A: Both of them.
A: Two. One to talk about the amazingly bright future while
the other screws the bulb into the water faucet.
A: Two. One to hold the bulb and the other to rotate the planet.
A: Two. One to hold the giraffe, and the other to fill the
bathtub with brightly colored machine tools.
A: Nobody knows. Extropians don't last as long as light bulbs.
A: None. If the government would just leave it alone,
it would screw itself in.
A: Extropians don't need light bulbs because they carry
their own light with them.
--
sentience@pobox.com Eliezer S. Yudkowsky
http://tezcat.com/~eliezer/singularity.html
http://tezcat.com/~eliezer/algernon.html
Disclaimer: Unless otherwise specified, I'm not telling you
everything I think I know.