OhJohnNo said:
Loonyyy said:
And OhJohnNo? That's not what the 2nd Law of Thermodynamics means. It means that for any irreversible thermodynamic reaction, there is a net increase in entropy. That's got nothing to do with "Chaos" or "Evil", it means that the "quality" of the energy is reduced. Leave the engineering to the engineers, and keep it out of the pseudo-philosophy please, we're still copping flack from the last time some idiot misapplied it and said that it disproved evolution.
Fffahahaha someone seriously tried to use it to disprove evolution?
Ahh I dunno why I'm surprised, on reflection I'm pretty sure I've seen it on FSTDT somewhere.
Anyway, correct me if I'm wrong but is not the 2nd law of thermodynamics the reason, at heart, that most living things need to consume other living things to survive?
Yeah, someone said that because evolution results in greater order, and less chaos, that the second law was violated. Said person was an engineer, and brought much shame to the profession I'm working towards. Naturally, just looking at an acorn violates his idea: If energy means increased entropy, with no exceptions, then the acorn should burn, and become a uniform pile of carbon. Instead, it grows into a tree. There are things called reservoirs in thermodynamics, and you can have an decrease in entropy in one part of the system, and an increase elsewhere. This is vital to refrigeration and air conditioning systems, which usually use the outside environment as a reservoir. He missed the part that says "Closed System", and didn't seem aware of thermal reservoirs. Said engineer probably was incapable of understanding refrigeration or air conditioners.
But actually, the second law has nothing to do with living things needing to consume things. That's a biological process. To do things, things need energy. Plants absorb light, and photosynthesise. Animals eat plants, and each other, and break down the chemical bonds, which is then used to "fuel" the body. Much like how an internal combustion engine needs fuel, which it burns, breaking the bonds and releasing energy in an expansion, which gives off heat. Without energy, the car will not go, and the person will not walk, talk, or anything else.
The second law actually refers to the condition of energy. Energy tends towards entropy, a state of disorder, of a sort. The end result of entropy, is that the sum of irreversible processes (All thermodynamic processes contain irreversible elements, but many have so little we call them "Ideal") will result in the universe being a uniform area, of broken down matter, and roughly uniform temperature. This is what we call the "Heat Death of the Universe" (I'm simplifying massively of course, but as an engineering student, that's how we roll). Some people misunderstand entropy, and think of it by the colloquial use of the word, and take it to mean chaos, and then use the misunderstanding of chaos to think violence and disorder, which has spread the notion that thermodynamics says that life is chaos, and the like, which is incorrect. The Laws of thermodynamics essentially describe how thermodynamic processes take place.
To quote wikipedia:
Zeroth law of thermodynamics: If two systems are each in thermal equilibrium with a third, they are also in thermal equilibrium with each other.
Basically, the basis for temperature. And, from this follows the notion that energy, in the form of heat, transfers from points of high energy, or temperature, to lower ones, until they reach equilibrium.
First law of thermodynamics: The increase in internal energy of a closed system is equal to the difference of the heat supplied to the system and the work done by it: ΔU = Q - W
Basically, the law of conservation of energy. In all thermodynamic processes, there is no net change in the heat content of the universe. The change in the internal energy of a system is equal to the heat absorbed by the system, minus the work done by the system.
Second law of thermodynamics: Heat cannot spontaneously flow from a colder location to a hotter location.
Weird wording, but basically, hot flows to cold, and not backwards. You can't make heat flow from a cold area to a hot area without the use of a thermal reservoir.
Third law of thermodynamics: As a system approaches absolute zero the entropy of the system approaches a minimum value.
Colder things have a lower entropy than hotter things.
Thermodynamics actually has pretty much nothing to do with what most people think it does, and I keep seeing it crop up in the wrong places. It's nothing more than the description of how energy transfers. Sorry that I came off as aggressive in my response, it's just a bug bear of mine, I've seen it often enough, and it's one of those things that's rarely understood in the context, and the usual phrasing of the laws doesn't help. It's like how many people will cite Newton's Third Law "For every action in nature, there is one both equal and opposite" to mean that every action has consequences, often when talking about politics and the like, which actually has nothing to do with it, all it means is that if I push on someone, their body exerts the same force on my hand, or if I fire a gun, the force which propels the bullet also pushes my arm back.
And that has been our physics lesson for today.
R version for the bone-idle: The human race - Do we need it?
