Hope for the best, don’t expect the worst. It’s my movie criticism mantra, but as the lights darkened at the Princess of Wales Theater for “Gravity’s” Canadian gala, already hailed as a masterpiece following a Venice Film Festival Premiere, it wasn’t just the fact that I was way up in the rafters wearing 3-D glasses over my already thick specs that was making me queasy. Early on, watching the oh, wow, visuals and the echoey emptiness of what it must be like to be doing routine maintenance in space (I so wanted “Pink Floyd”), I became bothered by narrative claustrophobia. Can one smell bullshit in space?

Despite all the gravity of Alfonso Cuaron’s 3-D space chamber opera, the story, co-written with his son, Jonas, reveals holes as gaping as those on any space station station ripped by the debris of an accidental explosion beyond the earth’s atmosphere.

In brief: Sandra Bullock plays Dr. Ryan Stone, a testy medical engineer pursuing research in space. George Clooney is Matt Kowalksy, the cheery professional astronaut on, yes, his last run. When space junk from a Russian mishap destroys their mission, their Harvard-educated brown-skinned colleague, their satellite, their station, and that of the Russians and, possibly, the Chinese, the pair struggle for survival, often tethered by a white umbilical cord.

The problem begins, but doesn’t entirely end, with Bullock’s character. She is nervous and brittle: but who isn’t? Okay, Clooney’s Galahad in a spacesuit isn’t. He wisecracks and story-tells and Cloonies to give “Gravity” its much-needed warmth and comic relief.

Dr. Stone (sinking like a ….) is just not a woman (or even a man) that could have passed the rigorous training process that NASA inflicts on its candidates. I don’t know the statistics, but even among the thousands or tens of thousands that want to become an astronaut (include me not!), less than one hundred achieve that vaunted status. Life is hard, becoming an astronaut nearly impossible.

When we first encounter Stone and Kowalsky while she repairs some failure like a nearly hired tech from the Geek Squad and he marks time, their dialog speaks of people who hardly know each other, not members of a small elite team that have trained, lived, flown and, likely, vomited together. They could be on a bus, polite strangers, two people at a wedding, one on the bride’s side, one on the groom’s.

Disaster, inevitably, strikes. Dr. Stone freaks out, spinning, spinning, spinning, hyperventilating and banging against satellite and space station and colleague corpse. Like a tumbled stone, she gradually reveals the tragic nugget of her neurosis. All anybody who knows NASA can say is “next candidate, please!” She would never have made the cut. So her arc from a professional woman emotionally untethered from her own life, that ultimately fights to survive and get her feet back on the ground, is baloney. Or space baloney, on sale at the Smithsonian National Air and Space Museum in shiny packages.

The set-up resembles “Open Water” in space. The nifty little seventy-nine-minute 2004 thriller written and directed by Chris Kentis about a cute scuba-diving couple accidentally left behind by the tour boat in shark-infested waters. Adrift, the pair go from hoping for rescue, to fending off sharks, hypothermia and exhaustion, all the while treading spiritual and emotional water.

Yes, it’s a trick, a movie incredibly intense because we are in the water with this man and woman as they struggle to survive, and every strength and weakness of their romantic bond, and personal character, reveals itself as they swim in the ocean’s fatal flush. They should be back at the harbor drinking Mojitos. They’re not. They never will be.

At the Princess of Wales screening, Canadian Astronaut Chris Hadfield attended and tweeted the next day: “Good morning! Gravity was fun last night. Fantastic visuals, relentless, Sandra Bullock was great. I’d fly with her.” Well, who wouldn’t fly with Bullock? She’s such a good sport. But, really, never in a million missions would Commander Hadfield place his life, or that of his crew, in her incapable hands.

I respect Hadfield’s gallantry, and “fantastic visuals” rings true. The visuals are fantastic. It’s also a safe reaction to another Hollywood fairy tale that fails to understand the incredible craft and skill of having “The Right Stuff.” However finely wrought, however mind-blowing the seventeen-minute takes, the revolution in 3-D technology, the movie misunderstands the incredible craft, physical stamina and mental acuity of those who go into space.

That’s not to say astronaut’s can’t and don’t crack. But when they do, they break in a control-freak, OCD way. Take the astronaut-turned-stalker Naval Captain Lisa Nowak. She flew on the Space Shuttle Discovery in 2006. The following year, she was arrested in Orlando for attempted kidnapping after pursuing a romantic rival from Texas to Florida, allegedly wearing disposable diapers so that she would not have to stop during the 900-mile car trip. Maybe you’ve seen the “Rocket Man” episode of TV’s “Law & Order: Criminal Intent.”

Nowak might have been a crazy stalker, but she had wanted to become an astronaut since she was six. And she massively trained for her opportunity to leave earth’s gravity in a souped-up tin can, logging 1,500-plus hours on thirty different aircraft, and multiple spacewalks during her 13 days on the shuttle. But the brittle but buff Dr. Ryan, with her panicky refrain that she repeatedly crashed her simulated escape pod during training, would never have made it out of the parking lot and onto the flight deck.