The Grandfather Paradox / How Does Time Travel Work? / How to Travel Into the Future / 1. The Waiting Game / 2. Time Dilation / 3. Suspended Animation / 4. Traveling as a Time Tourist / 5. Changing History Through Time Dilation

The Grandfather Paradox

The grandfather paradox raises a troubling question: What would happen if you traveled back in time and killed your grandfather? In that scenario, your grandfather would indeed be dead, just as he would be if you killed him in the present. However, this creates an inconsistency—you would still exist, since you’ve already been born. Essentially, you cannot simply “unborn” yourself. This is a basic question when considering how does time travel work.

How Does Time Travel Work?

To travel back in time, you would need a superluminal vehicle, which is capable of moving faster than the speed of light. To reach your intended destination, you must aim it at specific coordinates in both space and time. It’s important to note that Earth and the solar system are constantly moving at high velocities through the cosmos. Fortunately, superluminal vehicles can match these speeds.

To successfully arrive at your destination without incident, precise timing is essential. As you plan your journey further back in time, the calculations become increasingly complex. To ensure safe arrival, it’s advisable to target the space surrounding Earth rather than the planet itself to avoid collision. Ultimately, you would need to use a smaller ship to land. You would approach Earth from outer space.

How to Travel Into the Future

There are several methods to travel into the future—specifically, five intriguing ways, explaining different aspects of how does time travel work.

1. The Waiting Game

The simplest method is to simply wait. All of us are constantly moving into the future at a steady pace of one second per second. While our mental states can influence how we perceive the passage of time, the rate at which time moves remains consistent for everyone. However, time does flow differently depending on gravitational conditions. For instance, at sea level, time passes more slowly than it does at the top of a mountain, where gravity’s influence is weaker.

2. Time Dilation

Time dilation offers another fascinating approach. If you’re inside a moving object, such as an airplane or a rocket ship, time slows down for you relative to those who remain stationary. If you were to accelerate that rocket ship to the speed of light, time would effectively come to a standstill for the occupants. Upon returning to the launch site after traveling at near-light speed, you would find that everyone left behind has aged significantly. If the journey lasted for many centuries, those back on Earth would have experienced the full passage of that time. Meanwhile, you remained unchanged. This principle is critical in understanding how time travel works in theory.

3. Suspended Animation

Another method involves suspended animation. Our bodies age and progress through time at a constant rate due to our metabolism and the Brownian motion occurring within our cells. By slowing down or halting these processes, one could enter a deep sleep and awaken decades or even centuries later, having aged not a moment.

Returning from Your Past After Time Travel
When it comes to returning to the future after time travel, there are two scenarios to consider, depending on your intentions. One involves traveling as a tourist. The other, aiming to change history.

4. Traveling as a Time Tourist

In this scenario, you commandeer a faster-than-light spacecraft. Direct it toward the approximate position in space where Earth will be after a millennium. Since you can’t perceive where Earth will be in a thousand years—because it hasn’t reached that point yet from your current perspective—you must rely on your knowledge of the timeline. If you traveled to the past using a faster-than-light spacecraft and then returned, you would find that, despite any previous changes, like hypothetically killing your grandfather, the course of history remains remarkably unchanged. Your grandfather would still be alive. You’d walk away with a fascinating story to tell.

5. Changing History Through Time Dilation

5. **Changing History Through Time Dilation**
Conversely, if you choose to travel from your past into the future via the time dilation method—perhaps by orbiting Earth at near-light speed—you would arrive in a timeline drastically altered by your actions. In this case, you might find yourself in a “beta universe” where your grandfather never existed. Consequently, neither would you. While you could observe this altered reality, it doesn’t pose a problem since you hail from a different branch of the multiverse (the “alpha universe”). Thus, even though you have no place in the beta universe, your past experiences in another universe endow you with a unique perspective. It’s a critical aspect when debating how time travel works across different realities.

By understanding and leveraging these methods, the concept of time travel transcends mere science fiction. It invites us to explore the mysteries of our existence and the nature of time itself. This essentially answers the question: how does time travel work?

Quantum time travel: The experiment to ‘send a particle into the past’

Time loops have long been the stuff of science fiction. Now, using the rules of quantum mechanics, we have a way to effectively transport a particle back in time – here’s how