In many science fiction movies, spaceships race through the galaxy at extremely high speeds, seemingly ignoring many of nature’s laws that govern our universe. With what we know about the universe right now, it is impossible for any object to travel faster than the speed of light. Any man made object has not reached speeds even close to the speed of light, as the five planetary probes that we have launched to eventually travel among the stars move at speeds less than 1/10,000 of the speed of light. Alpha Centauri is the closest star system to Earth, but it is still a staggering 4.3 light years away. Therefore, at the rate that these probes are traveling, it would take each of these probes at least 100,000 to reach Alpha Centauri, but their trajectories won’t take them anywhere close to it. Rather, these probes will simply continue their journey through interstellar space for millions or billions of years to come.
If we wanted to travel to other stars within human lifetimes, we would need starships that are able to travel at speeds close to the speed of light. In order to do this, we would need entirely new types of engines built to travel at such high speeds. Similarly, spaceships traveling at such high speeds would require new types of shielding to protect crew members from instant death, as a spaceship traveling through interstellar space near the speed of light would be bombarded by billions of deadly high-energy cosmic rays. Even if we were able to accomplish this, we would still be met with other significant challenges. According to Einstein’s theory of relativity, time moves much slower to an object traveling near the speed of light. For instance, a starship embarking on a 50-light-year round trip to the star Vega would only take crew members about 2 years, but more than 50 years would have passed on Earth while they were gone. While the crew would have only aged two years, they would return to a considerably different world that they left. Therefore, it is clear that we are years away from interstellar space travel within human lifetimes, and even if are able to accomplish this we would still face other immense challenges.