Editing 1818: Rayleigh Scattering
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==Explanation== | ==Explanation== | ||
− | This comic suggests it is better to explain things in an easy-to-understand and intuitive manner, even if such explanations may not | + | {{incomplete|Incomplete explanation Needs fixing upping. DO NOT DELETE}} |
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+ | This comic suggests it is much better to explain things in an easy-to-understand and intuitive manner, even if such explanations may not be completely accurate. This is especially the case for children whose ability to grasp abstract physics has not yet fully developed. Giving the most complete and physically accurate explanation would make the concepts much more elaborate than necessary, and would cause major confusion in inexperienced listeners. | ||
The principle is demonstrated by the explanation on {{w|Diffuse sky radiation|why the sky is blue}}. The commonly given explanation for this is, as the comic title says, {{w|Rayleigh scattering}}. However, in order to understand how Rayleigh scattering works to produce a blue color, one must go into {{w|quantum mechanics}} and deal with properties of molecules in air and their effects on different wavelengths of light. Even then, one will also need to know about the inner workings of human visual perception to realize why the color we perceive isn't the wavelength that's being most strongly scattered (see [[1145: Sky Color]]). The child is not likely to understand this kind of explanation. | The principle is demonstrated by the explanation on {{w|Diffuse sky radiation|why the sky is blue}}. The commonly given explanation for this is, as the comic title says, {{w|Rayleigh scattering}}. However, in order to understand how Rayleigh scattering works to produce a blue color, one must go into {{w|quantum mechanics}} and deal with properties of molecules in air and their effects on different wavelengths of light. Even then, one will also need to know about the inner workings of human visual perception to realize why the color we perceive isn't the wavelength that's being most strongly scattered (see [[1145: Sky Color]]). The child is not likely to understand this kind of explanation. | ||
− | On the other hand, a much simpler explanation, such as "because air is blue" | + | On the other hand, a much simpler explanation, such as "because air is blue", also adequately explains the phenomenon, and is probably much more understandable to less physically inclined listeners. When a person who looks like a young [[Science Girl]] asks [[Blondie]] (possibly [[Miss Lenhart]]) why the sky is blue, [[Megan]] walks in and starts to explain in a very scientific way. This is criticized by Blondie, who then convinces her that the simpler explanation is sufficient, as there is a quantum mechanical explanation for every color, there is no need to elaborate on the sky's color any more than any other object's color. |
− | + | The last panel takes this position on explanations to the extreme by claiming that airplanes stay up because they have thousands of birds in their wings that hold them up by flapping. (For the more accurate but also simplified explanation, see [[803: Airfoil]].) This, while certainly easier to understand, is much farther from reality than the explanation in the previous panels. Even this is not as farfetched as it may first appear. For example, in most current grade school curriculums, children are taught that atoms are made of a central nucleus with electrons orbiting around it like planets orbit around the sun. This is also an extremely simplified and inaccurate model in light of quantum mechanics. Nevertheless, it is taught as fact at least until the children are ready to take on the more complete explanation. The child's reaction in this comic, "Wow!", suggests that not only she understood, but is also excited about learning, which could be more important to her development than hearing the "correct" answer up front. | |
− | + | The title text refers to another common question as for why leaves are green. This is commonly explained by the fact that they are filled with {{w|chlorophyll}}, a chemical used by plants for photosynthesis. Randall points out that it would be an equally valid question to ask why chlorophyll is green. This poses an interesting contrast to the answer to the question about the color of the sky, since even physicists are usually satisfied with the general explanation for leaves and don't feel the need to jump into describing quantum phenomena that cause chlorophyll to reflect green light. Also, "Why does chlorophyll scatter green light" may be a great question because chlorophyll reflects, not scatters, light and this challenges Megan-types to coherently explain the difference before they go challenging little children with pedantry. | |
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− | The title text refers to another common question as for why leaves are green. This is commonly explained by the fact that they are filled with {{w|chlorophyll}}, a chemical used by plants for photosynthesis. Randall points out that it would be an equally valid question to ask why chlorophyll is green. This poses an interesting contrast to the answer to the question about the color of the sky, since even physicists are usually satisfied with the general explanation for leaves and don't feel the need to jump into describing quantum phenomena that cause chlorophyll to reflect green light. Also, "Why does chlorophyll scatter green light" may be a great question because chlorophyll reflects, not scatters, light and this challenges Megan-types to coherently explain the difference before they go challenging little children with pedantry | ||
[https://what-if.xkcd.com/141/ What-if 141] also mentions the simpler explanation to the original question: Sunbeam has this relevant text: "Normal light interacts with the atmosphere through Rayleigh scattering. You may have heard of Rayleigh scattering as the answer to 'why is the sky blue.' This is sort of true, but honestly, a better answer to this question might be 'because air is blue.' Sure, it appears blue for a bunch of physics reasons, but everything appears the color it is for a bunch of physics reasons." There is also a footnote in that comment with an additional example: "When you ask, 'Why is the {{w|Statue of Liberty|statue of liberty}} green?' the answer is something like, 'The outside of the statue is copper, so it used to be copper-colored. Over time, a layer of copper carbonate formed (through oxidation), and copper carbonate is green.' You don't say 'The statue is green because of frequency-specific absorption and scattering by surface molecules.' " | [https://what-if.xkcd.com/141/ What-if 141] also mentions the simpler explanation to the original question: Sunbeam has this relevant text: "Normal light interacts with the atmosphere through Rayleigh scattering. You may have heard of Rayleigh scattering as the answer to 'why is the sky blue.' This is sort of true, but honestly, a better answer to this question might be 'because air is blue.' Sure, it appears blue for a bunch of physics reasons, but everything appears the color it is for a bunch of physics reasons." There is also a footnote in that comment with an additional example: "When you ask, 'Why is the {{w|Statue of Liberty|statue of liberty}} green?' the answer is something like, 'The outside of the statue is copper, so it used to be copper-colored. Over time, a layer of copper carbonate formed (through oxidation), and copper carbonate is green.' You don't say 'The statue is green because of frequency-specific absorption and scattering by surface molecules.' " | ||
− | + | ==Transcript== | |
− | + | :[Young Science Girl and Blondie are talking.] | |
− | :[ | + | :Science Girl: Why is the sky blue? |
− | : | ||
:Blondie: Because air is blue. | :Blondie: Because air is blue. | ||
− | :[Megan walks in | + | :[Megan walks in.] |
:Megan: No, the sky is blue because of Rayleigh scattering– | :Megan: No, the sky is blue because of Rayleigh scattering– | ||
:Blondie: Nah, it's because air is blue. Blue light bounces off it and hits our eyes. Same as why anything is any color. | :Blondie: Nah, it's because air is blue. Blue light bounces off it and hits our eyes. Same as why anything is any color. | ||
− | :[Zoom in on Blondie | + | :[Zoom in on Blondie.] |
:Blondie: It's why far-off mountains look blue – because of all the blue air in the way. | :Blondie: It's why far-off mountains look blue – because of all the blue air in the way. | ||
− | :[ | + | :[Back to view of three characters.] |
:Megan: There's a specific quantum mechanism by which– | :Megan: There's a specific quantum mechanism by which– | ||
− | :Blondie: Yeah but there's a physics mechanism for | + | :Blondie: Yeah but there's a physics mechanism for every color. You don't have to get all quantum right away. |
− | :[Frameless panel with | + | :[Frameless panel with Blondie and Science Girl.] |
:Megan (off-panel): ...OK, I guess. | :Megan (off-panel): ...OK, I guess. | ||
:Blondie: Any other questions? | :Blondie: Any other questions? | ||
− | : | + | :Science Girl: How do planes stay up? |
− | :[ | + | :[Back to all three characters.] |
:Megan: Well, the airflow– | :Megan: Well, the airflow– | ||
− | :Blondie: Tiny birds in the wings. Thousands. Flapping | + | :Blondie: Tiny birds in the wings. Thousands. Flapping Hard. |
− | : | + | :Science Girl: WOW! |
:Megan: ''NO!'' | :Megan: ''NO!'' | ||
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{{comic discussion}} | {{comic discussion}} | ||
− | [[Category:Comics featuring | + | [[Category:Comics featuring Science Girl]] |
[[Category:Comics featuring Blondie]] | [[Category:Comics featuring Blondie]] | ||
[[Category:Comics featuring Megan]] | [[Category:Comics featuring Megan]] |