Wormhole

A theoretical passageway through spacetime which makes it possible to pass instantaneously between two distant points in three dimensional space. Also known as an "Einstein-Podolsky-Rosen bridge" (thanks to Oolong for the correction there) connecting two quantum singularities.

Theoretically, a wormhole could be created by using gravity to bend/warp spacetime so that two distant points are brought closer together. However, to go any reasonable distance, it would take quite a bit of gravity. Probably more gravity than a ship could reasonably take. Then again, nobody has really taken the time to play around with a few black holes and try this stuff out. This is also the basic theory behind Warp drive in Star Trek, where spacetime is bent in front of the ship as to shorten the length of space there is to go.

A better way to view this is to visualize the fabric of spacetime as a piece of paper. Let's say you want to get from point A at the top of the paper to point B at the bottom. What's the shortest way? Classical physics says it's a straight line, but what if instead you fold the paper so that the two points are right next to each other a few microns apart? That's the idea behind a wormhole, instead of going in a straight line you bend the fabric of spacetime to bring the points much closer together.

In order to actually create a wormhole, you would have to have a region of spacetime with negative curvature. Experiments have actually been conducted which have created small scale wormholes by charging two large metal plates up, creating what is known as the Casimir effect. Of course, this is just a theoretical wormhole and is of little use, but it's a start...

worm = W = wound around the axle

wormhole /werm'hohl/ n.

[from the `wormhole' singularities hypothesized in some versions of General Relativity theory] 1. [n.,obs.] A location in a monitor which contains the address of a routine, with the specific intent of making it easy to substitute a different routine. This term is now obsolescent; modern operating systems use clusters of wormholes extensively (for modularization of I/O handling in particular, as in the Unix device-driver organization) but the preferred techspeak for these clusters is `device tables', `jump tables' or `capability tables'. 2. [Amateur Packet Radio] A network path using a commercial satellite link to join two or more amateur VHF networks. So called because traffic routed through a wormhole leaves and re-enters the amateur network over great distances with usually little clue in the message routing header as to how it got from one relay to the other. Compare gopher hole (sense 2).

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.

The wormhole is a favorite tool of science fiction authors though very few have actually taken the task of tackling their use beyond simply saying "I open a wormhole and go through to a point way far away" (a la Star Trek).

Before going too far into the uses of a wormhole, it is necessary to sit down and look at what one is.

A wormhole is a geometry of four-dimensional spacetime ... in which two regions of the universe are connected by a short narrow throat. A classical large scale wormhole is a solution of the Einstein's field equations, which governs the curvature of spacetime.

There (may) exist two types of wormholes - the "classic" Schwarzschild wormhole (also known as Einstein-Rosen bridge) that are two connected black holes (or one black hole with two throats in either diffrent parts of the universe or two diffrent universes). The Schwarzschild wormhole uses the negative square root as the solution for the geometry of space giving a wormhole where two places connect (potentially different universes) at the event horizon. The other solution aside from a black hole for the Schwarzschild geometry is the impossible white hole. With this it is seen to be a double ended black hole where you could see light falling into the other black hole the other place/universe once you were inside the event horizon too - not that would do you much good.

It is theorized that at the Planck level (really really small - see Planck length) there exist a multitude of wormholes constantly forming and dissolving so fast that light cannot pass through before the wormhole closes. The challenge here is to isolate one (very difficult) and then hold it open large enough to send something through it.

Holding it open is likely more close to being solved than isolation of one. To do this, one needs a source of "negative pressure" to keep the wormhole from collapsing. The tension in the matter that would provide this pressure turns out to be greater than the energy density of matter. The only type of matter that provides this is exotic matter - it has a negative energy density relative to light traveling through it. This type of matter is thought to exist and glimpses of its nature can be seen in the Casimir effect.

Ok, let's assume we've got a wormhole (or rather, a pair of mouths connected by a throat) that is big enough to be interesting (and safe) to more than physicists. What can you do with it? The most obvious thing is to send stuff through it and have it instantly pop out the other side. In one mouth and out the other. Makes things like the refrigerated storage in a soda machine pointless - you instead connect it up to a warehouse and never have to worry about running out. Taking a trip to is easy as walking down a hall.

Well, thats neat but when you start thinking of the other possibilities its rather boring. Let's take one mouth and send it on a trip at a relativistic speed. "Why?" you ask? Ahh - this is where it gets interesting. So, we sent one wormhole out and back. While doing this, it aged less than its companion mouth. Now you've got a time machine. If the loop trip (in space) aged it a day more than its companion then if you look through the younger mouth you will see tomorrow. Take care and realize that you can't go backwards in time to before the mouth was created (no, you couldn't use a time machine to visit the 13th century because the mouth wasn't created them). However, you can go back and forth between the opening of the mouth and the closing of the mouth to your heart's content.

In exploring this time machine some the grandfather paradox crops up. Assume for the sake of argument that the throat of a time separated wormhole existed enabling you to go back in time. As many physicist-philosophers understand it, free will is limited - the past and the future are already set forth in stone. It is simply as impossible to change the past (or future!) as it is to walk through a solid object. You cannot kill your grandfather or alter the past. Period.

It is in the realm of hard science fiction that wormholes have been most explored. This is most often used as a time travel device, though rather to receive information about the future than to change the past (though it is realized that this is all fixed anyways). From Robert L. Forward with Timemaster as the the most real and believable (and in interesting scene done three times over with the main character meeting himself from different points in the future) to Stephen Baxter with his more speculative The Light of Other Days along with Arthur C. Clarke (though it isn't as accurate on the time travel aspect - what would happen if you could hold a wormhole open long enough to see another place in history?) and again with Stephen Baxter with Timelike Infinity and Ring (part of the Xeelee series) where Humanity is dragging wormholes on a loop trip of thousands or millions years to get to the end of time.

Realize, that much of this is up for debate (and often is in the rooms of astrophysics grad students). Some claim that it is impossible to stabilize the black hole and the impracticality of threading the throat of a wormhole with exotic matter to force the throat out of the event horizon of the singularity that forms the wormhole.

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http://www.dd.chalmers.se/~f93jojo/sidan2.htm
http://casa.colorado.edu/~ajsh/schww.html
http://www.ucl.ac.uk/~zcapn39/blacknet.html
(not found or used, but reccomended:
M. S. Morris & K. S. Thorne (1988), ``Wormholes in spacetime and their use for interstellar travel: A tool for teaching general relativity'', American Journal of Physics, 56, 395-412)

It is, in my opinion, strange to think that my classmates and I at school (in English class actually) managed to come to the conclusion that a wormhole is actually the physical manifestation of a hypercube.

After having read Robert A. Heinlein's "...And He Built A Crooked House", I grew in my understanding of the four-dimensional hypercube. I already do have good spatial skills, having corrected a geometry teacher my Freshman year. I realized that in a three-dimensional universe, an object with four spatial dimensions bridges two points with little or no distance between those points, essentially skipping all space in between and thus "bending" space-time.

However, this does not account for the time difference between two points. Since time is relative to the speed of an object and its distance from other objects, a wormhole acts as an object with which time can be travelled through almost freely. I therefore believe that wormholes also require an added temporal dimension to allow for the change in time.

If one were to actually run thought experiments involving hupercubes and comparing their properties and behaviors to those of a wormhole, one would find that they are quite similar. Depending on the true nature of time and the behavior of temporal dimensions my ideas on wormholes containing an extra temporal dimension may be false. However, I would like to point out that I arrived at all of these conclusions simply through thinking about the subject of hypercubes and wormholes. To truly understand how my idea works one must read hypercube and understand fully what is a hypercube.

A hypercube is an object formed of eight cubes in the pattern of a cross folded together to form an object with four spatial dimensions. To see how these work in a three dimensional universe, one must imagine making an unfolded cube (a hypersquare) in a two dimensional universe and then folding it together to form a cube. Since the hypersquare then acts as a three-dimensional object in two-dimensional space, it thus can be used to link two points in space by "bending" space. The same happens in a three-dimensional universe when a hypercube, or wormhole, is created. An example of the results can be found in Heinlein's short story, "...And He Built A Crooked House".

Worm"hole` (?), n.

A burrow made by a worm.

 

© Webster 1913.