Seth Shostak Quotes
While human space travel is daunting, machines - with their indefinitely long lifetimes - could travel the galaxy. It might make little difference to them that bridging the distance from one star to the next could take hundreds of thousands of years or more.
Shostak, Seth. "Why Aliens Are Probably Machines." Space.com, Future US, 14 Nov. 2016.
We know that our solar system will die in several billion years, but there are also other comic dangers that in the past have wiped out most life species and could do so again. Hawking and some others believe that NASA and other future efforts to develop space travel are critical to the long term survival of the human race.
Seth Shostak is an American astronomer and author, and is currently the senior astronomer for the SETI Institute.