# Nearly Perfect Efficiency - 2nd Law of Thermodynamics

• ObjectivelyRational
In summary, the article discussed the concept of converting information into energy and the role of a "demon" in this process. It also mentioned the relationship between information and entropy, and the implications for the second law of thermodynamics. Questions were raised about the efficiency of this conversion and the difference between the traditional and generalized second laws of thermodynamics. The factors determining when it is appropriate to consider a part of a system as "the" system were also discussed.
ObjectivelyRational

https://phys.org/news/2018-01-efficiency.html

My questions are:
1. If "converting" information into energy requires a system (the demon I suppose) having a photodiode, processor, laser (light trap) all expending energy in order to cause the conversion, (i.e. the demon works ON the trapped particle) then how can it be said that "none of the information is lost but is instead almost entirely converted into work". i.e. How can we exclude the idea that work was provided to the system from the "outside" in an amount that looks like it was created by the "information" of the trapped particle?

2. What is the difference between the "traditional" second law of thermodynamics and the "generalized" second law of thermodynamics?

3. What factors determine conceptually when it is reasonable to describe some part of a system as "the" system, and to ignore the whole system (i.e. everything interacting with it), when discussing things like "efficiency" and the second law of thermodynamics?

I think this is in principle well known. Bennett and Landauer did show that in principle all operations of a computer can be performed reversible with the exception of the deletion of the memory. The physical entropy produced on deletion of the memory corresponds exactly to the information entropy of the memory. Hence a demon can produce work at the expense of his memory storing more and more information. In a true thermodynamic cycle, also the demon has to return to it's initial state, so that his memory has to be cleared. This produces the entropy for the whole process to be compatible with the second law.

DrClaude
DrDu said:
Bennett and Landauer did show that in principle all operations of a computer can be performed reversible with the exception of the deletion of the memory.

It seems that there a still some debates with respect to this when looking at some publications by J. D. Norton or L. B. Kish.

Could some kind person address my specific questions? I am genuinely curious.

ObjectivelyRational said:

https://phys.org/news/2018-01-efficiency.html

My questions are:
1. If "converting" information into energy requires a system (the demon I suppose) having a photodiode, processor, laser (light trap) all expending energy in order to cause the conversion, (i.e. the demon works ON the trapped particle) then how can it be said that "none of the information is lost but is instead almost entirely converted into work". i.e. How can we exclude the idea that work was provided to the system from the "outside" in an amount that looks like it was created by the "information" of the trapped particle?

2. What is the difference between the "traditional" second law of thermodynamics and the "generalized" second law of thermodynamics?

3. What factors determine conceptually when it is reasonable to describe some part of a system as "the" system, and to ignore the whole system (i.e. everything interacting with it), when discussing things like "efficiency" and the second law of thermodynamics?
1: They did not claim that the collection of information was efficient, only the 'conversion' of the collected information was claimed to produce almost as much work as is possible according to the generalized second law of thermodynamics.

2: I guess a generalized engine consists of a heat source, a heat sink and an information source, while there's no information source in a diesel engine.

3: I have no idea.

## 1. What is the 2nd Law of Thermodynamics?

The 2nd Law of Thermodynamics is a fundamental law of physics that states that in any natural process, the total entropy of a closed system will never decrease over time. In simpler terms, it means that energy will always flow from a hot object to a cooler object, and not the other way around.

## 2. How does the 2nd Law of Thermodynamics relate to efficiency?

The 2nd Law of Thermodynamics is closely related to the concept of efficiency because it sets limits on how efficient a system can be. This is known as the Carnot limit, which states that no heat engine can have an efficiency of 100%. This means that there will always be some energy lost or wasted in any system due to the law of entropy.

## 3. Can a system ever achieve perfect efficiency?

No, according to the 2nd Law of Thermodynamics, it is impossible for a system to achieve perfect efficiency. This is because some energy will always be lost as heat in any natural process, and the total entropy of a closed system will always increase.

## 4. What is meant by "nearly perfect efficiency"?

"Nearly perfect efficiency" refers to a system that has a very high efficiency, but not quite 100%. This means that the system is able to convert a large percentage of its energy input into useful work, but there is still some energy loss due to the 2nd Law of Thermodynamics.

## 5. How can we improve the efficiency of a system?

While it is impossible to achieve perfect efficiency, there are ways to improve the efficiency of a system. One way is to minimize energy loss by insulating the system, reducing friction, and using more efficient materials. Another way is to use advanced technologies, such as cogeneration, which can capture waste heat and use it for other purposes.

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