I took my father to see Gravity at the cheap theater today. And our reactions were exactly the opposite. We both rather liked it. But I loved the first hour and thought the last half hour was total rubbish. My dad thought the first hour was kind of boring and the last half hour was a thrill ride. He even seemed a little wobbly as we walked out of the film.

I was not prepared for just how realistic the film was. Almost from the first shot, I was squirming in my chair. And then, when the debris hit, I was lost. Part of this was due to the way the physics was done in the film. I’m sure that there were some things that were wrong, but by and large, Gravity was a treatise on Newton’s first and third laws. Once Dr Ryan Stone (Sandra Bullock) starts rotating, she continues to rotate. There is no friction to slow her down. That’s the first law! Later in the film she uses a fire extinguisher to propel herself to the space station. When it is empty, she is still floating away. So she throws the empty can and moves in the opposite direction. What a great example of the third law and conservation of momentum!

But none of that exactly explained why I so liked the film. The essence of it is Stone’s character. She isn’t a professional astronaut. She a medical engineer who has been taken up to space to add something on the Hubble Space Telescope. She is not having fun. In fact, she is behaving very much like I would. She is, in other words, a real person. Along with her is veteran space shuttle captain Matt Kowalski (George Clooney). He is the action hero cliche—albeit a more nuanced one than we usually get. As long as he is around, Stone can depend upon him. When he’s gone, she kind of freaks out. Again: just like I would. And I suspect like all of us would.

The problem comes at the one hour mark. At that point a little movie magic happens and Stone goes from “person doing her best to deal with unimaginably difficult situation” to Ripley at the end of Aliens. Suddenly she can do anything. But it isn’t just her attitude that changes. It is the plot. Before then, everything was careful. The parachute was caught on the space station, so she had to remove it. Stuff like that. But then, in the third act, it was all “will to succeed.” She still had to be smart and brave as she had been throughout the film, but suddenly she had a silly self-confidence and the unreasonable good luck that comes to Americans who are true of heart. (That’s interesting given that it is mostly a Mexican production.)

Ultimately, Gravity is a disaster film. It is just that it happens in space. And it is interesting because the main character is so poorly suited to the challenge. But at the end, it is clear that Stone is not behaving as she does for her own sake; she is doing it for ours—and this takes away from the realism that existed up to that point. Or at least that’s the best take on it. It is also possible that the writers decided to change a relatively complex character into a simple character. I don’t think so. Regardless, the last act has no drama in it. It is pure momentum—the plot speeding to its end as inexorably as the escape pod speeds to earth. Both are entirely predictable.

But two good acts is two more than most films have. And endings are always hard—especially when the beginning has been so good. Certainly, my father had a better experience. It’s better to end well. But I still thought the film worked. I was just disappointed.