Yea. I feel like it was sort of said in the movie, but not in a really explicit way so that maybe people who aren't as familiar with the science behind speed of light and travel or of it from science fiction stories may not have been aware what exactly was going on.This is one bit I really missed:
The missed the part near the end of the book, where we learn that because he moved away from Earth at such a rapid rate that more time has taken place on earth than for himself. It was basically a practical way to time travel into the future. It was a cool concept that was left out with why him returning wouldn't practically work at the end.
For Grace travelling closer to the speed of light (for most of the trip) means he gets to Tau Ceti from Earth having 'aged' around 4+ years, but like 12+ years passes on Earth. I don't think the coma would slow cellular aging and was more for controlling necessary food/water/oxygen.
He then spends a few months/year at Tau Ceti solving the stuff with Rocky and then sends the probes to Earth while going to Rocky's world in 40-Eridani. Which is a little bit closer to Tau Ceti than the Earth. So give him around 4 years. At one point he actually theorizes his actual age and the difference between how time has progressed on Earth.
I'll put this in spoiler because it's not something stated in the movie, but in the book and now with a sequel possibility....
The ending picks up after a number of years and he believes the gap is about 18 years. That he's 53 in cellular age, but it's actually been 71 years since he was born.
In the book he finds out while on Rocky's world that Sol has returned to normal illumination. This book says based on the time it took the probes to get to Earth, they implemented a solution within about a year. Then it took time for that light to makes it way to Rocky's planet at which point.
He's also walking with a cane, partly age, but also because Rocky's world has a higher gravity than Earth. The last scene is the same as the book with him teaching students.
So it seems like they are certainly leaving some open-ended stuff for a possible sequel. Also Rocky and Grace right before the end talk about wondering about the other stars and more life nearby.
In the book he finds out while on Rocky's world that Sol has returned to normal illumination. This book says based on the time it took the probes to get to Earth, they implemented a solution within about a year. Then it took time for that light to makes it way to Rocky's planet at which point.
He's also walking with a cane, partly age, but also because Rocky's world has a higher gravity than Earth. The last scene is the same as the book with him teaching students.
So it seems like they are certainly leaving some open-ended stuff for a possible sequel. Also Rocky and Grace right before the end talk about wondering about the other stars and more life nearby.
Good enough to post twice, I say!
