Why did entropy decrease after the big bang?

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Discussion Overview

The discussion revolves around the concept of entropy in the context of the early universe following the Big Bang. Participants explore the relationship between gravitational effects, uniformity of matter, and the implications for the second law of thermodynamics, considering both theoretical and speculative perspectives.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that the early universe was characterized by a uniform distribution of energy, which they argue had low entropy, raising questions about how this aligns with the second law of thermodynamics.
  • Others propose that uniformly distributed matter is inherently unstable in the presence of gravity, positing that high-entropy states are achieved when matter is concentrated in massive objects, such as black holes.
  • A participant reflects on the improbability of matter returning to a uniform distribution due to gravitational forces, agreeing that the entropy of the early universe was low and has increased over time.
  • Another viewpoint introduces the idea that entropy may depend on the curvature of space-time, suggesting that higher density configurations correspond to higher entropy, while lower density configurations appear unstable and low in entropy.
  • One participant draws an analogy with automotive engines, indicating that high energy states can coexist with high entropy, and speculates that the absence of stars in the early universe contributed to lower entropy due to a lack of heat generation.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between gravitational effects and entropy, with no consensus reached on how these concepts interact in the context of the early universe and the second law of thermodynamics.

Contextual Notes

Some claims rely on assumptions about gravitational stability and the nature of entropy, while others suggest a dependence on space-time curvature that remains unresolved. The discussion includes speculative theories that have not been definitively established.

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According to the big bang model, the very early universe was at one time filled with energy. The cosmic microwave background radiation shows that the energy of the universe was very uniform. The deviation of energy in the famous CMB radiation picture taken was on average just 1 in 100,000 the average temperature.

So why did uniformity decrease as galaxies were formed in the very early universe? Does this contradict the 2nd law of thermodynamics?
 
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Contrary to popular opinion, uniformly distributed matter is unstable in presence of gravitation and is actually the least likely state with very low entropy. Most probable high-entropy states are those where matter is all lumped together in massive objects, culminating in the creation of black holes.
 
Delta Kilo said:
Contrary to popular opinion, uniformly distributed matter is unstable in presence of gravitation and is actually the least likely state with very low entropy. Most probable high-entropy states are those where matter is all lumped together in massive objects, culminating in the creation of black holes.

Now that I think about it, gravitation does turn the tables. It would be impossibly improbable for objects such as planets/stars to uniformly distribute back in space again. So yeah, I would agree that entropy of the early universe was very low and has only increased since so the 2nd law of thermodynamics isn't wrong.
 
Consider that all matter and energy in the early universe was closer together than it is now. But at the same time moving away from the center.

Entropy might have a dependence on the curve of space/time, as the less curve the more entropy. So matter and energy that are not as close together have a lower gravity and thus appear to the observer to be unstable and a low entropy. But the higher density space/time with the matter and energy closer together has a higher entropy. It could be then that distance has a lot to do with it along with gravity and space/time as factors. In higher energy states we find that space/time can separate into space and time.

Your automotive engine for example is density packed with metals and uses high energy or heat from explosions of gasoline to push pistons and give you the ability to turn the wheels. In this high energy state, we have high energy but we still have Earth's gravity as well as high entropy. Which is why your fuel efficiency goes down so heat is a form of energy that has to do with it.

Then I'd say that stars generate heat to cause higher entropy and in the early universe there wasn't much heat as stars didn't form yet and provide the heat and higher gravity for higher entropy.

Just a theory, I could be wrong.
 

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