Gene McKenna

Find the Heavy Billiard Ball...
Fast-forward forty years in time — only a few miles in
space from long-since-defunct Shockley Semiconductor — to a
much-changed Silicon Valley. Transistors etched onto silicon
chips were as big as Shockley imagined. Software was even bigger.
Stanford was having a career fair, and one of the most popular
companies in attendance was the Microsoft Corporation. With
the 1990s dot-com boom and bull market in full swing, Microsoft
was famous as a place where employ-ees of no particular
distinction could make $1 million before their thirtieth birthday.
Grad student Gene McKenna signed up for an interview with
Microsoft's recruiter.
Suppose you had eight billiard balls, the recruiter began. One
of them is slightly heavier, but the only way to tell is by put-ting it on
a scale against the others. What's the fewest number of times you'd
have to use the scale to find the heavier ball?
McKenna began reasoning aloud. Everything he said was
sensible, but somehow nothing seemed to impress the recruiter.
With hinting and prodding, McKenna came up with a billiardball-
weighing scheme that was marginally acceptable to the
Microsoft guy. The answer was two.
"Now, imagine Microsoft wanted to get into the appliance
business," the recruiter then said. "Suppose we wanted to run a
microwave oven from the computer. What software would you
write to do this?"
"Why would you want to dolhat?" asked McKenna. "I don't
want to go to my refrigerator, get out some food, put it in the
microwave, and then run to my computer to start it!"
"Well, the microwave could still have buttons on it
too."
"So why do I want to run it from my computer?"
"Well maybe you could make it programmable? For example,
you could call your computer from work and have it start
cooking your turkey."
"But wouldn't my turkey," asked McKenna, "or any other
food, go bad sitting in the microwave while I'm at work? I
could put a frozen turkey in, hut then it would drip water
everywhere."
"What other options could the microwave have?" the
recruiter asked. Pause. "For example, you could use the com-puter
to download and exchange recipes."
"You can do that now. Why does Microsoft want to
bother with connecting the computer to the microwave?"
"Well let's not worry about that. Just assume that
Microsoft has decided this. It's your job to think up uses for it."
McKenna thought in silence.
"Now maybe the recipes could be very complex," the
recruiter said. "Like, 'Cook food at seven hundred watts for two
minutes, then at three hundred watts for two more minutes, but
don't let the temperature get above three hundred degrees."
"Well there is probably a small niche of people who
would really love that, but most people can't program their
VCR."
The Microsoft recruiter extended his hand. "Well, it was
nice to meet you, Gene. Good luck with your job search."
"Yeah," said McKenna. "Thanks."