1900: A physics genius wandering around Europe

Chapter 570 The Four Laws of Thermodynamics! Does the perpetual motion machine really exist? The law of increasing entropy! Heat death universe!

There are four major laws of thermodynamics.

These four laws are the core and foundation of the entire thermodynamics.

All thermal phenomena in the world can be explained by them.

The Zeroth law was proposed by Rutherford's son-in-law Fowler.

"If two thermodynamic systems are in thermal equilibrium with a third system, then the two systems must also be in thermal equilibrium with each other."

The Zeroth Law is consistent with human intuition, similar to the mathematical statement x=z, y=z, then x=y.

have nothing to say.

The first law was finally perfected by several physics giants such as Joule and Carnot.

“The increase in the internal energy of an object is equal to the sum of the heat absorbed by the object and the work done on it.”

But there is a more classic way to express it:
“Heat can be transferred from one object to another and can be converted to and from other forms of energy, such as mechanical energy.”

"But during the conversion, the total amount of energy remains the same."

When the first law of thermodynamics is extended to all energy, the famous "law of conservation of energy" is formed.

The law of conservation of energy was finally established after long-term production practice and a large number of scientific experiments.

It is an axiomatic theorem and is also very consistent with human intuition.

Since it was proposed, the law of conservation of energy has withstood countless challenges and ultimately remained standing.

Even relativity and quantum mechanics cannot overturn this law.

The third law of thermodynamics was proposed by Nernst alone.

“It is impossible to bring the temperature of an object to absolute zero by a finite number of steps.”

A corollary of this law is that at absolute zero, the change in entropy of any object is equal to zero.

Because at this moment all the atoms that make up the object have stopped vibrating.

Note that zero-point energy should not be substituted here.

Logically speaking, even at absolute zero, particles still have tiny vibrations, and the energy they possess is zero-point energy.

But it is not considered in the traditional definition of temperature.

Many people in later generations will wonder, since there is the lowest temperature in the universe, which is absolute zero -273.15℃, is there a highest temperature?

Hey, there really is!
That's the Planck temperature, which is about 1.4×10K.

It is the temperature formed when all matter and energy were concentrated in one point at the moment of the Big Bang.

This is an unimaginably high temperature.

You know, the core temperature of the sun is only 1500 million K.

The highest temperature that humans can currently create is about 5 trillion K, which is far from the Planck temperature.

The zeroth, first, and third laws have never experienced any disturbances since their birth.

Because these three laws are very consistent with people's simple feelings.

It’s just that physicists use the language of physics to express them in the form of laws, forming a rigorous logic.

Even the first law, although some people question it, has been proven correct by countless experiments.

This makes it more popular.

Moreover, these three laws are not well-known among ordinary people, and many people have never heard of them.

However, the second law of thermodynamics is completely different.

It should be the most famous law among the four laws.

In later generations, the Second Law became a battlefield where countless amateur scientists competed for supremacy.

Countless wild imaginations collide here, making it very lively.

The reason why the second law of thermodynamics has attracted so much attention is all because of three words: perpetual motion machine!
There are two types of perpetual motion machines: first-class perpetual motion machines and second-class perpetual motion machines.

The first type of perpetual motion machine is one that continues to do work without consuming energy.

This obviously violates the first law of thermodynamics.

"You want the horse to run, but you don't want it to eat grass."

How is this possible? It goes against people's common sense.

For example, Leonardo da Vinci once designed a classic perpetual motion machine.

There are many small metal balls in a wheel, and the heavy ball on the right is farther away from the center of the wheel than the heavy ball on the left.

Then, when the gravity on both sides is unbalanced, the wheels will keep turning.

Obviously, this is impossible to achieve.

Because Leonardo da Vinci did not take into account the problem of friction loss.

The energy consumed by friction is also part of the system.

Therefore, the first type of perpetual motion machine was easy to detect, and soon no one studied it anymore.

But the second type of perpetual motion machine is different.

First, it complies with the first law of thermodynamics.

Secondly, although it violates the second law of thermodynamics, the second type of perpetual motion machine itself is very confusing.

The second type of perpetual motion machine is one that absorbs heat from a single heat source and converts all of it successfully.

At first glance, this doesn't seem to be a problem.

The second type of perpetual motion machine fully complies with the law of conservation of energy, except that the heat-to-work conversion efficiency is 100%.

Although this efficiency is indeed too high and too perfect, it is rarely seen in nature.

But difficult doesn't mean impossible.

For example, the efficiency of matter-antimatter annihilation is also 100%.

This shows that the universe does not prohibit behavior with a conversion rate of 100%.

Therefore, many people are pursuing the second type of perpetual motion machine.

They believe that the reason they cannot produce it now is that the technology is not up to standard, and it will definitely be possible in the future.

People in the 19th century thought the same way.

Many people, even physicists, would like to overturn the second law.

Because once it is overturned, it means that it becomes possible to realize the second type of perpetual motion machine!

Human beings will have inexhaustible energy!

What an exciting breakthrough this is!

In later generations, some people made calculations.

There are 10 billion cubic meters of seawater on the earth's surface.

Using seawater as the sole heat source, even if the temperature of the seawater is only reduced by 0.25℃.

The heat released can be converted into enough electricity to be used by humans for a thousand years.

What kind of nuclear fusion is needed for this?

Running in
Therefore, when Ridgway asked the question, "Is the second law of thermodynamics necessarily correct?"

Everyone was shocked.

"Oh my God! Professor Bruce is not trying to overturn the Second Law?"

"Is this really possible?"

"The textbook says it very clearly, and the Second Law of Thermodynamics has been verified by many experiments. It can't be wrong, right?"

"Nothing is impossible. Newtonian mechanics has been overturned by Professor Bruce, so what's wrong with the second law?"

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Many students were very excited and talked about it.

In their minds, it was not surprising for Professor Bruce to come up with any theory.

Subverting the laws of thermodynamics is no problem!

Geniuses such as Oppenheimer and Wang Dezhao also looked excited.

Although they believe in their hearts that the Second Law cannot be broken.

After all, it has withstood so many experiments.

But he is that man after all!
The other party is synonymous with miracle!

However, bigwigs like Lang Zhiwan and de Broglie smiled at each other.

"Professor Bruce must be deceiving these students again."

"He probably wants to use this to bring up Maxwell's demon, the third mythical beast." "It hasn't been solved yet."

The bosses were right.

Under everyone's expectation, Li Qiwei said with a smile:

"I'm not the first person to ask that question."

"Before me, many physics experts have raised such doubts."

"Because the Second Law of Thermodynamics is so important."

“It has so much connotation.”

“Besides, it is also related to the perpetual motion machine that many people are obsessed with.”

"I guess most of you here don't really understand the second law of thermodynamics."

"Today, I would like to take this opportunity to tell you about it."

"The second theorem is the law of thermodynamics with the largest number of physicists involved and the most complex expression."

"The first statement is also called the Clausius statement."

"That is: heat cannot be transferred spontaneously and without cost from a low-temperature object to a high-temperature object."

"This is expressed in terms of the direction of heat conduction."

"For example, the refrigerator that everyone likes is based on this principle."

"If you want to cool, you have to use extra electricity to move the heat from the cold inside the refrigerator to the hot outside."

"Clausius's statement is consistent with our daily experience."

"For example, if you leave a cup of cold boiled water there, it won't get hotter and hotter. It will only get colder and colder until it reaches the same temperature as the environment."

"The second statement is called the Kelvin statement."

"That is: it is impossible to take heat from a single source and convert it all into work without causing other effects."

“This is expressed in terms of energy expenditure.”

"Kelvin's statement also shows that the second type of perpetual motion machine will never be realized."

"Because it is impossible for all the absorbed heat to be converted into work."

"Note that this statement is not a strict theoretical derivation, but an empirical axiom obtained based on a large number of experiments."

"The theory of heat engine efficiency invented by Carnot is a solid foundation."

"But because Kelvin's statement is an axiom developed on the basis of experiments, many people think it may not be completely correct."

"That's why perpetual motion machines of the second kind are currently popular."

“Whoever can invent a perpetual motion machine of the second kind will have overturned the second law of thermodynamics.”

Wow!
The eyes of the audience were fiery.

In this era, the correctness of the second law of thermodynamics was not as deeply rooted and questioned as it was in later generations.

Even in the academic field, there are many doubts.

"The Clausius statement and the Kelvin statement are equivalent and both represent the connotation of the second law of thermodynamics."

"At this time, some people might be curious."

"Hey, isn't it said that Maxwell's demon is related to the second law of thermodynamics?"

"Why is Maxwell not mentioned in the two major statements?"

"Don't worry."

"Here, we have to mention another crucial concept in the field of thermodynamics: entropy."

“In my opinion, a humanities scholar who knows nothing about entropy is as bad as a scientist who knows nothing about Shakespeare.”

"The theory of entropy may be the first law of all science!"

Wow!
Everyone was shocked!

They couldn't understand why Professor Bruce had such a high opinion of entropy.

"In 1865, Clausius discovered a new macroscopic state function while studying thermodynamics."

"He expressed it as dS = dQ/T."

"Where T represents the temperature of the system, dS represents the entropy change of the system, and dQ represents the heat change during the entropy change of the system."

"This formula states that if the temperature of a system does not change, then adding heat to the system will cause the entropy of the system to change."

"Then Clausius had an idea and he linked the concept of entropy to the second law of thermodynamics."

"Through rigorous mathematical derivation, he derived another form of the second law: dS ≥ dQ/T."

“That is, from the perspective of entropy, all spontaneous thermodynamic processes are irreversible.”

“What is reversible and irreversible?”

“If a system starts from state A, goes through process B, and finally becomes state C.”

"At this time, if there is another process B+, it can make the system change from state C back to state A and eliminate all other effects."

"Then we can say that B is a reversible process."

“Otherwise, B is an irreversible process.”

"According to Clausius's formula, any process that a thermodynamic system consisting of a large number of particles undergoes is irreversible."

"Take the example I just mentioned."

"Put a drop of ink into a glass of water."

"So, can you separate the ink from the water without causing any other effects?"

"Obviously, that's impossible."

“Because this is an irreversible process.”

“Someone said: No, I have a solution.”

"If I have enough energy and time, can I find the ink molecules one by one?"

"Unfortunately, this is not possible because it consumes energy and has other effects."

"There are many similar examples, such as reconciliation and so on."

"The concept of entropy proposed by Clausius has greatly expanded the connotation of thermodynamics."

"It allows physicists to think about the heat transfer process from another perspective."

"Immediately afterwards, Boltzmann redefined the concept of entropy from a microscopic perspective."

"He believed that entropy was a measure of the disorder of a system."

"For a system composed of a large number of gas molecules, entropy represents the degree of disorder of the molecules in the system."

“Boltzmann was the first to link the entropy and probability of a system together and to explain the statistical nature of the second law of thermodynamics.”

"This is the famous Boltzmann distribution."

"The basis of the Boltzmann distribution is the velocity distribution law of microscopic particles proposed by Maxwell."

"Based on Clausius and Boltzmann, the second law of thermodynamics has a new name: the law of increasing entropy."

“The transfer of heat and the work done are all converted into changes in the entropy of the system.”

Wow!
At this moment, all the students were listening with fascination.

Although they all studied thermodynamics.

But never before has a big man analyzed the ins and outs of the four laws of thermodynamics for them like today.

Especially the second law of thermodynamics, it turns out to be so complicated!
At this moment, Li Qiwei continued:

“There are many ways to express the law of increasing entropy.”

"One of the classic versions is that the entropy of an isolated thermodynamic system never decreases."

“An isolated system is one that has no material or energy exchange with the outside world.”

“It can be said that the law of increasing entropy has been disliked and questioned by everyone since its inception.”

"Because if it's correct, then it means our universe is heading toward heat death."

"Because one of the corollaries of the law of increasing entropy is that the entropy is maximum when the system reaches equilibrium."

"If the universe is viewed as an isolated system, then its end result is to reach a state of maximum chaos."

Wow!
Everyone suddenly felt an icy chill.

It seems as if there is a truth that secretly arranges the fate of everyone.

"However, at this moment, Maxwell stood up!"

(End of this chapter)