Earth in 100 years as seen by a modern Jules Verne; 2081: A hopeful View of the Human Future, by Gerard K. O'Neill. New York: Simon & Schuster. $14.95.

The year 2081 will be a time of interstellar travel, space colonies, and electronic bumper stickers. Then the world, as seen by futurist- physicist Gerard K. O'Neil, will be a place of interplanetary plenty as a result of mankind's accomplishments.

Just when it seemed that nobody was willing to write about bright tomorrows, Dr. O'Neill offers a welcome change of pace. But this book is more than just wishful Science fiction. O'Neil bases every prediction upon existing technologies -- and advancements within reach.

But most of all, this book is fun to read. It reawakens the imagination first sparked by those sci-fi novels and Saturday matinees of childhood -- in the days before doom-filled forecasts became the fashion.

At the same time, O'Neill points out a few sour bites in this pie-in-the-sky future. For example, he predicts small-scale nuclear terrorism will be prevalent in the unstable African nations of 2081. Hunger and poverty will also still be found, but for political rather than economic reasons. And O'Neill predicts that a good deal of Earth will be under the sway of dictators.

These pockets of darkness will reinforce the appeal of one of the author's favorite themes: the migration of mankind to space colonies. O'Neill, a Princeton professor, is well known for his best-selling study on this subject, "The High Frontier."

What he calls the "breakout from the nest- planet" is the linchpin for his vision of the future. Space colonies will serve as release valves for Earth's swelling populations, while offering safe havens for the noncomformists and free thinkers of tomorrow.

The colonies won't be limited by the physical boundaries that divide Earth and contribute to the pressures between nations. Each colony will be an oasis, a self-supporting world, able to choose its own climate and build out in any direction.

So while the developed nations of Earth will continue to offer an updated version of the good life a century from now, there will be pressures for people to want to move to the relative safety, freedom, and comfort of the colonies.

O'Neill prefaces his predictions with a look at earlier attempts to foretell the future by such writers as Jules Verne, Aldous Huxley, and George Orwell.

Some hit their target with amazing accuracy. For example, Verne, writing nearly a century before the Apollo 9 mission, portrayed the first moon expedition being launched from Florida, with a three-man crew, circling the moon prior to landing, and later splashing down on Earth in the ocean. However, he also thought the trip would be privately financed by an enterprising group of Civil War veterans.

O'Neill also describes what he calls "the drivers of change." These are the five technologies he believes will swing the future -- computers, automation, space colonies energy, and communication.

In each of these areas, he sees improvements helping to hurtle mankind beyond the stratosphere, while also hoisting the standards of living here on Earth.

Perhaps the most fascinating and certainly the most readable portion of the book chronicles a space colonist's visit to Earth in 2081. The young journalist from Fox Cluster (a group of colonies near the border of the solar system) learns about life in an open atmosphere, and records his impressions in short dispatches. After each of these passages, O'Neill explains how the observations relate to current technologies or his own expectations.

So while o'Neill's vision of the world of 2081 is a mixture of virtues and vices, O'Neill seems hopeful that we are moving in the right direction -- out toward space and the unlimited pos sibilities he sees in it.