Olivia says it's ridiculous, and even if it were possible, manipulating a light is nothing compared to manipulating the machine. Walter concedes the point. So she'll need to practice! She needs to find a teacher on the planet of Dagobah... Actually, Walter hauls out the typewriter that Fauxlivia used to use to communicate with the other side, and it's quantum entangled with the one over there, so it's perfect for testing her abilities.
He rolls a sheet of paper into the typewriter, and tells Olivia to clear her mind and to look into the mirror he has set up. "Imagine that you're looking at the typewriter on the other side. Now, press those keys using your mind."
She tries for like TWO SECONDS and nothing happens so she's ready to call it quits. Walter tells her it's like meditating, and she should focus on something specific, like a word or a phrase. She gives it another whirl, and stares intently into the mirror.
Meanwhile -- did it really take all this time? What kind of crappy-ass hospital was Peter staying in anyway? -- a nurse strolls into Peter's room, and is surprised not to find him there. She finds the envelope on which he's written "I AM GOING HOME" and she quickly grabs the phone.