Humans have always dreamed of traveling through space, fascinated by unknown worlds and the desire to explore distant galaxies. The greatest obstacle to space travel is the vast distances. In this article, we address the immense distances in space and the time required to reach distant stars and objects using spacecraft at various speeds. To illustrate how vast space is, we calculated how long it would take to reach some celestial objects using a car and the fastest spacecraft humanity has built. We also calculated how far we could travel at the speed of light. Even though the speed of light is not enough to travel far into space, we turned to the science fiction series Star Trek, where spacecraft achieve speeds much faster than light using the fictional Warp drive.
A Car Constantly Traveling at 130 km/h (80 mph)
Let's imagine that we could travel through space in a car. In many countries around the world, the maximum allowed speed on highways is 130 km/h or 80 mph, so we used this speed for our calculations. A car could eventually reach the Moon, taking about 123 days to get there. To Mars, the journey would take a long 48 years when it is closest to Earth and up to 352 years when it is at its farthest distance. The New Horizons space probe took 9.5 years to reach Pluto, a dwarf planet on the edge of the solar system. In a car, this trip would take at least 3,750 years. Proxima Centauri is the closest star to Earth, which is 4.24 light-years away. It would take 35 million years to reach this star in a car.
Pluto Colorful Composition. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Voyager 1 – The Fastest Human-Made Spacecraft Traveling Through Space
Voyager 1, launched way back in 1977, is the fastest spacecraft ever created by humanity, traveling through space at a speed of approximately 61,000 km/h (about 38,000 miles per hour). However, Voyager 1 is not the fastest spacecraft ever built. The Parker Solar Probe reaches speeds of 700,000 km/h (approximately 430,000 miles per hour), but that speed is only achieved when it passes closest to the Sun, using the Sun's gravity to accelerate. On the other hand, Voyager 1 travels through space and is currently the most distant human-made object.
Voyager 1 Entering Interstellar Space Artist Concept. Credits: NASA/JPL-Caltech
So, how fast is Voyager 1, and how long would it take to cover vast cosmic distances? Voyager 1 could reach the Moon in about 6 hours at its current speed. From Earth to Mars would take an acceptable 37 days when Mars is closest to Earth, and the journey to distant Pluto would take eight years. To reach Proxima Centauri, the nearest star to Earth, would take a staggering 75,000 years. From these calculations, our current technological capabilities are barely sufficient for exploring the solar system and only without a human crew. Perhaps in the foreseeable future, we can send a crew to Mars, the planet closest to Earth. For now, our technology is not advanced enough to send probes to the nearest stars.
Traveling at the Speed of Light
The speed of light in a vacuum is approximately 299,792 km/s (about 186,282 miles/s), equivalent to roughly 1.08 billion km/h (about 671 million miles per hour). According to the laws of physics, as described by Einstein's theory of relativity, this is the highest possible speed.
A Cauldron of Stars at the Galaxy Center. Credit: NASA/JPL-Caltech
According to relativity, it is theoretically impossible for objects with mass, such as spacecraft or humans, to travel at the speed of light. As an object's speed increases, its mass effectively grows, requiring ever more energy to accelerate further. To accelerate a massive object to the speed of light would require infinite energy, making such travel impossible according to current scientific understanding.
Let's disregard the laws of physics for a moment and assume that traveling at the speed of light is possible. If humanity possessed a spacecraft capable of traveling at light speed, how far could we go in space? Would the entire universe then be within our reach? Here's what we calculated.
At the speed of light, it would take just 1.28 seconds to reach the Moon, 3 minutes to get to Mars, and 4 hours to reach Pluto. The speed of light would be ideal for fast travel within the solar system. But is light speed sufficient for interstellar travel? Proxima Centauri, the closest star to us, is 4.24 light-years away. This means that light takes 4.24 years to reach Proxima Centauri, and the return trip would take the same time. Such journeys might be possible with human crews, but the passengers on such a spacecraft would have to spend a significant portion of their lives in space.
There are approximately 50 stars within a radius of about 15 light-years from Earth. A spacecraft capable of traveling at the speed of light would allow exploration of this part of space, most likely with unmanned probes. We can conclude that light speed is sufficient for traveling to the nearest stars, but traveling to the far reaches of our Milky Way or other galaxies would be impossible due to the time such journeys would take.
For example, the nearest black hole, V616 Monocerotis, is 3,300 light-years away from Earth, so it would take us just as many years to reach it at light speed. Clearly, such a journey is not feasible or sensible.
To reach the center of our galaxy, it would take us 26,000 years, and a journey to Andromeda, the nearest spiral galaxy, would take a staggering 2.537 million years.
Faster-Than-Light Travel
In the globally famous science fiction franchise Star Trek, spacecraft travel at speeds much faster than the speed of light. This is made possible by the fictional warp drive. The warp drive in Star Trek allows starships to travel faster than light by creating a "bubble" that warps space-time around the ship. This way, the ship doesn't violate the law of traveling faster than light within space but moves space-time around it. Although this drive is fictional, scientists have developed a theoretical model of a drive based on a similar idea.
The Alcubierre Drive is a theoretical concept that proposes a method for faster-than-light travel by warping space-time. According to this idea, a spacecraft wouldn't actually travel faster than light, but it would create a "bubble" around itself that contracts space-time in front of the ship and expands it behind. This way, the ship would effectively move through space-time while remaining stationary relative to the space within the bubble. For this to work, the theory suggests the need for exotic matter with negative energy, which scientists have yet to find or create. You can read more about the Alcubierre Drive here.
Star Trek and Warp Drive
While scientists haven't yet solved all the obstacles to building an Alcubierre Drive, let's return to Star Trek and warp-speed travel. In Star Trek, starships traveled using warp drives. As technology advanced, warp speeds became faster. Warp 1 equals the speed of light, Warp 2 is ten times faster than the speed of light, Warp 3 is 39 times faster, and so on. We chose three famous starships from Star Trek for which data on their maximum speed is available. Although the starships in the series couldn't continuously travel at maximum warp, for the sake of our calculations, we'll use the maximum speeds they are capable of.
The Starship of Captain Jonathan Archer from Star Trek: Enterprise
This ship has the designation NX-01. It is the first ship in the Enterprise series, crucial in exploring space and laying the foundation for the future Federation. Its maximum speed is Warp 5, which is 214 times faster than the speed of light. With this Enterprise, reaching Pluto from Earth would take only a minute and a half. It would take seven days to reach the nearest star, Proxima Centauri, and 15 years to reach the nearest black hole, V616. Reaching the center of our galaxy would take a whopping 121 years, and it would take an incredible 11,853,271 years to travel to Andromeda.
This ship would cover about 17 light-years at maximum speed in 30 days. Within 17 light-years of Earth, there are approximately 50–60 star systems with about 100 stars.
The Starship of Captain Jean-Luc Picard from Star Trek: The Next Generation
Captain Jean-Luc Picard's starship from Star Trek: The Next Generation was called USS Enterprise (NCC-1701-D). It was the fifth ship in the line to bear the name Enterprise and is one of the most famous ships in the Star Trek franchise. Its maximum speed is Warp 9.6, which is 1,909 times faster than the speed of light.
Picard's Enterprise would reach Proxima Centauri in just 19 hours and 28 minutes, and it would take about one year and nine months to reach the black hole V616 Monocerotis. Reaching the center of our galaxy would take 13 years and seven months, and traveling to Andromeda would take 1,328 years.
In 30 days, this ship could cover 156 light-years. Within a radius of 156 light-years from Earth, there are approximately 40,000 to 60,000 stars.
The Starship of Captain Kathryn Janeway from Star Trek: Voyager
The starship of Captain Kathryn Janeway from Star Trek: Voyager is called USS Voyager (NCC-74656). It is an Intrepid-class ship known for its mission in the Delta Quadrant. Its maximum speed is Warp 9.975, which is 5,126 times faster than the speed of light. Voyager would reach Proxima Centauri in just 7 hours. It would take seven months to reach the black hole V616 and five years to reach the center of our galaxy. Andromeda is still out of reach, and it would take this starship 495 years to get there.
At maximum speed, in 30 days, this starship could cover 421 light-years. Within a radius of 421 light-years from Earth, there are approximately 1.25 million stars.
The Future of Space Travel
The vastness of space is a limiting factor for space travel. The spacecraft we currently build can reach distant parts of the solar system and objects like Pluto in 10 or more years. Interstellar travel is currently unfeasible, as it would take our fastest spacecraft 150,000 years to reach the nearest star and return. For now, we are confined to traveling within our solar system. For interstellar travel, our technology would need to reach at least 20% of the speed of light so a probe could reach the nearest star in about 20 years. Plans for building such a spacecraft that would accelerate using powerful lasers from Earth exist, but we would have to wait another four years for the data such a probe would gather.
Milky Way galaxy and the neighboring Andromeda galaxy. Credit: NASA Goddard
To successfully explore the nearest stars, we would need a speed close to the speed of light. This would make about 50 stars within 15 light-years of Earth accessible for scientific research, although such journeys would be very long, and it would take several decades to receive data from the probes. Space is so vast that even spacecraft capable of traveling at the speed of light would only allow us to explore the nearest stars.
If the speed of light is impossible to achieve and faster-than-light travel isn't feasible, the likelihood of ever encountering an advanced extraterrestrial civilization is extremely low. The universe may be a whole of life, but the immense distances in space make contact between civilizations nearly impossible, at least in our part of the universe. The exception could be stars within star clusters, such as globular clusters, where stars can be as close as 0.1 light-years apart. However, even such a small distance is incredibly large for a civilization like ours. Voyager 1 would take about 1,769 years to reach a star that is 0.1 light-years away.
Are Faster-Than-Light Travels Possible?
Theoretically, faster-than-light travel is fascinating, but according to current scientific laws, especially Einstein's theory of relativity, it is impossible for objects with mass to move faster than light. However, several theoretical ideas suggest the possibility of "bypassing" this limitation:
Alcubierre Drive
This concept, proposed by physicist Miguel Alcubierre in 1994, is based on creating a "bubble" around a spacecraft, within which space-time remains intact. The bubble would contract space in front of the ship and expand it behind, effectively allowing for faster-than-light travel. The spacecraft would not actually move through space faster than light, but space around it would be warped. The problem is that this would require the use of exotic matter with negative energy, which has not yet been proven or discovered.
Wormholes
Wormholes are hypothetical tunnels through space-time that could connect distant points in the universe. Traveling through a wormhole could allow for an effective "shortcut" through space, meaning that a traveler would not need to pass through the entire distance between two points.
Although wormholes are mathematically possible within general relativity, there is no evidence that they exist or would remain stable long enough for practical use. Additionally, their maintenance could require exotic matter.
Tachyons
According to theory, tachyons are hypothetical particles that always move faster than light. However, their existence has not been proven. If tachyons did exist, they would violate some fundamental laws of physics, such as causality, which could lead to paradoxes, such as traveling backward in time.
Warp Drive
In Star Trek, warp drive uses a concept similar to the Alcubierre Drive, where the spacecraft doesn't travel faster than light in the traditional sense but instead warps space-time around it. Although fictional, this idea has inspired real-world physicists to explore the possibilities of warping space-time.
Quasicrystal Spaces or Higher Dimensions
In some theories, like string theory, the universe has more dimensions than we can perceive. Traveling through higher dimensions could allow for "shortcuts" in three-dimensional space. This idea is still highly speculative but theoretically intriguing.
Although these ideas are interesting, most of them are still in the realm of theory and science fiction. Currently, we do not have the technology or materials needed to realize faster-than-light travel, but ongoing research into exotic matter, space-time, and quantum physics continues to offer new possibilities for the future.