Need an example of decrease in entropy caused by heat input

[TheInquisitor]

During a suprisingly civilised discussion with a creationist, the 2nd law of thermodynamics inevitably came up. I explained that the light and heat from the sun is what allows the local entropy on Earth to decrease, but my creationist friend asked me for an example of a reduction in entropy caused by the input of heat apart from life.

I thought about crystals and snowflakes but from what I've read it seems that these forms actually have higher entropy for reasons I sort of understand but aren't very relevant anyway. If anyone can think of an example of the input of heat causing a decrease in entropy I'd appreciate it. Especially one that intuitively seems to lead to an increase in order. The snowflake seems more ordered, but it doesn't really apply for reasons previously mentioned. Thanks.

 

[Josan]

When water freezes it will give off heat to it's surroundings and have a decrease in it's own entropy, but the total will rise!

However, you ask for a decrease in entropy when a system recieves heat? It might very well exist, but I can't really come with any examples myself, or see how it can happen tbh. But I don't really see why you would need one anyone, the problem is that people think to much in layman terms when it comes to entropy, thanks to bastards like Ray Comfort. The use of order/disorder is purely reffering to the movement of particles in the substances and brownian motion.

Sorry I couldn't come with a better answer, I'm sure some genius will pop some knowledge on my ass

 

[ImprobableJoe]

As far as I can remember off the top of my head:

Entropy isn't exactly a measure of "order" although it is commonly misused as an equivalent term. Entropy is a measure of possible states of a system, or can be seen as the measure of how far away a system is from equilibrium. It is also sometimes described as a measure of the amount of available energy in a system... which is the description that makes your point. An input of heat to a system almost by definition creates a decrease in entropy, in every instance. Therefore you don't have to come up with an example outside of a definition of entropy.

 

[IBSpify]

I believe ShaneDK had a video about this and it turns out one of the examples creationists like to use is actually a decrease in entropy. the formation of rust is actually entropy decreasing, not increasing as they like to claim

I believe it's this video

 

[Zylstra]

Heat has never been 'added' to the universe

 

[Ozymandyus]

Heat has never been 'added' to the universe

But it has been added to systems like the Earth, which is what we are talking about.

Adding energy to a system can lead to greater order in multiple ways - depending on the energy source. For example, light energy can be used by photovoltaic cells to create electricity which can be used in various ways to increase order (whether by running machines that create finished products from raw materials or whatever, or used to store as chemical energy in batteries by separating ions).

On a different note is there a way to not have to read comments by people that are being purposefully obtuse?

 

[Josan]

It is also sometimes described as a measure of the amount of available energy in a system... which is the description that makes your point. An input of heat to a system almost by definition creates a decrease in entropy, in every instance.

I think you are confusing enthalpy with entropy...

Heat has never been 'added' to the universe

I'm having a bit of trouble with the word heat, as it is very easy to misunderstand and I usually discuss my physics in norwegian. The way I see it you can mean two things, 1) The universe has never recived heat (that is transfer of thermic energy due to difference in temprature), which I would agree with, where would the heat come from? Or 2) The universe has never had an increase in thermic energy, which it definitly has, however the temprature is dropping because the universe is expanding. Heat death or cold death both seem quite obvious and likely to me as of now.

 

[ImprobableJoe]

I think you are confusing enthalpy with entropy...

You may very well be right...

 

[Zylstra]

But it has been added to systems like the Earth, which is what we are talking about.

Earth is not a closed system. You cannot measure entropy on Earth in any meaningful way, as entropy applies to closed sytems

Adding energy to a system can lead to greater order in multiple ways - depending on the energy source

How do you plan to add enery to the universe?

. For example, light energy can be used by photovoltaic cells to create electricity which can be used in various ways to increase order (whether by running machines that create finished products from raw materials or whatever, or used to store as chemical energy in batteries by separating ions).

The light comes from outside the cell- you're not dealing with a truly closed system

 

[Ozymandyus]

Earth is not a closed system. You cannot measure entropy on Earth in any meaningful way, as entropy applies to closed sytems

Did you even read the first post? We are talking about systems with energy input from outside sources. So yes they will not be closed systems by definition. We all know that and you are Completely off topic. He is simply asking how energy input can increase order.

I don't know why I even respond to you as you can't ever seem to post things that are at all on point and you certainly never seem to have anything worthwhile to say. I'll just go ahead and ignore them from now on.

 

[Fordi]

During a suprisingly civilised discussion with a creationist, the 2nd law of thermodynamics inevitably came up. I explained that the light and heat from the sun is what allows the local entropy on Earth to decrease, but my creationist friend asked me for an example of a reduction in entropy caused by the input of heat apart from life.

Almost any example of non-uniform heating will do.

Entropy is the inverse of imbalance. If you heat an object unevenly, its entropy decreases because its average kinetic energy (heat) is out of balance. When the heat is removed, the object eventually falls back into equilibrium, becoming uniformly hot.

But then, it has low entropy with its environment, as it has yet to dissipate its heat thereupon.

This is kind of basic, but the creationist trapped you by asking the question in an obtuse way. Any imbalance in energy - be it gravity, heat, electricity - is a decrease in entropy. He trapped you by asking a question in a similar form to, "Can you give me an example of a drop in average kinetic energy turning liquid matter into a solid?", or "Can you give me an example of [complex or obtuse phrase] resulting in [exaggeratedly complex definition or common result of preceeding phrase]?"

He asked a tautology, and because, I assume, you didn't quite get what entropy is (few laymen do, except us masochistic few that engage with creationists, so I don't blame you), so didn't spot it. Blinded with science, you were.

 

[Fordi]

Earth is not a closed system. You cannot measure entropy on Earth in any meaningful way, as entropy applies to closed sytems

That's not entirely true; while earth is not a closed system, and the 2nd thermodynamic law can't (by definition) apply to open systems, entropy most certainly can be measured in an open system. It's merely an inverse measure of energy imbalance between domains of the system.

For example, the earth has continuous decrease of entropy between the seabed and the core, as the core heats pockets of the seabed at a roughly constant rate.

 

[TheInquisitor]

Thanks for all your responses.

I think I dug myself into a bit of a hole with my creationist friend. I realise that our intuitive sense of order doesn't always correspond to the thermodynamic context. Like the snowflake actually being a more entropic form than a blob of liquid water. But I was hoping to find an example where the intuitive definition of order and the thermodynamic defintion are in agreement.

One example that occured to me though was the Miller Urey experiment. If I recall correctly, that was an input of heat and electrical sparks into a mix of simple compounds that caused them to form into more complex molecules. Would it be correct to say that these organic molecules that were formed are less entropic than the compounds they were formed from?

Since the input of energy to the Earth by the sun is what is decreasing entropy and increasing order on Earth (in the intuitive sense of the word), I'm suprised to find that it's difficult to come up with another example of the order (in the intuitive sense) arising spontaneously due to an input of energy. Is it just that this is an atypical result of energy input?

I think it would be really helpful to the argument if we could find an example of energy input leading to an increase in order in the intuitive sense. I think a lot of creationists, especially the ones who don't run museums, are just genuinely convinced by misinformation. Having an example that is easily understood would really help.

If anyone can tell me whether the compounds formed by the Miller Urey experiments are in a less entropic state than the compounds they formed from I'd appreciate it. I'm think they do, but I'd like to be sure. Thanks again.

 

[IBSpify]

Since the input of energy to the Earth by the sun is what is decreasing entropy and increasing order on Earth (in the intuitive sense of the word), I'm suprised to find that it's difficult to come up with another example of the order (in the intuitive sense) arising spontaneously due to an input of energy. Is it just that this is an atypical result of energy input?

I think it would be really helpful to the argument if we could find an example of energy input leading to an increase in order in the intuitive sense. I think a lot of creationists, especially the ones who don't run museums, are just genuinely convinced by misinformation. Having an example that is easily understood would really help.

watch the ShaneDK video i embedded earlier in the thread it will give you the answer to your first question as well as an easy to understand example.

as to your question, it's not an atypical result of energy input, we just don't typically think about it, the very fact of heat transfer from the sun to earth and from earth to surrounding space increases and decreases entropy.

 

[TheInquisitor]

watch the ShaneDK video i embedded earlier in the thread it will give you the answer to your first question as well as an easy to understand example.

As I understand it, the example of the rusting of metal causing a decrease in entropy is a case where the matter is losing energy, rather than gaining it.

What I'm looking for is something like the way photosynthesis or solar panels work, but something that isn't life or a human designed machine, where the system is given energy and decreases it's entropy, rather than a system that loses energy and decreases it's entropy.

I'm a bit confused by the rust example. If the metal is losing energy while it's rusting, why isn't that an increase in entropy? Isn't it's capacity to produce "usable work" diminished in the rusted state? My understanding of it was that if a system loses energy, it necessarily increases in entropy. Is that wrong? No wonder the creationists love to bring up entropy. It's confusing.

 

[Josan]

As I understand it, the example of the rusting of metal causing a decrease in entropy is a case where the matter is losing energy, rather than gaining it.

What I'm looking for is something like the way photosynthesis or solar panels work, but something that isn't life or a human designed machine, where the system is given energy and decreases it's entropy, rather than a system that loses energy and decreases it's entropy.

I'm a bit confused by the rust example. If the metal is losing energy while it's rusting, why isn't that an increase in entropy? Isn't it's capacity to produce "usable work" diminished in the rusted state? My understanding of it was that if a system loses energy, it necessarily increases in entropy. Is that wrong? No wonder the creationists love to bring up entropy. It's confusing.

When a system recives heat it gains thermic energy, thermic energy is high entropy, and therefore it is an increase in entropy. Solar cells and photosynthesis are both poor examples, because they don't recieve heat, they recive electromagnetic radiation, and in both cases entropy increase.

Entropy isn't a measurement of the amount of avaible energy in that sense, it is a measurement of the order in the substance. And don't think "order" in layman terms, but think microscopic, in a colder substance, the molecules (or atoms) will move slower and be more structured. A perfect crystal at absoloute zero will have 0 entropy as all the atoms in the structure are stationary in the "correct" spaces, when something recives heat the thermic energy will increase and therefor entropy will increase. In almost all cases were energy changes form from one form to another, entropy will increase, that means that we will have more and more thermic energy, which is often quite useless. The energy quality decreases.

 

[Pulsar]

The wiki article on self-organization might help you.

 

[Deleted member 619]

Dead simple. the sun inputs energy to plants, via photosynthesis. We eat the plants and convert them to a form of energy that is usable to us, thereby decreasing entropy locally.

It should also be noted that, while entropy decreases locally, it actually increases for the whole system. When will cretinists ever learn that there is no way around second law of thermodynamics, and that such things as evolution are actually an affirmation of this law, rather than a contradiction.

 

[TheInquisitor]

Dead simple. the sun inputs energy to plants, via photosynthesis. We eat the plants and convert them to a form of energy that is usable to us, thereby decreasing entropy locally.

Indeed, but I was looking for an example of this other than life or a human-made machine.

 

[Homunclus]

What about chemical reactions like the production of ammonia that require great quantities of heat and pressure:

N2(g) + 3H2(g) ⇌ 2NH3(g)

The usage of heat as a means of creating more complex substances from simpler ones seems like an "intuitive increase of complexity"