“Consider a pair of brothers, identical twins. One gets a job as an astronaut and rockets into space. The other gets a job as an astronaut, too, but on this occasion he decides to stay home. After a year in space, the traveling twin returns home and they reunite.
NASA will be sending astronaut, Scott Kelly, on a one year mission starting March 2015 to the international space station. And while he is circling earth, his identical twin brother, Mark Kelly (also an astronaut), will stay here on earth.
“We will be taking samples and making measurements of the twins before, during, and after the one-year mission,” says Craig Kundrot of NASA’s Human Research Program at the Johnson Space Center. “For the first time, we’ll be able two individuals who are genetically identical.”
Now according to Einstein’s “Twin Paradox” and theory of relativity, the traveling twin should come back younger than the one that stayed on Earth. We’re about to find out!