Wormhole: Travel through Space Faster than Light

What is a Wormhole?

A wormhole (or Einstein–Rosen bridge or Einstein–Rosen wormhole) is a speculative structure linking disparate points in spacetime, and is based on a special solution of the Einstein field equations. In simple words, a theoretical passage through space-time could create shortcuts for long journeys across the universe.



Wormholes are consistent with the general theory of relativity, that means it's theoretically possible, but whether wormholes actually exist remains to be seen. Many scientists postulate that wormholes are merely projections of a fourth spatial dimension, just like how a two-dimensional (2D) being could experience only part of a three-dimensional (3D) object.

A wormhole might connect extremely long distances such as a billion light years, or short distances such as a few meters, or different points in time, or even different universes. It is like a portal through space, if you enter through it, you'll exit from somewhere else in the universe.
Visualisation of wormhole

Visualisation of wormhole is hard. But there is a famous simplified notion. Think of the space as a 2D plane or a sheet of paper. Now fold the paper and make a hole passing through that paper. As you can see, entering from top you reach the bottom which is actually two very distant points.

How does it work?

Wormhole required huge amounts of energy to sustain itself. According to calculations, sustaining a large wormhole would require impossible amounts of energy. So it would require exotic matter or negative matter. A wormhole requires a blackhole as a entrance which swallow everything including light and a theoretical whitehole from which everything exits. This is also also known as Einstein–Rosen bridges. A wormhole would collapse on itself.



However, physicists later reported that microscopic traversable wormholes may be possible and not require any exotic matter, instead requiring only electrically charged fermionic matter with small enough mass that it cannot collapse into a charged black hole.

What can it be used for?

1. Faster-than-light travel

The impossibility of faster-than-light relative speed only applies locally. Wormholes might allow effective superluminal (faster-than-light) travel by ensuring that the speed of light is not exceeded locally at any time. While traveling through a wormhole, subluminal (slower-than-light) speeds are used. If two points are connected by a wormhole whose length is shorter than the distance between them outside the wormhole, the time taken to traverse it could be less than the time it would take a light beam to make the journey if it took a path through the space outside the wormhole. However, a light beam traveling through the same wormhole would beat the traveler.

2. Time travel

If traversable wormholes exist, they might allow time travel. A traversable wormhole doesn't have a fixed entrance or exit i.e. traversable wormhole can be used from both sides.

A proposed time-travel machine using a traversable wormhole might hypothetically work in the following way: One end of the wormhole is accelerated to some significant fraction of the speed of light, perhaps with some advanced propulsion system, and then brought back to the point of origin. Alternatively, another way is to take one entrance of the wormhole and move it to within the gravitational field of an object that has higher gravity than the other entrance, and then return it to a position near the other entrance. For both these methods, time dilation causes the end of the wormhole that has been moved to have aged less, or become "younger", than the stationary end as seen by an external observer

Reference:

Wikipedia: Link to Wikipedia page

Space.com: What Is Wormhole Theory?
Credits:

By Panzi - English Wikipedia, CC BY-SA 3.0, Visualisation of Wormhole