Dream Sharing
How does it work? Cobb asks Ariadne this exact question. Set during the movie in preparation for the Fischer job.
"Professor Miles was right… you really are one of his best and brightest." Cobb said, intently watching Ariadne as she continued manipulating various features of the dream world. "Brighter than I was, anyway. I'm surprised…"
"Surprised about what?" Ariadne asked half-heartedly, her attention focused on constructing a nearby building of gothic origin.
"You haven't asked the conceptual question." He said, pulling a card from his pocket. "'How are we both dreaming the same dream?' I remember when I first went into the dream world, that was the first question on my mind."
"Really?" Ariadne shot him a quirky look. "How long ago was that?"
Cobb smirked. "Decades."
"Well, I'll be honest. I have been wondering about it, but I figured you would tell me eventually." Ariadne explained. "You are going to tell me, right?"
"You're right about one thing. You'll get the answer. Eventually." He handed her the card. "Recognize this?"
"Yeah, it's a picture of the warehouse we were just in…" she said. Cobb shook his head.
"It's a picture of the warehouse we are currently in. Except... something's missing."
Ariadne stared at the photo. The photograph indeed looked identical to the warehouse they were previously (and technically, still) in. The chairs were lined up the same way. She assumed the sleeping figure in one of the chairs was her, due to the red sweatshirt dangling off the seat, and Cobb was sleeping in the chair right next to her.
Something was missing? She honestly couldn't tell. Why he was making such a big deal of it.
"C'mon Ariadne. Remember."
Ariadne blinked. For some strange reason, his words were carrying an extreme amount of weight. She must have had to remember something important. But she didn't know what it was. What was she supposed to remember?
"It's hard, isn't it? Remembering things between the dream world and real life?" Cobb smiled. "It's easy to remember the dream the instant you've woken up, but you'll slowly forget it as time goes on. Dreams work the same way. Spend too much time in them, and you'll forget about what happened when you fell asleep."
"… and as the architect, I'm supposed to remember all details all the time?"
"Exactly." Cobb nodded. "I need you to be able design while your awake and build while you're dreaming. This is actually another test but unlike the previous one, it's designed to sharpen your memory."
Ariadne shot him a quizzical look. "What's there to remember, how we got in the warehouse?"
"No, that's not it." Cobb said. She may have been sharp, but she was a little hasty. "We've been under three times in the last hour. Each time, I've asked you to remember something about the warehouse, something that you were supposed to carry into the dream. That something is missing from the photograph."
Ariadne pinched the bridge of her nose and let out a frustrated sigh. "I'm not doing so hot, am I?"
"Not really." Cobb chuckled.
"What was it that I was supposed to remember then?" Ariadne asked, eyes returning back to the picture.
"This time, it was the briefcase." Cobb said. Sure enough, the picture was lacking a briefcase. "The dream sharing machine with all of the tubes…"
Ariadne nodded. "I remember now."
"You know, a good way to remember details like that is to associate something important with it." Cobb said. "If I told you the genesis of the dream sharing machine now, you'd probably remember it the next time we went under."
Ariadne frowned. "I thought you said you weren't going to tell me. Not yet anyway."
"'Yet' being the key word." Cobb said. "How do you think the process of dream sharing works?"
Ariadne paused. If she had to guess, the briefcase had some key factor behind it. It administers a sort of sedative, but that wouldn't explain the sharing part of the dream-sharing.
"The wires…" She started. "Tubes… they connect everyone somehow."
Cobb gave her an intrigued look. "Go on."
"People connected to the machine are fed some sort of electrical impulse by the tubes. Something small enough to be received by the brain, but not enough to wake up…" she theorized. "The briefcase has some sort of monitoring equipment to deliver the same electric signals to everyone connected by the tubes so they all experience the same thing."
Cobb smiled. She was incredibly bright. A little eccentric though.
"So I take it I was right?"
"Yes and no." Cobb answered. "You're right, there is a monitoring machine that sends everyone connected to the briefcase the same signals. But sending electrical impulses is a little too… science fiction. Also, the tubes are nothing more than an IV, carrying the sedative to keep you under."
"Then how-?"
"Try again. Think about sleeping, the technical parts of it." Cobb suggested.
Ariadne paused, this time for a little longer.
Sleep is categorized in five stages; stages 1-4 and REM sleep. Stages 2 and 4 are characterized by excessive brain activity which shows up on EEG recordings. REM is the stage in which dreaming actually occurs.
"The machine…" she stopped.
"I suppose saying that it works like magic isn't a good enough answer?" she asked jokingly. Cobb shook his head.
"Alright, well... you said that the brain is capable of using a higher percentage of itself while asleep. That means that the brain is always active, even through sleep. The parts that are usually turned off while we're awake must be sensitive to receiving stimuli." Ariadne proposed, determinedly. "The machine in the briefcase emits wave-like signals to everyone when they're in various stages of sleep. The machine converts actions done inside the dreams into signals and then sends those signals to everyone connected, like a radio will do with walkie-talkies on the same frequency."
"That's good. Very good. But you mentioned stages of sleep. Dreaming can only occur in the REM sleep stage." Cobb interjected. "The time period in which people change to a different sleep stage also varies per person."
"Yes, but REM sleep is a naturally occurring process." She defended, her voice rising. "Because the briefcase is delivering a sedative, it makes the brain chemistry stay in a perpetual REM stage of sleep. At least until the body filters it or the dream-sharing machine stops feeding the sedative. Since it's a synthetic form of sleep, everyone's brains are synced up with the chemicals in the sedative."
Cobb smiled. He made a mental note to thank Miles later.
"Well Ariadne, I'm impressed. You managed to pick up on all of my hints and you've come up with a more-than-reasonable explanation."
The petite girl did a double take. "… wait, I was right?"
"More or less. There are one or two things in your explanation that aren't quite there, but you've gotten the gist of it." Cobb said. "Now, here's the tricky part. In a couple of minutes, we're going to wake up. To pass this test, you have to repeat to me what you said just now about the dream-sharing process."
"Well I-…"
Ariadne was brighter than he ever was. But her stubbornness and determination were too inconsistent. They needed a little work.
"You can remember things easier between the dream world and real world by associating experiences with them. This is one of those experiences."
"I-…" she sighed. "I'll try."
"Try?" Cobb shook his head disappointedly. "I need better than that."
end