What is the main topic of the passage?

Today, I ask you to focus on the challenges of the Information Age. The dimensions of the Information Revolution and its limitless possibilities are widely accepted and generally understood, even by lay people. But to make the most of it, we must acknowledge that there are challenges, and we must make important choices. We can extend opportunity to all Americans or leave many behind.We can accelerate the most powerful engine of growth and prosperity the world has ever known, or allow the engine to stall.

Laughter can even provide a kind of pain relief. Scientists had proved that laughter produces endorphins -- chemicals in the body that relieve pain. They divided 40 university students into four groups. The first group listened to a funny cassette for 20 minutes. The other three groups listened to either an informative tape, or a cassette intended to relax them, or no tape at all. Scientists found that if they produce pain in the students, those who had listened to the humorous tape could tolerate the discomfort for much longer.