Expert: James Gort - 10/30/2011

Question
Dr. Gort,
Although I am not formally educated, I am, like many others, a fan of cosmology.
I am very interested in reading more about the "earth-like" planet found orbiting Gliese 581. It truly sparks my son's imagination!

My question is this: Using our current technology, how long would the trip take to reach this planet?
Can you break your answer down a bit? My son wants to go there, but I'm afraid I may have to tell him that he won't live long enough to see that. Will you help to put thing into perspective?
Thanks

Answer
Hi Jerry,

Although your son may eventually be able to get there, please explain to him that we'll have to develop a new form of rocket first. Because with our current technology, it would take almost as long as humans have walked the earth!

Gliese 581 happens to be about 20.3 light-years from earth. Since a light-year is close to 6 trillion miles, that means Gliese is about 120 trillion miles from earth. Our fastest human payload rockets were the ones used to go to the moon - they traveled about 7 miles per second. So, using our fastest rockets, it would take 500,000 years to get there!

So can we never get there? Well, Albert Einstein said we can't exceed the speed of light. So that means it MUST take more than 20 years to reach Gliese (even if we were riding a light beam). With our current technology, we can't even approach that. But someday, we may learn how to travel at least a fraction of the speed of light. If we could travel at one-half the velocity of light, it would only take 40 years to get there. And Einstein said we would age slower, so our astronaut going at that speed would "think" it only took a few years. So it might be possible some day - but not with the rockets we have today. Maybe your son will think of a new type of rocket which will get us to the stars much faster! Tell him to keep dreaming, and studying.

Cheers,

Prof. James Gort