Entropy: A little understood concept in physics [video] • Hacker News Board

Re: Entropy: A little understood concept in physics [video]

#161

Post by JumpCrisscross » Mon, Jul 03, 2023, 6:08 AM UTC

lisper wrote: post #112

JumpCrisscross wrote: post #103

Earlier quoted context omitted.

It’s pithy, but in the way of word play. Energy, colloquially, means useful energy. The question collides the conventional and technical definitions to create the illusion of profundity.

Pithy != profound. The intent was to get people to think about the fact that the word "energy" means different things in different contexts, and that the thing that actually has value is not energy but the absense of entropy.

> intent was to get people to think about the fact that the word "energy" means different things

But the question posed is weaker at prompting that than the sequence of questions posed by the video. It's a strange response that doesn't add to the discussion.

Re: Entropy: A little understood concept in physics [video]

#162

Post by lisper » Mon, Jul 03, 2023, 6:20 AM UTC

JumpCrisscross wrote: post #161

lisper wrote: post #112

Earlier quoted context omitted.

Pithy != profound. The intent was to get people to think about the fact that the word "energy" means different things in different contexts, and that the thing that actually has value is not energy but the absense of entropy.

> intent was to get people to think about the fact that the word "energy" means different things But the question posed is weaker at prompting that than the sequence of questions posed by the video. It's a strange response that doesn't add to the discussion.

> But the question posed is weaker at prompting that than the sequence of questions posed by the video.

You really think "what do we get from the sun" is a better prompt? I guess we're just going to have to agree to disagree about that.

We get all kinds of things from the sun. Tides. Light. Tans. But there is only one correct answer to why we worry about "energy production" and "energy shortages" when energy is supposedly conserved.

"What do we get from the sun?" has a lot of correct but off-point answers, which makes it IMHO more a prompt for the questioner to exhibit their superior knowledge than a well-designed Socratic question.

Re: Entropy: A little understood concept in physics [video]

#163

Post by jimmySixDOF » Mon, Jul 03, 2023, 7:15 AM UTC

Lichtso wrote: post #148

ithkuil wrote: post #130

Earlier quoted context omitted.

I guess what's confusing me in this scenario is that we're not saying that the two halves of the cylinder contain particles with different properties (e.g. different velocities) but only that we can "tell them apart" as if they were coloured differently, but otherwise behaving in exactly the same way. The former scenario is famously the setting for Maxwell's daemon. I was assuming this scenario is something else. I'm…

> only that we can "tell them apart" That is irrelevant, we don't need to be able to tell them apart, the membrane needs to be able to. Besides that, they can be completely identical. > I'm confused because on one hand I can see that it requires work to reorder the particles once they have been shuffled around. On the other hand I don't see how one could extract work while they get shuffled around if they all have th…

>That is irrelevant, we don't need to be able to tell them apart

There is some speculation that intelligent behavior evolved as a response to entropy as a way to exert control over future events in the environment.

https://www.santafe.edu/news-center/news/dedeo-intelligent-b...

Re: Entropy: A little understood concept in physics [video]

#164

Post by hilbert42 » Mon, Jul 03, 2023, 7:25 AM UTC

kergonath wrote: post #142

gorhill wrote: post #53

Earlier quoted context omitted.

My understanding: Global warming occurs because the previous equilibrium between incoming and outgoing energy has been broken by changes in the composition of the atmosphere. So until we reach a new equilibrium long after the atmosphere composition ceases to change, the outgoing energy will be less than the incoming energy.

That’s exactly it. Except that equilibrium will never be reached, it’s more like tending towards a steady state.

Right, better stated than me.

It would help if we could convey this across to the lay public. No doubt, the minutiae is complex and involved and the details will be argued over for years but at the high level it's pretty straightforward.

Seems to me many balk at climate science because the figures seem to magically appear from nowhere—they just pop out of climate scientists' mouths without explanation. A simple understandable explanation might reduce some of the noisy opposition.

Re: Entropy: A little understood concept in physics [video]

#165

Post by contravariant » Mon, Jul 03, 2023, 8:40 AM UTC

trenchgun wrote: post #160

contravariant wrote: post #150

Earlier quoted context omitted.

That constant is immaterial, it's just the conversion constant between two different units. It just turns out that for the units we're used the time unit is a lot larger than the space unit. The real difference has to do with the metric on spacetime, but that gets tricky to explain. Suffice it to say that a rotation involving 2 of the spatial dimensions, and the equivalent of a rotation for time and a spatial dimensi…

Is it because of th minus sign?

Pretty much yeah. A metric like x^2 - t^2 is quite different from one like x^2 + y^2 (and to some extent those are the only possible in 2d)

Re: Entropy: A little understood concept in physics [video]

#166

Post by [deleted] » Mon, Jul 03, 2023, 9:12 AM UTC

kergonath wrote: post #155

dekken_ wrote: post #149

Earlier quoted context omitted.

You can say what you like. Science is not about certainties. You can only control experiments to a particular degree and have no control of confounding factors which might interfere with your experiments. Do you really want to compare the totality of all universal processes to such trivial examples? I find it absurd.

You did not qualify the complexity below which it is acceptable to be certain of something so this is unlikely to be productive. You said that certainty was impossible and I gave you examples of certain things. Besides, both a ball and a glass of water are insanely complex systems. I am not sure we have the same definition of science, to be honest.

[deleted]

Re: Entropy: A little understood concept in physics [video]

#167

Post by [deleted] » Mon, Jul 03, 2023, 9:16 AM UTC

kergonath wrote: post #155

dekken_ wrote: post #149

Earlier quoted context omitted.

You can say what you like. Science is not about certainties. You can only control experiments to a particular degree and have no control of confounding factors which might interfere with your experiments. Do you really want to compare the totality of all universal processes to such trivial examples? I find it absurd.

You did not qualify the complexity below which it is acceptable to be certain of something so this is unlikely to be productive. You said that certainty was impossible and I gave you examples of certain things. Besides, both a ball and a glass of water are insanely complex systems. I am not sure we have the same definition of science, to be honest.

[deleted]

Re: Entropy: A little understood concept in physics [video]

#168

Post by [deleted] » Mon, Jul 03, 2023, 9:18 AM UTC

kergonath wrote: post #155

dekken_ wrote: post #149

Earlier quoted context omitted.

You can say what you like. Science is not about certainties. You can only control experiments to a particular degree and have no control of confounding factors which might interfere with your experiments. Do you really want to compare the totality of all universal processes to such trivial examples? I find it absurd.

You did not qualify the complexity below which it is acceptable to be certain of something so this is unlikely to be productive. You said that certainty was impossible and I gave you examples of certain things. Besides, both a ball and a glass of water are insanely complex systems. I am not sure we have the same definition of science, to be honest.

[deleted]

Re: Entropy: A little understood concept in physics [video]

#169

Post by [deleted] » Mon, Jul 03, 2023, 9:22 AM UTC

kergonath wrote: post #155

dekken_ wrote: post #149

Earlier quoted context omitted.

You can say what you like. Science is not about certainties. You can only control experiments to a particular degree and have no control of confounding factors which might interfere with your experiments. Do you really want to compare the totality of all universal processes to such trivial examples? I find it absurd.

You did not qualify the complexity below which it is acceptable to be certain of something so this is unlikely to be productive. You said that certainty was impossible and I gave you examples of certain things. Besides, both a ball and a glass of water are insanely complex systems. I am not sure we have the same definition of science, to be honest.

[deleted]

Re: Entropy: A little understood concept in physics [video]

#170

Post by [deleted] » Mon, Jul 03, 2023, 9:35 AM UTC

kergonath wrote: post #155

dekken_ wrote: post #149

Earlier quoted context omitted.

You can say what you like. Science is not about certainties. You can only control experiments to a particular degree and have no control of confounding factors which might interfere with your experiments. Do you really want to compare the totality of all universal processes to such trivial examples? I find it absurd.

You did not qualify the complexity below which it is acceptable to be certain of something so this is unlikely to be productive. You said that certainty was impossible and I gave you examples of certain things. Besides, both a ball and a glass of water are insanely complex systems. I am not sure we have the same definition of science, to be honest.

[deleted]