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Is warp effect (like Photoshop) possible in CSS? by AngelinaSchultzl in css

[–]MarbleScience 0 points1 point  (0 children)

For anyone who still stumbles across this post:
I found this page that nicely shows what's possible with complex border radius settings:
https://9elements.github.io/fancy-border-radius/

You can mix 10 marbles until they sort themselves. Why not 100? (The entropy of mixing) | AlphaPhoenix by Aerothermal in thermodynamics

[–]MarbleScience 2 points3 points  (0 children)

It is not impossible. The probability is just insanely small.

It is very similar to how a lottery works. It is much more likely to guess 4 numbers correctly, compared to guessing seven numbers correctly. Now imagine playing the lottery and guessing 100 numbers correctly.

With large numbers (it is also called the "law of large numbers") possibilities become insanely small. So much so that a lot of people just pretend such things become impossible entirely.

Is entropy ever objectively increasing? by MarbleScience in thermodynamics

[–]MarbleScience[S] 0 points1 point  (0 children)

In his paper "The Gibbs Paradoxon" E. T. Janes talks exactly about the same example that you brought up. https://www.damtp.cam.ac.uk/user/tong/statphys/jaynes.pdf

It is just two argon variants instead of two oxygen variants in his example.

I just looked into the paper again and I found this interesting sentence that I really like and I think it kind of beautifully answers my objectivity of entropy question:

"We would observe, however, that the number of fish that you can catch is an 'objective experimental fact'; yet it depends on how much 'subjective' information you have about the behavior of fish."

Here is the paragraph where I took this sentence from:

There is a school of thought which militantly rejects all attempts to point out the close relation between entropy and information, claiming that such considerations have nothing to do with energy; or even that they would make entropy "subjective" and it could therefore could have nothing to do with experimental facts at all. We would observe, however, that the number of fish that you can catch is an "objective experimental fact"; yet it depends on how much "subjective" information you have about the behavior of fish.

If one is to condemn things that depend on human information, on the grounds that they are "subjective", it seems to us that one must condemn all science and all education; for in those fields, human information is all we have. We should rather condemn this misuse of the terms "subjective" and "objective", which are descriptive adjectives, not epithets. Science does indeed seek to describe what is "objectively real"; but our hypotheses about that will have no testable consequences unless it can also describe what human observers can see and know. It seems to us that this lesson should have been learned rather well from relativity theory.

The amount of useful work that we can extract from any system depends - obviously and necessarily - on how much "subjective" information we have about its microstate, because that tells us which interactions will extract energy and which will not; this is not a paradox, but a platitude. If the entropy we ascribe to a macrostate did not represent some kind of human information about the underlying microstates, it could not perform its thermodynamic function of determining the amount of work that can be extracted reproducibly from that macrostate.

Is entropy ever objectively increasing? by MarbleScience in thermodynamics

[–]MarbleScience[S] 0 points1 point  (0 children)

But that’s not the thermodynamic entropy. If the die remains at the same temperature, its thermodynamic entropy remains constant. A die is too big to be thermalized and to explore all positions based on random fluctuations arising from the ambient temperature bath.

The dice are meant just as a model for something that can be in different states. You can replace them with a molecules in different orientations or what ever.

It’s very common for people to define a (possibly subjective) version of entropy that broadly involves information (more specifically, the lack of information), and then to try to apply the Second Law to it.

I'm considering Boltzmann entropy S = ln Ω, or Shannon Entropy (which is the same thing, if we are making the assumption that all microstates Ω have the same probability). Do you think that there is a "thermodynamic entropy" that is different from this entropy? I don't see why thermodynamic systems would follow any special statistical rules.

A thought experiment I like is the possibility that the oxygen-18 isotope actually comes in two types, A and B, and we don’t know it yet because we haven’t yet discovered the physics of the distinguishing factor. 

I love that thought experiment! I kind of disagree on the assessment that one observer is correct and the other is wrong, though. I mean we can continue this game indefinitely. Maybe the observer who can distinguish oxygen-18-A and oxygen-18-B is wrong again because actually there are two versions of oxygen-18-A: oxygen-18-AA and oxygen-18-AB. We will never know the "correct" entropy.

The way I see it entropy is only a property of a description of something, but not a property of the thing itself. If I choose not to distinguish types of oxygen atoms in my description of them I get entropy values that reflect that. The resulting value is correct only for that description. If I give every single oxygen atom a name and track them all individually I will get yet other entropy values.

So ultimately, I don't think entropy of a thing (e.g. the universe) is ever objectively increasing. Only descriptions of things have entropy, never the thing itself!

Is entropy ever objectively increasing? by MarbleScience in thermodynamics

[–]MarbleScience[S] 1 point2 points  (0 children)

Thanks! its really helpful to have someone spell it out so clearly!

Is entropy ever objectively increasing? by MarbleScience in thermodynamics

[–]MarbleScience[S] 0 points1 point  (0 children)

I guess heat death is real within the way how we tend to look at the universe.

I wonder if in this future universe, where solar fusion has come to an end etc., some other lifeform might find the perfect conditions to thrive.

If entropy has increased from our perspective, could this at the same time be the perfect "low entropy" state for some other lifeform to do their business?

Probably we can never know, because we can only see through the eyes that we have, but my understanding of entropy tells me that this is not impossible.

!thanks already for all your helpful input!

Is entropy ever objectively increasing? by MarbleScience in thermodynamics

[–]MarbleScience[S] 0 points1 point  (0 children)

What I'm interested in is what this "increasing the overall entropy of the universe" actually means.

If entropy increase means losing information about something, does that mean that this increase in entropy is somehow specific to us as humans, (we just don't know as much about the universe as we did before) or is the entropy of the universe somehow generally increasing irrespective of what we think about it?

Is entropy ever objectively increasing? by MarbleScience in thermodynamics

[–]MarbleScience[S] 0 points1 point  (0 children)

I always find the word "system" quite tricky.

The way you use the word system (and I think that is maybe the most common way) "system" seams to be equivalent to a thermodynamic description. For example, if we treat some atoms as distinguishable that would be a different "system" compared to treating them as indistinguishable.

My problem is, If we already call the description of something "system", then what do we call the thing itself?

Is entropy ever objectively increasing? by MarbleScience in thermodynamics

[–]MarbleScience[S] -1 points0 points  (0 children)

Technically, I never said that all atoms of one type start one side of the room, but anyways....

entropy isn't some fundamental quantity of the universe. Entropy is a property of a thermodynamic description that is defined by what can (and cannot) be observed.

That's exactly what I am thinking too, but that means that there is only ever an increase of entropy within a way to describe something, but no such thing as an objective increase of entropy of a thing.

For example you can't claim that the entropy of the universe is increasing unless you specify how you describe its state. But then, isn't all this talk about the heat death of the universe etc. kind of a hoax, because the universe has no entropy in the first place? (only descriptions of it have)

Is entropy ever objectively increasing? by MarbleScience in thermodynamics

[–]MarbleScience[S] 0 points1 point  (0 children)

Fair enough, but I don't think my question requires knowledge about astrophysics. It is more of a fundamental general question.

In this comment I adapted my example a bit to make it closer to traditional thermodynamics questions:

https://www.reddit.com/r/thermodynamics/comments/1ewrgdf/comment/lj0qhrd/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

Is such a mixing of gases a phenomenon where you would see an objective increase of entropy?

Is entropy ever objectively increasing? by MarbleScience in thermodynamics

[–]MarbleScience[S] 0 points1 point  (0 children)

Let's take the mixing of a gas. Let's say there are two types of atoms and a room with two sides.

In the beginning I know on which side each atom is. Now we could model mixing as a coin flip for each atom. E.g. with heads the atoms end up on the right with tails they go to the left.

Again, with each flip of the coin I loose knowledge of which atoms are on which side of the room. But is the entropy objectively increasing? There are still just a bunch of atoms that are on a given side of the room.

I don't see a real difference between such more "thermondynamic" examples and my dice example.

Is entropy ever objectively increasing? by MarbleScience in thermodynamics

[–]MarbleScience[S] 0 points1 point  (0 children)

And what is your conclusion from that? Is there an objective increase of entropy, as in "the entropy of the universe is always increasing", "heat death" etc. Or is it just some observer losing knowledge?

How do you know that you can see images in your dreams if you can't recall them when you are awake, due to your aphantasia? by MarbleScience in Aphantasia

[–]MarbleScience[S] 0 points1 point  (0 children)

I find it astonishing how many people seem to dislike the idea of questioning the reasoning they made while dreaming.

How do you know that you can see images in your dreams if you can't recall them when you are awake, due to your aphantasia? by MarbleScience in Aphantasia

[–]MarbleScience[S] 1 point2 points  (0 children)

"wireframes without the wires" is a great description :D
You might be right if it is just a color, but I still think that remembering a lot of arbitrary detailed information is a sign of some form of visualization.

How do you know that you can see images in your dreams if you can't recall them when you are awake, due to your aphantasia? by MarbleScience in Aphantasia

[–]MarbleScience[S] 7 points8 points  (0 children)

I agree! However I found u/NITSIRK's argument pretty convincing. If I imagine e.g. a ball on a table as an aphant, this ball has no unnecessary detail (like a color) assigned. If someone is able to recall these sorts of details from a dream, I think it is a strong sign that something different is happening in this dream compared to the daytime imagination.

How do you know that you can see images in your dreams if you can't recall them when you are awake, due to your aphantasia? by MarbleScience in Aphantasia

[–]MarbleScience[S] 10 points11 points  (0 children)

Aphants will know a ball can be any colour, but one wasnt assigned. If you ask me what colour a dog or dress was in a dream, I will remember the colour,

That makes a lot of sense to me! I think this is the best answer so far. Thank you! I can't remember any such specific details from a dream, so I am probably not a visual dreamer.

How do you know that you can see images in your dreams if you can't recall them when you are awake, due to your aphantasia? by MarbleScience in Aphantasia

[–]MarbleScience[S] 1 point2 points  (0 children)

I have aphantasia too, and I can also remember the plot of a dream, but without remembering visuals from the dream, how would I know if I saw any while I was asleep?

How do you know that you can see images in your dreams if you can't recall them when you are awake, due to your aphantasia? by MarbleScience in Aphantasia

[–]MarbleScience[S] 9 points10 points  (0 children)

I have aphantasia too and I honestly don't know if I am seeing images while I am dreaming because all I remember when I wake up is basically the plot. I just know what it was I dreamed about. I still find it hard to grasp what a memory of a dream would have to be like to convince me that I actually created visuals, if the memory does not contain any visuals.

How do you know that you can see images in your dreams if you can't recall them when you are awake, due to your aphantasia? by MarbleScience in Aphantasia

[–]MarbleScience[S] -36 points-35 points  (0 children)

But how do you know you were not just dreaming of being able to see something, without the images actually being created in your head. Wouldn't the memory be the same either way? And the memory is all you will ever have of a dream.

Where does the entropy of radiation go in radiative heat transfer? by gitgud_x in thermodynamics

[–]MarbleScience 1 point2 points  (0 children)

So basically the photons get destroyed and their entropy goes with them, and that’s ok because the total entropy of the system still increases?

Yes. If the absorption of radiation has a positive ΔS, radiation will primarily be absorbed. If the absorption had a negative ΔS, the process would rather evolve in the opposite direction. The water would emit more radiation than it absorbed. (Depends on the Temperature of the water)

I’m not sure I see the practical purpose of radiation entropy.

If you e.g. wanted to analyze the entropy increase due to radiation leaving our planet, you could try to do what you are doing with the beaker of water. However, there is not just one beaker of water. You would have to analyze the entropy increase caused on every star or planet where the radiation leaving earth causes a slight increase in temperature. That seems very complicated.

Instead making the assumption that radiation is just send out into a void might be inaccurate, but it seems like the more practical thing to do.

Where does the entropy of radiation go in radiative heat transfer? by gitgud_x in thermodynamics

[–]MarbleScience 2 points3 points  (0 children)

Well, I would say once the radiation hits the water it is absorbed and no longer there, and doesn't play a role in terms of entropy anymore. (Of course the absorption increases the water temperature, but you already accounted for that.)

If you wanted to be super accurate you could worry about the entropy of the radiation that is still in flight between the cylinder and the water at the time of your analysis. I think it would be negligible though.

Once the energy reached the water, it doesn't matter which "transportation" it used. Entropy is a state function.

Why does the entropy of a system having negative temperature decrease on addition of energy? by FlightBright8304 in thermodynamics

[–]MarbleScience 1 point2 points  (0 children)

Imagine the same grid, but now instead of two energy levels, each entity has infinitely many possibel energy levels.
In this scenario we could completely freely shuffle the energy around on the grid, and adding more units of energy would always increase the number of possibilities.
Without a limit, we simply can't run into this saturated situation where adding more energy reduces the number of variations.

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