go up, we cannot stop that, and the Sun will keep pouring quality onto us for billions of years whether we use it well or not. The rest is the fun part, the part with no answer. What we leave behind in the middle of all that rising entropy is up to us, and we have not even agreed on what leaving something good would mean.
A small discussion with my dearest friend Atakan.
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