## Monday, June 11, 2012

### Creating Wormholes - Getting Closer

Point. Line. Plane. Repeat. That's the point-line-plane postulate, the accepted methodology for visualizing any number of spatial dimensions.

Line. Branch. Fold. Repeat. That's the logic my project uses, and it really is the same idea, particularly in the way that you can start at any arbitrary dimension with any step in this three-step process, and continue on up from there.

But one of the sticking points for my project is this commonly asked question: how do you fold a dimension?

And the answer I usually give is to point people to the wikipedia article on wormholes, and the accompanying picture shown here which depicts a dimension being folded over on itself to create an instantaneous connection between two points that would ordinarily be widely separated. In my 2008 blog entry on the subject of wormholes I proposed that wormholes passing through one dimension or another would have different effects, based upon the logic of how one dimension's degree of freedom is different from another's based upon the logic of my approach to visualizing the dimensions. As you'll see in the article below, some wormholes have been proposed that would take us instantaneously to other universes with different basic physical laws, while others would allow us to jump to other points in the space or the space-time of our own universe.

Still, there are people who remain unconvinced. "Wormholes are science fiction", they say, "not something that can actually be done". And to the extent that no one has created a stable wormhole yet, that's correct, but wormholes are still a burgeoning area of research, as theoretical physicists develop and refine the ideas first put forth by some of the great minds of the twentieth century, including Einstein and Wheeler.

Now I'd like to show you some of the opening paragraphs from a recent New Scientist article, written by Marcus Chown, entitled Intergalactic Subway: All Aboard the Wormhole Express. Please click on the link to read the whole article.

You probably won't be surprised to learn that no one has yet come close to constructing... a wormhole. One reason is that they are notoriously unstable. Even on paper, they have a tendency to snap shut in the blink of an eye unless they are propped open by an exotic form of matter with negative energy, whose existence is itself in doubt.

Now, all that has changed. A team of physicists from Germany and Greece has shown that building wormholes may be possible without any input from negative energy at all. "You don't even need normal matter with positive energy," says Burkhard Kleihaus of the University of Oldenburg in Germany. "Wormholes can be propped open with nothing."

The findings raise the tantalising possibility that we might finally be able to detect a wormhole in space. Civilisations far more advanced than ours may already be shuttling back and forth through a galactic-wide subway system constructed from wormholes. And eventually we might even be able to use them ourselves as portals to other universes.

Wormholes first emerged in Einstein's general theory of relativity, which famously shows that gravity is nothing more than the hidden warping of space-time by energy, usually the mass-energy of stars and galaxies. Soon after Einstein published his equations in 1916, Austrian physicist Ludwig Flamm discovered that they also predicted conduits through space and time.

But it was Einstein himself who made detailed investigations of wormholes with Nathan Rosen. In 1935, they concocted one consisting of two black holes, connected by a tunnel through space-time. Travelling through their wormhole was only possible if the black holes at either end were of a special kind. A conventional black hole has such a powerful gravitational field that material sucked in can never escape once it has crossed what is called the event horizon. The black holes at the end of an Einstein-Rosen wormhole would be unencumbered by such points of no return.

Einstein and Rosen's wormholes seemed a mere curiosity for another reason: their destination was inconceivable. The only connection the wormholes offered from our universe was to a region of space in a parallel universe, perhaps with its own stars, galaxies and planets. While today's theorists are comfortable with the idea of our universe being just one of many, in Einstein and Rosen's day such a multiverse was unthinkable.

Fortunately, it turned out that general relativity permitted the existence of another type of wormhole. In 1955, American physicist John Wheeler showed that it was possible to connect two regions of space in our universe, which would be far more useful for fast intergalactic travel. He coined the catchy name wormhole to add to black holes, which he can also take credit for.

The trouble is the wormholes of Wheeler and Einstein and Rosen all have the same flaw. They are unstable. Send even a single photon of light zooming through and it instantly triggers the formation of an event horizon, which effectively snaps shut the wormhole.

This article continues with an excellent overview of the different advances in this field, bringing us to more detailed discussion of these most recent theories around the promise of us actually being able to create stable wormholes.

What's a wormhole? I would describe it as "what happens when you fold a dimension". What a simple idea, and yet what profound implications for the future that idea holds!

Enjoy the journey,

Rob

Next: Where'd All the Dark Matter Go?