# About the Entropy of the Universe

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• STAR GIRL
In summary, Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. The force exerted by the second body on the first body is called reaction, and they are equal and opposite. The Second Law of Thermodynamics states that in any cyclic process, entropy will either increase or remain the same. Entropy is a measure of the amount of energy unavailable to do work. While these laws may seem contradictory, they are both valid in all situations. The increase in universe entropy can be explained by it being an emergent property and nature's tendency to move towards states of high probability.
STAR GIRL
The Theory. Newton's Third Law of 1)Motion states: 'To every action there is an equal and opposite reaction'. ... The force exerted by the second body on the first body is called reaction. The action and reaction are equal and opposite.

2)Second Law of Thermodynamics : In any cyclic process the
entropy will either increase or remain the same. Entropy: a measure of the amount of energy which is unavailable to do work.
If every action has equal and opposite reaction... Than if I pushed a ball than it goes towards further... But it doesn't come back... Here the law did not applied because of the total force applied by me is decrease by air resistance and friction... And some force is used to do work... Its confusing means why Newton 3rd Law and Thermodynamic 2nd law opposite to each other... And universe entropy is increasing... Why it increasing why ? it doesn't obey Newton's 3rd...

STAR GIRL said:
Here the law did not applied because of the total force applied by me is decrease by air resistance and friction...

That's not correct. The force you must apply to the ball (and the force the ball applies to you) is actually increased because of air resistance if you want to accelerate the ball at the same rate as a ball being accelerated in a vacuum.

STAR GIRL said:
And some force is used to do work...

That's right, part of the total work is work done to move the air, part of it is in the form of energy lost to friction, and the rest is in the kinetic energy of the ball.

STAR GIRL said:
Its confusing means why Newton 3rd Law and Thermodynamic 2nd law opposite to each other... And universe entropy is increasing... Why it increasing why ? it doesn't obey Newton's 3rd...

Newton's third law and the second law of thermodynamics are not opposite of each other. Both are equally valid in all situations, including this one.

STAR GIRL
But why universe entropy increases?

My view is that entropy is what is called an emergent property. That is it only appears at a certain level of description. It is well known that at a fundamental level all processes are reversible. Think of a Feynman diagram of an interaction and the process can go both ways. Entropy is best visualized as a probability in that low entropy states are low probability of occurring so that nature tends to move towards states of high probability. Example – there is only one way to arrange a pack of cards in the standard order but many of any other order (about 10^68) so the cards are far more likely to be in any order bar the one they originally came as, excepting new packs. Boltzmann’s law states:

S = k ln W,

where S is the entropy and W is the number of configurations (k is Boltzmann’s constant). So any random process will tend to become more disordered.

## 1. What is entropy and how does it relate to the universe?

Entropy is a measure of disorder or randomness in a system. In the context of the universe, it refers to the overall level of chaos or disorganization in the universe. As the universe expands, the amount of entropy also increases, leading to a gradual increase in disorder and randomness.

## 2. How is the entropy of the universe calculated?

The entropy of the universe is calculated by taking into account the entropy of all systems within the universe, including matter, energy, and radiation. The total entropy is determined by the number of possible states or configurations a system can have, with higher entropy meaning more possible states and therefore more disorder.

## 3. Is the entropy of the universe constantly increasing?

Yes, according to the Second Law of Thermodynamics, the entropy of the universe is constantly increasing. This is because energy naturally flows from areas of high concentration to areas of low concentration, leading to an overall increase in disorder and randomness in the universe.

## 4. Can the entropy of the universe ever decrease?

In isolated systems, it is possible for the entropy to temporarily decrease in one part of the system while increasing in another, leading to an overall balance. However, in the entire universe as a whole, the entropy will continue to increase over time.

## 5. How does the concept of entropy apply to the concept of time?

The increase in entropy of the universe is often used to explain the concept of time's arrow, or the idea that time moves in a specific direction. As the entropy increases, the universe becomes more disordered and chaotic, making it increasingly difficult to reverse the effects and go back in time.

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