Among the issues behind traveling in space, with manned or even unmanned vehicles, energy, speed and propulsion rank first, and they are strictly related. How to produce the enormous amount of energy necessary to achieve the required thrust to propel a ship fast enough?
Making Interstellar Travel Possible
The system in our neighborhood, Alpha Centauri, is still at a distance of 4.2 LY—266,000 times the distance between the sun and the earth. To solve this conundrum, Sci-Fi devised wormholes, warp drives and hyperspace as solutions.
“The spacecraft would depart the point of origin (e.g. earth) using some conventional propulsion system and travel a distance (…) never locally breaking the speed of light, but covering the distance in an arbitrarily short time period of time just the same…This approach would allow a journey to say Alpha Centauri as measured by an earth bound observer (and spacecraft clocks) measured in weeks or months, rather than decades or centuries.” (Harold White, 2011)
Interstellar travel - Steven Hawkins into the universe
“Why bother with these seemingly impossible goals? Well, progress is not made by conceding defeat. History is replete with conquered impossibilities — flying machines, moon landings, and tapping the power of the atom, to name but a few. It took four decades to go from the first liquid rocket to the first landing on the moon, and three decades to go from the confirmation of radioactive decay to the first nuclear reactor.” (Marc G. Millis, NASA’s Glenn Research Center, 1998)
A solution could send robots first to colonize new worlds and then transport, or grow humans over there. Alternatively, the travelers could be set on suspended animation, very much like in movies (i.e. Alien).
There are other possibilities for future technologies, a further step into pure Sci-Fi. Is it truly impossible to travel faster than light? Two scientists, Hill and Cox, have recently extended Einstein’s calculations to explore the boundaries of faster-than-light, showing that his equations break down into mathematical singularities, where physical properties simply don’t hold.
“The actual business of going through the speed of light is not defined. The theory we’ve come up with is simply for velocities greater than the speed of light,” Hill declared. While it is dubious this can have any practical implication any time soon, the possibility itself is a game changer and can result in surprising outcomes.