Exploring the universe and traveling to the stars has always been a noble aspiration of humanity.
After thousands of years of development, humanity has reached the top of the food chain on Earth. People are increasingly curious about the vast universe. To better explore the universe and the stars, humanity hopes to break free from the Milky Way and venture into the greater cosmos.
So, can humans truly fly out of the Milky Way and explore the wider universe in their lifetime?
Humans hope to leave the Milky Way and enter the greater universe. (Illustrative image).
Whenever we look up at the stars, there is always a desire in our hearts to imagine leaving the Solar System and exploring the greater universe. Recently, American astronomers conducted a simulation experiment to estimate the time required for a spacecraft to escape the Milky Way at superluminal speeds.
The vast Milky Way seems to have become an invisible cage, trapping us inside, and no matter how long we spend in our lives, we cannot break free. According to the latest observational data, the overall diameter of the Milky Way may reach up to 150,000 light-years, and our Solar System is relatively close to the edge of the Milky Way.
Therefore, based on the current size of the Milky Way, even if we used a spacecraft that travels at the speed of light, after reaching the edge of the Solar System, we would still need to travel approximately 40,000 light-years to truly escape the Milky Way’s limits.
This figure is quite disheartening, and it seems that no matter how hard we try, we cannot escape this colossal cage. As one of the pioneering vessels in humanity’s journey to explore space, Voyager 1 is currently one of the farthest spacecraft from Earth.
In reality, leaving the Milky Way is not impossible. However, to achieve this goal, we need to address the issue of gravity and significantly increase our travel speed to escape the gravitational pull of celestial bodies.
With the current level of technology, humans can escape Earth at a suborbital speed, which is the minimum speed required to overcome Earth’s gravitational force. Suborbital speed can be classified into several levels. Generally, the speed reached by an aircraft is the first suborbital speed, which allows the aircraft to maintain an orbit around the Earth. Satellite launches and space missions can achieve second suborbital speeds, allowing them to escape Earth’s gravity and travel into further orbits.
To escape the gravitational pull of larger mass objects, we need higher suborbital speeds. (Illustrative image).
According to calculations and practical data, to leave Earth and break free from its gravitational shackles, a spacecraft must reach a second suborbital speed. However, the speed of light is the fastest speed in the universe that we currently know, approximately 300,000 km/s, referred to as the sixth suborbital speed.
In contrast, the current Voyager 1 spacecraft has reached a third suborbital speed. If it follows the established orbital model, it may achieve its goal of flying out of the Solar System. However, this speed is far from sufficient to escape the gravitational pull of the Milky Way.
To break free from the gravitational pull of larger mass objects, we need even higher suborbital speeds. According to calculations, the orbital speed of the Solar System is about 230 km/s, while the escape velocity of the Milky Way is as high as 537 km/s.
To truly leave the Milky Way and escape its gravitational influence, scientists have proposed the concept of a fourth suborbital speed. They believe that it is necessary to achieve at least a fourth suborbital speed to fly out of the Milky Way. This means that the spacecraft itself must travel at least 317 km/s. Taking the Parker Solar Probe, the fastest spacecraft currently, as an example, its speed has reached an astonishing 200 km/s. Although this speed exceeds Voyager 1’s third suborbital speed, it still falls short of what’s required to leave the Milky Way.
The speed of Voyager 1 is still far from the required speed to leave the Milky Way. (Illustrative image).
Besides speed, humanity also faces immense challenges. Compared to the rapid changes occurring among celestial bodies in the universe, our lifespan is merely a few decades, making time a significant obstacle to escaping the galaxy.
Taking the fastest Parker Solar Probe as an example, it takes about 1,500 years to travel one light-year in space. Based on this speed calculation, assuming the state of the universe remains unchanged, it would take nearly 7,000 years to reach the nearest star system to us.
However, the reality is that most galaxies in the universe are receding at different rates, meaning their distances from us are constantly increasing. This change occurs faster than the speed of light, so in reality, it would take even longer to reach our destination.
Considering that our goal is to leave the Milky Way, traveling at the speed of light from our Solar System would take approximately 40,000 years to arrive. In other words, even if we reach the sixth suborbital speed, which is the speed of light, we would still need 40,000 years to leave the Milky Way.
For the Parker Solar Probe, even if it is fortunate enough to avoid the risk of being torn apart by a planet’s gravitational force during its flight, it would still take hundreds of thousands of years to escape the galaxy. By then, it remains unknown whether humanity will still exist.
Most galaxies in the universe are receding at different speeds.
Although some scientists have proposed the concept of superluminal speeds, we must acknowledge that this remains an extremely complex and challenging issue. According to their simulation studies, when speeds reach 2,083 times the speed of light, we could reach the Kuiper Belt in just ten seconds and take just over ten hours to reach the star that is only 4.2 light-years away from us.
However, at this speed, it would still take at least 96 years to fly out of the Milky Way. Although this time has significantly decreased compared to tens of thousands of years ago, it is still a number that is nearly unattainable within a single human lifetime.
In other words, even if technology reaches a certain level, leaving the galaxy is still not a task that can be accomplished within a single generation.
