“Think of space-time as the skin of this apple. You currently are here.” He placed his finger on the right side of the apple. “You wish to go here.” He placed his finger on the left side of the apple. “In order to get there, you would have to travel a considerable distance.” He traced his finger from left side of the apple, over the top and to the other side. “Imagine if you had the ability to cross through the apple.” He turned the apple ninety degrees and Joe saw a tunnel now passing through it. “This is a wormhole. It will allow you to get to the other side of the apple in far less time than it would have taken for you to pass along its skin.”
Wiki says: “If a worm is travelling over the skin of an apple, then the worm could take a shortcut to the opposite side of the apple’s skin by burrowing through its center, rather than travelling the entire distance around, just as a wormhole traveler could take a shortcut to the opposite side of the universe through a topologically nontrivial tunnel.”
However, my roommate says that how they work is that you change space-time itself and bring them together so that the entrance of the apple is right next to the exit and the worm passes through nearly instantaneously.
I don’t know ANYTHING about this kind of stuff, but I think I’ve heard basically what your roommate heard. Imagine the apple squeezing/twisting/stretching/turning so that point A and point B are touching and as soon as the worm breaks the skin, he’s already coming out the other side. But like I said, I really don’t know anything about that kind of stuff.
I wondered the same thing when I read about them as a kid. If you cut through a sphere, you would only be making your trip somewhat shorter. To really do something impressive, I would think you’d have to fold the entire universe in half. That seems like a tall order.
Here’s a diagram of how a wormhole is supposed to work.
It’s a 2D representation of what would actually be in 3 dimensions. But say you wanted to go to the moon. Rather that building a rocket and travel along good, ol fashion, spacetime, why not bend or fold the fabric of space (as seen in the diagram), then punch a hole, so you can get around the conventional “long way”.
I’ve over simplified, because that’s all I really know about the idea. From what I know it’s theoretically possible, but the engineering, energy, understanding (let alone navigating such a thing) is absurdly out of any practical reach… even in the foreseeable future, I wouldn’t bother holding your breath.
I’m sure I’ve made some major assumptions, and hopefully someone like Stranger, Ring, Chronos or another physicist will be along shortly…
It’s both, but your roommate is closer. What you’re missing is that in the apple analogy, the surface of the apple is embedded within a space of more dimensions. In other words, we visualize the two-dimensional surface of the apple floating within a three-dimensional canvas.
Imagine instead that the 2-D surface of the apple is the the only space where something can exist. It’s a funny thing to think about, because normally apples have readily accessible interiors, but not this time. So there isn’t already a pathway directly through the apple, because the “inside” isn’t an allowable position. Instead, you have to warp and distort the surface until two points on opposite sides connect. Then and only then is there actually a route to travel, and it would indeed be much shorter than traveling along the undisturbed surface.
More or less, except that there’s no difference whatsoever between the Universe being folded in half, and it not being folded in half. So if you had some way to do the cutting and re-attachment, you could do it just as well without first folding the Universe.
Note, of course, that nobody’s figured out any way to do the cutting and re-attaching, nor any way to cause it to stay re-attached. Theoretical work has been done on the subject, but it all just ends up replacing one impossibly difficult task with a different impossibly difficult task, like procurring matter with a negative energy density.
