1145: Sky Color - Revision history

Markhurd: clean up; explainxkcdization of transcript

2013-04-22T16:25:47Z

clean up; explainxkcdization of transcript

Davidy22: Undo revision 25939 by 176.31.9.212 (talk) Block 176.31.9.212, spambot.

2013-01-22T03:10:20Z

Undo revision 25939 by 176.31.9.212 (talk) Block 176.31.9.212, spambot.

176.31.9.212: /* Explanation */

2013-01-22T00:52:22Z

‎Explanation

96.255.179.169: /* Explanation */ "infinitely" is improperly used here. The questions are merely significantly harder.

2013-01-12T05:57:00Z

‎Explanation: "infinitely" is improperly used here. The questions are merely significantly harder.

68.102.58.19: clarification

2012-12-31T23:34:56Z

clarification

Lcarsos: /* Explanation */ helping the "helpful" anon with why this is correct

2012-12-13T23:01:08Z

‎Explanation: helping the "helpful" anon with why this is correct

Lcarsos: Reverted edits by 174.75.123.17 (talk) to last revision by 118.92.41.33

2012-12-13T23:00:15Z

Reverted edits by 174.75.123.17 (talk) to last revision by 118.92.41.33

174.75.123.17: /* Explanation */

2012-12-13T22:58:41Z

‎Explanation

174.75.123.17: /* Explanation */

2012-12-13T22:55:52Z

‎Explanation

118.92.41.33: /* Explanation */ Removed additional explanation after rereading earlier section.

2012-12-12T04:15:57Z

‎Explanation: Removed additional explanation after rereading earlier section.

@@ Line 12: / Line 12: @@
 Another point of this comic is that we often think that we understand a scientific phenomenon (e.g. why is the sky blue?); however, a certain simple question (e.g. why isn't the sky violet?) can often uncover large gaps in our actual understanding.
-{{W|Rayleigh scattering}} is the phenomenon that explains the color of the sky, where light of every wavelength gets scattered in the air by the inverse quartic (fourth power) of its wavelength as given in the comic. In the {{w|visible spectrum}}, blue light has a wavelength of 450–495 nm while violet has a shorter wavelength of 380–450 nm. Violet light does indeed get scattered more than blue light, however the lower portion of the spectrum for sunlight consists of blue light and eyes are much more sensitive to blue light than violet light. This leaves the impression of a blue sky. A good explanation, including why blue and not violet, can be found in [http://math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html Usenet Physics FAQ :: Why is the sky blue?] (but note that human color perception [http://blog.asmartbear.com/color-wheels.html is more complicated] than described there).
+{{W|Rayleigh scattering}} is the phenomenon that explains the color of the sky, where light of every wavelength gets scattered in the air by the inverse quartic (fourth power) of its wavelength as given in the comic. In the {{w|visible spectrum}}, blue light has a wavelength of 450–495&nbsp;nm while violet has a shorter wavelength of 380–450&nbsp;nm. Violet light does indeed get scattered more than blue light, however the lower portion of the spectrum for sunlight consists of blue light and eyes are much more sensitive to blue light than violet light. This leaves the impression of a blue sky. A good explanation, including why blue and not violet, can be found in [http://math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html Usenet Physics FAQ :: Why is the sky blue?] (but note that human color perception [http://blog.asmartbear.com/color-wheels.html is more complicated] than described there).
 The title text refers to a {{w|mirror image}}, and is discussed by Richard Feynman in a famous BBC documentary [http://www.youtube.com/watch?v=6tuxLY94LXw], as one of the problems which he used to have fun with first years (British English for first year student or freshman).
@@ Line 25: / Line 25: @@
 ==Transcript==
-:[Girl and her mother. The mother is at a desk and facing the girl.]
+:[Girl and her mother, Megan. Megan is at a desk and facing the girl.]
 :Girl: Mommy, why is the sky blue?
-:Mother: Rayleigh scattering! Short wavelengths get scattered ''way'' more (proportional to 1/''<span title="lambda">&#955;</span>''<sup>4</sup>). Blue light dominates because it's so short.
+:Megan: Rayleigh scattering! Short wavelengths get scattered ''way'' more (proportional to 1/''<span title="lambda">&#955;</span>''<sup>4</sup>). Blue light dominates because it's so short.
 :Girl: Oh.
 :Girl: So why ''isn't'' the sky violet?
-:Mother: Well, because, uh... ...hmm.
+:Megan: Well, because, uh... ...hmm.
 :Caption: My hobby: Teaching tricky questions to the children of my scientist friends.

@@ Line 7: / Line 7: @@
 }}
-perfectly,
+==Explanation==
-It informational resource, I'll bookmark it and visit it again!
+The point of this comic is that often, curious children ask their parents simple questions about understanding how the world works. [[Randall]]'s hobby is to make those questions significantly harder to stump the parents and  make them uncomfortable.
 ==Transcript==

@@ Line 7: / Line 7: @@
 }}
-==Explanation==
+perfectly,
-The point of this comic is that often, curious children ask their parents simple questions about understanding how the world works. [[Randall]]'s hobby is to make those questions significantly harder to stump the parents and  make them uncomfortable.
+It informational resource, I'll bookmark it and visit it again!
-−
-Another point of this comic is that we often think that we understand a scientific phenomenon (e.g. why is the sky blue?); however, a certain simple question (e.g. why isn't the sky violet?) can often uncover large gaps in our actual understanding.
-−
-{{W|Rayleigh scattering}} is the phenomenon that explains the color of the sky, where light of every wavelength gets scattered in the air by the inverse quartic (fourth power) of its wavelength as given in the comic. In the {{w|visible spectrum}}, blue light has a wavelength of 450–495 nm while violet has a shorter wavelength of 380–450 nm. Violet light does indeed get scattered more than blue light, however the lower portion of the spectrum for sunlight consists of blue light and eyes are much more sensitive to blue light than violet light. This leaves the impression of a blue sky. A good explanation, including why blue and not violet, can be found in [http://math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html Usenet Physics FAQ :: Why is the sky blue?] (but note that human color perception [http://blog.asmartbear.com/color-wheels.html is more complicated] than described there).
-−
-The title text refers to a {{w|mirror image}}, and is discussed by Richard Feynman in a famous BBC documentary [http://www.youtube.com/watch?v=6tuxLY94LXw], as one of the problems which he used to have fun with first years (British English for first year student or freshman).
-−
-A mirror image is a virtual image produced by the reflection of light on a mirror.  In the mirror image, only front and back are switched around - like a printing press or a rubber stamp. Left and right are still left and right in an absolute reference frame - wave your left arm in front of the mirror and the "mirror person" also waves the arm on the left side. It is only when using "personal" reference frame - tied to the individual - that we can say that the "mirror person" is moving their right arm.
-−
-The start of the word would still be closest to the door, the end of the word closest to the window, as in the real room, only the person in the mirror is facing the other way. The apparent inversion comes from the fact that the mind projects itself onto the person in the mirror, and the writing on his paper will be illegible (from "his" right to left instead of from "his" left to right)
-−
-To help understand why this effect happens, imagine that you are holding a sign which says "MIX" and facing a mirror.  Initially, you face the sign towards you.  The M is on the left and the X on the right.  Now, you turn the sign around so that the sign faces the mirror.  Now, even without paying any attention to the mirror, simply because you have turned it around, now the M is on the right and the X is on the left and if you could see through the back of the sign, it would say "XIM" from your perspective.  When you look at it in the mirror, you are now able to see that orientation and it appears to read "XIM".  If instead of turning the sign around horizontally to look at it in the mirror, you flipped it vertically and looked at it in the mirror, it would appear to say "WIX" in the mirror.  Thus the mirror is only revealing how the text is oriented relative to your eyes. (Or, to put it more succinctly: mirrors ''don't'' reverse left to right, ''turning around'' does.)
-−
-{{w|Richard Feynman}} was a famous American theoretical physicist.
 ==Transcript==

@@ Line 8: / Line 8: @@
 ==Explanation==
-The point of this comic is that often, curious children ask their parents simple questions about understanding how the world works. [[Randall]]'s hobby is to make those questions infinitely harder to stump the parents and  make them uncomfortable.
+The point of this comic is that often, curious children ask their parents simple questions about understanding how the world works. [[Randall]]'s hobby is to make those questions significantly harder to stump the parents and  make them uncomfortable.
 Another point of this comic is that we often think that we understand a scientific phenomenon (e.g. why is the sky blue?); however, a certain simple question (e.g. why isn't the sky violet?) can often uncover large gaps in our actual understanding.

@@ Line 14: / Line 14: @@
 {{W|Rayleigh scattering}} is the phenomenon that explains the color of the sky, where light of every wavelength gets scattered in the air by the inverse quartic (fourth power) of its wavelength as given in the comic. In the {{w|visible spectrum}}, blue light has a wavelength of 450–495 nm while violet has a shorter wavelength of 380–450 nm. Violet light does indeed get scattered more than blue light, however the lower portion of the spectrum for sunlight consists of blue light and eyes are much more sensitive to blue light than violet light. This leaves the impression of a blue sky. A good explanation, including why blue and not violet, can be found in [http://math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html Usenet Physics FAQ :: Why is the sky blue?] (but note that human color perception [http://blog.asmartbear.com/color-wheels.html is more complicated] than described there).
-The title text refers to a {{w|mirror image}}, and is discussed by Richard Feynman in a famous BBC documentary [http://www.youtube.com/watch?v=6tuxLY94LXw], as one of the problems which he used have fun with first years (British English for first year student).
+The title text refers to a {{w|mirror image}}, and is discussed by Richard Feynman in a famous BBC documentary [http://www.youtube.com/watch?v=6tuxLY94LXw], as one of the problems which he used to have fun with first years (British English for first year student or freshman).
 A mirror image is a virtual image produced by the reflection of light on a mirror.  In the mirror image, only front and back are switched around - like a printing press or a rubber stamp. Left and right are still left and right in an absolute reference frame - wave your left arm in front of the mirror and the "mirror person" also waves the arm on the left side. It is only when using "personal" reference frame - tied to the individual - that we can say that the "mirror person" is moving their right arm.

← Older revision		Revision as of 04:15, 12 December 2012
Line 23:		Line 23:

	{{w\|Richard Feynman}} was a famous American theoretical physicist.		{{w\|Richard Feynman}} was a famous American theoretical physicist.
−
−	The mirror question is also a bit of a trick question, because actually the axis of reflection only depends on the relative positions of you, the writing, and the mirror. If you hold a mirror perpendicular to a page of writing, and perpendicular to the lines of the writing (i.e. down the right- or left-hand side of the page), the writing will be reflected left-to-right in the mirror. But if you hold the mirror so that it lies along the top of a single line of text, then that text will be reflected top-to-bottom in the mirror.

	==Transcript==		==Transcript==