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Battling Entropy

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Re: Battling Entropy

#11

Post by agumonkey »

Rainymood wrote: post #6

>The second law of thermodynamics states that “as one goes forward in time, the net entropy (degree of disorder) of any isolated or closed system will always increase (or at least stay the same).”[1] That is a long way of saying that all things tend towards disorder. This is one of the basic laws of the universe and is something we can observe in our lives. Entropy is simply a measure of disorder. You can think of it…

I'm trying to learn all this, I have the same issue. So far my best interpretation is that order means energy-transfering organization, a solid is ordered, a gaz is not. It's not to be seen as complex vs simple, a machine is more complex than a bunch of cold molecules, but it's would be less chaotic in that sense.

Another definition is the number of possible microstates that can be reached. A cold universe of evenly distributed particles would be the upper limit of these microstates.

ps: coursera just started this https://www.coursera.org/learn/statistical-thermodynamics

Re: Battling Entropy

#12

Post by cygx »

Rainymood wrote: post #6

>The second law of thermodynamics states that “as one goes forward in time, the net entropy (degree of disorder) of any isolated or closed system will always increase (or at least stay the same).”[1] That is a long way of saying that all things tend towards disorder. This is one of the basic laws of the universe and is something we can observe in our lives. Entropy is simply a measure of disorder. You can think of it…

Personally, I don't like the description of entropy as disorder.

Mathematically, it's a measure of spread of a probability distribution (the more spiked a distribution, the lower the entropy, which is an 'ordered' state insofar that things are arranged in specific places instead of randomly thrown all over the place).

Depending on your point of view, I would describe entropy in physics as microscopic indeterminacy (essentially the number of microscopic states that are part of your statistical ensemble defined in terms of macroscopic constraints), or as microscopic freedom (essentially the volume of microscopic phase space accessible to time evolution of a system in thermodynamic equilibrium).

Re: Battling Entropy

#13

Post by urgoroger »

Rainymood wrote: post #6

>The second law of thermodynamics states that “as one goes forward in time, the net entropy (degree of disorder) of any isolated or closed system will always increase (or at least stay the same).”[1] That is a long way of saying that all things tend towards disorder. This is one of the basic laws of the universe and is something we can observe in our lives. Entropy is simply a measure of disorder. You can think of it…

It might be easier to view entropy of a state as sort of the probability that that state would occur after randomly arranging all of its parts (usually particles). In fact this is pretty close to the actual definition.

Here's an example: Suppose you had a container and you put some marbles at the bottom such that there are reasonably large gaps between the marbles. Now if you close and then shake the container hard (this is the 'random arrangement' process), then it is with high probability when you open the container that the marbles will be arranged reasonably spread out across the bottom. In this sense, when the marbles are spread kind of far apart in the container, it is in a state of high entropy (probability).

There is also the chance that when you open the container the marbles form a perfect straight line at the bottom. However, this is much more unlikely, so that you would consider this a low entropy state.

Now, consider the universe in place of the container, and subatomic particles as the marbles. Randomly configuring all of these particles, it would be really hard to end up with a stars, galaxies, humans. These are like straight lines in the marble example. It is much more likely you just get a soup of somewhat uniformally distributed particles (as in the marbles just being sort of randomly spread out from each other). This is what you describe as "a perfectly uniformly distributed of zero temperature mass (or maybe absoute zero, not sure) of grey energy is the perfect order". It wouldn't really be 'perfect' in some senses of the word though, which may be your cause of confusion. It would be more like if you took a snapshot of the static on an old TV.

Re: Battling Entropy

#14

Post by ForHackernews »

> Let’s imagine that we start a company by sticking 20 people in an office with an ill-defined but ambitious goal and no further leadership. We tell them we’ll pay them as long as they’re there, working. We come back two months later to find that five of them have quit, five are sleeping with each other, and the other ten have no idea how to solve the litany of problems that have arisen. The employees are certainly not much closer to the goal laid out for them. The whole enterprise just sort of falls apart.

Is that true? I mean, it sounds intuitively appealing (especially if you fancy yourself a boss-type) but has anyone actually done this experiment?

Maybe some of those 20 people are ambitious and take it upon themselves to lead the project, maybe they all form a self-organizing collective and make sensible decisions by consensus, maybe they hold a vote to elect a de facto CEO...

Re: Battling Entropy

#15

Post by gdhbcc »

ForHackernews wrote: post #14

> Let’s imagine that we start a company by sticking 20 people in an office with an ill-defined but ambitious goal and no further leadership. We tell them we’ll pay them as long as they’re there, working. We come back two months later to find that five of them have quit, five are sleeping with each other, and the other ten have no idea how to solve the litany of problems that have arisen. The employees are certainly n…

There was a german entrepreneur who did something like that. He picked a bunch of young software developers and gave them an office and budget to do what they like with it. It didn't end well, they spent the budget on gaming chairs and spent most of their time playing video games

Re: Battling Entropy

#16

Post by leni536 »

esalman wrote: post #10
saagarjha wrote: post #2

This article begins with an analogy to the thermodynamic concept of entropy, and then attempts to relate it to other kinds of "entropy" by making the simplification that entropy is equivalent to disorder. That's all fine and well, but then I really thinks it goes too far: you really can't try to "reduce entropy" in your business by looking at a physical process, nor is coughing "the transfer of energy as heat". It's…

Interestingly, biological beings seems to defy the second law by working to reduce disorder, or surprises, in the sensory system. This is the meat of Karl Friston's Bayesian hypothesis of the brain.

> biological beings seems to defy the second law

Well, maybe they seem but they certainly don't. Biological beings are not closed systems.

Re: Battling Entropy

#17

Post by saagarjha »

esalman wrote: post #10
saagarjha wrote: post #2

This article begins with an analogy to the thermodynamic concept of entropy, and then attempts to relate it to other kinds of "entropy" by making the simplification that entropy is equivalent to disorder. That's all fine and well, but then I really thinks it goes too far: you really can't try to "reduce entropy" in your business by looking at a physical process, nor is coughing "the transfer of energy as heat". It's…

Interestingly, biological beings seems to defy the second law by working to reduce disorder, or surprises, in the sensory system. This is the meat of Karl Friston's Bayesian hypothesis of the brain.

The second law only applies to closed systems, which living things are not. While they may internally reduce entropy, when you consider them along with the environment they live in, they end up producing heat and other disorder that is far in excess to the small amount of order they have created.

Re: Battling Entropy

#18

Post by kgwgk »

dr_dshiv wrote: post #8

Entropy has been increasing since the big bang, when it was at minimum value. While the total energy didn't change since then, there has been a vast increase in the potential locations of that energy and a vast increase in the number of different interactions possible within that energy. This increases entropy because the possibility space has increased. Boltzman entropy is defined as the number of potential microsco…

Thermodynamical entropy is not a physical property of a system. It’s a property of our description of the system as a macroscopic state.

Quantum (von Neumann) entropy is a related but different concept. It’s worth noting that it is constant for a closed system.

Cosmological entropy can be defined in different ways. In summary, entropy means many things and not all “entropies” behave in the same way.

Re: Battling Entropy

#19

Post by posterboy »

urgoroger wrote: post #13
Rainymood wrote: post #6

>The second law of thermodynamics states that “as one goes forward in time, the net entropy (degree of disorder) of any isolated or closed system will always increase (or at least stay the same).”[1] That is a long way of saying that all things tend towards disorder. This is one of the basic laws of the universe and is something we can observe in our lives. Entropy is simply a measure of disorder. You can think of it…

It might be easier to view entropy of a state as sort of the probability that that state would occur after randomly arranging all of its parts (usually particles). In fact this is pretty close to the actual definition. Here's an example: Suppose you had a container and you put some marbles at the bottom such that there are reasonably large gaps between the marbles. Now if you close and then shake the container hard (…

The common depiction is of a bunch of particles of two kinds, sorted into separate compartments by kind, which will mix if a divider is removed. In this picture, every part of one kind receiving a partner of the other kind, that can be called a state of order. If we take heat instead, every particle swinging differently is more chaotic--at least in my understanding--than all synching up so that their speeds relative to each other are zero ... 0 degree is just not higher order, because "high" is associated with high frequency (or energy or order).

In your shaky example, you transmit energy to the system by shaking, so if shaking a certain way, you'd well expect standing waves, if shaking a bit more you'd pulverize the marble and ultimately a hot plasma with density gradients. I wonder how hard you'd have to shake and swirl to eventually get a black hole, for which the notion of entropy doesn't even really make sense, if you aren't inside.

Re: Battling Entropy

#20

Post by infinite8s »

esalman wrote: post #10
saagarjha wrote: post #2

This article begins with an analogy to the thermodynamic concept of entropy, and then attempts to relate it to other kinds of "entropy" by making the simplification that entropy is equivalent to disorder. That's all fine and well, but then I really thinks it goes too far: you really can't try to "reduce entropy" in your business by looking at a physical process, nor is coughing "the transfer of energy as heat". It's…

Interestingly, biological beings seems to defy the second law by working to reduce disorder, or surprises, in the sensory system. This is the meat of Karl Friston's Bayesian hypothesis of the brain.

You forgot to include the sun in your analysis.
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