Computers
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The Human Web
A thought experiment:
a Web site with a page for everyone now living, and a page for every human
being that's lived on earth, going back to the start of the species homo
sapiens. That would be 6 billion pages for the living, and, say, 80
billion for the dead. The pages would be linked into a giant family tree.
Each page would have a photo, basic statistics
such as dates of birth and death, a list of abodes, and a brief catalog
of the subject's aspirations and accomplishments.
Mind Limits Computers
The major limitation
on the power of computers is that their workings must be understood in
detail by humans in order for them to be designed and programmed. For
example, modern microprocessors have millions of transistors, enough to
make a hundred independent processors operating in parallel in a single
chip. If they could cooperate effectively, they'd together have much more
computing power than the single processor that we currently build on that
chip, which executes one stream of instructions. But we humans have no
effective programming discipline that allows us to understand the working
of a hundred cooperating automata, even though our own brains are organized
this way, with billions of simple neurons connected in a complicated way
and operating in parallel.
The only way we'll be able to develop computers
as effective as our brains is to grow them or evolve them, so that their
capabilities are no longer limited by the need for humans to understand
in detail how they work. But at that point we will no longer completely
control them, either.
If Moore's law continues as it has for decades,
in another 20 years the fastest microprocessors will have approximately
the same raw computing capacity as the human brain. At that point it will
be very interesting to see what sorts of intelligences we can evolve.
Debugging
It is amazing how much
time programmers spend hunting down defects ("bugs") in computer
programs. This is because the way humans think is so different from the
way computers work. Computers programs follow exact instructions very
precisely, so if a piece of information is missing or in the wrong format,
or an unforseen condition arises, they "crash." Humans just
don't think this way. Because of human error, debugging well-written computer
programs takes about as long as writing them, and no one ever finds all
the bugs.
It is very easy to make
even a small program too complicated for anyone to understand. Programs
that can't be understood can't be debugged effectively. The hallmark of
a master programmer is the ability to formulate the solution to a complex
problem in a simple way, so it's obvious how it works, and easy to debug.
Very difficult bugs are ones that are hard
to reproduce, such as when several things happen almost at the same time,
in a sequence that wasn't anticipated by the programmer. You might have
to run the program for several days to make the bug happen once, and then
you might not have much information about the details of what caused the
problem. The secret to avoiding these bugs is good, correct design. No
amount of debugging will fix bad design. A kludgey fix for one problem
will just cause another problem.
Hacking
When virtuoso computer programming is shown
in movies and television, it's made to look like playing a video game
– it's all quick twitchy moves in graphical environments. In reality,
programming is thoughtful, and mostly text-based, more like writing a
short story than playing Doom.