, and entrepeneur
best known for inventing the concept of the O'Neill Colony
Educated at Swarthmore College and Cornell University, he became an instructor at Princeton University in 1954. In 1956, still at Princeton, he published a two-page letter entitled "Storage-Ring Synchrotron: Device for High-Energy Physics Research" in Physical Review, which became a blueprint for high-energy physics research over the next four decades. He set up a lab at Stanford University to house his synchotron prototype, and by 1965 the apparatus was powerful enough to perform the world's first colliding beam experiment.
In the same year, he was given a full professorship at Princeton, and decided to devote himself to teaching introductory physics. He replaced old problems with new learning guides, which proved to be so effective that Princeton implemented them in other courses as well. He discovered that the physics of orbit were especially popular with students, largely because of the then avant garde Apollo program, so he began assigning more space-related projects, and found his own interest in the field growing as well.
He wrote a book on space travel called The High Frontier in 1977, and in 1978, he founded the Space Studies Institute (SSI) to research and develop new technologies for space colonization and space exploration. He invented the mass driver and, along with SSI, built a working model. Freeman Dyson is quoted as saying that O'Neill's designs never failed for technical reasons: if they didn't work, it was because they were economically or politically unworkable.
In 1983, O'Neill founded the GeoStar corporation to launch the world's first GPS system into orbit. Two years later, he contracted leukemia, and shortly afterward, the first two GeoStar launches both failed, sending the company into the dust.
O'Neill died in 1992. Shortly before his death, he designed the VSE train network, one of the fastest and most efficient, not to mention most ambitious, transportation designs to date. It was his last major project, and has not yet been fully realized... but keep your eyes open.