I’m on Industrial Light & Magic’s motion capture stage, standing inside what they call “the cave.” It’s not much to look at: two big screens angled at 90 degrees, awash in a smeary blur of images. But put on a pair of modified 3D glasses, and bam — it’s the Holodeck, and I’m on Tatooine standing face to face with one of the most famous robots in movie history. I walk around C-3PO, crouching one moment then jumping the next. The mo-cap performer across the room raises his hand, and the CG Threepio waves. It’s exhilarating and immersive, and it’s all happening in real time.