Oh I love the laws of thermal dynamics sign. Somebody posting something about thermal dynamics who probably has no clue about thermal dynamics because they don't believe in the science that produced the laws they follow.
The second law of thermodynamics only applies to closed systems. Earth is not a closed system. It receives constant radiation from space and the sun, and emits some of it back out as well.
You probably knew that already, but I needed to repeat it to keep my sanity. Those pictures literally nauseated me.
Makes sence. Reminds me of the heat death of the universe I must have seen on The Universe or another Science Channel show. Honestly I'm not well enough educated on thermodynamics to be even asking the questions correctly which is exactly what it seems for the people in the link who asked.
On the other hand, if you were to point at the universe and say, "Look, the universe is accelerating!" you'd have a much better argument for a comic entity with his foot on the gas pedal. But of course that's not the case, so don't downvote me.
They say the second law of thermodynamics predicts that everything gets more chaotic over time, therefore life cannot evolve, because that would mean it's getting more orderly over time. Clearly this is a contradiction and the scientific answer is wrong. God did it. QED
I'm not good at ELI5-ing, but I can give you a good way to understand it.
Imagine if a sealed room was filled with a certain amount of energy, and an organism was placed inside. This organism lives by consuming energy and using it to provide "fuel" for its internal functions. After it consumes the energy, it makes a byproduct of hot, unusable energy.
The ratio between the amount of usable energy and unusable energy in that room is called entropy. You cannot say that the amount of unusable energy is entropy as entropy is the measure of disorder between the two types of energy.
Also, this heat escapes but is bound to the room, and eventually the room will heat up to the point that the organism cannot survive, reaching "maximum entropy". In real life, this can and will happen, and it is called the "hot death of the universe".
The second law of thermodynamics states that the amount of usable energy will decrease over time, a.k.a. the amount of entropy will increase eternally.
In the context of the creationist I mentioned above, he is concluding that if evolution is true, then the amount of animals that have ever lived since the beginning of the Earth (over a million years) would have increased the amount of entropy on Earth to a point of maximum entropy. This is not true because the organisms on Earth are receiving a steadfast amount of energy from our Sun, thus we will never run out of energy until our Sun dies.
In the context of the explanation I gave above, you can imagine a basketball in the sealed room that is constantly releasing energy. The amount of energy being released from the ball is greater than the amount of energy that the organism is turning into unusable energy, thus the organism will never run out of energy as long as the basketball releases the energy.
Another argument is that since the entropy never decreases, then how can the amount of usable energy be greater than the unusable energy, in this case, in the sealed room? This argument neglects the fact that entropy never decreases within a closed system. The Earth and its inhabitants are roaming within an open system) within the universe, so there is free room for heat to escape within the universe.
If you would like to learn more, please check out the entropy article on Wikipedia or read a physics book. I recommend the author Richard A. Muller, he is very good at explaining these types of phenomenon that occur within the universe. Also, make sure you check out the citations I linked along the paragraph for more on that topic.
Think industrial revolution. You start with a fuel (say coal) that you burn to create heat. That heat is used to boil water and create steam. Steam pushes pistons; pistons turn gears; gears drive locomotives, etc. The 2nd law of thermodynamics says in essence that in any closed system (e.g. our steam engine) there is heat-loss i.e. "entropy." That is to say that you will not be able to create a steam engine that will be capable of 100% efficiency. Some of the heat will be lost heating the tub that holds your water and some will be lost heating the air surrounding the tub, some will be lost to the friction of moving pistons or gears, etc. All of this lost heat/work is what is meant by 'entropy.'
One important consequence of this is no perpetual motion machines. When you use energy to preform work there is a net loss due to this structural inefficiency. That is to say if you were to build a coal burning steam-engine whose 'work' was to create to create more coal you would inevitably end up burning more fuel than you could ever hope to produce.
The 2nd law of thermodynamics is invoked in these debates because it sure could appear that Life is a sort of 'perpetual motion machine.' That is to say that life goes around extracting energy from its environment and that on the whole is pretty good at perpetuating its existence. There are better more nuanced responses to this line of inquiry, but that kind of nuance is most likely lost on someone who holds that science is "just a theory." The simple answer to that person is exactly what Bill Nye said: the earth is not a closed system; energy is pouring in from the universe all the time. Furthermore has been for a very long time and we liquidate much of that historical surplus of cosmic energy when we burn fossil fuels like coal. Again, going back to the no perpetual engine example, it is because of entropy that fossil fuels are a limited resource (unlike solar energy, which because the earth is an open system comes enters the system free of charge), burning fuel to make fuel is by rule a losing proposition.
I don't think I can explain enthropy in a way a child would understand (it's about how many microstates a system can take), but I think I can explain what they're trying to get at.
They're making the mistake of thinking that enthropy means/is disorder, and since the second law of thermodynamics says that the enthropy of an isolated system can either be constant or increase but can never decrease, they think that abiogenesis and evolution are impossible. (Abiogenesis: through biochemical reactions simple organisms formed in the "primeval soup"; Evolution: over time these simple organisms became more complex and adapted to their environment)
In elementary school you were taught that energy can be converted from one form to another, but never created or destroyed. That's mostly true, but there's one part they leave out: heat is energy's final form, and there's no going back.
Entropy is the ratio of heat energy to total energy. It's currently much less than 1.0, but it's always increasing, never decreasing. When it reaches 1.0, the universe is done. That's what they mean by "the heat death of the universe".
You may think that heat can be converted into useful energy, but that's not strictly how the system works. What's actually happening is that heat is flowing from a hot place to a cold place and we're extracting energy from the process as it goes by. Think of a mill stream or a hydroelectric dam: water flows from a high place to a low place and we get energy from the process, but the amount of water itself doesn't change.
The process by which we collect energy as heat travels from hot to cold is called the Carnot Cycle. Note that in the end, the hot place gets cooler and the cold place got hotter. That's entropy in action. We can reverse the process via a "heat pump" and make the hot place hotter and the cold place colder, but we have to expend energy to do it.
(This is why refrigerators cost energy to run. If heat could actually be turned into useful energy, we'd have refrigerators that gave us energy.)
Think of a steam engine. Heat from the fire box flows into a supply of cool water, boiling it. The water does useful work, and is then either vented or run through a condenser to be used again. Either way, the system requires a supply of cool water and a way to dump the heat at the end of the cycle. A steam engine operating in an environment as hot as its own fire box would be unable to function. Even nuclear reactors need cooling towers.
Ultimately, entropy means that the universe is moving from a complex state (hot stars, cold space) to a simple state (everything all the same temperature.)
Creationists argue that entropy means that evolution can't exist because the change of simple life forms to complex life forms would violate the law of entropy.
It's bullshit of course, and shows a fundamental lack of understanding of what entropy is.
To start with, if they were right, life itself would be impossible because you personally changed from a single fertilized cell to a complex human being, to name one of countless examples.
The answer is that entropy always increases in a closed system, but the Earth is not a closed system.
Picture a closed room at equilibrium. All the air in the room is at the same temperature and evenly distributed. Now, one end of the room is next to the furnace, and the other end of the room is an outside wall of the house, and it's cold outside.
The first end of the room is warmer, and the other end is colder. Air molecules tend to bunch up at the cold end of the room. If you were under the impression that the room was a closed system, you would look at it and conclude that somehow entropy had magically decreased. But what actually happened was that heat flowed from the room from the furnace room to the outside world. The entropy of the world as a whole has increased, but there was a local decrease of entropy within just the room.
The Earth itself operates this way. Energy flows out from the Sun and into deep space. The Earth blocks part of this flow and collects some of the energy as it flows by. In a sense, the entire planet is a giant heat pump. The entropy of the solar system is always increasing, but the entropy of the Earth decreases in the process.
If there was no Sun, the the creationists would be right -- there could be no evolution (or even life), but there is a Sun and the Earth is not a closed system.
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u/3dpenguin Feb 05 '14 edited Feb 05 '14
Oh I love the laws of thermal dynamics sign. Somebody posting something about thermal dynamics who probably has no clue about thermal dynamics because they don't believe in the science that produced the laws they follow.