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Why is the sky blue?

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Re: Why is the sky blue?

#241

Post by hackeraccount »

staplung wrote: post #18

In The Cuckoo's Egg Cliff Stoll recounts an episode from the oral defense of his astrophysics PhD thesis. A bunch of people ask questions but one prof holds back until... """ “I’ve got just one question, Cliff,” he says, carving his way through the Eberhard-Faber. “Why is the sky blue?” My mind is absolutely, profoundly blank. I have no idea. I look out the window at the sky with the primitive, uncomprehending wonder…

I remember reading this - first thing I thought of too when I saw the headline.

Re: Why is the sky blue?

#242

Post by margalabargala »

Nevermark wrote: post #211
margalabargala wrote: post #12

Earlier quoted context omitted.

The "Rayleigh Scattering" comic is really spot on. Air is blue. The reason air is blue is blah blah blah physics, see the article we're all commenting on, but at the end of the day air is blue. We don't demand the same elaborate physics questions for why a ripe banana peel is yellow.

Color can be due to reflection, emission, filtering. The sky is not blue for the same reasons that a banana is yellow. But the reasons behind color in both cases is interesting regardless.

"Reason" is a matter of one's choice of level of abstraction.

The reason a banana peel is yellow is that in a lit environment, it makes yellow light hit your eye.

The reason air is blue, is that in a lit environment, it makes blue light hit your eye.

Obviously one can go further to deeper reasons. Go deep enough and no different colors have the same reason. But you not understanding the level of abstraction in use doesn't make me wrong.

Re: Why is the sky blue?

#243

Post by reactordev »

fragmede wrote: post #232
reactordev wrote: post #195

Earlier quoted context omitted.

I wouldn’t be so sure, for a decade all we had was G and we used more and more of it until we died of dysentery outside Eagle River.

You were supposed to ford the river!

You know our supplies were:

1 axle.

1 wheel.

1 bundle.

100 boxes of ammo.

10,000lbs of bear meat.

2lbs of squirrel meat.

We sank like a rock.

Re: Why is the sky blue?

#244

Post by mr_toad »

librasteve wrote: post #116

Why is the sky black? - at night (of course) - there are ~1 septillion stars that are all shiny

If the universe was infinite and eternal you’d expect the night sky to be white - all the gaps between stars would be filled in with stars further away.

Re: Why is the sky blue?

#245

Post by mr_toad »

zkmon wrote: post #82

Okay, why does visible light have that range of frequencies?

Our eyes have evolved to detect frequencies that can pass through air. There wouldn’t be much point detecting frequencies that are blocked by air.

Re: Why is the sky blue?

#247

Post by librasteve »

mr_toad wrote: post #244
librasteve wrote: post #116

Why is the sky black? - at night (of course) - there are ~1 septillion stars that are all shiny

If the universe was infinite and eternal you’d expect the night sky to be white - all the gaps between stars would be filled in with stars further away.

this! guess this is the definitive proof that the visible universe is finite

Re: Why is the sky blue?

#248

Post by mr_toad »

jxdxbx wrote: post #131

If you say that air isn’t “really” blue because the reason it is blue is different than the reason that other things are blue (e.g. most blue things in daily life absorb frequencies other than blue), this is equivalent to saying that birds with blue feathers due to structural coloration—where instead of pigment, microscopic structures interfere with light—don’t “really” have blue feathers. This is just silly. Some bi…

At the end of the day all colors are due to electrodynamics.

Re: Why is the sky blue?

#249

Post by mr_toad »

aaroninsf wrote: post #43

Not discussed but should be: Prior to the great oxygenation event, Earth's sky was not blue; it was likely red-orange, carbon dioxide and methane being primary components.

Surely it would have still been mostly nitrogen.

Re: Why is the sky blue?

#250

Post by munificent »

pierrec wrote: post #176
munificent wrote: post #165

Earlier quoted context omitted.

I'm familiar with "steamer clams", but not "clam steamers". In "shrimp fried rice", "shrimp" is a noun adjunct [1], which is when you use a noun as an adjective. The charming ambiguity comes from it being unclear whether "shrimp" is an adjunct noun modifying "fried rice" ("shrimp fried-rice") or modifying the past participle verb "fried" ("shrimp-fried rice"). [1] https://en.wikipedia.org/wiki/Noun_adjunct [2] https:…

I thought the charming ambiguity came from "fried" either acting as an adjective or as a verb. These aren't just any shrimp, they're chef shrimp, and they've prepared some delicious fried rice for us. Isn't that incredible? Shrimp fried rice.

Right. It's a noun phrase either way. The question is whether it is rice that were fried by shrimp ("shrimp-fried rice") or fried rice containing shrimp ("shrimp fried-rice").
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