About Time and Wormholes

All objects, like our computers and mice, are three-dimensional. Everything has length, width, and height. But there is another dimension, the dimension of time. Traveling through time means traveling through the fourth dimension of spacetime.

Consider a car driving in a straight line; it is traveling in a one-dimensional spacetime. Turning left or right adds a second spatial dimension. Bouncing up and down on a winding mountain road means traveling in three-dimensional space. But how can time travel be achieved? How can we find a path to the fourth dimension?

Science fiction movies often feature a giant, energy-consuming machine, a time machine, to open paths to the past or future. This concept might be a bit far-fetched, and reality might be vastly different, but the idea itself isn't entirely crazy.

Physicists have also been racking their brains over time tunnels, but we will explore this issue from another angle. We don't know if gateways to the past or future can exist within the bounds of natural law. In fact, we believe they might, and we've even given them a name—wormholes.

In reality, wormholes are everywhere, but they are so minuscule that they are invisible to the naked eye. Wormholes are incredibly tiny, existing in every nook and cranny of the universe and space. You might disagree, but please, read on.

Nothing is perfectly flat or solid. If you look closely, you'll find tiny holes and cracks everywhere (when viewed microscopically). This is a fundamental principle of physics, and it applies to time as well.

Imagine a billiard table. Its surface appears smooth and flat, but up close, it's not. Its surface is filled with cracks and tiny holes. Even a smooth object like a billiard ball has small cracks, fine lines, and tiny holes. This is undeniable in three-dimensional space, but believe me, it's also true in the fourth dimension. In time-space, there are also small cracks, fine lines, and tiny holes, constantly shrinking to the smallest possible scale, even smaller than molecules and atoms. What we are referring to is Quantum Foam, and wormholes exist within it.

In the quantum realm, tiny tunnels or shortcuts through spacetime constantly form, disappear, and reform. They actually connect two separate regions and two different points in time.

Unfortunately, these real time tunnels are only about 10^-33 centimeters in size, far too small to accommodate humans. But the concept of wormhole time machines is inspiring more ideas.

Some scientists believe it might be possible to capture one of these wormholes and enlarge it trillions of times, making it large enough for humans or even spacecraft to pass through.

Assuming sufficient energy or technology, it might be possible to construct a giant wormhole in the universe. It's not to say it's definitely feasible, but it would be an extraordinary machine, with one end near Earth and the other in distant interstellar space.

Theoretically, wormholes could have many other uses. If both ends were opened in the same location, with no distance separating them but existing at different times, a spacecraft could land near Earth and have traveled back to ancient times, perhaps when dinosaurs would have been fortunate enough to witness its arrival.

Wormholes are also a bewilderingly complex concept.

Hawking once devised a simple time experiment, but it didn't work. Why? Hawking believes one of the reasons is the well-known problem of paradoxes encountered during travel.

This scenario is a cosmologist's nightmare. Such a time machine would violate the fundamental laws governing the entire universe, namely causality, leading to a reversal of cause and effect, which is always contrary to our common sense. Otherwise, the universe would inevitably descend into chaos.

Therefore, we believe that circumstances will eventually arise to prevent paradoxes from occurring.

So, while microscopic wormholes do exist, and it might be possible to enlarge them someday, their fleeting existence makes them unusable as time machines.

This doesn't mean all time travel is impossible.

Satellites orbit the Earth. Every spacecraft has an extremely precise clock. Despite their accuracy, they gain about one-third of a nanosecond per day. The system must correct this deviation; otherwise, the subtle difference would disrupt the entire system, causing an error of about six miles per day in all GPS devices on Earth, leading to unimaginable chaos.

The problem isn't with the clocks; the clocks run fast because time itself passes faster there than on Earth. The reason for this peculiar phenomenon is Earth's immense mass...

Einstein realized that matter warps time, slowing it down like the slow-moving parts of a river. The heavier an object, the longer it warps time. This astonishing fact opens a door of hope for traveling into the future.

At the center of the Milky Way, 26,000 light-years away, lies the most massive object in the entire galaxy.

A black hole, with a mass equivalent to 4 million suns, is compressed into a single point by its own gravity. The closer you get to a black hole, the stronger its gravitational pull. At a certain point, even light cannot escape.

Black holes are hidden within a spherical region of darkness with a diameter of 15 million miles. Black holes like this have a powerful influence on time, slowing it down more than any other object in the Milky Way, making them natural time machines.

Imagine astronauts orbiting a black hole for five years, which equates to ten years passing on Earth. When they return to Earth, everyone on Earth will have aged five years more than them.

Of course, this isn't entirely feasible. Its advantage over wormholes is that it doesn't create paradoxes and doesn't destroy itself in a feedback loop, but it is indeed very dangerous.

Fortunately, there is another method of time travel, our last and most promising hope for building a true Time Machine.

Traveling through the fourth dimension for time travel will never be as simple as a walk in the park, but there is, in fact, an astonishing direct route. You simply need to move at an extremely, extremely fast speed, even faster than the high speed required to avoid being sucked into a supermassive Black Hole. The secret lies in another wondrous cosmic fact – there exists a universal speed limit – 186,000 miles per second, the well-known Speed of Light. It is the fastest speed in existence and one of the most authoritative scientific theorems.

Believe it or not, by moving at speeds close to the Speed of Light, you can travel to the future.

Similar instruments have already been built.

At CERN in Geneva, Switzerland, stands the world's largest particle accelerator. Deep underground, within a 16-mile-long circular pipe, a beam of trillions of tiny particles resides. The moment the machine starts, they accelerate from rest to 60,000 miles per hour. As more energy is added, these particles can accelerate continuously until the particle stream can orbit the pipe at a speed of 11,000 revolutions per second. This speed is extremely close to the Speed of Light, but it can never reach it, only 99.99% of the Speed of Light. Once they reach this speed, they can also travel through time.

Normally, these particles decay after 25 billionths of a second. But when accelerated to near the Speed of Light, their lifespan becomes 30 times longer. These particles are living time travelers.

It's really that simple. If we want to travel to the future, we just need to run faster, much faster. (Seeing this, I was speechless.)

The above references "Into the Universe with Stephen Hawking: Time Travel" from the Discovery Channel. Interested friends can go and watch it.

However, friends who read science fiction novels and watch science fiction movies don't need to take it too seriously. If you take it too seriously, it loses its fun. Reading is for enjoyment, so why get bogged down in academic issues.