The Baffled Brain

In the sci-fi movie The Matrix, people lie motionless in pods of nutrients while they "dream” that they are living normal lives in the year 1999.

-  By Carl Zimmer

In the sci-fi movie The Matrix, people lie motionless in pods of nutrients while they "dream” that they are living normal lives in the year 1999. Their version of reality is being fed into their brains by advanced computers to keep them passive slaves of a malevolent cyber-intelligence. They see what their brains are stimulated to see, not what is there.

Look around you. What do you see? Perhaps a cat sitting in a comfortable chair. But are you sure the cat is really there? Okay, we're teasing you. You're probably not lying in a plastic pod 200 floors up in some alien power station. On the other hand, The Matrix isn't all fantasy. Given sufficient knowledge of the human brain, it would be possible to make people see whatever you wanted them to see, rather than what was in front of their eyes. That's because we see with our brains, not with our eyes. Make the right nerve cells fire in the right order, and we can't tell the difference between a real cat and one that exists only in our minds.

The brain is sometimes compared to a computer that processes input from two cameras (our eyes). In fact, it is a mass of grayish jelly weighing about a kilogram and a half with stalk-like extensions called eyes. You could call it a bio-computer-and it's a powerful one at that. Your bio-computer whips through vision tasks with tremendous speed.