Why do we crave science fiction? From books to movies, we just can’t get enough of the “what if” scenarios new science and technologies tantalize us to imagine. We can push controversial topics out into the future and examine them with different eyes. Are we better off, or worse? The questions sci-fi films prompt are key, but there are a few other key elements a film must have to impress. In addition to stunning cinematography and music, the best sci-fi films are highly developed in the rigor of their plot, character development, their accurate adherence to scientific principles, and the director’s own instinctive understanding of other disciplines.

Chrisopher Nolan’s “Interstellar” and Guo Fan’s more recent “The Wandering Earth II” are both high budget, visually stunning sci-fi films focused on the survival of humanity in outer space. But which manages to keep us hopelessly hooked throughout?

One consistently powerful theme in Interstellar is clear. It is centered on the love between characters, particularly that between Cooper and his daughter Murphy. Dramatic tension builds intensely from the moment Coop explains to Murphy that he will leave and she gives him a message from the future to stay. This small dramatic irony, along with the dangling question surrounding Cooper’s return builds all kinds of emotions in our psyche. The highly developed relationship between father and daughter is something most can identify with deeply. As Brand later states, "Love is the one thing we are capable of perceiving that transcends dimensions of time and space.” Coop and his daughter's love across time and space become the key to everything.

Take another look at “The Wandering Earth II.” Director Guo Fan uses three main lines to tell the grand story of "wandering with the Earth", but the narration of some lines are convoluted and not delicate enough, or detailed enough for us to maintain dramatic tension and our sense of emotion. The line between Tu Hengyu, played by Andy Lau, and his daughter Ya Ya is also about the relationship between father and daughter. Tu’s love for his daughter is selfless and he is even willing to break the rules and risk prison for the sake of continuing Ya Ya's digital life. However, not much time is spent on a developed relationship between the two. The film doesn’t let us feel Tu Hengyu’s deep love for his daughter. When we realize Ya Ya has died in a car accident, we initially feel the need to continue her digital life, but the plot changes abruptly and our emotions are cut off and left unresolved.

The rigor of the scientific principles involved in a film affects the plot’s plausibility in the mind of the audience. Well researched scientific events challenge our minds and keep our interest focused on the events. “Interstellar” is based on a large number of scientific principles such as gravitational time dilation. It adheres consistently to the principles of relativity in which time is perceived differently on different planets. Time transcends everything for the characters-even death.

Nolan hired Professor Kip Stephen Thorne, Nobel Prize winner in physics, as the scientific advisor of Interstellar. Thorne took months to explain to Nolan the science related to black holes and shared much of his own material. He described Interstellar as a "science fiction film made from the very beginning in accordance with real science."

Guo Fan, director of The Wandering Earth II, also consulted professors at the Chinese Academy of Sciences to ensure the scientific rigor of Wandering Earth 2 and to show respect for science, however, a situation in which a nuclear bomb detonates the moon is just not supported by scientific principles. “The Wandering Earth II” falls short of Interstellar's obsessive pursuit of cinematic scientific rigor.

Film is not a stand-alone art which can be created in a vacuum. Directors must have deep and rigorous thinking in various disciplines, such as philosophy, psychology, musicality, and countless others.

In order to develop mood and characters properly, directors must be able to imagine and replicate complex emotions as well as elicit the emotions of the viewers. Interstellar is a complete success in this regard. It is Cooper’s desire to protect his children and their future that drives him to embark on this deathly adventure. Coop's mission, for all its persistence, is a love affair. The beacon of his voyage, the end of his journey, is always where his daughter is. From a psychological point of view, since most have experienced love and being loved, it’s more convincing and empathic to "save the world" with love. But the director of the “Wandering Earth II” isn’t thinking about this point properly. For example, in a clip that someone needed to sacrifice, Zhang Peng, played by Sha Yi, demands "All Chinese space flight squadrons, those over fifty years old, step out!" This scene have ethical problem partly. From a philosophical point of
view, the value of life should not be judged according to age. And choosing death over life is an intimately personal matter. So this scene is an attempt to force the film to a higher level but it isn’t successful.

The ultimate audio-visual experience is also one of the most important factors in determining whether a film can become a top science fiction film. Interstellar, in my opinion, is a film that takes the audio-visual language to the extreme. For example, in Interstellar's theme song Cornfield Chase, Hans Zimmer uses a combination of orchestral music and synthesizer to show the vastness of the universe, and also used a very unique pipe organ to express Cooper's all-embracing love for his children. The use of these unique instruments and the composition by Hans Zimmer make this piece both large and moving. Nolan also uses music as an important medium to promote the development of the plot and drives the audience's emotions. For example, the soundtrack "Mountains" is used when Coop and Brand arrive at Miller Planet. As an hour on the planet equals seven years on Earth, in this score, Zimmer fosters a ticking that represents the passage of time. The ticking occurs every 1.25 seconds, and each tick equals a day on Earth, which creates a sense of compactness in time. As Brand begins to look for the wreckage, the music changes; When Cooper realizes the ship is facing a huge wave instead of a mountain, the music gradually intensifies, with more and more heavy notes, making us feel as if we are in front of the huge wave. The music here is one of the main reasons why this moment is the climax of the film.

In "The Wandering Earth II", although the composer uses a combination of orchestra and electronic music to create the sense of vastness of the universe, in the soundtrack "Space Elevator", some upward minor scales are used to describe the process of acceleration of the space elevator, which is quite shocking. However, most of the score in this film lacks the integration of story and emotion, “The Wandering Earth II's” director and composer's ability to tell a story with music still falls short of Nolan's and Hans'.

The culmination of emotion and imagination developed so carefully during the production of sci-fi films can be incredibly cathartic. A great film of this genre can lead us beyond history, beyond regions, even beyond all cultural constraints, to meet unfamiliar and familiar people, and to see unprecedented things. “Interstellar” can invariably be considered one of the best sci-fi films of all time as it weaves the vastness of the universe, the smallness of individuals, and the love that traverses everything into a magnificent epic of time and space in the form of a story. It reminds us that in the hopeless and lonely corner of a vast star, only love can transcend time and space.