Sometimes it seems that the stars are quite close and we can go to them and even settle on some planets. But space is huge, and man is limited - primarily by the laws of physics. Will we be able to reach at least a nearby star? Let's try to figure it out.
We live in an age of technological and scientific progress: space stations enter asteroid orbits, two probes entered interstellar space (even if they flew there for more than a decade), billionaires are building rockets and planning to engage in space tourism, we are creating breathtakingly sized particle accelerators on which hope to find more fundamental particles and interactions. But all this is happening not so far from us - in a broad sense. All this is done on Earth. The International Space Station is located just 408 kilometers above the surface of the planet, while the Moon - our satellite and the nearest celestial body - is almost one light second away from us, 384,400 kilometers from Earth.
Will we - as a species, as a civilization - ever literally reach other stars? Can we even travel to Proxima Centauri four light years away - ourselves, in high-tech spacecraft? Or can we just send probes and robots without leaving the solar system?
As science fiction writer Douglas Adams wrote: "The cosmos is huge." The cosmos is truly mind-bogglingly huge - we can't even fully imagine how much.
Take, for example, the same Proxima Centauri - the nearest star. As we mentioned above, it is located four light years from us. In order to understand what this means, you just need to understand in your head that in order to get there, you will have to fly to it at a constant speed of 300 thousand kilometers per second for four years. The fastest spacecraft ever launched by humans would take tens of thousands of years, or more precisely, 80,000 years for New Horizons to fly to Proxima Centauri.
Nonetheless, science fiction continues to reassure that we will one day make it to other stars. Captain Kirk and Spock travel from world to world on their warp drive, violating local political laws. Han Solo and Chewie can easily cross 12 parsecs, despite all the inconsistency. In Paul Anderson's novel Tau Zero, travelers fly on a Basserd-powered ship that collects matter from space and converts it into fuel, constantly accelerating and gradually approaching the speed of light. Examples can be listed for a very long time.
Science fiction seems prophetic at times. Take, for example, mobile (and first - cell) phones: in 1966, the Star Trek series featured a communicator that closely resembles the clamshell we are used to, while Motorola introduced the world's first cell phone only in 1973. But science fiction is still fiction. The authors of the works, no matter how close they make them to scientific data, bypass, and sometimes hide the main obstacles - like the laws of physics.
And we are not talking about some lengthy rules that do not apply to every moment in time. It's about the physical laws of the Universe, which will easily destroy all your castles in the air if you try to ignore them.Your short life depends on these laws, which requires an atmosphere, a certain pressure, temperature and much more.
Imagine that someone on Earth decided to send a spacecraft to another star, while obeying the laws of physics. So that everything is not initially sad, we will even lower the bar. Let it not be a massive starship with many passengers who can't wait to get to some resort planetoid.
And we are not talking about a squad of space troops equipped with futuristic weapons, which were sent to a nearby star to protect the colonists from some xenomorphs, giant beetles or gigantic worms.
Let's say we are talking about a small robotic vehicle that will be sent from Earth to Alpha Centauri. The fastest spacecraft ever launched is New Horizons, it flies at 58.5 thousand kilometers per hour. It will take this brave little probe about 80,000 years to reach Alpha Centauri.
For the most part, the fact is that we do not have a powerful enough power plant. The most promising option for today is the ion engine, which NASA used on its Dawn spacecraft. According to some assumptions, such an engine would help reach Alpha Centauri in about 19 thousand years after the gravitational maneuver around the Sun.
This would already allow us to save a considerable 60 thousand years - the time that we could spend on inventing new methods of acceleration, new engines. We could invent a functional Alcubierre engine or the same Basserd engine, for example, which means we could find ways to manipulate to a high degree not only matter, but also space-time itself.
However, aside from pure speculation and take a look at what is available to us today, the best way to get to a nearby star, let at least send a probe to it, is to use solar sails like those offered by Breakthrough Starshot. They can use sunlight and powerful ground lasers to accelerate.
Basically, the idea is to send small, lightweight vehicles on solar sails - they are much easier to accelerate. For example, the same Breakthrough Starshot initiative plans (or planned) to accelerate a whole series of such probes using an array of powerful ground-based lasers to 15-20% of the speed of light. Thus, these probes could reach Alpha Centauri in 20-30 years (not a bad result compared to 80 thousand years). Extrapolating from this idea, then on arrival, the probes could be programmed to create at least a communication network at the destination.
In addition, NASA has been testing a futuristic technology known as EmDrive for a while. True, to this day it is nothing more than an interesting concept and speculation, but if it ever manages to get EmDrive to work as intended - which means that in space there will be no need for any fuel to move - then you will still have to take into account the laws physics. Do not forget that it is impossible to move faster than light. To which the same NASA has another answer: the warp drive.
This engine is based on the concept, research and calculations of Miguel Alcubierre, who proposed it in 1994. If physicists and technicians someday succeed in translating this bold idea into reality, then such an engine will allow them to do exactly what often happens in science fiction: to compress space and move in it faster than light. But for now, it all comes down to concept art of hypothetical warp-powered ships and very complex mathematics. For the operation of such an engine, so-called exotic matter, possessing the properties of negative energy, is required - no scientist today can say what it is and where it comes from. And this, in turn, is a rather big obstacle on the way to the implementation of such a technology.
At what stage, in fact, are we today, speaking of the readiness to travel to another star, even the nearest one? In short: there is still no human on Mars, and we haven't been on the Moon since 1972. The concept of Breakthrough Starshot probes has remained a concept since 2017. If we talk about scientists, then astrobiologist Adam Frank of the University of Rochester (read an interview with him in the upcoming issue of our magazine) believes that we are unlikely to fly to the stars, but we will definitely colonize the solar system if we survive climate change. We can only wait and dream.