(Caution: potential spoilers for The Martian lie below. Proceed with care or courage. Or both.)
So, if you're at all active on the movie scene, you will have seen Ridley Scott's latest reel The Martian, starring Matt Damon. Just to get the air clear, it's an incredible movie, and a real achievement within the Sci-Fi genre. Having directed numerous space-based movies, it doesn't come as a surprise that Mr. Scott's Mars-based adventure was and still is a smash hit.
However, despite all of its cosmic awesomeness, there is one scientifically implausible aspect to this film, as is often the case with this genre of cinema. And no, it's not the part where he gets sent into space underneath a thin blanket.
It's actually all to do with the gravitational effects that take their tolls on the human body whilst in a lower-gravity atmosphere. We're all aware that astronauts have to do workouts in space, in order to retain their muscles, right? Well, the same applies on Mars. It's a smaller planet, hence less dense, hence less gravity. What beats me about The Martian? Well, we never saw Matt Damon working out.
And no, I'm heterosexual, thank you very much.
And on top of that (despite The Martian being set in the future), even with the most advanced tech we currently have we would never plan for anybody being sent to Mars to return. Scientifically, if they were to stay on Mars for over nine months, the second they hit Earth's tarmac, their bodies would turn into a puddle. Nice...
So to recap, there's no way someone could have successfully returned to Earth's gravity after having not exercised on Mars. It simply wouldn't be possible. Don't get me wrong, I loved the whole happy ending thing, but realistically, Mark Watney would be a shapeless blob by now.