藍色的天空，是因為空氣是藍色的嗎？

http://www.psaudio.com/pauls-posts/the-sky-is-not-blue/

There is no denying sky, ocean, and thick ice, are blue. Stare up to see the azure sky broken only by the white of clouds. Yet measure some blue air, ocean, or ice, and you will find not one molecule of color in it.
Should we conclude what we see is wrong because we have measured proof there is no blue contained in air, water, or ice? Should we not trust our eyes or ears when we sense that which measurements prove wrong?

這辯證很有趣，
測不出來，不表示相同，只表示該測量方法看不出差異；
音響，最終還是得以耳鑑定。