Chapter 130: Time Travel-The Only Path on the Doomsday Icefield(Dragon Rain)

In recent days, Huafeng’s mind had been filled with images of wormholes, and he had even begun contemplating the possibility of time travel.

A wormhole is a concept arising from general relativity. It refers to a peculiar kind of celestial object in the universe. Although there is no experimental evidence proving that wormholes truly exist, scientists have predicted that they may exist as shortcuts between distant points in spacetime, imagining them as connections between otherwise empty regions of space. However, a recent study suggests that wormholes may exist between distant stars. They are not tunnels through spacetime. Rather, wormholes may contain a fluid approaching perfect uniformity, capable of flowing back and forth between two stars. This characteristic of the fluid might be a sign confirming the existence of wormholes.

This recent theory has led scientists to question whether wormholes might exist between different ordinary stars and neutron stars—for example, between normal stars and neutron stars. Such objects might possess certain detectable distinguishing features. To investigate these differences, researchers designed a model of an ordinary star with a passage running through its center, allowing cosmic matter to travel through it. Two stars sharing a wormhole would have a unique form of connection because a wormhole has two openings.

Because the strange matter inside a wormhole could flow like a liquid between stars, the two stars would exhibit unusual patterns of pulsation. These pulsations would release different kinds of energy, including extraordinarily powerful energy.

Scientists have proposed two types of wormholes: one for interstellar and intergalactic travel within our own universe, and another for travel between different universes.

A wormhole is a miraculous tunnel through which one could travel across space and time, making interstellar and even intergalactic journeys no longer a dream. Scientists believe wormholes are extremely unstable. Without exotic matter possessing negative energy to hold their mouths open, they would suddenly collapse in an instant. However, according to research conducted by German and Greek physicists, wormholes may remain open without the aid of such exotic matter. This discovery suggests that, one day in the future, humanity might discover wormholes in space. Perhaps a civilization far more advanced than ours has already used a galactic subway system formed by wormholes to travel between different galaxies.

Are wormholes time machines, or could they connect two different spacetimes?

Astrophysicists believe that wormholes may be natural time machines. Maintaining a wormhole in an open state could allow us to return to the past or enter the future. Of course, there is still no evidence that macroscopic wormholes exist in the universe.

We are merely studying this strange form of spacetime based on the predictions of Einstein’s general theory of relativity. Time machines appear only in science-fiction films, and events moving against the direction of the arrow of time seem almost impossible. Yet Einstein’s theory of spacetime permits time travel. Certain spacetimes predicted by relativity could allow time to run backward. By bending spacetime and connecting two distant regions, they could make travel through three-dimensional space extremely rapid, greatly compressing journeys of tens of thousands of light-years.

Astrophysicist Eric Davis believes that if we could keep a wormhole continuously open, we could return to the past or enter the future. But where are the wormholes? We have not yet found evidence that they exist in the real universe. Even if wormholes do exist, perhaps they could not accommodate even a single person, let alone a spacecraft.

In response, physicists have proposed a theory known as closed timelike curves, suggesting that time machines might be possible to construct. Traveling through spacetime via a wormhole would not violate the speed-of-light limit. Apparent faster-than-light motion would actually be the result of spacetime distortion, producing the effect of superluminal travel through extreme warping of spacetime.

According to scientific research, keeping a wormhole continuously open would require vast quantities of exotic matter, about which we know very little. Such matter would involve quantum theory, while general relativity cannot explain it. Astrophysicist Robert Owen believes that when an object enters a wormhole and attempts to travel through time, various physical laws would restrict the process, as though some mechanism of nature were forcing the wormhole to close. According to quantum theory, maintaining a wormhole as a time machine could cause enormous amounts of energy to accumulate, eventually “destroying” the wormhole. Therefore, time travel would have to be completed before the wormhole closed.

Before studying wormholes, scientists must spend time resolving the problems between general relativity and quantum theory. A new theory may ultimately provide the foundation for time travel.

5. Related Theories

There are several ways of describing wormholes.

The first is as a tunnel through space. Imagine a sphere: if you walk along its surface, the distance is long, but if you travel along a straight line through its interior, the distance is shorter. The wormhole is that straight-line passage.

The second is as a connection between a black hole and a white hole. A black hole can create a potential well, while a white hole can create an inverted potential well. The universe is three-dimensional; if the potential well is regarded as a fourth dimension, then a wormhole is a fifth-dimensional connection between the potential well and the inverted potential well. If one were to draw the universe, the potential well, the inverted potential well, and the wormhole together, the result would resemble a Klein bottle: the mouth would be the black hole, the junction between the body and neck would be the white hole, and the neck would be the wormhole.

The third is the time tunnel you mentioned. According to Einstein, time travel is possible, but you could only observe events, much as one watches a film, without changing what has happened. Time is linear, and events are like beads already threaded onto a string. You cannot alter the beads or rearrange their order.

The fourth is the transportation of space through a tremendous thrust produced by forces acting upon the surrounding area in a fixed manner. For example, imagine a section of vacuum in water suddenly being filled by water in a particular shape. The enormous pressure of the water would force out whatever was inside, creating a corresponding phenomenon. Perhaps this could be achieved by borrowing forces that already exist in nature, much as one uses the power of flowing water to generate electricity—only with an additional twist.

The ordinary “perfect” black holes under discussion are simplified models. In detail, the black holes we consider neither rotate nor possess electric charge. If we take rotation and/or electric charge into account, matters become much more complicated. In particular, it may be possible to enter such a black hole without colliding with its singularity. The interior of a rotating or charged black hole may be connected to a corresponding white hole, allowing one to enter through the black hole and emerge from the white hole. This combination of a black hole and a white hole is called a wormhole.

A white hole might lie extremely far from its black-hole counterpart. In fact, it might even exist in a “different universe”—that is, a region of spacetime completely disconnected from our own except through the wormhole itself. A conveniently located wormhole would provide an efficient and convenient way to travel enormous distances, perhaps even to another universe. Perhaps the exit of a wormhole could be situated in the past, allowing one to pass through it and travel backward in time. In general, wormholes sound extraordinarily appealing.

Before deciding that this theory is correct and setting out to search for wormholes, however, there are two things you should know. First, wormholes almost certainly do not exist. As we noted above when discussing white holes, the fact that they are valid mathematical solutions to a set of equations does not mean that they exist in nature. In particular, when black holes form through the collapse of ordinary matter—as all the black holes we believe to exist are thought to have formed—they do not produce wormholes. If you fell into one, you would not emerge somewhere else. You would strike the singularity, and that would be the only place you could go.

Moreover, even if a wormhole were formed, it would be considered unstable. Even the slightest disturbance—including the disturbance caused by your attempt to pass through it—could make it collapse.

After Schwarzschild discovered the Schwarzschild black hole, theoretical physicists spent nearly half a century exploring the Schwarzschild solution to Einstein’s field equations. The Kerr solution, the Reissner–Nordström solution, and the later Newman solution mentioned above were all developments arising from research into Schwarzschild’s solution. The wormhole I am introducing here is also a descendant of Schwarzschild’s work.

When physicists began contemplating white holes, wormholes first appeared in the Schwarzschild solution. Through an Einsteinian thought experiment, physicists discovered that spacetime could be curved. Under such circumstances, they were astonished to find that if a star formed a black hole, spacetime at the Schwarzschild radius—that is, at the event horizon—would be completely perpendicular to the original spacetime.

Ever since wormholes were discovered in the Schwarzschild solution, physicists have been fascinated by their properties.

Let us first consider a classic function of a wormhole: connecting a black hole and a white hole to form an Einstein–Rosen bridge. Matter would be completely broken down into elementary particles at the black hole’s singularity, then transmitted through the wormhole—that is, the Einstein–Rosen bridge—to the location of the white hole, where it would be emitted.

A wormhole has no event horizon. Instead, it possesses only a separation surface connecting it to the outside world. Through this separation surface, the wormhole connects with hyperspace, yet the curvature of spacetime there is not infinite. It is like one curve in a plane touching another curve; in the case of a wormhole, it is as though a four-dimensional tube were tangent to a three-dimensional space. The curvature of spacetime at that point is not infinite. Therefore, we could pass safely through the wormhole without being destroyed by overwhelming gravity.

Astrophysicists have suggested that wormholes may be natural time machines. Although no behavior involving travel beyond a wormhole has ever been observed, and there is no direct evidence that wormholes themselves truly exist, scientists continue to study this strange form of spacetime based on the predictions of Einstein’s general theory of relativity.

Astrophysicist Eric Davis believes that if a wormhole could be kept continuously open, it would be possible to return to the past or enter the future. But where are the wormholes? No evidence has yet been found that they exist in the real universe.

We know very little about exotic matter, which would involve quantum theory. Therefore, before studying wormholes, one would have to complete the journey through time before the wormhole closed.