Chapter 1: The Allure of Black Hole Travel

We've all witnessed adventurous characters in films or TV series who navigate black holes (also known as wormholes) like commuters riding the subway: enter one end and pop out the other, having traversed immense distances in an instant. This portrayal, while entertaining, leads us to believe that such phenomena are grounded in reality. After all, we know that every depiction we see on screen is a precise reflection of life as we know it.

Consider the cinematic truths: bullets send people flying backward, defibrillators miraculously restart hearts, and DNA evidence unfailingly identifies the perpetrator. So, it stands to reason that black holes are our cosmic subway, offering delightful wormholes for us to explore without a second thought.

If black holes indeed exist for our amusement, let’s delve into how we might leverage them to travel further than our rudimentary chemical rockets, futuristic ion thrusters, or even those ambitious Muskmobiles could take us in countless lifetimes.

To embark on this cosmic recipe, we first need our main ingredient: an abundance of mass. This presents a challenge, as we’ll require several thousand sun-sized stars. But let’s imagine we can simply gather them from the cosmos as if they were ingredients on our kitchen table. Once we accumulate enough mass, we can compress it until the resulting gravitational field is potent enough to warp spacetime itself.

At this juncture, we might take a moment to savor a well-deserved drink. Personally, I find that a robust Australian Cabernet from Penfolds pairs nicely with the topic of black holes, though your preferences may vary. Perhaps a Chianti or, for the more adventurous, a glass or two of Chateau Carbonnieux alongside some lobster sautéed in white wine with a hint of ginger would suffice.

Now, we face the critical requirement that our pair of black holes must be entangled. Without this entanglement, the coveted Einstein-Rosen bridge remains out of reach. This is akin to the soufflé dilemma: you can’t simply smash two hardboiled eggs together and expect a fluffy soufflé. Instead, we must start with fresh eggs, separate the whites, and whisk until they form peaks—no peaks, no soufflé; no entanglement, no E-R bridge.

But how do we create a pair of entangled black holes? Let's explore some fundamental physics: to generate a pair of entangled photons, we can pass a single photon through a specialized prism, yielding two entangled photons, each at half the frequency of the original. These entangled photons serve to bewilder Einstein with their “spooky action at a distance.”

Thus, to fashion a pair of entangled black holes, we simply need to push our previously crafted black hole through a colossal prism.

Yes, there are practical challenges. For instance, even a modest black hole with twelve solar masses has a substantial event horizon—about 30 kilometers in diameter. Consequently, we’ll need to visit a specialty store with a credit card that can handle hefty purchases. Furthermore, we’ll require a pickup truck, as fitting such a prism into a family car or even a midsize SUV is impractical.

Specifically, if we wish to work with a 20,000 solar-mass black hole—large enough to ensure that tidal forces won’t obliterate any passengers—we’re looking at an event horizon of roughly 500 million kilometers in diameter. Thus, our prism must exceed this measurement, ideally around one billion kilometers across.

Let’s hope our pickup truck is up to the task! I suggest a Ford F650, but if you’re a fan of RAM trucks, feel free to choose that instead. Just steer clear of GM models—they often fall short of expectations. It might also be wise to call ahead and ensure that the local specialty store has a prism of sufficient size to avoid a fruitless trip.

Assuming we’ve procured our massive prism and returned home, it’s time to maneuver the black hole through it. I recommend donning rubber gloves to avoid any mishaps. In fact, using a broomstick might make this task easier—or, if you have a teenage daughter, you might repurpose one of her old boyfriends for this endeavor (teenagers often hide these under their beds, alongside forgotten candy wrappers).

Once we’ve successfully pushed the black hole through the prism, we should witness the emergence of a pair of entangled black holes. Between these two black holes lies, although invisible to us, the coveted Einstein-Rosen bridge!

Now, it’s time for another well-deserved glass of wine!

However, our journey is far from over. We need to relocate one of the black holes to a suitable destination; after all, having them next to each other isn’t practical. We certainly don’t want to enter one black hole in our kitchen only to exit in the downstairs bathroom!

Next, we must move one of the black holes to a more advantageous location. It would be imprudent to target somewhere like Cancun or even Tahiti, as a 10,000 solar-mass black hole would simply absorb the entire Earth and everything else in our solar system. Therefore, we must prepare ourselves to move both black holes.

Who knew creating an Einstein-Rosen bridge would require such effort? Maybe it should be dubbed the Awful-Lot-Of-Effort bridge instead!

After another fortifying glass of wine, we can commence moving our two black holes in opposite directions. This task may prove challenging; as Newton pointed out (and we all know how annoying those smarty-pants can be), relocating a 10,000 solar-mass black hole demands energy equivalent to its mass (thanks to Einstein’s e=mc² principle). So, it’s time to refuel our pickup truck and get moving!

Assuming we can afford the necessary energy to nudge our black holes in the desired directions, we’ll need to bide our time as they travel. Then, we’ll have to exhaust our credit cards once more to bring them to a halt at the intended locations. Curse you, Mr. Newton!

At this point, I strongly recommend another glass of wine, particularly since it may take millions of years to reach this stage. A well-aged Australian Shiraz would surely lift our spirits.

Now, after all our hard work, we finally possess a pair of entangled black holes separated by vast distances, with an Einstein-Rosen bridge silently connecting them. And since we’ve been prudent enough to create sufficiently large black holes, travelers using this interstellar subway system won’t have to worry (too much) about being spaghettified by the destructive tidal forces of smaller black holes.

Yet, our task is not complete. Time to finish the bottle and perhaps even open a new one.

We face a minor complication with our Einstein-Rosen bridge: the majority of solutions to the equations governing the E-R bridge indicate that the spacetime within it expands at a rate surpassing the speed of light. This means we can enter one black hole, but we’ll never reach the other side. Our journey will be constrained by the speed of light (approximately 300,000 kilometers per second), while the spacetime within the bridge expands even faster. To make matters worse, the more energy we expend attempting to traverse the E-R bridge, the faster it will expand due to our energy input.

The old adage “you can’t get there from here” certainly applies.

Perhaps it’s fortunate that we’ll be trapped within the perpetually expanding E-R bridge. This way, we’ll avoid the disappointment of remembering that nothing can escape a black hole’s gravitational grip. After all, that’s precisely why they’re called black holes! Nothing can ever escape. The mass of a black hole warps spacetime so severely that trying to flee in a straight line leads you right back to its core, as the gravitational field distorts spacetime into a geodesic. What do you think of that for a solution to the metric tensor?

It’s worth pondering why so many sci-fi films and shows overlook these inconvenient details.

Oh well, let’s power up the warp drive and head to the nearest liquor store before it closes. I just hope they understand Klingon...

Chapter 2: Black Hole Travel in Action

In the video "Travel INSIDE a Black Hole," we explore the fascinating yet complex phenomena of black holes and how they might allow for interstellar travel.

Meanwhile, "Can you travel to a new universe through a rotating black hole? - Ask a Spaceman!" delves into the intriguing possibilities and theoretical implications of traveling through rotating black holes.