Answer in Europe: Let me apply for a state grant and I'll get back to you on that.
Answer in American academia, c.1900-1950: None. Back then universities actually paid janitors to replace light bulbs.
Answer in American academia, c.1950-1970: One. But s/he was not allowed to touch that bulb again until all eleven of the other bulbs in the building had been replaced.
Answer in American academia, 1990-present: One. But s/he has to provide the bulb, s/he will get paid as a "part-time, adjunct light-bulb replacer," and if s/he falls off the ladder while doing it s/he's out-of-luck because s/he doesn't have any health insurance or benefits.
The "new complexity" answer: Two: One to write directions explaining how to insert and twist the bulb that are so overly complicated that no human could possible follow them; the other to pretend to understand those directions and "fake it" by simply screwing the light bulb in.
The post-modern answer: Two: One to screw in the light bulb, and one to explain that there is no such thing as a "new" light bulb.
The minimalist answer: 100; each twisting the bulb a fraction of an inch for over an hour.
The computer music answer: One. And after sitting at a computer terminal for 3 1/2 months designing a "virtual" light bulb, the composer will realize that it's still not as good as a plain old "analog" bulb s/he could have purchased for 20 cents at a hardware store, which most people - including the composer - would rather look at anyway.
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Q: Why did Mozart kill his chickens?
A: Because they always ran around screaming, "Bach! Bach! Bach!"
"I'm told that Wagner's music is not as bad as it sounds."
Mark Twain
Speilsberg thought of an idea for a action drama about famous musicians played by superstars.
Sylvester Stallone, Steven Segall, Bruce Willis, and Arnold Schwartzenegger all showed up. Speilberg told them to pick what musician they wanted to be as long as they were famous.
"I'll be Mozart because I've always admired his classial music," said Stallone.
"I liked Chopin's piano music and I think I'll play his role," said Bruce.
"I think I'll be Beethoven because he wrote excellent music," Segall said.
Speilburg was excited because he loved this idea. When he asked who Arnold would be, Arnold said, "I'll be Bach".