Inception, Fact and Fiction

Inception is a 2010 science fiction film written, co-produced, and directed by Christopher Nolan. He explored "the idea of people sharing a dream space...That gives you the ability to access somebody's unconscious mind. What would that be used and abused for?"

So let's get some scientific principles first,

Lucid Dreaming is a dream in which one is aware that he is dreaming. often when one is asleep, there is something in consciousness which declares that what then presents itself is but a dream. 

In a lucid dream, the dreamer has greater chances to exert some degree of control over their participation within the dream or be able to manipulate their imaginary experiences in the dream environment.

Australian psychologist Milan Colic has explored the application of principles from narrative therapy (is a form of psychotherapy using narrative) with clients' lucid dreams, to reduce the impact not only of nightmares during sleep, but also depression, self-mutilation, and other problems in waking life. Colic found that clients preferred direction for their lives, as identified during therapeutic conversations, could lessen the distressing content of dreams, while understandings about life—and even characters—from lucid dreams could be invoked in "real" life with marked therapeutic benefits.

In 1985, Stephen LaBerge performed a pilot study which showed that time perception while counting during a lucid dream is about the same as during waking life. Lucid dreamers counted out ten seconds while dreaming, signaling the start and the end of the count with a pre-arranged eye signal measured with electrooculogram recording. A German study, by D. Erlacher and M. Schredl, also studied motor activity and found deep knee bends took 44% longer to perform while lucid dreaming. However, a 1995 study in Germany indicated that lucid dreams can have varied time spans, in which the dreamer can control the length. The study took place during sleep and upon awakening. They required the participants to record their dreams in a log and record how long the dreams lasted.

While dream control and dream awareness are correlated, neither requires the other—LaBerge has found dreams that exhibit one clearly without the capacity for the other; also, in some dreams where the dreamer is lucid and aware they could exercise control, they choose simply to observe. 

In 1992, a study by Deirdre Barrett examined whether lucid dreams contained four "corollaries" of lucidity:  

1. knowing that one dreams, 
2. that objects will disappear after waking, 
3. that physical laws need not apply, 
4. and having clear memory of the waking world, 

and found less than a quarter of lucidity accounts exhibited all four. 

A related and reciprocal category of dreams that are lucid in terms of some of these four corollaries, but miss the realization that "I'm dreaming," were also reported. 

Scores on these corollaries and correctly identifying the experience as a dream increased with lucidity experience. 

In a later study in Barrett's book, The Committee of Sleep, she describes how some experienced lucid dreamers have learned to remember specific practical goals such as artists looking for inspiration seeking a show of their own work once they become lucid or computer programmers looking for a screen with their desired code. However, most of these dreamers had many experiences of failing to recall waking objectives before gaining this level of control.

Now let's back to the movie,

In the not-too-distant future, technology has been developed that allows multiple individuals to experience the same dream. While the underlying structure of the dream is controlled by one person (the Architect), other people populate the dream with manifestations of their subconscious, or Projections. And Tom Cobb (the main character) knows exactly how to exploit this system. He is a mercenary thief of ideas, a corporate espionage agent who specializes in invading dreams and extracting vital information. However, his greatest challenge is to perform the opposite task. He must infiltrate another person’s mind and plant an idea there. Business tycoon Saito wants to break up an energy empire, in the interests of promoting competition. He hires Cobb to insert an idea (the concept of dissolving the conglomerate) into the mind of young Robert Fischer, the incoming owner. This, unfortunately, is more difficult than it would appear – in order for the idea to take hold, it must appear to have come via inspiration, not suggestion. Cobb and his team promptly set to work devising their reverse-heist operation, with some help from Ariadne a remarkably skilled dream Architect. Their plan – to lure Fischer further and further into a web of nested dreamscapes, while subtly planting the germ of an idea. But unfortunately, Cobb is struggling with his own inner demons. Torn by guilt over the loss of his wife Mal, he produces subconscious images of her in the dreamscape, leading to disastrous effects.

Deirdre Barrett, said that Nolan did not get every detail accurate regarding dreams, but their illogical, rambling, disjointed plots would not make for a great thriller anyway. However, "he did get many aspects right," she said, citing the scene in which a sleeping Cobb is shoved into a full bath, and in the dream world water gushes into the windows of the building, waking him up. "That's very much how real stimuli get incorporated, and you very often wake up right after that intrusion".

Nolan himself said, "I tried to work that idea of manipulation and management of a conscious dream being a skill that these people have. Really the script is based on those common, very basic experiences and concepts, and where can those take you? And the only outlandish idea that the film presents, really, is the existence of a technology that allows you to enter and share the same dream as someone else."

The idea of the movie is very genius and creative, but most of the story still just fiction.