I think if there’s one thing that true fans of science fiction might all agree on, it’s that we long for another world. I don’t mean an “if only things were different” other world, but a literal another world — another planet to visit, another ground to walk on, another gravity to experience, another sky to see. And that is what James Cameron has given us in Avatar.

This movie is a gift to anyone who takes science fiction seriously. I really do feel as if I’ve visited the planet Pandora, and I didn’t even see the movie in IMAX — just in regular ol’ 3D. (I hope to remedy that next weekend.) And I must say that it was a little bit of a letdown to come to the end of the movie and take off my 3-D glasses and discover that I was still on Earth. Simply put: Avatar is the closest I will ever come to visiting another planet, and it was an exhilarating trip. Really.

I’ve been wondering whether any movie could possibly justify the eight gazillion dollars rumored to have been lavished on Avatar, but damn if every single penny isn’t up there on the screen. And I don’t mean just the visual effects, though they are beyond stunning. This is a real world, so fully realized that surely geologists and biologists and cognitive scientists and other conceptual specialists had to have been onboard.

The many creatures who populate this lush world clearly evolved together and fill their ecological niches beautifully. The mind-blowing physical aspects of the planet — the impossibly tall trees (impossible to our Earth-attuned eyes, at least), the gravitational anomalies — are the result of the solidly realistic facts of Pandora: its gravity is lower than ours; it orbits in the shadow of a massive gas giant (which would make things gravitationally and magnetically different).

That might sound like unnecessary detail to have been heaped on, but even to minds of nonscientific bent, it lends it all a plausibility that, you’d think, couldn’t be faked. Our brains just know when things feel right, even if we don’t always understand why we feel that way. Pandora feels real.

It’s all so awesome — as in the old-fashioned sense of the word: inspiring awe — that I, at least, found it easy to forgive the fact that the story, also by Cameron, takes few risks: it’s a straightforward narrative the likes of which we’ve seen many times before, though it is pulled off extremely well, with just a few moments that are cheesy or obvious. It’s Dances With Wolves, basically — and I don’t mean that as an insult.

Jake Sully (Sam Worthington) is the soldier who goes native on Pandora, a Marine who’s been paralyzed from the waist down and subsequently given the opportunity to take over a job his identical twin brother, a scientist, started, and cannot finish because of his untimely death: Inhabit a body, an avatar, cloned from the DNA of both humans and the natives, the Na’vi, and go amongst the Na’vi and learn from them. The avatar bodies are keyed to particular researchers, so Jake is the only one who can fill in for his brother.

We humans are on Pandora for all the reasons we’ve ever gone anywhere, it seems: to take what we want from this place in spite of what the people who are already there have to say about that. I wish that weren’t so tediously familiar, but it’s hard to imagine, unfortunately, a human future that doesn’t unfold along these lines. So, if there’s a Na’vi village atop a gigantic cache of “unobtainium” the humans are keen to get their hands on, well, the natives — “savages” and “blue monkeys” as the mining company twerp (Giovanni Ribisi) in charge likes to call them — will have to go.

Once transformed, Jake exuberantly enjoys the freedom of his new Na’vi body — he’s 11 feet tall, blue-skinned, and surprisingly athletic. While on Pandora, he learns about life among the Na’vi from a sort of warrior princess, Neytiri (Zoe Saldana), who initially views him as an ignorant child.

The scientists on the planet, led by Dr. Grace Augustine (Sigourney Weaver), are initially skeptical of Jake, since he hasn’t been trained in using the avatar or in the Na’vi culture. Meanwhile, the military protecting the mining colony, led by Col. Miles Quaritch (Stephen Lang), assume that Jake, one of their own, will work as a double agent, gathering the intelligence that the humans need in order to undermine the natives, which Jake readily agrees to.

The Na’vi are entirely sympathetic — Cameron created them via motion-capture-assisted CGI, with human actors supplying the performances — and they are as completely realistic as their environment. Cameron has solved the problems that have rendered previous CGI characters dead-eyed and unwatchable.

Not that the Na’vi are perfect or their world a paradise; Pandora may be beautiful, but it is rife with dangers. It’s just that they’re different, and different in ways that humans cannot even begin to conceive of until we — through Jake — become part of them.