Yes, entropy I observe, as a burning candle not ever being unburned and so forth, but what about all the living things we see on our planet? It is surely a more structured form of matter than before, and although I have heard explanations I haven’t grasped the explanation of how in spite of the apparent structuring, entropy still increases.
In: Physics
The total entropy of the universe (or a separate closed system) is still increasing when life exists, which is the only thing that is counted in the law that entropy always increases. The sun spreads huge amounts of energy out which increases entropy, and life simply holds onto some of that energy for a relatively short period of time. Organisms also release heat when they consume food or just exist, which also increases entropy. There is also nothing in the laws of thermodynamics that say you can’t slow down entropy to a near halt, just that entropy can never decrease.
The key is that entropy will increase for an entire system as a whole, not necessarily for each separate subsystem.
Solar energy from our sun strikes the Earth’s surface.
In the case of a complex living thing, like a flower, drawing a line around the entire system means drawing a line around the plant *and* the sun, and other things.
Consider something like an air conditioner.
It takes heat and moves it against the gradient of temperature. Heat wants to flow from hot to cold, but we have somehow made a device that causes heat to flow from cold to hot.
The thing is, it takes energy to make this happen. That’s why you gotta have it plugged into the wall. That energy when used ends up being released as excess heat.
Much like the burnt candle, that excess heat energy cannot be used to perform other actions, or if it can, it can not do so to the extent the original energy was. Heat energy is less usable to us than is the electrical energy it started as.
If the surroundings get too hot, then the heat will have nowhere to go, and will continue to build up. This is what causes overheating, our system is unable to get rid of the excess heat that it creates as a byproduct of doing *work*.
That idea that we can overheat and be unable to perform work *even though* there is still energy in all of that heat, is the main idea of entropy. There is still energy, its just in a state which we cannot make use of that energy.
A low entropy structure is one that you can use to perform a lot of work. Gasoline is low entropy. We can extract a lot of work out of it. Your burnt candle is high entropy – there’s really not much work we can get out of it.
All of us living things are entropy creating beings. We are high complexity, low entropy beings, sustained by creating more than equal amounts of high entropy around us. We consume low entropy food and excrete high entropy waste, and use the difference in those two in order to maintain our low entropy state.
So on the global scale, entropy is always increasing. However locally, you can cause an apparent decrease in entropy in one object by causing an equal to or greater than amount of entropy in another object.
Living things are not a closed system, they produce lots of entropy. We excrete digested food and metabolism byproducts like CO2, we radiate heat, we do lots of things that increase the overall entropy around us. Life is basically a non-closed system that constantly and incessantly increases the entropy outside of it to keep it low inside. We’re basically an entropy pump. A bucket floating in the middle of the ocean trying to stay empty.
Latest Answers