The massive space station Elysium, home to the wealthy and powerful, orbits a devastated Earth. Sony Pictures

Packed to the rafters with action and allegory, the science fiction thriller "Elysium" is set in a dystopian future society where pollution and overpopulation have rendered the planet almost inhabitable. Almost. The lower classes still knock about in slum cities, policed by menacing robots. Those who aren't starving to death labor in factories to provide goods for the wealthy One Percenters, who live in luxury on a giant orbital space station called Elysium.

Matt Damon headlines as Max, a reformed criminal and factory worker among the suffering masses on Earth, circa 2154. When a workplace incident goes awry, Max must make his way up to Elysium to save himself and -- no pressure -- the future of the human race.

In its quieter moments, "Elysium" proves to be a smart and observant film, and it does what all good science fiction tends to do: The film examines contemporary issues -- social, ecological, technological -- and extrapolates them out to the event horizon of the Future. We take a look at the science behind the science fiction. (Warning: Several plot spoilers dead ahead.)

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"Elysium" portrays a terminally crowded Earth in 2154.Sony Pictures

In the opening sequences of "Elysium," Earth has been ravaged by pollution and overpopulation. The city of Los Angeles in 2154 is a giant shanty town, with millions of desperate citizens vying for limited resources.

According to the numbers in a recent study by the United Nations, world population from 2000 to 2050 in expected to grow by 47 percent -- from 6.1 billion to 8.9 billion. Projections past that get a little dicey, but one number-crunching scenario from the same study produces -- and we quote -- "an almost unimaginable world population of 134 trillion by 2300."

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To escape the lethal overcrowding on Earth, the world's wealthiest citizens construct the massive space station known as Elysium, taking the name from the heavenly afterworld of Greek mythology. Elysium citizens enjoy a utopian existence while denying the Earth-bound access to their superior technology.

The orbital structure in "Elysium" is a rotating torus-style station, which uses centrifugal force to produce artificial gravity, keeping the residents (and the atmosphere) from flying off into space. The design is based in part on the Stanford Torus model, developed by NASA in the 1970s, with its use of a ring-and-spokes system, and mirrors to redirect sunlight.

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The director of "Elysium," South African filmmaker Neill Blomkamp, also directed the very fine 2009 sci-fi film District 9, an allegory on the apartheid system. In that film, futuristic rifles are used to essentially detonate victims from long range. Blomkamp provides similarly gory sequences in Elysium, by way of Max's advanced railgun weapon.

Railguns work by using magnets, as opposed to internal explosions, to accelerate projectiles up to speeds of Mach 7. The railgun has been around for a while as an experimental technology, but for now they're too big and require too much energy to make a practical field weapon. The U.S. Navy recently test fired a prototype railgun and announced that military contractor Raytheon had been awarded a contract to develop the technology.

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Max gets a cybernetic tune-up from the slum's resident surgeon. Yes, he's the surgeon.Sony Pictures

Although it's more suggested than explicitly shown in the film, Max and his enemies employ a cybernetic system that lets them plug weapons directly into their brains and bodies. The film's villain Kruger, played by Sharlto Copley, has multiple implants on his arm and face that serve as ports for his weapons. Max, meanwhile, gets a rather invasive neural implant at the base of his skull that allows him to control his exoskeleton and weaponry.

Cybernetic weapons have been a staple in science fiction for decades. Several systems are already in use by the military, depending on how you define your terms in regard to man-machine interface. Helmet-mounted display (HMD) technology, for instance, augments eyesight for pilots and soldiers. But as of now, dermal bio-weapon ports are squarely on the fiction end of science fiction.

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Max is desperate to reach a "Med Bay" pod, which cures all illness but is restricted to the wealthy.Sony Pictures

In the world of "Elysium," medical nanotechnology has progressed to the point where wealthy citizens each have their own "med bay" in the home. Fully automated, the device looks like a full-body MRI scanner, but it can diagnose and heal all injuries and disease -- making the residents of Elysium virtually immortal.

In the real world, medical nanotechnology is a growing field of study, with billions of dollars in public and private funding over the last decade. No surprise, since nanotechnology has potential application in virtually every field of medicine. The medical miracles depicted in the film -- one character has his face literally rebuilt -- suggest a hyper-advanced form of molecular nanotechnology, in which tissue is repaired or replaced at the atomic level.

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In one of the film's more terrifying story threads, humanoid robots called Droids police Earth's cities, bullying citizens and even hiring themselves out as private security for visiting executives from Elysium. The robots are familiar enough -- we've seen variations on this template from Asimov to Star Wars -- but they're unnervingly realistic. The spectacular CGI work gives "Elysium's" robots a sense of weight and mass. They're agile, but not too agile. They move in the way you might expect humanoid robots to move in a near-future setting.

In fact, they look worryingly similar to the recently unveiled ATLAS robot from the U.S. Defense Advanced Research Projects Agency (DARPA). The 6-foot-tall, 330-pound robot sports hydraulic joints for carrying heavy objects, and a laser-based navigation system. Check out the very unsettling video below.

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An renegade orbital shuttle from Earth makes a run at the space station Elysium.Sony Pictures

In yet another of the film's allegorical story threads -- director Blomkamp is big on allegory -- Earth-bound citizens regularly try to "cross the border" into Elysium by packing orbital shuttles full of refugees, then making a run for the space station. In one scene, a character says the journey takes about 19 minutes from launch to (crash) landing within the inner torus surface.

The vehicles in the film are a cross between reusable orbital spacecraft like NASA's Space Shuttle, and vertical take-off and landing (VTOL) aircraft such as the Harrier Jump Jet. As for getting to an orbiting space station in 19 minutes? Maybe, but it's all about timing. It would take a little over eight minutes for a shuttle to get to low earth orbit. But it usually takes days to sync up orbit with the International Space Station.