Nothing fascinates me more than the concept of a wormhole in spacetime. And I can explain why with one sentence:

Human beings are tormented with an everlasting itch for things remote.

For that reason, the open road always softly calls. A wormhole – specifically a traversable wormhole – is a speculative passage through spacetime that can connect one part of the universe with another. Meaningful human space exploration, and the ability to colonize other parts of the galaxy, rests solely on the necessity for the existence of shortcuts through the fabric of spacetime.

Why? Because space is big. The nearest exoplanet to Earth is Proxima B, which orbits the star Proxima Centauri, located ~4.22 light-years away. In 2016, NASA’s Juno probe reached speeds up to ~165,000 mph (~0.0246% the speed of light) as it entered Jupiter’s obit, making it the fastest spacecraft ever built. At that speed, it would take Juno ~17,154 years to reach Proxima B. Of course, Juno was a small unmanned probe, and there is currently no feasible way to accelerate (or decelerate) a spacecraft large enough to carry human beings at that speed. Not to mention the extensive laundry list of currently unsolvable issues associated with preserving human life for many millennia during an interstellar voyage between the stars.

Wormholes could be the solution to the problem – that distant space exploration via propulsion methods doesn’t even qualify as futile. Unfortunately, wormholes have never actually been proven to exist in any capacity. However, mathematically speaking, Einstein’s general relativity predicts that wormholes theoretically COULD exist, and do not violate the fundamental laws of physics (though they are not likely to occur naturally). He’s saying there’s a chance!

So… what’s missing? Let’s get into specifics with a clever trick question: how much energy would it take to open and stabilize a traversable wormhole? The answer is simple – none. Unless for some reason you’re quantifying using absolute values. That’s because to open and contain a wormhole, tremendous amounts of negative energy would be required because its properties would need to be gravitationally repulsive.

The Einstein field equations comprise the set of 10 equations in Einstein’s general theory of relativity that describe the fundamental interaction of gravitation as a result of spacetime being curved by mass and energy. The strength of the gravitational attraction between two objects represents the amount of gravitational energy in the field which attracts the objects towards each other (Einstein was smart). Now, imagine a tunnel through spacetime, where intuitively, any and all parts of the walls would contain some form of mass and energy. If so, the hypothetical tunnel would instantaneously become unstable and collapse on itself before even a single photon could traverse the passage.

Hence the need for some form of exotic matter that exhibits negative gravitational mass and energy density properties to combat the inward force from the distorted fabric of spacetime. Presently, it’s not entirely clear if such matter exists in the universe. But consider this: a universe in which positive energy dominates should theoretically condense and eventually collapse under its own weight. But our universe is actually expanding, indicating that negative energy dominates the cosmological tug-of-war!

The expansion of our universe is attributed to the unknown phenomenon called dark energy, which is believed to account for 68% of all mass-energy in the universe. The strange form of energy could, in fact, be the missing particle needed to act as a gravitational repellent to stabilize a wormhole. However, while dark energy may somehow occur naturally – detecting, gathering, and introducing it deliberately is well beyond our technological capabilities. In theory, only a Kardashev scale Type II + civilization would comprehend such complexity and could possess such technology (for reference, Earth’s power output is believed to be 0.7279 on the Kardashev non-linear scale).

Astronomy is such a challenging science because you cannot recreate a celestial object in a lab and study its mannerisms directly. However, we’ve got to start somewhere – but where?

How about with black holes? Awareness of black holes has been around for many decades, I even recall learning of the mysterious objects as early as elementary school. Now, direct visual evidence has been produced to further confirm their existence. An incredibly massive and dense region of space that exerts a powerful gravitational force such that not even light can escape its pull. What’s intriguing is that a black hole may not be a one-way ticket to nowhere! That is, if both Hawking radiation and the law of conservation of quantum information theories are accurate.

Enter the black hole paradox. Stephen Hawking famously predicted and provided a theoretical argument stating that, despite consuming large amounts of energy and information, black holes will shed mass and eventually evaporate over incredibly long periods of time. But how can that be? The law of conservation of quantum information states that information exists forever, it can never be erased. If a black hole consumes information and nothing can escape – and will eventually shrink and evaporate – yet information cannot be erased or destroyed – where does all the energy and information go?! It must exit through a white hole in another part of the universe, or in another universe altogether.

The far lesser known white hole is essentially the opposite of a black hole. A hypothetical region of spacetime which cannot be entered from the outside, yet matter, energy, and information can escape from within. If a black hole has a corresponding white hole (or multiple white holes) somewhere in the universe, a wormhole would be their bridge, indicating that shortcuts through spacetime do exist.

But again, we can’t exactly travel to a black or white hole and take a peek at what’s going on inside. So instead of examining the large and distant, how about the small and present? Quantum mechanics, and specifically, quantum entanglement may hold the key. Some physicists theorize that wormholes already exist, appearing and disappearing all around, but are just too small to observe. Quantum mechanics is the fundamental theory of nature at its smallest scale of energy levels. It rose to popularity due to the inability to reconcile observations with classical physics.

Entanglement is a bizarre and exciting phenomenon that occurs when particles interact or share spatial proximity, such that their quantum state cannot be described independently, even when separated by large distances. If you observe a particle in one place, its entangled particle counterpart – even if light years away – will instantly change its properties, as if the particles are connected by a mysterious communication channel. Wild! Until recently, entanglement had only been observed in tiny objects such as atoms, but now, new studies report seeing entanglement in devices almost visible to the naked eye. Therefore, the unanswered question is – how far can it scale? Unclear. But further identifying a link between theoretical wormholes and quantum entanglement could give a concrete realization of the idea that wormhole geometry and entanglement are correlated manifestations of the same physical reality.

I’ll be the first to admit, it’s certainly unreasonable to expect wormhole travel to exist anytime soon. The necessary advancements in knowledge of exotic matter, energy inverters, supergeometry, and quantum math will likely require generations of innovation. And even once the math checks out, there will be monumental hurdles with engineering the hardware. BUT it’s also unreasonable to call it impossible.

There were times in human history when the brightest minds on the planet thought the earth was flat, that the atom was the smallest particle, that mankind would never take flight. All disproven through advancements in research and technology. STEM (science, technology, engineering, math) has become an extremely prominent part of today’s education. As a result, the youth of today will be well-equipped to rethink the “impossible”, and I am wildly optimistic and genuinely excited about the scientific discoveries of the future.

Remember – man would have never discovered new oceans without the courage to lose sight of the shore.

Wormholes are a gateway to the stars. An opening to countless exotic and potentially habitable worlds, quietly waiting in silence for the first courageous explorers to pay a visit.