Entropy as Disorder: History of a Misconception

Re:Entropy as Disorder: History of a Misconception by dr_dshiv on Saturday September 21, 2019 @03:19PM (#21037314)

I liked this article. Really clear. I found some of my own misconceptions. For instance, that uniformity and gradients are ways of characterising entropy.

The example of oil and water is great. While they are separated with a gradient, there is no latent tendency to flow together and mix.

But, it's only gravity that makes the oil and water issue hard to understand. With no gravity, they would not be evenly divided.

We still don't understand gravity, as it relates to entropy. Usually entropy makes things spread out, but gravity makes things come together. Weird.

[ Parent | on HN ]

Re:Entropy as Disorder: History of a Misconception by Florin_Andrei on Saturday September 21, 2019 @04:23PM (#21037710)

I dunno. I always thought "entropy = disorder" was a big simplification, almost in the realm of lies to children. Entropy is what it is; the pattern detection algorithms in our heads are not always very good at judging global properties such as order.

I do have a degree in Physics, so perhaps that's the source of this belief I've held - probably from countless impromptu discussions with fellow physics geeks. You wanna know the entropy of this system? Calculate it, don't eyeball it.

[ Parent | on HN ]

Re:Entropy as Disorder: History of a Misconception by novaRom on Saturday September 21, 2019 @05:24PM (#21037999)

How to define disorder? I always struggle to understand that. Less compressible state?

[ Parent | on HN ]

Re:Entropy as Disorder: History of a Misconception by dr_dshiv on Sunday September 22, 2019 @01:37AM (#21039858)

More potential for free energy flow across a gradient. That's what I still associate with entropy

[ Parent | on HN ]

Re:Entropy as Disorder: History of a Misconception by archgoon on Saturday September 21, 2019 @03:39PM (#21037425)

> We still don't understand gravity, as it relates to entropy. Usually entropy makes things spread out, but gravity makes things come together. Weird.

If 'gravity' weirds you out, put the mixture in a centrifugal chamber and let it spin. You get the same gradiated separation.

> Usually entropy makes things spread out, but gravity makes things come together. Weird.

It's no weirder than saying that hydrogen atoms exist because the proton attracts the electron.

[ Parent | on HN ]

Re:Entropy as Disorder: History of a Misconception by dr_dshiv on Saturday September 21, 2019 @03:55PM (#21037535)

The centrifugal chamber is using energy, so I don't know about that comparison.

But the attractive forces of protons and electrons ARE weird. Do know how attraction/integration can lower entropy?

[ Parent | on HN ]

Re:Entropy as Disorder: History of a Misconception by maciejw on Saturday September 21, 2019 @03:43PM (#21037457)

I also liked the article. I lack theoretical knowledge to determine if the system that is affected by gravity can still be considered "isolated" as per 2nd law of thermodynamics. I think this is not really relevant here, as the article focuses more on the common mental model, that disorder always increases with time. This model is not only incorrectly labelled (as entropy), but also misleading when used to describe some processes in the world.

This oil/vinegar example is immediately useful for other areas too. We have oil and vinegar in the dressing. They eventually become separated and we need to put effort to mix them together. Now replace oil and vinegar with leave/remain, blue/red or whatever else...

[ Parent | on HN ]