“We used to look up at the sky and wonder at our place in the stars. Now we just look down and worry about our place in the dirt.” This lament from the main character in Interstellar, a semi-retired NASA pilot, carries a distinctly dystopian vibe and, indeed, the prospects for humankind at the outset of the film are dire. Set sometime in the not-too-far future (director Christopher Nolan never divulges an exact date), Interstellar depicts an Earth wracked with famine and plagued by a shortage of technological resources. Humanity’s only hope, it seems, lies with a motley crew of scientists and astronauts who must find a new home for what is left of the human race.

At its heart, Interstellar is classic space-travel science-fiction, and Nolan – an acclaimed filmmaker whose previous hits include Memento and the Dark Knight trilogy – tips his hat to a number of stalwarts in the genre, from Metropolis to 2001: a Space Odyssey, Blade Runner and even Avatar. But this is no chrome-clad futuristic world. Instead, human civilization has returned to an agrarian society, with a population that struggles to feed itself amid conditions that closely mimic the “Dust Bowl” of America’s heartland in the 1930s.

After a somewhat drawn-out beginning, the film picks up pace when an enigmatic NASA physicist (played by Michael Caine) reveals a plan to save humanity by jumping ship. But before he can figure out how to get the Earth’s entire population into space, through a conveniently placed wormhole and onto an alien planet in another galaxy, he must find out which of the 12 -planets on the other side of the wormhole is best suited for human habitation. With this in mind, NASA sends astronauts to assess the -planets’ potentials. When positive signals are received from three of them, a follow-up mission is organized in which Cooper, the aforementioned pilot-turned-unwilling-farmer, must manoeuvre a spacecraft and its crew of researchers through the wormhole to find out which planet best fits the bill.

With his easy Texan charm, actor Matthew McConaughey is perfectly cast as Cooper, the “space cowboy” who is also a father desperate to return to his children – especially his daughter, with whom he shares a special bond. Throughout the film, Nolan deftly combines the cold realities of interstellar travel with the messy business of human emotion, as Cooper agonizes not just about the success of their mission, but also about how long he has been away from Earth.

This is where the physics element of the film begins to shine through. Even with a handy wormhole at our disposal, interstellar travel is a lengthy business. The film is absolutely full to the brim with physics – not surprising, considering that the idea for it was born when a physicist, Kip Thorne, and a film producer, Lynda Obst, decided it would be fun to base a film on Thorne’s complex astrophysics research. The pair had previously collaborated on Contact, the 1997 film based on Carl Sagan’s novel, and after shopping their idea around Hollywood for several years it eventually ended up in the hands of Nolan and his scriptwriter brother Jonathan. Thorne remained heavily involved in the film’s development (he is an executive producer) and he has also published a book, The Science of Interstellar, to explain the physics that went into it.

The book was rushed into print in time for the film’s release and is a bit sloppily edited for my taste. From the perspective of your average cinema-goer though, a more serious flaw is that it reads like a cosmology textbook. While scientifically trained fans of Interstellar will gain much from it, others will be put off by the level of detail. Personally, I was initially thrown by its higgledy-piggledy order (the book does not follow the film’s timeline), but I did find Thorne’s system of labelling the book’s chapters with “T” for “truth”, “EG” for “educated guess” and “S” for “speculation” useful because it helped to distinguish established science from far-out guesswork.

The best part of the book, though, is the way that it shows how keen both Thorne and Nolan were to get the science right, and how the demands of the plot were matched to the rigours of reality. For example, at one point Nolan asked whether it was possible for one of the planets in the film to experience time dilation so extreme that one hour on its surface would translate into seven years on Earth. Thorne, for his part, did some serious research on what the astrophysical phenomena in the film would actually look like to nearby observers. He and a British visual-effects company, Double Negative, developed code to solve the equations that describe how light approaching a camera (or an eye) would misbehave in the vicinity of a spinning supermassive black hole.

In general, I had little issue with the science depicted in Interstellar. I did cringe slightly at its explanation of how, exactly, a wormhole was placed at such a convenient location, but (spoilers ahead) I found the idea of a four-dimensional “hypercube” lying deep within a black hole intriguing, and I could even suspend my disbelief about Cooper encoding complex data into the ticking of a wristwatch. As an avid science-fiction fan, I am reasonably happy to overlook a few stretched truths for the sake of a really good plot twist. But what distracted and annoyed me from very early on was the way Interstellar dealt with “habitable” planets. Data from NASA’s Kepler telescope indicates that there could be as many as 40 billion Earth-sized planets in the Milky Way, including 11 billion that may be orbiting Sun-like stars. Of these 11 billion possibilities, astronomers have already identified 47 Earth-like exoplanets that lie within the habitable zones of their stellar systems. None of them, however, are anywhere near a black hole. So why is it, then, that the five-dimensional time-travelling benevolent overlords in Interstellar – who can, after all, manipulate the laws of space–time to create wormholes, and who have a very good reason to care about the survival of humanity – choose new home planets for us in such an unappealing galactic neighbourhood? While I realize that the wormhole and black hole in Interstellar made the film exciting, surely they could have been incorporated in a way that did not make these god-like beings seem stupid, mean, or both.

Nolan wanted to make a science-fiction film that got the science right while also exploring the complex human issues around interstellar travel. On the whole, he succeeded. One could, perhaps, ask whether there is much point in having such complicated science depicted so accurately in a film, given that most viewers will be unable to tell (without reading Thorne’s book) what is and what isn’t fiction. However, after decades in which mainstream science-fiction films have happily flouted pretty much every known physical law, a film in which the science is, for a change, mainly true, can only be a good thing. Knowing that some directors make serious efforts to get the science right is, in itself, probably enough to inspire a few viewers – and perhaps even to push them to find out why a “black” hole can glow so brightly.