We humans have known for a very long time that going to the stars will be difficult, if not impossible. The motto of NASA, Per Aspera Ad Astra, a latin phrase meaning "through hardship to the stars," comes down to us all the way from Seneca the Younger, a contemporary of Nero. Even today, when our metaphors of exertion and ambition are many --"swing for the fences," "go for gold" -- when we strain to capture the difficulty of a task, or the enormity of an achievement, "reach for the stars" is the first and most natural phrase that comes to mind. Our hierarchy of the ultimate human accomplishments is in this sense remarkably stable at the top.
And with good reason, because interstellar travel is in fact very difficult. With today's best propulsion technology, chemical rockets, it would take between 50 and a 100 millennia to reach Proxima Centauri, the nearest star to the Sun. The ideas we have about how to expedite such a journey are just that: ideas. They belong to the realm of speculation. Nonetheless, they are beginning to take on an empirical glow. To be sure, the bundle of technologies that could conceivably send a spacecraft to another star won't be here within the decade, or even within several, but neither are those technologies mere magical realism -- indeed, planning for their development has begun in earnest.
It's an admirable idea, but it will be like crawling to the stars. We will need something that goes far beyond rocket technology, be it chemical or nuclear. To read more, click here.