Chapter 128: The Time Wormhole

After a brief rest, they resumed their studies, this time turning their attention to the exploration of spacetime wormholes—a subject that particularly intrigued Hua Feng.

A spacetime wormhole, also known as an Einstein–Rosen bridge or sometimes as a “throat,” is a narrow tunnel that might exist in the cosmos, connecting two distinct points in spacetime.

The concept of wormholes was first introduced in 1916 by Austrian physicist Ludwig Flamm and later hypothesized in 1930 by Albert Einstein and Nathan Rosen while studying gravitational field equations. They proposed that wormholes could allow instantaneous spatial transfer or even time travel.

Einstein’s theory posits that a “wormhole” is essentially a slender tube linking distant regions of the universe. Dark matter is thought to sustain the openings of these wormholes. They might connect parallel universes or nascent “baby” universes, offering the tantalizing possibility of time travel. Wormholes could also serve as spacetime tunnels linking black holes and white holes, hence sometimes being called “gray paths.”

Theoretically, wormholes are spatial tunnels connecting remote regions of spacetime, akin to whirlpools in the ocean—ubiquitous yet fleeting phenomena. These spacetime vortices arise from the combined effects of stellar rotation and gravitational forces. Much like a whirlpool brings the water surface closer to its depths, wormholes can instantaneously draw two distant regions of space into proximity.

The earliest mention of “wormholes” dates back to 1916 with Flamm’s work, and the concept was later refined in 1935 by Einstein and Rosen, lending the name “Einstein–Rosen bridge” to these structures. Typically, when people refer to “wormholes,” they mean spacetime wormholes—conceived as potential cosmic shortcuts enabling instantaneous transit through spacetime. However, Einstein himself doubted their physical existence, so for many years, wormholes were regarded merely as mathematical curiosities.

In 1962, Robert Fuller and John Wheeler published a paper proving that wormholes connecting two parts of the same universe would be unstable. Then, in 1963, New Zealand mathematician Roy Kerr proposed hypotheses that renewed theoretical support for wormholes. Like humans, stars undergo a life cycle, and Kerr suggested that a dying star maintaining rotation could form what are known in films as “dynamic black holes.” If an object is launched along the axis of rotation and surpasses the gravitational limits at the black hole’s center, it might enter a so-called “mirror universe.” The “hyperspace” experienced by astronaut Cooper inside the black hole in the film “Interstellar” can be interpreted as an entry into such a mirror universe. Passing from our universe into the mirror universe itself constitutes a form of spacetime traversal.

The “galactic wormhole theory” stems from breakthroughs in dark matter research. Dark matter refers to matter that does not interact via electromagnetic forces and cannot be observed through electromagnetic waves. Unlike wormholes, dark matter’s presence has been confirmed through gravitational effects. In 2013, a research team at the International School for Advanced Studies in Trieste charted a detailed map of dark matter distribution within the Milky Way. By combining this with the latest cosmological models of the Big Bang, they discovered that not only does the Milky Way satisfy the conditions for wormholes to exist, but the entire galaxy might itself be a colossal wormhole.

According to theoretical models developed by Italian astrophysicist Paolo Salucci and colleagues, this hypothesis could indeed be validated. More importantly, it prompts a more precise reconsideration of dark matter research: might dark matter itself represent another dimension? Or could it be an interstellar transportation system?

At present, the wormhole hypothesis remains speculative, yet scientific progress depends on bold conjectures. Humanity once believed atoms were the smallest units of matter, only to discover neutrons and protons later. Similarly, for a long time, the universe was thought to consist solely of ordinary matter, but the discovery of dark matter overturned that notion. The essence of scientific conjecture lies in breaking existing constraints and advancing understanding through relentless questioning and revision. As Salucci remarked, “In any case, we must always ask ourselves: what is it, really?”

The wormhole concept initially arose from studies of the Schwarzschild solution. When theoretical physicists analyzed the white hole solution, an Einstein thought experiment revealed that spacetime itself need not be flat. If a star collapses into a black hole, spacetime at the Schwarzschild radius—the event horizon—is perpendicular to the original spacetime. In such a curved spacetime, this structure signifies a black hole.

A portion inside the event horizon connects with another part of the universe, forming a “hole” that can be either a black hole or a white hole. This curved event horizon is called the Schwarzschild throat, a specific type of wormhole.

Since the discovery of wormholes within the Schwarzschild solution, physicists have become deeply interested in their properties.

Wormholes connect black holes and white holes, allowing matter to transit through the wormhole—known as the Einstein–Rosen bridge—where matter is completely decomposed into fundamental particles at the black hole’s singularity, then transmitted to the white hole and emitted outward.

Wormholes can also manifest in normal spacetime as sudden appearances of superdimensional regions. Theoretical predictions attribute many characteristics to wormholes, but due to space limitations, these are not further elaborated here.

In sum, our understanding of black holes, white holes, and wormholes remains limited; they are still shrouded in mystery, with many questions yet to be explored. Astronomers have found indirect evidence for black holes, but white holes and wormholes remain theoretical constructs, frequently appearing in science fiction.

In the universe, the “cosmological constant” is nearly zero. This constant, also called the “vacuum energy,” represents the energy present in empty space devoid of matter.

Einstein introduced this concept internally. During the early expansion of the universe, the cosmological constant was essential, and in particle physics, vacuum energy is considered a natural property. But why has the cosmological constant effectively become zero in today’s universe? Coleman explained that, in the early universe before the Big Bang, wormholes connected many universes, cleverly adjusting the cosmological constant to zero. As a result, one universe could spawn another, and countless tiny wormholes might exist, connecting the past and future of one universe or linking to others.

Even if wormholes exist and are stable, traversing them would be highly unpleasant. Radiation passing through wormholes—from nearby stars, the cosmic microwave background, and so forth—would be blue-shifted to extremely high frequencies. Attempting to pass through would expose one to lethal doses of X-rays and gamma rays. Wormholes likely emerged alongside black holes.

If you stand at one end of a wormhole at exactly 12:00, you would emerge from the other end at exactly 12:00.

Wormholes, or Einstein–Rosen bridges, are narrow cosmic tunnels possibly connecting two different points in spacetime.

Einstein’s thought experiments revealed that spacetime itself need not be flat. In curved spacetime, the portion inside a black hole’s event horizon connects orthogonally with another region of the universe.

Wormholes link black holes and white holes, transferring matter between them. Matter is broken down into fundamental particles at the black hole’s singularity and then transported through the wormhole to the white hole, from where it radiates outward.

Wormholes can act as superdimensional conduits and can also appear within normal spacetime.

Unlike black holes, wormholes lack an event horizon but have a boundary interface with the external world. Through this interface, wormholes facilitate superdimensional connections. The junction between wormholes, black holes, and white holes is a spacetime tunnel connecting two closed spacetime regions where curvature is finite, allowing safe passage without destruction by gravitational forces.

Black holes, white holes, and wormholes remain unresolved mysteries in modern cosmology, particularly regarding spacetime and gravitation. The existence of black holes has only been indirectly evidenced. Current observations and theories pose many new questions. For example, a cold star capable of forming a black hole will collapse to densities surpassing atomic nuclei, nucleons, and neutrons. If collapse continues, neutrons might be crushed. What, then, are the fundamental constituents of matter inside black holes? What repulsive forces counterbalance gravity to halt collapse at a certain stage? Without repulsion, a black hole would collapse indefinitely to a point of infinite density and zero volume—an outcome forbidden by physical laws.

Today, the cosmological constant is virtually zero.

Physicists have long believed that wormholes’ immense gravitational forces would destroy anything entering, rendering them unsuitable for cosmic travel. However, if wormholes do exist, then it is conceivable that standing at one end at 12:00 would lead you to emerge from the other end at exactly 12:00.

In sum, wormholes—Einstein–Rosen bridges—are narrow cosmic tunnels potentially connecting two distinct points in spacetime.