Is the entropy increasing or decreasing?

Question

Expanding on a previously posted question and answers:

http://answers.yahoo.com/question/index?qid=20071231134856AAMQdEo&r=w

It is possible to set up a laboratory device that will vibrate a container which has a mix of sand, pepple, and gravel, with control over the amplitude of the vibration. As the container is vibrated continuously, if the amplitude is large, the mix will tend to become uniform. Yet if the amplitude is made small, the mix will tend to sort out, with the gravel migrating towards the top while the sand filters towards the bottom. By varying the amplitude, even as the vibration is nonstop, the mix can be sorted or blended. How is this explained in terms of entropy which is supposed to be always rising as per 2nd Law of Thermodynamics?

Many say that the 2nd Law of Thermodynamics prove that things always tend towards greater disorder unless "work is done on it", but how does that apply here?

So, batman-will-live-on, you agree that we can have spontaneous order even as entropy continues to rise inexorably?

Kokiri, from a thermodynamic entropy point of view, you've hit this DEAD on. Any macroscopic ordering that might spontaneously appear would have almost no bearing on the overall total entropy.

That's right, tinkertailorcandlestic, and therefore an open system like the container can exhibit spontaneous order even as entropy is rising. "Because work is being put into it".

Even as entropy is going up, as everyone says, order can still spontaneously arise, whether or not it's caused by "outside work".

second-sun, well, but even if we include the shaker with the can, so that we have a closed system, is the entropy rising or not? If it is rising, how is that order appears? If it is decreasing, how is that possible for a closed system?

second-sun, the 2nd Law of Thermodynamics is true for any closed system, not necessarily only for the entire universe.

Answer 1

The increase in heat of the system caused by the vibration of the jar increases the entropy far more than the decrease in entropy resulting from a sorted jar.

Remember that entropy of a system is proportional to heat of the system, from a quantitative standpoint.

Answer 2

Always increasing.

You are sorting the rocks back together yourself so WTF?

You are ADDING energy into the mix, it is not an isolated environment so it appears to be comming back together, but the fuel you are burning (or water you are daming) to create the electricity for your "vibrating laboratory device" is experiencing an increase in entropy, so it all balances out with entropy still increasing.


The law states that the TOTAL entropy in the UNIVERSE is increasing. You are talking about an isolated experiment.

Answer 3

increasing.

Duh.

Any rocket science would know that you imposter.

Answer 4

"Many say that the 2nd Law of Thermodynamics prove that things always tend towards greater disorder unless "work is done on it", but how does that apply here?"

Um, isn't the "device that will vibrate a container" doing work on the contents of the container?