WORMHOLES

A wormhole is a theoretical connection, often referred to as a tunnel, between two black holes. The two black holes could be in two different locations in the same universe, or they could be located in two different universes. In the case of both the former and the latter, each black hole would necessarily be located in a different time, in keeping with the concept of spacetime as delineated in Albert Einstein's theory of general relativity.

In fact, it was Albert Einstein and Nathan Rosen who discovered the mathematical possibility of wormholes, but they called them “bridges” in 1935. These Einstein-Rosen bridges, as wormholes were first called, would not allow any object to pass through, they theorized, because the middle of the wormhole would twist or pinch until it separated, creating a singularity, a literal dead end.

A black hole is formed when the resulting matter from a supernova explosion collapses until all the matter is squashed into a point at which volume is zero and density, gravity, and the curvature of spacetime are infinite. That point is called the black hole's singularity. A wormhole connects two singularities.

Spacetime is a four-dimensional continuum that consists of three-dimensional space with the traditional x, y, and z axes plus a fourth coordinate—time—added to make four-dimensional spacetime. Einstein theorized that one could not know the location of an object independent of both its place (spatial coordinates) and instance (time coordinate) with respect to the observer or observers. For example, if person A in San Diego observes the location of the sun at time A, and person B in Cairo observes the same object at time B, then the sun exists in different places in space-time. If one considers that a few time zones separate these observers, as opposed to light-years [Page 1445]between celestial objects, the importance of space-time with respect to location and instance becomes more evident. Expanding the concept from the scale of the earth to the scale of the universe allows one to conclude that two black holes connected by a wormhole must exist in different times if they exist in different locations.

Artist's illustration of a spacecraft passing through a wormhole to a distant galaxy. A wormhole is a hypothetical topological feature of spacetime that is essentially a shortcut through space and time. Assuming that general relativity is correct, wormholes may existThere is no evidence, however, for anything like a wormhole in the observed universe. Source: NASA.

Thus, a wormhole would allow rapid time travel, cutting an interstellar trip from several millennia down to a few days or a few hours. There would be many possibilities for the direction of time travel. If the first black hole lies at point A in the past, and the second black hole lies at point B in the future, then a wormhole could take one forward in time, as well as backward. If, like the Einstein-Rosen bridges, the wormholes pinch, they could close, become attracted to a different singularity, and reopen an alternate pathway through spacetime.

Although the discovery of black holes and the behavior of visible matter that surrounds them lend support to wormholes' existence, the study of wormholes is still considered by most to be speculative in nature.

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