Ah, isn't that usually referred to as the second law?

And in any case, it refers only to closed systems. Given the current state of our ignorance about the extent of our universe (or indeed, what that really means), I do not think that the 2nd law, which was formulated for far smaller and simpler systems, can be used as a final rule to which *everything* must bend.

Thank u Sir,

So, the 2nd law is not exhaustive. That means there may be another universe governed by other set of laws. But what makes us think that universe has 'boundaries'? any logic?

Excerpt from Book: "How Life Really Works"

Is time-travel impossible? Why does water only run downhill? Why is it easy to lose money but difficult to acquire it? The answer to these and many other puzzling questions rests in the Second Law of Thermodynamics, in Entropy.

The so-called Second Law relates closely to the term Entropy. An understanding of this fundamental law of nature and its ramification provides great insights in the way the world really works. Entropy, as expressed by the Second Law, is the ultimate Natural Law because it determines the flow of what we call "time". Thus, entropy deals with the very existence of the universe. The term entropy describes phenomena that have the most profound effect on all events in human existence, including our ability to achieve happiness by aligning ourselves with Objective Reality.

The Second Law holds a unique position in science because it has never evolved from a theory such as the Theory of Relativity or the Theory of Quantum Mechanics. The Second Law is empirical. There is no fully satisfactory theoretical proof for the Second Law, although there are some connections to Quantum Mechanics, Probability and Relativity. Once a Unified Field Theory, the Theory of Everything, is developed, it will and must account for Entropy. Many scientists, who claimed that this Law is paradoxical in nature, have tried to attack it. However, in all instances the alleged paradoxes were due to faulty reasoning. The Second Law has prevailed and has established itself as the most fundamental of all Natural Laws.

The profound nature of the Second Law manifests itself in every aspect of human existence. It covers questions pertaining to the obscure beginnings of the universe to the way we pour milk in our coffee. I remember my high school teacher posing the question: You have a cup of very hot coffee that you would like to drink as soon as possible, let us say, within 5 minutes. Should you first add the desired quantity of cold milk to the coffee and then let the coffee sit for 5 minutes? Alternatively, do you let the coffee sit for 5 minutes and then add the same quantity of milk?

The answer is not intuitive but it is simple, if we are familiar with the Second Law: The rate of heat exchange between the hot coffee and the ambient air depends on their temperature differential. The higher the temperature differential, the faster will be the rate of exchange. Within the 5-minute waiting period, heat transfers to the air at a higher rate if we do not add the cold milk initially to the coffee. If we add the milk at the beginning, instead of at the end of the 5 minutes, the energy transfer will slow down and the coffee will be markedly hotter at the end of 5 minutes.

This revelation does not appear to be a momentous event. It was only intended to indicate the pervasiveness of the Second Law, especially in view of the fact that most people are seemingly ignorant of it. The point is, the Second Law is not intuitive. We have to acquire the relevant knowledge by a rational thought process in order to take advantage of it. The cup of coffee is not important but the principle behind the cup permeates all of our existence: In order to optimize the effectiveness of our actions it is helpful to understand the implications of Entropy.

Entropy describes the degradation of energy to perform work. What is energy? On the high school level, we simply defined energy as the capacity to do work. However, the real question is, What factor, precisely, is doing this work? Why does energy have the capacity to perform work? The HOWs in life are easy, the WHYs are the tough ones.

Energy is the raw material of the universe. At the time of the Big Bang, about 13.7 billion years ago, there was nothing but raw energy. There was no mass with a physical attribute. It was only much later in the nascent universe that this primal energy transformed itself into physical mass, stars, nebula and black holes. Stars, and particularly supernovas, are the factories of the elements, such as iron, from which human beings are formed.

As we know from Einstein's famous formula E = m c^2, mass and energy are freely convertible into each other. The Hydrogen Bomb demonstrates this conversion in a spectacular fashion. Most of the energy it generates is due to the conversion of matter into energy. Such conversion of matter into energy, and vice-versa, is also a less spectacular event in everyday phenomena although it is usually so minuscule as to escape our attention: When we exercise vigorously, we convert chemical energy into radiated heat energy. All this radiated energy that leaves our body has mass, just as light has energy and weight, although it will not register on our bathroom scale.

In cognizance of these basic facts, we can stipulate that energy is the basic raw material that makes up the universe and all that is contained within it, including human beings. The essence of the universe is the unity of energy, time and space.

Energy is essentially a heat phenomenon. Heat and work are mechanisms by which systems exchange energy with one another. The mechanical equivalent of heat is called a Joule. 4.2 joules are the equivalent of one calorie, the amount of heat required to raise the temperature of one gram of water by one degree Celsius.

In order for energy to perform work, a difference must exist between energy at a high potential and energy at a more randomized, diluted, potential. The term entropy is a measure of the degree to which energy has lost the capacity to perform useful work. Entropy signifies the dilution, the randomization of energy. We may look at water in two lakes, connected by a canal. Unless the lakes are at a different level, unless they are at a different energy potential, there is plenty of water, but all this water has no potential energy and cannot perform any useful work because it cannot change levels. This ability or inability to perform useful work is an analogy to and is at the heart of the term entropy and the Second Law of Thermodynamics.

Let us back up a little: This whole subject of Thermodynamics sounds like a very complicated affair. Indeed, it is both very simple and extremely complex. There are three Laws of Thermodynamics, but we need to concern ourselves only with the first two laws because they are closely interwoven and can actually be expressed in one sentence: The total energy content of the universe is constant and the total entropy, the non-usable energy, is constantly increasing. There you have it: The combination of the first and second law of thermodynamics.

Very interesting, but what does it mean? It means that energy cannot be created or destroyed. It can be transformed into mass, chemical energy, heat energy, latent energy and work, but it cannot be created and it cannot disappear. Energy is also in a constant, inevitable and irreversible process of becoming increasingly randomized. Salt crystals may be dissolved in a beaker of water without losing its identity as salt. The salt became more randomized when it dissolved in the water. The Law of Entropy decrees that it cannot reconvert itself to the less randomized, crystalline version. The salt cannot reconstitute itself as crystals, unless we introduce external energy to evaporate the water.

The amount of energy in the universe was established at the time of the Big Bang. At that point, energy was extremely concentrated and ordered. Since then, the universe has expanded vastly and energy has become more diluted and randomized. It is inherent in the nature of the universe that this process must and will continue. If it were to stop, the universe would cease to exist.

This increasing randomization of energy, entropy, is part of the structure of the universe. The energy dilemma does not involve the amount of energy that is available; it involves the form in which the energy is available. The universe is involved in a constant process of converting one form of energy into another form and in doing so, it inevitably must convert part of the original energy into more randomized, less usable, heat energy. Potential energy is organized energy whereas heat represents randomized, disorganized energy. Heat energy is irretrievable energy. Although the energy contained in heat is not destroyed, it has become unavailable for producing work. All forms of energy are degraded incessantly and irreversibly to an inferior, lower-quality, more-randomized form of energy: Heat.

By the same principle, the solar energy that pours out of the furnace of the sun travels on and on until it eventually becomes scattered throughout the universe: It becomes so randomized that it becomes unusable for the performance of work. Therefore, we must stipulate that entropy, as a measure of the randomness of energy in the universe, is always increasing.

The question arises, what will happen when all the usable energy in the universe is converted into randomized heat energy and is no longer capable of performing such work as expanding the universe. We refer to this condition as the Heat Death of the Universe: Once all the energy in the universe is converted to and randomized as heat, then the universe will be in a state of energy equilibrium, everything will be of the same temperature and entropy will remain constant. This is where science gets more complicated and involves the microwave background radiation consisting of photons near, but not quite at, absolute Zero. Scientists have recently detected this microwave background radiation and have thus confirmed the connectivity between Thermodynamics and Quantum Mechanics.

Before we go on to some practical manifestations of entropy, we need to be aware of a very important characteristic of entropy: The Laws of Thermodynamics pertain only to a system that we refer to as a closed system: An entity that does not exchange energy, information or mass with anything outside the system. The universe in its totality is a closed system because no new energy is injected into it. Therefore, all laws of Thermodynamics apply to the universe. Earth is not a closed system because our sun constantly injects it with new energy. This infusion of energy into the non-closed system of the earth makes it possible to comply with the Second Law while achieving an increase in the complexity of life forms, as necessitated by the process of evolution.

The laws of thermodynamics are among the very few laws of nature that describe phenomena that are an integral part of the origin of the universe, of the Big Bang. The other laws in this category are gravity, relativity, nuclear binding forces and electromagnetism. Human beings need not concern themselves with the effects of relativity or quantum mechanics. However, the phenomena of thermodynamics constantly and profoundly affect all human beings.

If there are any laws that have truly universal applicability and that also affect ordinary human affairs, they are the Laws of Thermodynamics. The following statement contains the essence of Entropy: In any transformation of energy from one form to another, useful energy is lost irreversibly. The German physicist Clausius first used the term Entropy in 1865 to describe the nature of the Second Law of Thermodynamics. Even great physicists of that period, like James Maxwell, had trouble with a concept involving only negatives and dealing with the idea of measuring a state of disorder. Today we can condense the statement of Entropy by stating: Entropy in a closed system can never decrease. There are no exceptions to this statement.

The Second Law decrees that water can only flow downhill. Objects do not run uphill by themselves. If we wish to have water run uphill, we must supply outside energy to pump it up the hill.

A clock gradually runs down because the latent energy in its spring is used to run the clock and part of this energy is converted to irretrievable heat. Because the heat cannot be reconstituted into usable energy, this energy is lost irretrievably and the clock cannot rewind itself.

Even in the most complex energy transformations, there is a forward direction to the process because only an outside energy source can reverse a heat-process within a closed system. The burning of gasoline in a car creates mechanical energy and heat. However, no process in the universe will allow the exhaust gases to re-combine with the heat energy and reconstitute the original gasoline: The heat energy of the burning gasoline has achieved a higher and irreversible state of randomization: The entropy of the system, and the universe, is irreversibly increased, as required by the Second Law.

The close relationship of entropy to the statistical laws of probability becomes clear when we hold a stack of five coins in a hand and throw them on a flat surface. Instead of retaining their previous order and proximity, they scatter and increase their randomness. The fall of the coins generated and dissipated the tiniest little bit of heat and the lack of this heat prevented the coins from reforming in the same stack as before. Entropy always drives all transformation of energy in such a way as to increase irreversible randomness.

Ice must have a tendency to melt because H2O molecules in ice crystals are more orderly than in the form of water. Ice crystals tend to become randomized by changing from orderly ice crystals to a more disorderly state as a liquid.

Water must evaporate: A gaseous structure is more randomized than a liquid state.

Time can only flow in one direction: The arrow of time can only move from the dead past to the non-existing future. The Second Law is closely interwoven with the laws of probability. Therefore, the laws of entropy are statistical laws. If we apply statistical laws applicable to entropy to future events, they provide meaningful results; if we apply them to past events, they are meaningless. Therefore, time can flow only from the dead past toward the future, which does not yet exist. Time travel will always remain impossible: It is inherently impossible to move from one state of non-existence to other states of non-existence. The Second Law decrees that the universe would have to cease to exist in order to allow for time-travel.

The laws of thermodynamics are the descriptors of the universe and do not permit perpetual motion machines. We would only waste our time and money if we were to attempt building a machine that not only can run forever, but that could even produce excess energy while doing so.

Heat flows from a hot object to a cold object, never the other way around. When we drop a hot peace of metal in a container of cold water, the metal cools and the water heats up until their temperatures have equalized. During this process the entropy, the randomness of the system consisting of the water and the metal, increases and no further useful work can be performed because there is no longer a temperature differential between the water and the metal: The system has become randomized.

This manifestation of the Second Law can be stated quite simply: Heat energy will not flow from a cooler to a warmer body. It would be foolish to try to warm our hands on a block of ice although there is considerable heat in the ice. If we compare the heat of ice with the heat of liquid hydrogen, ice would appear to be very hot, indeed. It would be easy to build a machine that runs on the heat differential between the cold block of ice and the much colder liquid hydrogen. However, since the heat in the ice is at a much lower level than the heat in our body, heat cannot flow from the ice to our hands. We cannot warm our hands by immersing them in ice. We have always known this fact. Now we know why we cannot warm our hand by touching a block of ice.

Bridges and buildings will inevitably collapse, unless entropy is counteracted by the addition of new energy, such as money, energy, power or labor, to the system. If we do not paint the bridge, it will eventually, but inevitably, collapse.

Money is not energy but it represents energy. Therefore, money becomes randomized automatically, in compliance with the Second Law. As we only know too well, money has a distinct tendency to dissipate, to randomize. On the other hand, the creation of wealth requires an infusion of energy from a source outside the system, such as a competent strategy or the contribution of additional capital or labor.

We know empirically, that things do not organize themselves into artifacts that are more complex unless new energy is inserted from outside the system. This fact is obvious because a broken window will not repair itself. Without competent management, without the energy to organize and structure transactions, a business will fail, a victim of entropy.

Without new software, without the infusion of new energy from outside the computer system, a computer will never acquire new capabilities, but its hard-drive will fill up with defects and clutter due to the degeneration of the data it holds. A well known fact.

The Second Law of Thermodynamics is closely interwoven with the future of the universe and with all life on earth. Sometimes people say that the existence of life on earth violates or contradicts the Second Law. However, this is not the case; we know of nothing in the universe that violates the Second Law.

The definition of life revolves around three prerequisites: The organism must be able to replicate itself, the organism must be capable of energy conversion and the organism must be subject to evolution. The essence of evolution is an increase in complexity, as is obvious when we consider the evolution of living organisms over eons of time.

An increase in complexity entails an increase in the orderliness of the organizational character of the organism: Life represents a decrease of entropy, a decrease of randomness. Such a decrease in randomization can only come about as a result of an infusion of energy from the outside of the closed system, from the outside of the organism. Therefore, the ability to utilize energy by converting it to a usable form, is the essence of all things that we call alive or living. In the case of life on earth, the outside energy is derived from the sun. No sunlight, no life on earth.

This is the chain of life on earth: No energy, no evolution. -- No evolution, no life -- No energy, no life

The discussion of energy is significant, because nothing happens in the universe without energy. The whole universe is a cauldron of energy conversions. As far as human beings are concerned, we need to remember that the standard of living of a person or a nation is determined primarily by the availability of usable energy sources, such as oil or nuclear energy. Without sources of energy to turn our wheels and to compensate for entropy, humanity would revert to the primeval existence of hunters and gatherers.

Many people have trouble understanding the principle of entropy because it is a concept of negatives, because it is a measure of the disorder, of the randomness of a closed system. Every biochemical function requires a decrease in entropy, which can only be achieved by the infusion of energy into a life-sustaining system.

Many people erroneously believe that everything that we use up can be recycled and reused if we only develop the appropriate technology. However, the Second Law makes it inherently impossible to achieve complete reconstitution or recycling. In order to recycle a used product, we must insert additional energy in the collecting, transportation and reprocessing of used materials and this energy expenditure contributes to the overall entropy, the randomness, of the environment. Thus, discards can be recycled only by the expenditure of additional energy and at the expense of increasing the entropy of the universe as a whole. On a light note: Every time someone lights a cigarette, he increases the entropy of the universe and contributes to the energy death of the universe.

Why is this discussion of entropy and the Second Law so important to us, to ordinary human beings? After all, most of us are more concerned with living a happy life, than the heat death of the universe. The problem is that the Second Law has a tendency to interfere with our happiness because it has a pervasive, pernicious effect on our lives. It is imperative that we are aware of the impairments caused by entropy in order to counteract them effectively.

If we encounter a problem in life, it is most important to be fully cognizant of the precise nature and cause of the problem. In trying to resolve the problem, it would be counter-productive to invoke the help of imagined superior beings, instead of dealing with the problem in a realistic, purposeful manner. Unless we understand the nature of entropy, we cannot resolve the deleterious effects that make it difficult to achieve desired results. Therefore, a profound knowledge of the Second Law is extremely important to our quest for happiness.

"Murphy's Law" is well known. After allowing for many humorous embellishments and variations on the basic theme, Mr. Murphy’s proposition states: "Anything that can go wrong will go wrong." A corollary version claims: "Left to themselves, things tend to go from bad to worse".

We laugh about this aspect of life because we have all experienced the effect of Mr. Murphy's Law on many occasions. Rather than recognize Murphy's Law as a humorous version of a basic law of nature, we usually look upon it as a quirk of nature. Nothing could be further from the truth: When we look at the Second Law of Thermodynamics, we realize that Mr. Murphy's law is an inescapable consequence of the principle of Entropy.

Unless we constantly insert new energy into a house by maintaining it, painting it, repairing it, the structure will eventually but inevitably be leveled to the ground. Its molecules will move from a lower level of randomization, from structure, to a higher level of randomization, towards unstructured debris.

Entropy is the reason why paint peels, why hot coffee turns cold. Furthermore, entropy is the reason why investments have a preordained inclination to go sour -- unless we enhance success by inserting into the investment system additional energy in the form of strategy, work, calculated risk or other forms of energy. Entropy ensures that sugar, which becomes more randomized when it is dissolved in water, will not reconstitute itself in the crystalline form -- unless we apply heat energy from outside the system and evaporate the water.

Wherever we look, whatever we do, we must be acutely aware of the immutable laws of thermodynamics, especially the easily overlooked Second Law: Entropy. This fundamental law of physics ranks with other fundamental manifestations of the universe such as gravity, time and electromagnetism.

Anything that can go wrong not only will go wrong, it must go wrong, as decreed by the Second Law of Thermodynamics

Thanks Ibrahim.

Entropy: A concept that is not a physical quantity

https://www.researchgate.net/publication/230554936_Entropy_A_concept_that_is_not_a_physical_quantity