Due to the mind-boggling distances and speeds required, interstellar travel would be extraordinarily difficult, if not impossible, for humanity to achieve. But new research highlights another challenge: communication breakdowns.
The star system closest to ours is alpha centauriIt’s over 4 light years away, so barring any fancy sci-fi technological revolutions over the next few centuries, if we want to spread across the stars, we’re going to have to do it “slowly”.
This means we need some form of propulsion that will get us close to that speed, but not exceed it. speed of light. But even if we achieve this ambitious goal, this futuristic mode of transportation will present all kinds of communication challenges, scientists explained in a paper recently uploaded to the preprint database. arXiv.
The first problem is that light itself can only travel at a limited speed. Although this does not seriously hinder communications near Earth, engineers already have to deal with this difficulty when communicating with probes sent throughout the solar system. For example, it takes a few minutes for messages to reach Mars, but hours to reach the outer planets. For longer-distance communications (such as the imaginary scenario of sending a spacecraft to a star system light-years away) this means it would take years for any message to reach the craft.
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But this is not the only obstacle. special relativity It teaches us that clocks are not synchronized in the universe. Passengers in the spacecraft will experience time dilation, and in this case, time will be extended. flow slower More than it would be for people on Earth. This impact is already measurable; For example, it must be taken into account when synchronizing signals from GPS satellites.
However, in the scenario we imagine, our passengers are moving as close to the speed of light as possible. This is absolutely essential for outward propagation. galaxy. Due to time dilation, travelers will not be able to experience journeys that take years; For them, it may only be weeks or months, depending on how quickly they move.
This time dilation will cause serious problems in coordinating messages that require a significant amount of mathematics. Although it’s frustrating, that’s not the hardest part. interstellar trip. Instead, spacecraft traveling at near the speed of light would be subject to periods of severe communications blackout.
In their paper, the researchers explored two hypothetical interstellar travel scenarios. In the first, rovers would continue to accelerate their spacecraft at a constant acceleration of 1 g; this was the same acceleration that the Earth naturally provided. gravity. This will take spaceships even closer to the speed of light.
Interestingly, this kind of constant acceleration event horizon. If Earth humans sent a message to the spacecraft, it would be limited to the speed of light. He would move rapidly towards the spaceship, but in the meantime the ship would move away from the signal. If the message was sent early enough, it would eventually reach the ship after a significant delay. But if they waited too long, the message would never arrive; The spacecraft would always be one step ahead of the message, and from their perspective, signals from Earth would eventually dim.
The second scenario presents different challenges. Researchers evaluated the condition of a spacecraft sent to a distant point. At first the spacecraft accelerates steadily, but in the middle of its journey it spins around and slows down so it does not fly past its target. This scenario will bring its own communication challenges.
First, the spacecraft would stop receiving messages. Soil After a certain period of time. These messages would eventually reach the spacecraft, but only after the craft reached its destination and stopped moving.
On the other hand, the spacecraft would be able to send signals to Earth, and these signals would always reach their targets. In addition, signals sent from the target (for example, an already established colony on a distant planet) always reached the spacecraft traveling in that direction.
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However, the signals sent from the spacecraft to its destination would not arrive until shortly before the craft got there, and all messages sent at that time would be piled up announcing the craft’s arrival.
These facts mean that communication with spacecraft at speeds close to the speed of light will be very difficult. All interstellar vehicles must operate independently because they will be disconnected from Earth after a certain period of time. If a problem arises, they will be able to tell people on Earth, but they will not get a response.
Additionally, distant colonies would not be aware that a spacecraft was being launched toward them until shortly before the ship arrived.
No matter what, interstellar travel will be a lonely journey.