A time warp can be thought of as anything that disrupts the flow of time by making it go faster or slower.
While the idea may seem fantastical, time warps were predicted by Albert Einstein's pioneering theories of special relativity and general relativity, which were published in the early 20th century, Live Science reported.
In a nutshell, Einstein argued that gravity was not a force but instead originated from curvatures in space-time—the three dimensions of space and the one dimension of time combined—caused by uneven distributions of mass.
So anything with mass is essentially a time warp. However, the effect is only detectable for objects with large masses—such as planets, stars or black holes—which can create significant distortions in space-time. Objects such as ourselves or, say, a football only create extremely tiny distortions, which for all intents and purposes are undetectable to us.
In fact, if you were able to somehow place a clock close to a black hole and observe it from far away, you may notice that it would appear to tick more slowly than your own watch or another clock that was next to you. This effect is known as gravitational time dilation, and it results from distortions in space-time.
Traveling at high speeds can also cause time dilation, with greater velocities producing a more significant effect. For example, if you could travel in a spaceship at the speed of light, time would essentially come to a standstill for you from the viewpoint of an observer back on Earth. This scenario could be described as time travel because you would move into the future faster than the observer.
These are extreme examples, but the effects of time dilation do have real-world consequences for human activities. Notably, GPS satellites have to take general relativity and special relativity into account so that they can accurately determine your position on Earth.
"GPS satellites work by having super-accurate clocks aboard the satellite," Ken Olum of Tufts University's Institute of Cosmology told Live Science. "The clocks on the satellites run at different speeds, depending on what distance from Earth they are. They also run a different speed depending on the motion of the satellite."
But aside from massive objects warping space-time, there are other theoretical phenomena that could produce similar effects. One of these is wormholes—theoretical tunnels that link two points in space-time, potentially creating shortcuts that matter could pass through almost instantaneously.
Scientists have never found a wormhole. But like black holes, they were first predicted by the theory of general relativity, although they weren't actually called by this name until 1957. One recent study, conducted by Harvard physicist Daniel Jafferis, found that traversable wormholes theoretically might exist.
"Traversable wormholes are possible, consistent with the known laws of physics," Jafferis previously told Newsweek. "Given that space and time are curved and warped by gravity—as known since 1916, when Einstein figured out general relativity—people long wondered whether there could be a tunnel in space that one can get through connecting two different places."
However, for such a wormhole to be stable and traversable, it would require an exotic—and as yet undiscovered—form of energy, known as "negative energy."
Another possible type of time warp could arise from a theoretical concept known as "cosmic strings," first proposed by Princeton astrophysicist Richard Gott in 1991. According to his hypothesis, these string-like objects—which may be found throughout the universe—are almost like one-dimensional analogues to black holes. They are essentially, infinitely thin, but stretched out.
Explaining this idea in a 2009 lecture, also credited to his Princeton colleague Michael Strauss, Gott said: "A black hole is a point, of zero dimensions. A cosmic string is a long, stretched out, very massive object, with a gravitational field which is not spherically symmetric around a point—like a black hole—but cylindrically symmetric around a line. Cosmic strings have no ends and therefore are either infinite in extent or are closed loops."
He went on: "They are predicted to exist by various particle physics theories, created in the Big Bang, but unlike black holes, there is no observational evidence that they actually do exist. For the sake of argument, we'll assume they do."
Gott argued that if two of these strings whiz past each other in a particular way at close to the speed of light, they could create closed curves in space-time, which could act as a sort of time machine.
"You might think that if you could go faster than the speed of light, you would see time reverse direction. But there is no way we can go faster than the speed of light," Gott said. "So that won't work. However, in general relativity, the trick we will try to use is to use curved-space time to take a shortcut between two points to go faster than light. If we're clever, we can use this to travel back in time."
However, this idea is highly speculative, and Gott himself said that to travel back in time you would need unimaginable amounts of energy. Furthermore, you wouldn't be able to travel back before the date when the time machine was created.
"To make this work in practice, there are a few practical difficulties," Gott said. "First, you have to find some cosmic strings—a problem, because they haven't been discovered yet. These have to be particularly massive strings, with a mass of at least four times 10 to the power of 16 for every inch of length. You have to get them each moving at 0.9999992 times the speed of light."
He went on: "The energy required to do this is roughly the rest-mass energy of an entire galaxy. So we're not about to apply to NASA to build one of these things quite yet! But it is interesting to demonstrate that the laws of physics allow time travel in principle."
Benjamin Shlaer, a physicist at the University of Auckland in New Zealand, told Live Science that our best chances of finding exotic matter or time warps in the future is through observational cosmology—the study of the structure, evolution and origin of the universe using such instruments as telescopes.
"It's pretty clear that all of our so-called safe assumptions about what actually exists are probably not true if you go to extreme regimes," Shlaer told the site. "And we could hope that these are questions we can ask and answer in the field of cosmology."