Cinema Peer Review: ‘Sunshine’

In Danny Boyle’s 2007 outer space thriller Sunshine, a group of scientists are trying to save our dying sun in the year 2057 with a seemingly counterintuitive method: sending a bomb into its core. As the sun’s weakened rays have turned the Earth into an icebox, their mission is to deliver a “payload” of their planet’s last remaining nuclear energy to bring the—ahem—sunshine back to its former glory.

One small problem with the central plot of the movie is that the sun isn’t scheduled to go out for another 5 billion years. But Boyle had the help of a science consultant, CERN physicist Brian Cox, to dream up a scientifically feasible scenario to propel our heroes sunward. Cox suggested the idea of a Q-ball, a compact, dense collection of supersymmetric matter drifting around the universe. According to Cox’s commentary on the film, “if [a Q-ball] sat still in the heart of a neutron star, it could… eat the star from the inside out.” Cox contends that we “would need a bomb if something drifted in there” to “restore fusion actions to [their] former glory.”

Supersymmetry and Q-balls are thus far only theoretical, although Cox asserts that he and the physicists at CERN will prove or disprove their existence by 2017. However, as Anthony Kaufman writes in his review on the Sloan Science and Film blog our sun wouldn’t be dense enough to hold a Q-ball; it would “fly right through the sun.” Leading Q-ball researcher UCLA physicist Alexander Kusenko notes that a much denser neutron star would be more likely to capture one.

Even if our sun did capture a Q-ball, scientists say that would actually increase the intensity of the sun’s radiation, contrary to the film. Rather than Australia becoming a frozen tundra, “[we] would be fried,” according to Kusenko.

And then, when our heroes set off a stellar bomb successfully in the heart of the sun, it would take much longer than the eight and a half minutes (the length of time light takes from the sun to the Earth) shown in the film for Earth to see the effects. According to Colin Johnston in his paper on the “Science of Sunshine,” the time it takes photons to get from the core of the Sun to its surface could take up to 40,000 years. This is because the photons have to travel about twice the distance from the Earth to the Moon to cover that distance from core to surface, and they don’t really travel in straight lines. A photon’s path is more commonly described as a “random walk”; it travels a short distance, runs into a hydrogen nucleus, then is shot out of that nucleus at random. It’s just as likely to be sent backward as forward! So all in all, affecting the core of the sun is not the best plan to avert the looming apocalypse. Also this is all mostly moot because the Q-ball explanation never actually makes it into the movie, just the commentary tracks.

Other details of the film vary in terms of plausibility. The gold shields on the Icarus II spaceship and the characters’ spacesuits would work well to protect against the sun’s rays, because gold is a “perfect radiator.” But we are far from attaining the technology that would allow us to get as close to the sun as the cinematic ships.

There’s also one scene where two characters try to propel through space from the Icarus I to the Icarus II without spacesuits. While the pair could potentially survive in space for about 30 seconds with only scraps of insulation for protection, contrary to what the engineer Mace (Chris Evans) yells before the airlock opens, they should not have held their breath when entering space in order to survive. In the extremely low pressure of the vacuum of space, the air trapped in a person’s lungs would expand and shred their organs, as well as force air bubbles into the bloodstream that would make quick work of the ill-fated astronaut. It’s for this same reason that deep-sea scuba divers do not hold their breath when they ascend from the depths of the ocean.

At one point in the film, the Icarus II makes it close enough to Mercury to watch the planet cross the Sun in real time. But in reality, according to Cox’s commentary, it would take a lot of “slingshotting” around other planets to get into Mercury’s orbit or even that close to it, because of how small the planet is. Those kinds of maneuvers would usually take anywhere from five to seven years. And getting to the sun is no easy feat:  any ship launched to the Sun will “share the Earth’s orbital velocity around the Sun (about 30 km/s),” Johnston notes, so to pull any ship sunward, that speed needs to be cancelled out, which no existing rocket booster can do.

The basic premise of the film is ridiculous, and the complicated scientific hoops to save it go largely unexplained anyway. But the diversity of the crew is refreshing in a science fiction story, and the twists and turns are compelling (if confusing). The movie takes its absurd premise and uses it to address the philosophical problem of what happens when people stare at the sun for too long. But on the scientific front, Sunshine doesn’t hold a candle to the truth.

Rating: 1 out of 5 healthy Suns (or 4 dying ones).