I have a feeling you're probably shitposting, but the walls are just a metaphorical synonym for boundary and/or boundary conditions. Entropy is a thermophysical value of that system.

The modeler defines the system, boundaries, and surroundings depending on what they're trying to figure out. You can define the system around anything or space. For mechanical engineers, the system can be an ICE chamber for a car. For a cosmologist, it can be the universe. If you consider the entire universe, it's an isolated system. Might be an open system if you consider just the observable universe (i.e., galaxies and other cosmological entities). Though I've never attempted a problem of this scale because I'm not an astronomist.

Shitposting?
Not I call others trolls because they have different opinion about theoretical stuff, while having lack of knowledge.
If anybody is shitposting here, it has to be Lifthrasil.

Metaphorical synonym? That's not how physics laws work.
Wall is a wall which can limit the area and reflect back matter and energy, not a boundary which can change in time.
Just take a cylinder we take the gas in it is in max entropy, then you increase the size of the cylinder, then gas pressure will drop, with temperature too, it won't be anymore at max entropy.

So if the universe is in constant expansion or contraction, then how can entropy can stay constant if the volume of the area is changing? It can't, so the universe is not probably not a thermodynamic system.

Isolated and with walls is 2 different things.

What is success?
The answer might depend on the definition.

Everything's he's said so far is accurate. I just had a major issue with your interpretation of walls. It's an invisible wall / border / boundary that you define for the sake of analyzing the interactions of matter and energy between the system and its surroundings. Yes, your example is correct (assuming ideal gas EOS).

And for now, I'd consider the entire universe as an isolated system even if it is expanding or contracting. That expansion or contraction is happening because of forces within that universe. I believe most astronomists think it's initial momentum from the Big Bang that is being accelerated by dark energy. But again, this falls outside my knowledge of thermodynamics.

well he didnt say much , just linked that 2nd thermodinamics law, and called me a troll (false claim), did he read it ?nope

another part which gives my theory more weight :
"
Gravitational systems
Commonly, systems for which gravity is not important have a positive heat capacity, meaning that their temperature rises with their internal energy. Therefore, when energy flows from a high-temperature object to a low-temperature object, the source temperature decreases while the sink temperature is increased; hence temperature differences tend to diminish over time.

This is not always the case for systems in which the gravitational force is important: systems that are bound by their own gravity, such as stars, can have negative heat capacities. As they contract, both their total energy and their entropy decrease[76] but their internal temperature may increase. This can be significant for protostars and even gas giant planets such as Jupiter.

As gravity is the most important force operating on cosmological scales, it may be difficult or impossible to apply the second law to the universe as a whole
"
it is enough to read the last sentence
no wall + gravity is more than enough to assume universe as a whole is not subjected to the 2nd law of td , and as such it wont end in a maximized entropy state

I'm just smarter than him, and this angered him.

Let's look at the communication chain:

Timboli is incorrect because it's not entropy that ends the universe. Under heat death, the universe has a finite amount of high, structured energy before devolving into thermodynamically stable products + entropy. Rather, entropy is a rough measurement of the universe's lifespan. For example, old people do not die because of their age or natural causes; it's because of some organ failure triggering a series of events that leads to irreversible brain death.

Unfortunately, what happened here is Lifthrasil misinterpreted when you said "entropy is false" by saying it does exist when you inherently implied that during heat death, no more entropy can be created (correct). Then you misinterpreted his misinterpretation instead of clarifying. Then I came barging in here to correct a side remark mistake you made. Now we're all suddenly in an anime comedy skit.

Of course, I'll leave it to him to fully clarify as I've been wrong with misinterpreting intent here a couple times before.

Decide for yourself what constitutes success.

Refuse to be held to anyone else's definitions.

That is all.

"Feeling"? That's literally all he ever does.

Even stopped clocks can be right twice a day. Even people I severely disagree with will say accurate and agreeable things from time to time. Everything needs to be considered on a case-by-case basis when it comes to people. Unlike beautiful maths and physics problems that almost always follow governing laws and equations.

Oh this Orkhepaj is really an annoying fabrication of my Boltzmann brain.
I hope the next fluctuation provides better memories.

use more multi acc:P

Oh lord, my brain hurts trying to comprehend all of this.

Only with respect to the current conversation. In every single case I've worked with entropy, it's to understand the thermodynamics of a relatively smaller system. And I don't think I'm wrong. The universe started from a point of low entropy and there will always be a net increase in entropy in the universe so long the temperature is nonzero Kelvins. So yes, net entropy is a rough way of the lifespan of the universe. Let's say your genetics have a hard limit on total cumulative beats within its lifetime. You can slow your BPM and increase lifespan / slow down its death, but there's nothing you can do to increase the total cumulative beats. It's a direct analogy to my understanding of entropy limit in the universe. Now I'm confused at what you're actually trying to say because what you summarized isn't what I interpreted...

I'm not on anyone's team, I'm not writing nonsense (not that I'm actively aware of), and I'm not "attacking" you. It's otherwise just pointing out to you that you should be able to define boundaries of the universe for thermodynamic calculations. Because if you learned about this stuff in university, it's what they do. That's literally how people come to the conclusion that the entire universe, including dark matter and dark energy, is an isolated system because there is no known mass or energy being transferred between the edges of the entire universe that we know of so far through mathematical modeling. By concluding that the entire universe is an isolated system, the inherent assumption is that entropy is always net increasing. Like I said, I'm not on their team and you literally just copied and pasted stuff off Wiki. So you're also accusing your opponents of literally doing the same thing; I haven't even linked anything in this thread. And no, I'm not lying about making walls with respect to defining a system, its surroundings, and doing mass and energy transfer calculations over that interface. I've literally done it in dozens of problems, just not at a cosmic scope.

I always like when I see Orkhepaj posting in a thread.

Things get much more interesting.

Yes, it's the end that doesn't matter.

Or... is it? :P

I tried so hard, but in the end I got ninja-ed :P.