GDC3 comments on Rationality: Appreciating Cognitive Algorithms - Less Wrong

37 Post author: Eliezer_Yudkowsky 06 October 2012 09:59AM

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Comment author: GDC3 07 October 2012 05:13:54AM 1 point [-]

When the sky is white, it's not the sky; it's clouds blocking the sky. When the sky is black it's just too dark to see the sky. At least that was my intuition before I knew that the sky wasn't some conventionally blue object. I guess its a question of word usage whether the projective meaning of "blue" which is something like "looks blue under good lighting conditions" should still be applied when it's not caused by reflectance. Though it's not blue from all directions is it?

Comment author: DanielLC 07 October 2012 05:30:12AM 2 points [-]

I would consider the clouds part of the sky, like the air, or the stars.

Comment author: [deleted] 07 October 2012 08:58:56AM 2 points [-]

I'd say “sky” is a relative concept and depends on where you are. If I was on the mountainside and had clouds below me, I still wouldn't say I'm in the sky. (But I would if I was on a plane, so it's not as simple as “anything that's above me”.)

Comment author: DanielLC 07 October 2012 05:49:50PM 2 points [-]

And I'm on the ground right now. There doesn't seem to be any clouds above me, but if there were, they'd be in the sky, and the sky would have white splotches.

Comment author: CCC 07 October 2012 10:36:39AM 2 points [-]

I consider anything that is contiguously attached to the planet (or moon) which I am currently on (e.g. a man on a mountaintop), or less than about two metres from the ground (e.g. a man jumping up and down) to not be in the sky. Anything further than that from ground surface, and either currently ascending or able to maintain that altitude, counts as 'in the sky'; anything further than that from ground surface and not able to maintain that altitude, counts as 'falling from the sky'.

Comment author: Kindly 07 October 2012 04:27:35PM 2 points [-]

If I jump out of a second-floor window, I'm certainly falling, but I'm hardly falling from the sky.

Comment author: CCC 08 October 2012 07:13:54AM 0 points [-]

The building is contiguously attached to the ground (unless it's some sort of flying building). You need to be more than two metres away from it and falling to count as 'falling from the sky'.

For safety reasons, it's probably also better to throw an object - I'd suggest a tennis ball - if you actually want to perform an experiment. You could get it to the state 'falling from the sky' by throwing it hard enough horizontally from a fourth- or fifth-floor window, or dropping it off a bridge.

Hmmm... I may need to update my definition to consider the 'dropped-from-a-bridge' case.

Comment author: DanielLC 07 October 2012 05:56:19PM 0 points [-]

I'd say that it has to be far enough from the ground that you wouldn't notice the parallax effect if you walked around below it, it has to be above the horizon. Also, it can't be an airplane or something. I'm not sure why exactly that last rule is there, given that meteors and such count. Maybe most people would consider it part of the sky. I'd say it's in the sky, but not part of it.

Comment author: [deleted] 07 October 2012 09:01:33AM 0 points [-]

I guess its a question of word usage whether the projective meaning of "blue" which is something like "looks blue under good lighting conditions" should still be applied when it's not caused by reflectance.

What would you call a glass absorbing red/orange/yellow light and letting the rest through?

Comment author: GDC3 07 October 2012 07:11:34PM 4 points [-]

As I understand it, the sky does let red-yellow light through. It scatters blue light and lets red light through relatively unchanged. So it looks red-yellow near the light source and blue everywhere else.

Comment author: [deleted] 07 October 2012 09:17:49PM 0 points [-]

Yes.