A Wormhole In Your Backyard

Diagram of A Wormhole

The diagram sketched below is a highly simplified version of what scientists call a “wormhole.” A wormhole is a passage through space-time creating shortcuts for very long trips across the universe. Wormholes are predicted by Einstein’s theory of general relativity. Keep in mind wormholes can suddenly collapse at any time. Multitudes of dangers of high radiation and contact with all kind of exotic matter are also involved with wormhole production.

In 1935, physicists Albert Einstein and Nathan Rosen used the theory of general relativity to propose the existence of “bridges” through space-time. These paths, called Einstein-Rosen bridges or wormholes, connect two different points in space-time. These paths theoretically create a shortcut reducing travel time and distance. Of course, no one we know has ever traversed a wormhole, so no one can say if a particular wormhole traverses half of the space in the Milky Way, or just the distance between planets in our Solar System. It’s not really known yet if an existing wormhole has two mouths or six – or even a dead end-especially with folded space. What if all the mouths are connected?

Artist’s impression of a wormhole.

Determining Where A Wormhole Goes

What if the simple fold is non-directional? What if the ‘fold’ connects galaxies, or even dimensions? Einstein’s theory of general relativity mathematically predicts the existence of wormholes, but none have been discovered to date. A negative-mass wormhole might be located by the way its gravity affects light passing by. General relativity allows for the existence of wormholes where the mouth of each is a black hole. One must keep in mind a naturally occurring black hole, formed by the collapse of a dying star, would not necessarily create a wormhole.

Science fiction is filled with stories of traveling through wormholes. But the reality of such travel is more complicated. Size is a big problem. Wormholes are predicted to exist on microscopic levels to about 10-33 centimeters. But with an expanding universe expands, look for many wormholes to stretch into a larger size.

Another problem comes from stability. The predicted Einstein-Rosen wormholes would be useless for travel because they collapse quickly. But more recent research found a wormhole containing “exotic” matter could stay open and unchanging for much longer periods of time. Exotic matter, not dark matter or antimatter, contains negative energy density and a large negative pressure. If a wormhole contained sufficient exotic matter, whether naturally occurring or artificially added, it could be used as a method of relaying information to a far-off destination, or sending travelers through space.

Wormholes may not only connect two separate regions within the universe, they could also connect two different universes. Similarly, scientists have conjectured if one mouth of a wormhole is moved, it could allow for time travel [Weird Science: Wormholes Make the Best Time Machines]. “A wormhole is not really a means of going back in time, it’s a short cut, so that something that was far away is much closer,” NASA’s Eric Christian wrote.

Although adding exotic matter to a wormhole might stabilize it enough where passengers could travel safely through it, there is still the possibility the addition of “regular” matter would allow the portal to be used. Today’s technology is insufficient to enlarge or stabilize wormholes—pending finding one. However, scientists continue to explore the concept as a method of space travel with the hope technology will eventually be able to take advantage.

From Dr. Eric Christian: “The first thing I should say is that there is no proof that wormholes exist. They are allowed for in the math of General Relativity, but they’ve never been observed, and no one can figure out how one would actually be created. If they do exist, then there will probably be some material rotating around the outside of the wormhole and it might look “something” like a hurricane.

Einstein Rules

Albert Einstein in 1905.
Albert Einstein in 1905.

None of the eminent physicists put the whole story together. That was left to the young Albert Einstein (1879-1955), who already began approaching the problem in a new way at the age of sixteen. By 1905 he had shown FitzGerald and Lorentz’s results followed from one radical assumption: the laws of physics and the speed of light must be the same for all moving observers, regardless of their state of relative motion. For this to be true, space and time can no longer be independent. Rather, they are “converted” into each other in such a way as to keep the speed of light constant for all observers. Space and time are relative – they depend on the motion of the observer who measures them- and light is more fundamental than either. This is the basis of Einstein’s theory of special relativity.

Fourth Dimension

Light-cone diagram showing the world-line of a moving observer.
Light-cone diagram showing the world-line of a moving observer.

Minkowski To The Rescue

Hermann Minkowski.
Hermann Minkowski.

Einstein did not quite finish the job, however. Contrary to popular belief, he did not draw the conclusion space and time could be seen as components of a four-dimensional space-time fabric. That insight came from Hermann Minkowski, who announced it in 1908 with the dramatic words: “Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality”.

Four-dimensional Minkowski space-time is pictured above in a two-dimensional light-cone diagram, with the horizontal axes representing “space” (x) and the vertical axis “time” (ct). The walls of the cone are defined by the evolution of a flash of light passing from the past (lower cone) to the future (upper cone) through the present (origin). All of physical reality is contained within this cone; the region outside (“elsewhere”) is inaccessible because one would have to travel faster than light to reach it. The trajectories of all real objects lie along “world-lines” inside the cone (like the one shown here in red). The apparently static nature of this picture, in which history does not seem to “happen” but is rather “already there,” has given writers and philosophers a new way to think about old issues involving determinism and free will.

Einstein Evolves

Einstein initially dismissed Minkowski’s four-dimensional interpretation of his theory as “superfluous learnedness.” However, he changed his mind quickly. The language of space-time (known technically as tensor mathematics) proved to be essential in deriving his theory of general relativity.

Is faster-than-light-speed possible? If so, does it involve the use of the Worm Hole Theory?

Faster than light speed is not possible within the theories we currently think explain the Universe. That does not mean it is impossible, since our understanding of the Universe is limited. Many of us hope some way will be found to circumvent “The Laws of Physics.” A wormhole is not really a means of going faster than light – or backward or forward in time – it’s a shortcut so that something far away is much closer. You can think of an ant on a piece of paper. If an ant could fold the paper around and poke a hole through it, it could get to the far end much faster if it just walked. That’s what a wormhole does in 3D, 4D, 5D, … or 11D space.

The Movie ‘Interstellar’ Is Self-Explanatory

A poster for the 2014 film "Interstellar" shows the spaceship Endurance flying through a wormhole. Credit: Paramount Pictures
A poster for the 2014 film “Interstellar” shows the spaceship Endurance flying through a wormhole. Credit: Paramount Pictures

Sci-fi fans who hope humanity can one day zoom to distant corners of the universe via wormholes, as astronauts do in the recent film “Interstellar,” shouldn’t hold their breath. Wormholes are theoretical tunnels through the fabric of space-time potentially allowing rapid travel between widely separated points. It is depicted in Christopher Nolan’s Interstellar,” which recently opened in theaters.

While wormholes are possible according to Einstein’s theory of general relativity, such exotic voyages will likely remain in the realm of science fiction, said renowned astrophysicist Kip Thorne of the California Institute of Technology, who served as executive producer on “Interstellar.” [‘Interstellar’: A Space Epic in Pictures]

Thorne, one of the world’s leading authorities on relativity, black holes and wormholes, told Space.com that there are very strong indications that wormholes would not allow human travel, currently by the laws of physics. “The major barrier has to do with a wormhole’s instability,” he said. Wormholes – if you don’t have something threading through them to hold them open – the walls will basically collapse so fast that nothing can go through them,” Thorne said.

Holding wormholes open would require the insertion of something that anti-gravitates – namely, negative energy. Negative energy has been created in the lab via quantum effects. One region of space borrows energy from another region not having any to begin with, creating a deficit. “So it does happen in physics,” Thorne said. “But we have very strong, but not firm, indications that you can never get enough negative energy that repels and keeps the wormhole’s walls open; you can never get enough to do that.” Likely, traversable wormholes – if they can exist at all – almost certainly cannot occur naturally, Thorne added. “That is, they must be created by an advanced civilization.”

And that’s exactly what happens in “Interstellar”: Mysterious beings construct a wormhole near Saturn, allowing a small band of pioneers, led by a former farmer named Cooper (Matthew McConaughey) to journey far afield in search of a new home for humanity, whose existence on Earth is threatened by global crop failures.

Anyone interested in learning more about the science of “Interstellar” – which also features gravitational time dilation and depictions of several alien planets orbiting close to a supermassive black hole – can check out Thorne’s new book, which is called The Science of ‘Interstellar.’

Kevin Roeten
A former Chemical Engineer, Kevin Roeten enjoys riding the third rail of journalism: politics and religion. He is a Guest Columnist for the Asheville Citizen-Times, and the Independent (Ohio), writes for numerous blogs, is an amateur astronomer, and delves into scientific topics.