# When will the entropy of universe(an isolated system) stop increasing?

• kntsy
In summary, the conversation discusses the concept of entropy in the universe as an isolated system. It is argued that if the universe continues to expand forever, then the overall entropy will increase nonstop. However, if the universe reaches a point where it starts collapsing and results in a new universe, there may be a decrease in entropy during the big bang. The exact point at which the internal entropy starts to decrease is uncertain, but it is suggested that entropy may only change locally on a universal scale.
kntsy
Consider the universe as an isolated system, its entropy always increase? when stop?

dS=>dq\T, as dq=o in universe an isolated system, dS always bigger than zero.

so increase nonstop?

One answer should be that if it is isolated and keep expand forever, the overall entropy does increase nonstop.

But if the universe can reach a point in spacetime when it starts collapsing instead of expanding you could argue that the energy which has been spread out over vast distancies (cold objects, CMB) will now be doing work in this crunch and if the crunch results in a new universe (big bang) obviously at some time it must go against the second law and decrease.

I´m not sure how to decide when the internal entropy starts to decrease. But if the crunch actually spawns a new universe surely it must be a large drop in entropy during a big bang? A thought is that entropy doesn't really change on the universal scale, only locally.

## 1. What is entropy?

Entropy is a measure of the amount of disorder or randomness in a system. In thermodynamics, it is often described as a measure of the unavailable energy in a closed system.

## 2. Why does the entropy of the universe always increase?

This is due to the second law of thermodynamics, which states that in any isolated system, the total entropy will always increase over time.

## 3. Will the entropy of the universe ever decrease?

It is highly unlikely that the entropy of the universe will ever decrease. This is because the universe is considered to be an isolated system, and the second law of thermodynamics holds true for all isolated systems.

## 4. Is there an end point to the increase of entropy in the universe?

Based on our current understanding of thermodynamics, it is believed that the entropy of the universe will continue to increase until it reaches a state of maximum entropy, also known as the "heat death" of the universe. However, this is still a topic of debate and further research is needed.

## 5. Can we reverse the increase of entropy in the universe?

Based on the second law of thermodynamics, it is not possible to reverse the increase of entropy in the universe. However, some scientists have proposed the idea of using advanced technology to delay the heat death of the universe, but this is still just a theoretical concept.

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