I stumbled upon an article a few months ago that I've been meaning to blog for a while and never got around to.
The original article is by Chris van den Broeck, and deals with the subject of warp drives.
Yes, warp drives. The Alcubierre warp drive engine is a device that stretches the spacetime around a spaceship, forming what is known in scientific literature as the "warp bubble" (really, that's what we call it). Within the warp bubble, the ship is moving at "normal speeds", but outside of the bubble, the ship is moving faster than the speed of light. The geometry for this is known and well understood, and the means of producing it are also fully understood.
You're probably wondering, if we know how to make a warp drive, why we haven't actually... you know... made a warp drive. And that's a wonderful question. We haven't made a warp drive because it requires a lot of stuff that probably doesn't exist, namely negative energy mass. It requires a whole lot of it. Like, ten times the positive mass of the entire universe in negative mass.
Van den Broeck proposed an idea to get around this, one elegant in both its simplicity and apparent absurdity.
Here's what you do: Take a bag. Distort space, so that the inside of the bag is bigger than the outside of the bag. The inside is big enough to hold a spaceship, and the outside if around the Planck length. Now stick your spaceship inside of the bag, and then put a warp bubble around the bag. It requires a lot less negative energy. Voila! Crisis averted.
|Schematic from original article.|
Region II is the bag.
Region I is where the ship is.
Region IV is the warp bubble
We've gone from warp drives to the bag of holding, and we're not even done yet. We're going all the way to Narnia.