As an expert in the field of thermodynamics and information theory, I can provide a comprehensive explanation of the concept of negative entropy, also known as "negentropy."

Entropy is a measure of the amount of disorder or randomness in a system. It is derived from the second law of thermodynamics, which states that the total entropy of an isolated system can never decrease over time. The law implies that natural processes tend to move towards a state of greater disorder or higher entropy. Entropy is often associated with the dispersal of energy, and in the context of thermodynamics, it is related to the efficiency of energy transfer and the amount of energy that is unavailable to do work.

The concept of negative entropy, or negentropy, is somewhat counterintuitive because it suggests a decrease in the disorder of a system. In thermodynamics, this would mean that energy that was previously unavailable for work is now made available. This can occur in localized systems, but it is important to note that the overall entropy of the universe, according to the second law, must still increase. This means that while you might see a decrease in entropy in a specific part of a system, the surrounding environment will experience an increase in entropy that is greater than the decrease.

In the context of information theory, negentropy is used to describe the amount of information or order in a message. Claude Shannon, the father of information theory, introduced the concept of entropy to quantify the uncertainty or information content in a set of messages. Negative entropy, in this context, would mean a reduction in uncertainty or an increase in the predictability of a message.

The statement "More entropy means 'more energy wasted', less entropy means 'less energy wasted'" is a simplified way of looking at the concept. It is true that in a thermodynamic system, higher entropy often corresponds to a larger amount of energy that is dispersed and not available to do useful work. However, it is not accurate to say that entropy itself is "wasted" energy. Instead, it is a measure of the unavailability of energy to perform work.

The idea that "A negative entropy means that 'wasted' energy is transformed into work" is a bit misleading. While it is true that in certain processes, such as in a Carnot engine, the system can extract some of the energy that was previously unavailable and convert it into work, this does not mean that the energy was "wasted" in the first place. Instead, it was not accessible for work under the conditions of the initial state of the system.

It is also important to clarify that "On some local processes you can obtain a negative entropy, but the global process has always a positive entropy." This statement is correct in the sense that while local decreases in entropy can occur, they are always accompanied by a larger increase in entropy elsewhere in the system or the environment. This is in accordance with the second law of thermodynamics, which ensures that the total entropy of the universe is always increasing.

In summary, negative entropy or negentropy is a concept that suggests a decrease in the disorder of a system, which can occur locally but must result in an overall increase in the universe's entropy. It is a complex concept that touches on the principles of thermodynamics, information theory, and the nature of energy and information.

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More entropy mean "more energy wasted", less entropy means "less energy wasted". A negative entropy means that "wasted" energy is transformed on work. On some local processes you can obtain a negative entropy, but the global process has always a positive entropy.read more >>