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Entropy: A little understood concept in physics [video]

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

#41

Post by jjaken »

hilbert42 wrote: post #12
willis936 wrote: post #9

Earlier quoted context omitted.

Which debate over global warming are you referring to? There are debates that involve atmospheric chemists that discuss Earth darkening cause and effects. https://en.m.wikipedia.org/wiki/Albedo

Right, the average person hasn't a clue about albedo, nor do they know why say CO2 and CH4 increase global warming whereas others such as O2 are more benign. It may help lower the temperature of the debate if they did. Edit, we're pitching this discussion at the level he has—the lay public. Scientific argument over the minutiae is another matter altogether.

Yeah debates in climate science are about phenomena laypeople don’t even know exist. It’s about how what we observe happens. No one is arguing about what we’re observing, eg global warming.

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

#42

Post by koningrobot »

interestica wrote: post #30
pxeger1 wrote: post #21

Earlier quoted context omitted.

He seems to exaggerate the importance of things when they make for a good story and sound interesting. This is a classic flaw in popular science but I think he's got a lot more egregious with it over the years. The worst example I remember, which is actually what drove me to unsubscribe, was when he said that the golden ratio was "a pretty five-y number" because it can be written as 0.5 + 0.5 * (5^0.5). Anyone with a…

> Anyone with a good mathematical background could tell you there's nothing five-y about 0.5 at all. Um, I disagree? Visually, the 5 is memorable here. "Fivey" just seems to mean "lots of the number 5"?

I think the point is that 0.5 is 1/2, and the 5 digit only appears because of our base 10 presentation of numbers.

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

#43

Post by Solvency »

vehicles2b wrote: post #33
spuz wrote: post #27

I think the concept would be easier for me to understand if we talked about the inverse of entropy - i.e. some kind of measurement for the concentration of useful energy or "order". I think it would then be more intuitive to say that this measurement always decreases. Do we even have a word for the opposite of entropy?

I find it intuitive to think of such “ordered” distributions as having a higher compression ratio. (Ie compare the file sizes of zipping a file with just ones or just zeros vs zipping a file with a uniform, random mixture of ones and zeros.)

Huh? I've never really understood this metaphor.

Take any photograph in Photoshop. First, save one copy of it as a compressed JPG.

Now, on the original, add a small densely repeating tiled pattern multiplied on top as a layer. Like a halftone effect, dot texture, whatever. Technically you're adding more order and less chaos. The resulting image won't compress as efficiently.

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

#44

Post by cjs_ac »

spuz wrote: post #27

I think the concept would be easier for me to understand if we talked about the inverse of entropy - i.e. some kind of measurement for the concentration of useful energy or "order". I think it would then be more intuitive to say that this measurement always decreases. Do we even have a word for the opposite of entropy?

Ectropy has been suggested, but the term is not in common use.

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

#46

Post by dist-epoch »

Solvency wrote: post #43
vehicles2b wrote: post #33

Earlier quoted context omitted.

I find it intuitive to think of such “ordered” distributions as having a higher compression ratio. (Ie compare the file sizes of zipping a file with just ones or just zeros vs zipping a file with a uniform, random mixture of ones and zeros.)

Huh? I've never really understood this metaphor. Take any photograph in Photoshop. First, save one copy of it as a compressed JPG. Now, on the original, add a small densely repeating tiled pattern multiplied on top as a layer. Like a halftone effect, dot texture, whatever. Technically you're adding more order and less chaos. The resulting image won't compress as efficiently.

The idea is to use the best compressor possible. So called Kolmogorov complexity.

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

#48

Post by lll-o-lll »

szundi wrote: post #6

Just after Sabine’s

Yes, and the Sabine video contained far more information (lower entropy?) and one genuinely interesting idea I’d never heard before. The idea that heat death may not be the end of intelligent life! The concept this relies on is the idea that macro states are actually just combinations of micro states all of which have the same probability. E.g. the sequence 1, 2, 3, 4, 5 and 3, 1, 4, 2, 5 are equally likely if you are selecting 5 random numbers (1-5), but the ordered sequence is an important state to us. The Big Bang -> heat death is just super unlikely state to super likely state, but these macro states are poorly defined. They matter to us. So perhaps the universe goes on with complex life harvesting neg-entropy from a heat death configuration of micro states as they slowly transition from “extremely unlikely” to “likely” in the context of something incomprehensible to humans. I feel like the idea would need more mathematical meat on the bones to go further, but still an intriguing thought!

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

#49

Post by uoaei »

lisper wrote: post #11

A pithier way to introduce this topic: the first law of thermodynamics, a.k.a. the law of conservation of energy, is that energy cannot be created nor destroyed, only transformed from one form to another. In light of this, how can there ever be a shortage of energy? [Note that this is intended to be a rhetorical question advanced for the purposes of pedagogy. If you find yourself wanting to post an answer, you have m…

Energy is actually a red herring -- what's relevant here is work.

Useful work, aka information, is work that can be employed in dynamics vis a vis processing. Useless work, aka heat, is the devil's share of the energy expenditure which is lost as entropy when undergoing a process.

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

#50

Post by passion__desire »

javajosh wrote: post #38

Entropy only made sense when I learned it from the perspective of statistical thermodynamics. It's a very programmerly understanding, IMHO, and it's quite intuitive. EXCEPT that the language used is ridiculous: grand canonical ensemble indeed! Anyway, the idea that a system can be in some number of specific states, and that equilibrium is that unique situation where the number of possible specific states is at its ma…

Entropy is mathematical force to be honest.
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