We should be afraid, above all, of squandering our grand opportunities.
Today many hundreds of millions of people enjoy a material standard of living higher than any but a fortunate few attained just a century ago. More than that: Things we take for granted today, such as instant access to distant friends and to the world's best artistic and intellectual productions, were barely imaginable then.
How did that miracle happen?
The enabler was new basic knowledge. Insight into electromagnetism allowed us to transmit both power and information; first steps in understanding the quantum world have supported microelectronics, lasers, and a host of other technologies. Understanding the true origin of diseases allowed their prevention or cure; molecular understanding of plant and animal metabolism supported vast improvements in agriculture, yielding richer harvests with far less human labor.
Fundamental breakthroughs, by their nature, cannot be predicted. Yet there is every reason to hope for more, soon. The tools of quantum science and molecular biology are sharper than ever, and now they can be harnessed to extraordinary, ever-strengthening computer power. Opportunities beckon: the challenge of making quantum computers, real possibilities for enhancing human minds and increasing the span of healthy life, and others not yet imagined.
What could go wrong?
Gibbon, in describing the fall of Rome, spoke of "the natural and inevitable effect of immoderate greatness" and of "the triumph of barbarism and religion". Those forces—the diversion of intellectual effort from innovation to exploitation, the distraction of incessant warfare, rising fundamentalism—triggered a Dark Age before, and they could do so again.