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What is entropy?
Entropy is commonly thought of as disorder or chaos, but in trying to explain it to someone last week, this can get a little confusing. Play the podcast for a different way of thinking about entropy.
Click through for the transcript and further sources.
Entropy: Spread your particles (CultureCast #026)
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Transcript
Hey CultureCrew, this is Joshua Hwang bringing you another 90 Seconds to Culture podcast.
Entropy: Spread your particles
In Isaac Asimov’s famous short story “The Last Question”, characters throughout a future history ask their all-powerful universal computer one question. The computer can never answer this question however, it only states that there is “INSUFFICIENT DATA FOR A MEANINGFUL ANSWER”. In an era when we can harness sunpower for all our needs, what happens when the stars run down? The last question is “Can we re-ignite the stars after they have run out of energy?” Or “Is it possible to reverse the entropy of the universe?”
Entropy is how spread out particles or energy is in an area. For example: when an ice cube melts, the entropy of the ice cube increases because its energy and its particles are more spread out in the liquid form than in the solid form.
The relation to “The Last Question” is that when a system’s entropy is maximized you can’t get any useful work from the system. As water flows from higher to lower over a power generator, that change in height causes energy to be formed in the generator. But if the water were to level off, if the water were spread out evenly, the entropy would be maximized. No useful work could occur. Similarly in the Last Question, when the sun’s energy is used up, this means the sun’s entropy is maximized, no energy can flow out, because the sun is in a uniform state.
The second law of thermodynamics states that the entropy of the universe always increases. But maybe if we can find a way to reverse it, we can have light again.
Sources / Further Reading:
Isaac Asimov - The Last Question - A short story about entropy, well worth the read. Definately my favourite sci-fi short story of all time.
Wikipedia: Entropy
Wikipedia: Introduction to entropy
Wikipedia: Entropy (energy dispersal)
[tags]entropy, physics, last question, asimov, energy dispersion, chaos, podcast, culture[/tags]
(image from Ankher via flickr)
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