And ran into a stone wall.
After three decades of trying, scientists reluctantly concluded that a faster-than-light drive was an impossibility, at least within the realm of any known theory of the Universe. They gave up.
But a government does not give up so easily, especially a unified government which already controls the entire habitat of the human race. Most especially a psychologically and sociologically enlightened government which sees the handwriting on the wall, and has already noticed the first signs of racial claustrophobia—an objectless sense of frustrated rage, increases in senseless crimes, proliferation of perversions and vices of every kind. Like grape juice sealed in a bottle, the human race had begun to ferment.
Therefore, the Solar Government took a slightly different point of view towards interstellar travel—Man must go to the stars. Period. Therefore, Man will go to the stars.
If the speed of light could not be exceeded, then Man would go to the stars within that limit.
When a government with tens of billions of dollars to spend becomes monomaniacal, Great Things can be accomplished. Also, unfortunately, Unspeakable Horrors.
Stage One: A drive was developed which could propel a spaceship at half the speed of light. This was merely a matter of technological concentration, and several billion dollars.
Stage Two: A ship was built around the drive, and outfitted with every conceivable safety device. A laser-beam communication system was installed, so that Sol could keep in contact with the ship all the way to Centaurus. A crew of ten carefully screened, psyched and trained near-supermen was selected, and the ship was launched on a sixteen-year round-trip to Centaurus.
It never came back.
Two years out, the ten near-supermen became ten raving maniacs.