Interstellar Matthew McConaughey, Anne Hathaway, Jessica Chastain. Directed by Christopher Nolan. Rated PG-13. Now playing.

For all its reliance on detailed scientific explanations and rows of mathematical formulas, the essence of Christopher Nolan’s Interstellar comes in a speech from scientist and astronaut Amelia Brand (Anne Hathaway), making an impassioned plea for the value of love as a mysterious, mystical concept that binds humanity together and can transcend petty things like space and time. Interstellar turns out to be less hard-headed than soft-hearted, a three-hour, effects-heavy sci-fi epic about how, like, all you need is love, man.

While the movie’s science is dense and complicated and often borderline nonsensical to someone without a degree in physics, its emotions are grossly simplistic and almost never convincing. Nolan spends the first 45 minutes of the movie focused on the simple life of farmer Cooper (Matthew McConaughey) and his two kids, especially precocious daughter Murphy (Mackenzie Foy), and the filmmaker’s vision of hard-scrabble survivors of a vague future catastrophe (there are references to food shortages, dwindling population and the collapse of certain facets of the government) is hazy and not particularly compelling. Once Cooper, a former pilot, gets recruited by what remains of NASA for a top-secret world-saving mission, though, the movie picks up considerably.

Along with three other astronauts (including Brand), Cooper is sent into the far reaches of space to search for an inhabitable planet that can sustain humanity after the Earth’s resources give out (a prospect getting closer by the day). Cooper’s conflicted emotions over leaving his family behind for a mission from which he may never return come off as sub-Spielbergian retreads, but Nolan excels at depicting more visceral emotions of basic survival as Cooper and his crew explore harsh, unpredictable new worlds. It takes more than an hour before Interstellar offers up its first astonishing set piece, but watching the characters attempt to escape a mountain-size wave on a planet covered in water is more than worth the wait.

With more than an hour of footage shot with IMAX cameras (see the movie projected in 70mm IMAX at the Brenden Palms if you can) and a heavy reliance on practical effects, Interstellar looks amazing, and its otherworldly images have real weight and substance. When the crew heads to a harsh, icy planet, the desolate cold is palpable. Aided by cinematographer Hoyte Van Hoytema, Nolan creates overwhelming, often breathtaking suspense in a number of sequences.

And then he totally botches the landing. Interstellar’s last 20 minutes or so is a hokey cop-out, a rejection of all the preceding scientific wonder in favor of goopy declarations of love and sentimental platitudes. After exploring the farthest corners of the universe and attempting to ask fundamental questions about existence, Nolan falls back on a greeting-card conception of life, as hollow and chintzy as the movie’s best moments are thrilling and grand.