Journey to the end of the universe—measured one step at a time

Let’s reimagine the walk of all walks. Not just a neighborhood stroll or a long-distance trek, but a bold journey to the universe’s edge. This isn’t your average hike—it’s an epic quest across time and space. You’ll need far more than sturdy boots. Pack snacks, maybe a full interstellar buffet. Most importantly, you’ll need a way to break every known law of physics.

The cosmos doesn’t hold back its wonders. As you begin, imagine stars being born, their nuclear fires flaring to life. Their glow travels across vast clouds, lighting up entire stellar nurseries. You’ll pass the remnants of massive suns collapsing into black holes, dense regions where even light gets trapped. Whole galaxies smash into each other in slow-motion dances, their gravity stretching and bending spacetime like a living fabric. Time no longer behaves. It warps and twists in ways Einstein could barely predict.

This isn’t just a walk. It’s a passage through the grand theater of the universe. Each scene is a cosmic masterpiece—creation, destruction, and transformation on the largest scale. As you continue, the vastness becomes overwhelming. We are just flickers—small, brief lives in a place so immense, it challenges imagination. Still willing to keep going? Let’s take it step by step—hypothetically, of course.

There’s a major snag: walking in space doesn’t work. Not because of laziness—we’ll give you the benefit of the doubt—but because there’s no surface. No friction. No gravity to keep your feet planted. Astronauts don’t walk in space; they float. Your steps would just turn into awkward kicks in the void. You’d flail and spin, going nowhere fast.

To make this work, we’ll need to bend the rules. We’ll say your walking speed—about 3 miles per hour (5 kilometers per hour)—acts like rocket thrust. You're a self-contained treadmill, pushing forward endlessly, shrugging off the laws of motion and thermodynamics.

With that sorted, the journey continues through stunning and dangerous places. You’d pass through vast clouds where stars are born—dense, glowing regions called nebulae. Nearby black holes distort light, bend time, and rip apart anything too close. One misstep and you could fall into a gravity well with no return. Even the beauty comes with a price.

Walking the universe is no simple dream. It’s a challenge packed with physics-defying problems, deadly environments, and time-warping riddles. But even as a thought experiment, it reminds us how small we are—and how curious. Because the real adventure isn't just the walk itself. It’s daring to imagine it at all.

First, nebulae—vast clouds of gas and dust—may look dense and colorful in images, but they are actually incredibly sparse, with densities often lower than the best vacuums we can create on Earth. Walking through a nebula would be akin to trying to hike through a near-perfect void. Additionally, their sizes span light-years, making them incomprehensibly vast. Without a clear surface or medium to walk on, any progress would be limited to floating in a frictionless environment.

Stellar nurseries, where stars are born, are equally inhospitable. These regions teem with intense radiation from young stars and supernova remnants. Ultraviolet and X-ray radiation would be lethal to any unprotected human, frying biological tissue and electronics alike.

Furthermore, gravitational forces within these regions can be chaotic, as protostars form and interact dynamically, creating turbulent zones that would make stable footing impossible. Walking through such a place would require not just radiation shielding but also navigation systems capable of adapting to constantly shifting gravitational forces.

The dangers increase exponentially near black holes. A black hole’s immense gravity warps spacetime itself, creating a region known as the event horizon, beyond which not even light can escape. Approaching this region would subject a human to tidal forces so extreme they would be “spaghettified”—stretched and compressed simultaneously—long before reaching the event horizon.

Even if you could somehow avoid being torn apart, the lack of a physical path to walk on and the relativistic effects of time dilation would make movement and communication incomprehensible in human terms. For example, time near a black hole slows dramatically relative to distant observers, meaning a step forward could translate to years of elapsed time elsewhere in the universe.

Other stellar bodies like pulsars and neutron stars pose their own unique challenges. Pulsars emit intense electromagnetic radiation in focused beams, which would instantly incinerate any nearby object, let alone a human walker. Neutron stars, meanwhile, have gravitational fields so strong that a mere teaspoon of their matter weighs billions of tons. Walking near one would crush anything underfoot long before you could make a single step.

The universe is vast, and it’s growing bigger by the second. Thanks to cosmic expansion, the distance to the edge of the observable universe is approximately 46.5 billion light-years from Earth. Light, which zips along at 186,282 miles per second (300,000 kilometers per second), takes billions of years to cover that ground. Your walking pace? A bit slower.

To calculate your journey, let’s convert light-years into something more “walkable.” One light-year is roughly 5.88 trillion miles (9.46 trillion kilometers). Multiply that by 46.5 billion, and you’re looking at a total of 273 sextillion miles (that’s 273 followed by 21 zeros).

Now, divide by your 3 mph walking speed. Drumroll, please: it would take you approximately 10 quadrillion years to walk to the edge of the observable universe. That’s about 725 million times the age of the universe itself, which is a sprightly 13.8 billion years old. Even if you’re a speed walker, let’s be real: you’re not making it.

Here’s the kicker: the universe isn’t sitting still while you’re trekking. It’s expanding, and it’s doing so at an accelerating rate. This phenomenon, powered by dark energy, means that galaxies are zooming away from us faster and faster over time. In practical terms, the finish line keeps moving farther away.

Recent studies estimate the universe’s expansion rate, known as the Hubble constant, to be around 70 kilometers per second per megaparsec (a megaparsec is 3.26 million light-years). This means that for every additional megaparsec—or 3.26 million light-years—you go out into the universe, galaxies are receding 70 kilometers per second faster. The value of the Hubble constant, however, has been a hotbed of scientific debate.

Two main methods are used to calculate the Hubble constant, and they don’t quite agree.

One method involves observing the cosmic microwave background radiation, the leftover light from the Big Bang, using instruments like the Planck satellite. This method suggests a lower value, around 67.4 km/s/Mpc.

Another approach involves observing supernovae and Cepheid variable stars in nearby galaxies, yielding a slightly higher value of about 73 km/s/Mpc. Scientists such as Adam Riess, a Nobel laureate, and the SH0ES (Supernovae H0 for the Equation of State) team, have led the charge in refining these measurements.

Meanwhile, George Efstathiou and teams working with Planck data champion the lower estimates. The discrepancy—known as the "Hubble tension"—remains one of the biggest mysteries in modern cosmology.

Will the expansion of the universe ever slow down, halt, or even reverse? Most evidence suggests it’s unlikely. Observations of distant supernovae, conducted by researchers such as Saul Perlmutter, Brian Schmidt, and Adam Riess (all Nobel Prize winners for their work), revealed that the universe’s expansion is accelerating rather than decelerating. This acceleration is driven by a mysterious force called dark energy, which is thought to make up about 68% of the universe.

Dark energy acts as a repulsive force, counteracting gravity and pushing galaxies apart at ever-increasing speeds. While its nature remains elusive, dark energy’s dominance suggests the universe will keep expanding forever. Scientists have modeled several potential end scenarios:

Big Freeze: The most likely outcome, where expansion continues indefinitely, and galaxies, stars, and even atoms drift apart as the universe cools to near absolute zero.

Big Rip: If dark energy grows stronger over time, it could tear galaxies, stars, planets, and eventually atoms themselves apart.

Big Crunch: If gravity somehow overcomes dark energy (unlikely based on current evidence), the universe could reverse its expansion, collapsing back into a singularity.

Each of these theories builds on decades of research, from Edwin Hubble’s initial discovery of universal expansion in 1929 to the modern era of satellite observatories like the James Webb Space Telescope, which continues to refine our understanding of these cosmic forces.

Okay, so a stroll to the end of the universe is out of the question. But what about some starter walks closer-to-home? Let’s bring it down a few notches.

The Earth’s circumference at the equator is about 24,901 miles (40,075 kilometers). At 3 mph, walking nonstop, you’d circle the globe in 347 days. Add in time for sleeping, eating, and Instagramming your journey, and you’re looking at a solid year-plus adventure. Bonus: no space suit required.

But what if you want to minimize your steps? The shortest walking route around the Earth would be along the poles, where the circumference is slightly smaller at 24,860 miles (40,008 kilometers). Still, the difference is minimal—it might save you a day or two, but you’re still looking at nearly a year of walking.

Then there are the obstacles. Oceans cover about 71% of the planet, so unless you’re part amphibian, you’ll need a way to cross them. Some walkers have tackled this problem by island-hopping or taking ferries, but if you’re a purist, you might argue that hopping onto a boat disqualifies you.

Mountainous terrain adds another layer of difficulty. Walking across the Himalayas, for instance, would not only slow you down but also increase the physical toll. Choosing flat routes, such as deserts or plains, could help minimize fatigue and time, though the lack of water sources might pose a problem. If you’re serious about efficiency, you might opt for walking across relatively flat continents like Australia or Africa, avoiding steep climbs and frigid conditions.

Lastly, consider infrastructure. Urban areas with well-maintained roads and paths make for easier walking, whereas dense forests, swamps, or ice fields will undoubtedly slow you down. Ultimately, your route will depend on how much adventure you’re looking for versus how quickly you want to complete your circumnavigation.

The solar system’s edge, marked by the heliopause, lies about 11 billion miles (18 billion kilometers) from Earth. That’s where the solar wind from our Sun gives way to interstellar space. Walking this distance would take you roughly 419,000 years. Hope you like a long road trip.

The Milky Way galaxy spans about 100,000 light-years in diameter. That’s roughly 588 quadrillion miles (946 quadrillion kilometers). Walking across it at 3 mph would take you an almost incomprehensible 22 billion years. For perspective, that’s about 1.6 times longer than the age of the universe. Hope you brought good shoes.

Sure, these calculations are ludicrously impractical. But they highlight just how immense the cosmos is—and how small we are by comparison. Walking may not be the fastest or most efficient way to explore the universe, but as a metaphor, it’s a reminder of the human desire to journey, explore, and imagine.

Even if the destination is light-years beyond reach, the wonder of it all is closer than you think.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

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