Wormholes — The Hidden Portals (2024)

Searching for the other side of the universe

Our quest to push the scientific knowledge frontier forward led to the growth of understanding regarding our universe. Alexander Friedmann predicted that in the past there was a time when everything we observe today was concentrated at a point, creating an infinite density. Then, took place the event of the Big Bang, which made everything that was earlier close, to be separated apart. As time passed, Hubble observed that almost all the galaxies were redshifted — pointing towards the expansion of our universe. Soon the idea of connecting these separate regions transformed into many theories. These theories’ predictions ranged from travelling at the speed of light to the opening of a portal called a wormhole, connecting distant places.

Yes, you heard it right — a wormhole is sort of a portal. A wormhole can be visualized as a tunnel with two ends at separate points in spacetime (i.e., different locations, different points in time, or both). Such a tunnel would be acting as a shortcut between its endpoints. The simplest way of imagining a wormhole is the window of your room. When you peep outside the window, both the internal environments of the room and outside are completely different — similarly, the wormhole connects two different regions in time and space.

• The opening of a wormhole is called the “mouth” — and every such mouth is connected by the wormhole’s “throat.” The throat can expand into the belly or even multiple bellies.

Ludwig Flamm while studying the already known Schwarzschild black hole solution, proposed the existence of a white hole. Both describing two different regions of spacetime connected by a spacetime conduit. Ludwig Flamm had first proposed them in 1916. Then in 1935, Albert Einstein and Nathan Rosen predicted that the theory of relativity permits “bridges”, called Einstein-Rosen bridges, in space-time, these bridges are the ones that we call wormholes today. Then came the physicist John Wheeler in 1955 — it was his paper that coined the term “wormholes”. His paper also provided the first diagram of a wormhole as a tunnel connecting two openings in different regions of spacetime.

According to their principle, Albert Einstein and his pupil Nathan Rosen explained that the singularity at the center of a black hole is connected to another singularity, this gives rise to a theoretical object called a white hole.

You might be confused between a black hole and a white hole. Let’s make it simple, the black hole draws matter into it, whereas a white hole throws matter out. In mathematical terms, a white hole is a time-reversed black hole. Do white holes exist? Well, no one’s ever witnessed a white hole, but the equations of general relativity predict their existence.

Some scientists believe, an object falling into a black hole doesn’t vanish but travels through the wormhole, and with some changes or not, comes out of the white hole from the other side in another region of space.

Question mark over their existence

Einstein himself believed that it’d be difficult to use wormholes for time travel because:

• A wormhole is extremely unstable and it would collapse in upon itself almost instantaneously, without any delay.
• Due to intense gravitational force inside the black hole, any object travelling inside a black hole would be ripped, and would never make it out from the other side.

Roy Kerr came forward with a solution using a Kerr black hole — a rotating black hole. In Kerr’s solution, it’s actually possible to travel through the rotating black hole and miss the singularity at the center, so you could come out the other side. His solution is based upon the fact that everything in the universe is rotating — the stars, galaxies — so when the star collapses into a black hole, it’s likely that it’ll rotate too.

How to detect a wormhole?

Physicists propose that minute changes/deviations in the orbit of stars near supermassive black holes could be used to detect wormholes.

“In case, you’ve two stars, one on either side of the wormhole. The star on our side should feel the gravitational effects of the star that’s on the other side. The gravitational flux will go through the wormhole,” — says Dejan Stojkovic, a cosmologist and professor of physics at the University of Buffalo in New York

He even says, focusing on perturbations in the path of a star(S2) that astronomers have observed orbiting Sagittarius A. — observing the data collected over a longer period of time or developing techniques to track its movement more precisely would be fruitful in searching for wormholes.

There are many divisions of these wormholes based upon the time for which they exist(in case they exist in reality). For instance, permanent wormhole( that sticks around for a while); transient wormhole( that vanish fast); stable wormhole( that does not collapse if perturbed); static wormholes( that do not change with time); dynamic wormholes( that change with time), etc. The basic division of wormholes is as follows(note: we’ll particularly deal with traversable wormholes in this article):

• Intra-universe wormholes — connect two regions that belong to the same universe.
• Inter-universe wormholes — connect two regions that belong to two different universes.
• Non-Traversable Wormholes: If two particles entering from opposite sides of the wormhole meet somewhere in the tunnel, the wormhole is non-traversable.
• Traversable Wormholes — Scientists predict a possibility that after Big Bang, quantum fluctuations at the smallest scale might’ve created infinite traversable wormholes — linked through cosmic strings. And, in the initial moments of formation of our universe, the ends of these wormholes might’ve detached from each other, and these might be at great distances apart —say, billions. They could be everywhere, in case traversable wormholes exist in reality.
• Based on the circumference of the “mouth” relative to the Planck length, the wormholes can be further divided into microscopic or macroscopic.

Some physicists believe that microscopic traversable wormholes have a possibility of existence, and they might not require any exotic matter, but requiring electrically charged fermionic matter with just a small mass that it cannot collapse into a charged black hole.

Some scientists believe a wormhole might not only connect places separated by a gap of a billion light-years apart but the wormholes could also be used to travel in the past or future. But there are other physicists who believe time travel wouldn’t be possible using a wormhole. They believe it’s just a shortcut between two points in space. Stephen Hawking said that it’s a possibility to create wormholes, but these wormholes cannot be used for time travel. He further said, inserting a particle into it will destabilize it extremely fast to prevent its use — This is known as the Chronology Protection Conjecture.

Wormholes are intrinsically unstable. These wormholes collapse with the wink of an eye — so they’re not the right choice for travel. While exotic stabilization schemes have been proposed, there is yet no evidence that these can work or wormholes exist.

• Scientists predict, that in order to stabilise such wormholes we would need exotic matter. Exotic matter — This term is often used to describe matter that behaves differently from ordinary matter — Exotic matter is a hypothetical kind of matter that has both a negative energy density and negative pressure or tension that exceeds the energy density. All known forms of matter have positive energy density and pressures or tensions that are always less than the energy density in magnitude. Exotic matter(in case exists) can stabilise the wormhole to an extent that it could stay open for longer durations.

The vacuum of space-time is filled with quantum fields, the fundamental quantum building blocks that are responsible for the formation of other forces and particles that we experience, and these quantum fields have an intrinsic amount of energy. It’s possible to construct scenarios in which the quantum energy in a particular region is lower than its surroundings, making that energy negative at a local level. Such negative energy exists in the real world in the form of the — Casimir effect. — It involves two parallel conducting plates, energy outside the plates would be more than the energy inside the plates. Both the plates are tightly packed and are close to each other in a vacuum. Both the plates experience pressure which produces attraction. During these interactions, negative energy can be created, but on extremely small scales. The Casimir effect has been proven and tested.

Understanding the concept of negative mass/energy

The matter we know has positive energy and hence causes a positive curvature of space-time. A region with extreme negative curvature would be needed to stabilize a wormhole using matter with negative energy because this gives rise to a repulsive gravity.

Negative mass doesn’t exist in reality as it violates Newton’s 2nd and 3rd laws

F=ma (Newton’s second law)

When the mass is negative in the above equation, the same would be the case for force, that is to say, the force will also be negative. So, it’ll behave in a manner opposite to its original nature. In fact, negative mass reacts oppositely to all the forces. That is to say: When we push on negative mass it moves towards us. Similarly, once we try to pull it towards us, it drifts away from us.

Some scientists even believe that negative mass existed during the early moments of our Universe in equal amounts as there was positive mass. They further predict, that if presently the positive and negative matter particles exist in Universe, they must be forming a plasma.