pie-in-the-sky

Googleが画期的なメガネを開発しました。
Google Glass: What You Can and Can't Do With Google's Wearable Computer
What can't you do with them?
Of course, there are a number of things you can't yet do with Glass. Sure, you can't do a lot of pie-in-the-sky things -- like look into the future -- but there are some things I expected them to do that they simply can't.
http://abcnews.go.com/Technology/google-glass-googles-wearable-gadget/story?id=19091948&page=2

ここで気になったのはpie-in-the-skyという表現です。この表現は以前Othello先輩が取り上げられておられましたが、（http://d.hatena.ne.jp/A30/20110829/1314575835）復習と共に、今回はその語源についても触れてみたいと思います。
まず、pie-in-the-skyは「《くだけて》夢物語、希望的観測《良さそうだが実現不可能なこと》」という意味です。（『ウィズダム英和辞典　第３版』三省堂）どうしてこのような表現ができたのか気になったので調べてみると、Wikitionaryに次のような記載がありました。
1911, phrase originally in reference to the promises of religion taken from a song written by Joe Hill, "The Preacher and the Slave", a parody of the Salvation Army hymn "In the Sweet By and By". Hill was associated with the Industrial Workers of the World (commonly known as the Wobblies), who organized migrant laborers. When the workers returned to the cities, they faced the Salvation Army.
　You will eat, bye and bye,
　In that glorious land above the sky;
　Work and pray, live on hay,
　You'll get pie in the sky when you die
つまり、この表現はJoe Hillの歌からきているのですね。
このメガネでメールを読んだり打ったり、道を調べたりもできるそうです。テクノロジーの発達はすごいです。（Jakie）