Interstellar Travels: From Point A to Point B
By cosmic standards, the human race is very fragile and weak: an increase in temperature by 50 degrees, an increase in ionizing and ultraviolet radiation, the absence of water, a decrease in oxygen in the atmosphere - all this leads to its inevitable death. And there is nothing surprising in the fact that the human mind began to look for the possibility of the existence of other planets with favorable conditions for our lives in order to “deploy” a backup on them. However, if a planet is found, the question of transportation remains open. In today's post, we will talk about the methods and prospects of interplanetary and interstellar travel.
The technologies available to mankind today do not allow spacecraft to reach even the closest star in one human life. For example, the closest star to the Sun - Proxima Centauri - is located 4.2 light-years away. To Alpha Centauri (the closest star system to us, which includes Proxima Centauri) 39 trillion km. Modern spacecraft can overcome this distance in 70 thousand years. It becomes clear that none of the people can overcome such distances. Hence the need to find a new way to go on an interstellar journey.
Space engines today
Scientists are trying to develop new technologies for space engines, but not one of them, with the exception of the solar sail (about it below), is brought to the level of experimental samples.
Chemicals
The only proven technology to date is the rocket engine. Its simplified scheme is as follows:
Combustion in space is impossible due to the absence of a natural oxidizing agent, therefore the rocket must be equipped with it along with fuel. But, unfortunately, the efficiency of chemical rocket engines is extremely low (compared to other technologies), therefore, such an “engine” is no good for interstellar flights.
Nuclear
One of the projects that came closest to reality was Orion, a manned spacecraft project for long-distance space missions. Two options were created under the project: the first starship would have a total mass of about 40 million tons and would reach Alpha Centauri in 1800 years. Accordingly, he was conceived as a “ship of generations”. The second one weighed about 400,000 tons and theoretically should have reached its destination in 130 years. However, limiting the payload made the second, more attractive option unsuitable for manned flights.
Antimatter engine
The essence of this engine is the interaction of matter and antimatter, after which there is instant mutual annihilation with the release of a huge amount of energy. This energy will be enough to reach point B. But even the best of the theoretically possible engines operating on antimatter will require about ten railway tanks of fuel to accelerate to cruising speed and the same amount for braking at the destination. And here the question arises: why not work with this technology? The answer is simple: the cost of producing one gram of antimatter will cost tens of billions of dollars. In addition, the storage of antimatter is an unresolved scientific problem, since antimatter should not come into contact with any atom of ordinary matter for a certain amount of time, otherwise an explosion will occur.
Solar Sail
There are ideas for ensuring the movement of spaceships in which fuel is not used. They are called the solar sail (or light sail, or photon sail). Photons emitted by stars can exert pressureto physical objects. And if the ship is equipped with a large, ultra-thin and light sail, then the pressure of sunlight will be enough for its movement. In addition, such a sail can be influenced by other radiation sources, for example, a heavy-duty laser placed in near-earth orbit, which will be constantly directed to the ship. The catch is that a solar sail the size of Afghanistan is needed to move the shuttle .
Travel problems
The main problem of the trip is not even fuel or engine, but the amount of time it takes. Without the creation of technologies for immersing a person in a long state of suspended animation, it is necessary to send not a ship, but a small planet to the stars. However, there is a possibility that a completely different civilization will fly to the destination.
However, theoretical physicists do not give up. Moving in space with a speed exceeding the speed of light is impossible due to the fact that the mass of the subject will tend to infinity according to the formula E = mc 2. However, in accordance with the theory of relativity, the speed of light is maximum inside space-time; changing the space-time itself, you can move at unlimited speed. For example, the expansion of the Universe can occur at a speed much higher than the speed of light, but at the same time, the movement inside the Universe itself cannot exceed the speed of light.
Below we describe two ways with which theoretically it is possible to “cut off” the road and be in the right place and time.
Short road to the stars
The first method: through wormholes
This method is based on the assumption that there are “loopholes” in space, the existence of which was substantiated by Einstein and Rosen in 1935. Fiction lovers know these loopholes under the terms “space-time tunnels”, “wormholes”, “wormholes” and so on. These tunnels connect two points in the space-time continuum. They allow you to move from point A to point B.
Even if people someday can create a scientific and instrumental way of detecting space-time tunnels, and if their existence is confirmed experimentally, then it is possible to determine where in this universe this rabbit hole will lead, modern science does not represent even theoretically.
The very idea of moving with the help of such a tunnel attracts theoretical physicists not only as a way to get to the stars during the life of one generation, but also as a scientific and practical trick that circumvents the theoretical impossibility of time travel. Of course, the space-time tunnel cannot be a full-fledged time machine, since the traveler cannot choose the time at which he leaves at the other end of the tunnel. However, science cannot yet offer other possibilities.
What do wormholes look like? For humans and the devices at our disposal, they are invisible, because they do not emit in any known range. But, let's say, humanity has made one of the greatest discoveries in the history of basic sciences and discovered the entrance to the wormhole. How to use it? Alas, a ship from any material known to science today is theoretically incapable of traveling through a space-time tunnel - presumably, if such an object enters a wormhole, it will collapse. In 1988, American physicist Kip Thorne hypothesized that “exotic matter” is needed to travel through the space-time tunnel. Under such a frivolous name, physicists mean matter with “exotic” properties:
In addition to the shell, science needs to solve such a difficult task as preventing the exit from the tunnel from being blocked while a hypothetical ship is inside it. The fact is that a moving object will create a gravitational wave inside the tunnel, distorting the space, which can lead to premature closure of the exit from the tunnel. And this means that everything that appears at that moment inside it will simply disappear from our Universe.
The second way: in Bubble Alcubierre
In 1994, theoretical physicist Miguel Alcubierre proposedto circumvent the limitation of the speed of light by concentrating not on moving a person, but on moving part of the space itself. For this, it is necessary to create a space-time bubble around the spacecraft, which will exist independently of the rest of the universe.
The method of moving in space proposed by the physicist is the idea of compressing the space in front of the ship and stretching behind it. At the compression boundary, a so-called wave forms, which a hypothetical ship must ride. This wave does not move in space the ship itself, but a certain limited amount of undistorted space. In fact, a peculiar spatial bubble is created around the ship, whose boundaries are formed by the described distortions of the matter of space itself.
Thus, despite the fact that inside the bubble itself, light will always move faster than the ship, the bubble itself will move through ordinary space faster than light. Given the fact that the ship does not formally move inside the bubble, overloads during acceleration and braking will not act on it.
Alas, the possibility of creating such a technology is also associated with the use of exotic matter. And even if science can (for example, thanks to the Casimir effect ) realize an engine “capable of distorting space” in metal, then an enormous amount of energy will be required to move an object like a spaceship.
Conclusion
In order to create the technology of interstellar flights in the next 50-100 years, the best scientists need to methodically conduct scientific research, research and development work on a number of options for propulsion systems. The fact is that to this day no one can say in which direction one should move in order to create an "interstellar" engine. It is possible that one of the directions presented in this review will allow mankind to equip an expedition to the stars in the next century.
Most technologies today are practically not close to the technical implementation of all those ideas put forward by theoretical physicists, so in the near future it is unlikely to get to the stars, and especially with the help of “mole holes” or the Alcubierre bubble.
Non-lyrical digression
Why did we decide to post this post on our blog? Reading the welcome messages of people who come to Mail.Ru Group, you notice that most of us are interested in one form or another in the future - up-to-date technologies, trends, sci fi, finally. Many of us adore Kubrick's Space Odyssey, read and hoarsely discuss futurological predictions at dinner, and some make them up. We decided that it would be great to blog about the future from different angles and from different angles. Any ideas for the following posts? Thoughts on the prospects of interstellar travel? Waiting in the comments!