The solar system has not been of particular interest to science fiction writers for a long time. But, surprisingly, our “native” planets do not cause much inspiration for some scientists, although they have not yet been practically explored.
Having barely cut a window into space, humanity is torn into unknown distances, and not only in dreams, as before.
Sergei Korolev also promised to soon fly into space "on a trade union ticket", but this phrase is already half a century old, and a space odyssey is still the lot of the elite - too expensive. However, two years ago, HACA launched a grandiose project 100 Year Starship, which involves the gradual and long-term creation of a scientific and technical foundation for space flights.
This unprecedented program should attract scientists, engineers and enthusiasts from all over the world. If everything is successful, in 100 years humanity will be able to build an interstellar ship, and we will move around the solar system like trams.
So what are the problems that need to be solved to make stellar flight a reality?
TIME AND SPEED ARE RELATIVE
Strange as it may seem, the astronomy of automatic vehicles seems to some scientists to be an almost solved problem. And this despite the fact that there is absolutely no point in launching automata to the stars with current snail speeds (about 17 km / s) and other primitive (for such unknown roads) equipment.
Now the American spacecraft Pioneer 10 and Voyager 1 have left the solar system, there is no longer any connection with them. Pioneer 10 is moving towards the star Aldebaran. If nothing happens to him, he will reach the vicinity of this star ... in 2 million years. In the same way crawl across the expanses of the Universe and other devices.
So, regardless of whether a ship is habitable or not, to fly to the stars, it needs a high speed close to the speed of light. However, this will help solve the problem of flying only to the nearest stars.
“Even if we managed to build a star ship that could fly at a speed close to the speed of light,” K. Feoktistov wrote, “the travel time only in our Galaxy will be calculated in millennia and tens of millennia, since its diameter is about 100,000 light years. But on Earth, much more will pass during this time.
According to the theory of relativity, the course of time in two systems moving relative to one another is different. Since at large distances the ship will have time to develop a speed very close to the speed of light, the difference in time on Earth and on the ship will be especially large.
It is assumed that the first goal of interstellar flights will be alpha Centauri (a system of three stars) - the closest to us. At the speed of light, you can fly there in 4.5 years, on Earth ten years will pass during this time. But the greater the distance, the greater the difference in time.
Remember the famous Andromeda Nebula by Ivan Efremov? There, flight is measured in years, and earthly ones. A beautiful story, to say the least. However, this coveted nebula (more precisely, the Andromeda galaxy) is located at a distance of 2.5 million light years from us.
According to some calculations, the astronauts' journey will take more than 60 years (according to starship hours), but an entire era will pass on Earth. How will the space "Neanderthals" be met by their distant descendants? And will the Earth be alive at all? That is, the return is basically meaningless. However, like the flight itself: we must remember that we see the Andromeda galaxy as it was 2.5 million years ago - so much of its light reaches us. What is the point of flying to an unknown target, which, perhaps, has not existed for a long time, in any case, in its former form and in the old place?
This means that even flights at the speed of light are justified only up to relatively close stars. However, vehicles flying at the speed of light live so far only in a theory that resembles science fiction, though scientific.
A SHIP THE SIZE OF A PLANET
Naturally, first of all, scientists came up with the idea to use the most efficient thermonuclear reaction in the ship's engine - as already partially mastered (for military purposes). However, to travel in both directions at a speed close to the speed of light, even with an ideal design of the system, the ratio of the initial mass to the final mass is not less than 10 to the thirtieth power. That is, the spaceship will look like a huge train with fuel the size of a small planet. It is impossible to launch such a colossus into space from Earth. Yes, and collect in orbit - too, it is not for nothing that scientists do not discuss this option.
The idea of a photon engine using the principle of matter annihilation is very popular.
Annihilation is the transformation of a particle and an antiparticle during their collision into any other particles that are different from the original ones. The most studied is the annihilation of an electron and a positron, which generates photons, the energy of which will move the spaceship. Calculations by American physicists Ronan Keane and Wei-ming Zhang show that, based on modern technologies, it is possible to create an annihilation engine capable of accelerating a spacecraft to 70% of the speed of light.
However, further problems begin. Unfortunately, using antimatter as a rocket fuel is very difficult. During annihilation, flashes of the most powerful gamma radiation occur, which are detrimental to astronauts. In addition, the contact of positron fuel with the ship is fraught with a fatal explosion. Finally, there are no technologies yet to obtain enough antimatter and store it for a long time: for example, an antihydrogen atom "lives" now for less than 20 minutes, and the production of a milligram of positrons costs $25 million.
But, let's assume, over time, these problems can be resolved. However, a lot of fuel will still be needed, and the starting mass of a photon starship will be comparable to the mass of the Moon (according to Konstantin Feoktistov).
BROKEN THE SAIL!
The most popular and realistic starship today is considered to be a solar sailboat, the idea of which belongs to the Soviet scientist Friedrich Zander.
A solar (light, photon) sail is a device that uses the pressure of sunlight or a laser on a mirror surface to propel a spacecraft.
In 1985, the American physicist Robert Forward proposed the design of an interstellar probe accelerated by microwave energy. The project envisaged that the probe would reach the nearest stars in 21 years.
At the XXXVI International Astronomical Congress, a project was proposed for a laser spacecraft, the movement of which is provided by the energy of optical lasers located in orbit around Mercury. According to calculations, the path of a starship of this design to the star Epsilon Eridani (10.8 light years) and back would take 51 years.
“It is unlikely that we will be able to make significant progress in understanding the world in which we live, based on data obtained from travels in our solar system. Naturally, thought turns to the stars. After all, earlier it was understood that flights around the Earth, flights to other planets of our solar system are not the ultimate goal. To pave the way to the stars seemed to be the main task.These words do not belong to a science fiction writer, but to the spacecraft designer and cosmonaut Konstantin Feoktistov. According to the scientist, nothing particularly new in the solar system will be found. And this despite the fact that man has so far only flown to the moon ...
However, outside the solar system, the pressure of sunlight will approach zero. Therefore, there is a project to accelerate a solar sailboat with laser systems from some asteroid.
All this is still theory, but the first steps are already being taken.
In 1993, a 20-meter-wide solar sail was deployed for the first time on the Russian ship Progress M-15 as part of the Znamya-2 project. When docking the Progress with the Mir station, its crew installed a reflector deployment unit on board the Progress. As a result, the reflector created a bright spot 5 km wide, which passed through Europe to Russia at a speed of 8 km/s. The patch of light had a luminosity roughly equivalent to that of the full moon.
So, the advantage of a solar sailboat is the lack of fuel on board, the disadvantages are the vulnerability of the sail design: in fact, it is a thin foil stretched over a frame. Where is the guarantee that the sail will not get holes from cosmic particles along the way?
The sail version may be suitable for launching robotic probes, stations and cargo ships, but is unsuitable for manned return flights. There are other starship designs, but they somehow resemble the above (with the same massive problems).
SURPRISES IN INTERSTELLAR SPACE
It seems that many surprises await travelers in the universe. For example, just leaning out of the solar system, the American device Pioneer 10 began to experience a force of unknown origin, causing weak deceleration. Many suggestions have been made, up to yet unknown effects of inertia or even time. There is still no unambiguous explanation for this phenomenon, a variety of hypotheses are considered: from simple technical ones (for example, the reactive force from a gas leak in an apparatus) to the introduction of new physical laws.
Another spacecraft, Voyager 1, detected an area with a strong magnetic field at the edge of the solar system. In it, the pressure of charged particles from interstellar space causes the field created by the Sun to thicken. The device also registered:
- an increase in the number of high-energy electrons (about 100 times) that penetrate into the solar system from interstellar space;
- a sharp increase in the level of galactic cosmic rays - high-energy charged particles of interstellar origin.
The space between the stars is not empty. Everywhere there are remnants of gas, dust, particles. When trying to move at a speed close to the speed of light, each atom colliding with the ship will be like a particle of high-energy cosmic rays. The level of hard radiation during such a bombardment will increase unacceptably even during flights to the nearest stars.
And the mechanical impact of particles at such speeds will be likened to explosive bullets. According to some calculations, every centimeter of the starship's protective screen would be fired continuously at a rate of 12 shots per minute. It is clear that no screen can withstand such exposure for several years of flight. Or it will have to have an unacceptable thickness (tens and hundreds of meters) and mass (hundreds of thousands of tons).
Actually, then the starship will consist mainly of this screen and fuel, which will require several million tons. Due to these circumstances, flights at such speeds are impossible, all the more so because along the way you can run into not only dust, but also something larger, or get trapped in an unknown gravitational field. And then death is inevitable again. Thus, even if it is possible to accelerate the spacecraft to subluminal speed, then it will not reach the final goal - there will be too many obstacles on its way. Therefore, interstellar flights can only be carried out at significantly lower speeds. But then the time factor makes these flights meaningless.
It turns out that it is impossible to solve the problem of transporting material bodies over galactic distances at speeds close to the speed of light. It makes no sense to break through space and time with the help of a mechanical structure.
MOLE HOLE
Science fiction, trying to overcome the inexorable time, invented how to "gnaw holes" in space (and time) and "fold" it. They came up with a variety of hyperspace jumps from one point of space to another, bypassing intermediate areas. Now scientists have joined science fiction writers.
Physicists began to look for extreme states of matter and exotic loopholes in the universe, where you can move at a superluminal speed contrary to Einstein's theory of relativity.
This is how the idea of the wormhole was born. This burrow links the two parts of the Universe like a carved tunnel connecting two cities separated by a high mountain. Unfortunately, wormholes are only possible in absolute vacuum. In our universe, these burrows are extremely unstable: they can simply collapse before a spaceship gets there.
However, to create stable wormholes, you can use the effect discovered by the Dutchman Hendrik Casimir. It consists in the mutual attraction of conducting uncharged bodies under the action of quantum oscillations in a vacuum. It turns out that the vacuum is not completely empty, there are fluctuations in the gravitational field in which particles and microscopic wormholes spontaneously appear and disappear.
It remains only to find one of the holes and stretch it, placing it between two superconducting balls. One mouth of the wormhole will remain on Earth, the other will be moved by the spacecraft at near-light speed to the star - the final object. That is, the spaceship will, as it were, punch through a tunnel. Once the starship reaches its destination, the wormhole will open up for real lightning-fast interstellar travel, the duration of which will be calculated in minutes.
WARP BUBBLE
Akin to the theory of wormholes bubble curvature. In 1994, Mexican physicist Miguel Alcubierre performed calculations according to Einstein's equations and found the theoretical possibility of wave deformation of the spatial continuum. In this case, the space will shrink in front of the spacecraft and simultaneously expand behind it. The starship, as it were, is placed in a bubble of curvature, capable of moving at an unlimited speed. The genius of the idea is that the spacecraft rests in a bubble of curvature, and the laws of the theory of relativity are not violated. At the same time, the bubble of curvature itself moves, locally distorting space-time.
Despite the impossibility of traveling faster than light, nothing prevents space from moving or propagating the warp of space-time faster than light, which is believed to have happened immediately after the Big Bang at the formation of the Universe.
All these ideas do not yet fit into the framework of modern science, but in 2012, NASA representatives announced the preparation of an experimental test of the theory of Dr. Alcubierre. Who knows, maybe Einstein's theory of relativity will someday become part of a new global theory. After all, the process of learning is endless. So, one day we will be able to break through the thorns to the stars.
Irina GROMOVA
1) Does the headlights illuminate other objects and reflect back into the eyes?
No. As you know, you can not exceed the speed of light. This means that in one of the directions the light cannot shine at all, because it is not able to exceed the speed of the car, so it will never go out of the headlights. However, we live in a multidimensional world and not all light shines in one direction.
Imagine a two-dimensional car without mass (that is, moving at the speed of light) that emitted two photons, one up and one down. The two beams separate from the vehicle and remain behind it. They move at the same speed of light but cannot move forward just as fast, since one of the velocity vectors is up/down, so we overtake them. These photons then encounter some obstacle in their path, such as a road sign or a tree, and are reflected back. The problem is that they can no longer catch up with you. Other people walking on the sidewalk are able to see the reflected light, but you have already left and will never see it.
Here you go, everything can be explained on the mere fact that all light moves at the same speed, no matter where. It hardly has anything to do with the theory of relativity.
However, there is also a more hardcore version.
2) Can things moving at the speed of light have headlights? Can they even have vision?
This is where the crazy truth of relativity really comes into play, so don't be ashamed if you don't understand something, but again the answer is no.
You may be familiar with the concept of relativistic time dilation. Suppose a friend and I get on different trains and go towards each other. Driving by, if we look through the window at the wall clock in each other's compartment, then both notice that they go slower than usual. This is not because the clock slows down, but because the light between us comes into play: the faster we move, the slower we age relative to less mobile objects. This is because time is not absolute for all objects in the universe, it is different for each object and depends on its speed. Our time depends on our speed in the universe. You can think of it as moving in different directions on the scale of spacetime. There is a certain problem here, because our brain is not adapted to understand the geometry of space-time, but tends to represent time as an absolute. However, after reading a little literature on the subject, you can normally take it as a natural fact: those who move quickly relative to you age more slowly.
Suppose your friend is sitting in a hypothetical car and is speeding at the speed of light. So, let's substitute its speed into our formula and see what the answer is.
Oh-oh! Looks like he didn't have any time at all! There must be something wrong with our calculations?! It turns out that it doesn't. Time. Not. Exists. For. Objects. On the. Speeds. Sveta.
It just doesn't exist.
This means that things at the speed of light cannot perceive "happening" events in the same way that we perceive them. Events cannot take place for them. They can take actions, but they cannot gain experience. Einstein himself once said: "Time exists so that everything doesn't happen at once". This is a coordinate designed to build events into a meaningful sequence, so that we can understand what is happening But for an object that moves at the speed of light, this principle does not work, because all happens at the same time. A traveler at the speed of light will never see, think or feel anything that we consider meaningful.
Here is such an unexpected conclusion.
Shadows can travel faster than light, but cannot carry matter or information
Is superluminal flight possible?
Sections in this article have subheadings and you can refer to each section separately.
Simple examples of FTL travel
1. Cherenkov effect
When we talk about superluminal motion, we mean the speed of light in a vacuum. c(299 792 458 m/s). Therefore, the Cherenkov effect cannot be considered as an example of superluminal motion.
2. Third observer
If the rocket A flies away from me with speed 0.6c to the west, and the rocket B flies away from me with speed 0.6c east, then I see that the distance between A and B increases with speed 1.2c. Watching the missiles fly A and B from the outside, the third observer sees that the total removal velocity of the missiles is greater than c .
However relative speed is not equal to the sum of the speeds. rocket speed A regarding the rocket B is the rate at which the distance to the rocket increases A, which is seen by an observer flying on a rocket B. Relative velocity must be calculated using the relativistic velocity addition formula. (See How do You Add Velocities in Special Relativity?) In this example, the relative velocity is approximately 0.88c. So in this example we didn't get FTL.
3. Light and shadow
Think about how fast the shadow can move. If the lamp is close, then the shadow of your finger on the far wall moves much faster than the finger moves. When moving the finger parallel to the wall, the speed of the shadow in D/d times greater than the speed of a finger. Here d is the distance from the lamp to the finger, and D- from the lamp to the wall. The speed will be even greater if the wall is at an angle. If the wall is very far away, then the movement of the shadow will lag behind the movement of the finger, since the light takes time to reach the wall, but the speed of the shadow moving along the wall will increase even more. The speed of a shadow is not limited by the speed of light.
Another object that can travel faster than light is a spot of light from a laser aimed at the moon. The distance to the Moon is 385,000 km. You can calculate the speed of movement of the light spot on the surface of the Moon by yourself with small fluctuations of the laser pointer in your hand. You might also like the example of a wave hitting a straight line of beach at a slight angle. With what speed can the point of intersection of the wave and the shore move along the beach?
All these things can happen in nature. For example, a beam of light from a pulsar can run along a dust cloud. A powerful explosion can create spherical waves of light or radiation. When these waves intersect with a surface, circles of light appear on that surface and expand faster than light. Such a phenomenon is observed, for example, when an electromagnetic pulse from a lightning flash passes through the upper atmosphere.
4. Solid body
If you have a long, rigid rod and you hit one end of the rod, doesn't the other end immediately move? Is this not a way of superluminal transmission of information?
That would be right if there were perfectly rigid bodies. In practice, the impact is transmitted along the rod at the speed of sound, which depends on the elasticity and density of the rod material. In addition, the theory of relativity limits the possible speeds of sound in a material by the value c .
The same principle applies if you hold a string or rod vertically, release it, and it begins to fall under the influence of gravity. The top end you let go starts to fall immediately, but the bottom end will only start moving after a while, as the loss of the holding force is transmitted down the rod at the speed of sound in the material.
The formulation of the relativistic theory of elasticity is rather complicated, but the general idea can be illustrated using Newtonian mechanics. The equation of longitudinal motion of an ideally elastic body can be derived from Hooke's law. Denote the linear density of the rod ρ , Young's modulus Y. Longitudinal offset X satisfies the wave equation
ρ d 2 X/dt 2 - Y d 2 X/dx 2 = 0
Plane wave solution travels at the speed of sound s, which is determined from the formula s 2 = Y/ρ. The wave equation does not allow the perturbations of the medium to move faster than with the speed s. In addition, the theory of relativity gives a limit to the amount of elasticity: Y< ρc 2 . In practice, no known material approaches this limit. Note also that even if the speed of sound is close to c, then the matter itself does not necessarily move with relativistic speed.
Although there are no solid bodies in nature, there is motion of rigid bodies, which can be used to overcome the speed of light. This topic belongs to the already described section of shadows and light spots. (See The Superluminal Scissors, The Rigid Rotating Disk in Relativity).
5. Phase velocity
wave equation
d 2 u/dt 2 - c 2 d 2 u/dx 2 + w 2 u = 0
has a solution in the form
u \u003d A cos (ax - bt), c 2 a 2 - b 2 + w 2 \u003d 0
These are sinusoidal waves propagating at a speed v
v = b/a = sqrt(c 2 + w 2 /a 2)
But it's more than c. Maybe this is the equation for tachyons? (see section below). No, this is the usual relativistic equation for a particle with mass.
To eliminate the paradox, you need to distinguish between "phase velocity" v ph , and "group velocity" v gr , and
v ph v gr = c 2
The solution in the form of a wave may have dispersion in frequency. In this case, the wave packet moves with a group velocity that is less than c. Using a wave packet, information can only be transmitted at the group velocity. Waves in a wave packet move with phase velocity. Phase velocity is another example of FTL motion that cannot be used to communicate.
6. Superluminal galaxies
7. Relativistic rocket
Let an observer on Earth see a spaceship moving away at a speed 0.8c According to the theory of relativity, he will see that the clock on the spacecraft is running 5/3 times slower. If we divide the distance to the ship by the time of flight according to the onboard clock, we get the speed 4/3c. The observer concludes that, using his on-board clock, the pilot of the ship will also determine that he is flying at a superluminal speed. From the pilot's point of view, his clock is running normally, and interstellar space has shrunk by a factor of 5/3. Therefore, it flies the known distances between the stars faster, at a speed 4/3c .
But it's still not superluminal flight. You can't calculate speed using distance and time defined in different frames of reference.
8. Gravity speed
Some insist that the speed of gravity is much faster c or even infinite. See Does Gravity Travel at the Speed of Light? and What is Gravitational Radiation? Gravitational perturbations and gravitational waves propagate at a speed c .
9. EPR paradox
10. Virtual photons
11. Quantum tunnel effect
In quantum mechanics, the tunnel effect allows a particle to overcome a barrier, even if its energy is not enough for this. It is possible to calculate the tunneling time through such a barrier. And it may turn out to be less than what is required for light to overcome the same distance at a speed c. Can it be used to send messages faster than light?
Quantum electrodynamics says "No!" Nevertheless, an experiment was carried out that demonstrated the superluminal transmission of information using the tunnel effect. Through a barrier 11.4 cm wide at a speed of 4.7 c Mozart's Fortieth Symphony was presented. The explanation for this experiment is very controversial. Most physicists believe that with the help of the tunnel effect it is impossible to transmit information faster than light. If it were possible, then why not send a signal to the past by placing the equipment in a rapidly moving frame of reference.
17. Quantum field theory
With the exception of gravity, all observed physical phenomena correspond to the "Standard Model". The Standard Model is a relativistic quantum field theory that explains the electromagnetic and nuclear forces and all known particles. In this theory, any pair of operators corresponding to physical observables separated by a spacelike interval of events "commutes" (that is, one can change the order of these operators). In principle, this implies that in the Standard Model the force cannot travel faster than light, and this can be considered the quantum field equivalent of the infinite energy argument.
However, there are no impeccably rigorous proofs in the quantum field theory of the Standard Model. No one has yet even proven that this theory is internally consistent. Most likely, it is not. In any case, there is no guarantee that there are no yet undiscovered particles or forces that do not obey the ban on superluminal movement. There is also no generalization of this theory, including gravity and general relativity. Many physicists working in the field of quantum gravity doubt that the simple concepts of causality and locality will be generalized. There is no guarantee that in a future more complete theory the speed of light will retain the meaning of the limiting speed.
18. Grandpa Paradox
In special relativity, a particle traveling faster than light in one frame of reference moves back in time in another frame of reference. FTL travel or information transmission would make it possible to travel or send a message to the past. If such time travel were possible, then you could go back in time and change the course of history by killing your grandfather.
This is a very strong argument against the possibility of FTL travel. True, there remains an almost improbable possibility that some limited superluminal travel is possible that does not allow a return to the past. Or maybe time travel is possible, but causality is violated in some consistent way. All this is very implausible, but if we are discussing FTL, it is better to be ready for new ideas.
The reverse is also true. If we could travel back in time, we could overcome the speed of light. You can go back in time, fly somewhere at low speed, and arrive there before the light sent in the usual way arrives. See Time Travel for details on this topic.
Open questions of FTL travel
In this last section, I will describe some serious ideas about possible faster-than-light travel. These topics are not often included in the FAQ, because they are more like a lot of new questions than answers. They are included here to show that serious research is being done in this direction. Only a short introduction to the topic is given. Details can be found on the Internet. As with everything on the Internet, be critical of them.
19. Tachyons
Tachyons are hypothetical particles that travel faster than light locally. To do this, they must have an imaginary mass value. In this case, the energy and momentum of the tachyon are real quantities. There is no reason to believe that superluminal particles cannot be detected. Shadows and highlights can travel faster than light and can be detected.
So far, tachyons have not been found, and physicists doubt their existence. There were claims that in experiments to measure the mass of neutrinos produced by the beta decay of tritium, neutrinos were tachyons. This is doubtful, but has not yet been definitively refuted.
There are problems in the theory of tachyons. In addition to possibly violating causality, tachyons also make the vacuum unstable. It may be possible to circumvent these difficulties, but even then we will not be able to use tachyons for superluminal transmission of messages.
Most physicists believe that the appearance of tachyons in a theory is a sign of some problems with this theory. The idea of tachyons is so popular with the public simply because they are often mentioned in fantasy literature. See Tachyons.
20. Wormholes
The most famous method of global FTL travel is the use of "wormholes". A wormhole is a slit in space-time from one point in the universe to another, which allows you to get from one end of the hole to the other faster than the usual path. Wormholes are described by the general theory of relativity. To create them, you need to change the topology of space-time. Maybe this will become possible within the framework of the quantum theory of gravity.
To keep a wormhole open, you need areas of space with negative energies. C.W.Misner and K.S.Thorne proposed to use the Casimir effect on a large scale to create negative energy. Visser suggested using cosmic strings for this. These are very speculative ideas and may not be possible. Maybe the required form of exotic matter with negative energy does not exist.
The current speed record in space has been held for 46 years. When will he be beaten? We humans are obsessed with speed. So, only in the last few months it became known that students in Germany set a speed record for an electric car, and in the USA they plan to improve hypersonic aircraft in such a way that they develop speeds five times the speed of sound, i.e. over 6100 km / h. Such aircraft will not have a crew, but not because people cannot move at such a high speed. In fact, people have already moved at a speed that is several times higher than the speed of sound. However, is there a limit, having overcome which our rapidly rushing bodies will no longer be able to withstand overloads? The current speed record is equally held by three astronauts who participated in the Apollo 10 space mission ", - Tom Stafford, John Young and Eugene Cernan. In 1969, when the astronauts flew around the moon and returned back, the capsule in which they were, developed a speed that on Earth would be equal to 39.897 km / h. "I think that one hundred years ago, we could hardly have imagined that a person would be able to move in space at a speed of almost 40 thousand kilometers per hour, "says Jim Bray of the aerospace concern Lockheed Martin. ), which is being developed by the US Space Agency NASA. As conceived by the developers, the Orion spacecraft is a multi-purpose and partially reusable - should bring astronauts into low Earth orbit. It may well be that with its help it will be possible to break the speed record set for a person 46 years ago. The new super-heavy rocket, which is part of the Space Launch System, should, according to the plan, make its first manned flight in 2021. This will be a flyby of an asteroid in a near-lunar orbit. Then, many-month-long expeditions to Mars should follow. Now, according to the designers, the usual maximum speed of the Orion should be approximately 32,000 km/h. However, the speed reached by Apollo 10 could be surpassed even if the basic configuration of the Orion was maintained. what we are planning now. But even the Orion will not represent the peak of human speed potential. "Basically, there is no other limit to the speed at which we can travel other than the speed of light," says Bray. The speed of light is one billion km/h. Is there any hope that we will be able to overcome the gap between 40 thousand km / h and these values? Surprisingly, speed as a vector quantity denoting the speed of movement and direction of movement is not a problem for people in the physical sense, as long as it is relatively constant and directed in one direction. side. Therefore, people - theoretically - can move in space only slightly slower than the "velocity limit of the universe", i.e. the speed of light. But even assuming that we overcome the significant technological hurdles associated with building fast spacecraft, our fragile, mostly water bodies will face new dangers associated with the effects of high speed. And so far only imaginary dangers can arise, if people can travel faster than the speed of light by exploiting loopholes in modern physics or by discoveries that break the pattern. How to withstand overloads However, if we intend to move at a speed of over 40 thousand km / h, we will have to achieve it, and then slow down, slowly and with patience. Rapid acceleration and equally rapid deceleration are fraught with mortal danger to the human body. This is evidenced by the severity of bodily injuries resulting from car accidents, in which the speed drops from several tens of kilometers per hour to zero. What is the reason for this? In that property of the Universe, which is called inertia or the ability of a physical body with mass to resist a change in its state of rest or motion in the absence or compensation of external influences. This idea is formulated in Newton's first law, which says: "Every body continues to be held in its state rest or uniform and rectilinear motion, as long as it is not forced by the applied forces to change this state. "The state of rest and movement at a constant speed is normal for the human body," explains Bray. "We should rather worry about the state of a person at the moment of acceleration “About a century ago, the development of durable aircraft that could maneuver at speed led pilots to talk about strange symptoms caused by changes in speed and direction of flight. These symptoms included temporary loss of vision and a feeling of either heaviness or weightlessness. The reason is g-forces, measured in units of G, which is the ratio of linear acceleration to the acceleration due to gravity on the Earth's surface under the influence of attraction or gravity. These units reflect the effect of free fall acceleration on the mass of, for example, the human body. An overload of 1 G is equal to the weight of a body that is in the Earth's gravity field and is attracted to the center of the planet at a speed of 9.8 m / s (at sea level). which a person experiences vertically from head to toe or vice versa are truly bad news for pilots and passengers. slowing down, blood rushes from the toes to the head, there is a feeling of oversaturation, as in a handstand. "Red veil" (the feeling that a person experiences when blood rushes to the head) occurs when the blood-swollen, translucent lower eyelids rise and they close the pupils of the eyes. And, conversely, during acceleration or positive g-forces, the blood drains from the head to the legs, the eyes and brain begin to experience a lack of oxygen, since the blood accumulates in the lower extremities. there is a loss of color vision and rolls, as they say, a "gray veil", then a complete loss of vision or a "black veil" occurs, but the person remains conscious. Excessive overloads lead to a complete loss of consciousness. This condition is called congestion-induced syncope. Many pilots have died due to the fact that a "black veil" fell over their eyes - and they crashed. The average person can endure an overload of about five Gs before losing consciousness. Pilots dressed in special anti-g suits and trained in a special way to strain and relax the muscles of the torso so that the blood does not drain from the head, are able to fly an airplane at g-forces of about nine Gs. "For short periods of time, the human body can withstand much more G-forces than nine Gs," says Jeff Sventek, executive director of the Association Aerospace Medicine, located in Alexandria, Virginia. - But very few people can withstand high G-forces for a long period of time. "We humans are able to endure huge G-forces without serious injury, however, only for a few moments. put US Air Force Captain Eli Bieding Jr. on a Holloman viabase in New Mexico. In 1958, when braking on a special rocket-powered sled, after accelerating to 55 km / h in 0.1 seconds, he experienced an overload of 82.3 G. This result was recorded by an accelerometer attached to his chest. Beeding's eyes were also covered with a "black veil", but he escaped with only bruises during this outstanding demonstration of the endurance of the human body. True, after the arrival, he spent three days in the hospital. And now into spaceAstronauts, depending on the vehicle, also experienced quite high G-forces - from three to five Gs - during take-offs and when returning to the dense layers of the atmosphere, respectively. prone position in the direction of flight. Upon reaching a stable cruising speed of 26,000 km / h in orbit, astronauts experience speed no more than passengers of commercial flights. If overloads will not be a problem for long expeditions on Orion spacecraft, then with small space rocks - micrometeorites - are more and more difficult. These particles the size of a grain of rice can develop impressive and at the same time destructive speeds of up to 300 thousand km / h. To ensure the integrity of the ship and the safety of its crew, the Orion is equipped with an external protective layer, the thickness of which varies from 18 to 30 cm. In addition, additional shielding shields are provided, and clever placement of equipment inside the ship is used. important for the entire spacecraft, we must accurately calculate the approach angles of micrometeorites,” says Jim Bray. Rest assured, micrometeorites are not the only obstacle to space missions, during which high speeds of human flight in vacuum will play an increasingly important role. during the expedition to Mars, other practical problems will have to be solved, for example, to supply the crew with food and counteract the increased risk of cancer due to the effects of space radiation on the human body. Reducing travel time will reduce the severity of such problems, so the speed of movement will become more and more desirable oh. Next Generation SpaceflightThis need for speed will raise new obstacles in the way of space travelers. NASA's new spacecraft that threaten to break the Apollo 10 speed record will continue to rely on time-tested rocket propulsion chemistry systems used since the first spaceflights. But these systems have severe speed limits due to the release of small amounts of energy per unit of fuel. Therefore, in order to significantly increase the speed of flight for people going to Mars and beyond, as scientists recognize, completely new approaches are needed. “The systems that we have today are quite capable of getting us there,” says Bray, “but we all would like to witness a propulsion revolution." Eric Davis, a senior research physicist at the Institute for Advanced Study in Austin, Texas, and a member of NASA's Breakthrough Motion Physics Program, a six-year research project that ended in 2002, identified three of the most promising means, from the point of view of traditional physics, capable of helping humanity achieve speeds reasonably sufficient for interplanetary travel. In short, we are talking about the phenomena of energy release during the splitting of matter, thermonuclear fusion and annihilation of antimatter. The first method consists in the fission of atoms and is used in commercial nuclear reactors. The second, thermonuclear fusion, is creating heavier atoms from simpler atoms—the kind of reactions that power the sun. This is a technology that fascinates, but is not given to the hands; it is "always 50 years away" - and it always will be, as the industry's old motto goes. "These are very advanced technologies," says Davis, "but they are based on traditional physics and have been firmly established since the dawn of the Atomic Age." According to optimistic estimates, propulsion systems based on the concepts of atomic fission and thermonuclear fusion, in theory, are capable of accelerating a ship to 10% of the speed of light, i.e. up to a very worthy 100 million km / h. The most preferred, albeit elusive, source of energy for a fast spacecraft is antimatter, the twin and antipode of ordinary matter. When two types of matter come into contact, they destroy each other, resulting in the release of pure energy .Technologies to produce and store - so far extremely small - quantities of antimatter already exist today. At the same time, the production of antimatter in useful quantities will require new special capacities of the next generation, and engineering will have to enter into a competitive race to create an appropriate spacecraft. But , says Davis, quite a few great ideas are already being worked out on the drawing boards. Spaceships powered by antimatter energy could accelerate for months and even years and reach greater percentages of the speed of light. At the same time, overloads on board will remain acceptable for the inhabitants of the ships. At the same time, such fantastic new speeds will also be fraught with other dangers for the human body. Energetic hailAt a speed of several hundred million kilometers per hour, any speck of dust in space, from pulverized hydrogen atoms to micrometeorites, inevitably becomes a high-energy bullet that can pierce a ship's hull."When you move at a very high speed, this means that the particles flying towards you move at the same speeds," says Arthur Edelstein. Together with his late father, William Edelstein, a professor of radiology at the Johns Hopkins University School of Medicine, he worked on a scientific work that examined the effects of exposure to cosmic hydrogen atoms ( on people and equipment) during ultra-fast space travel in space. Although its content does not exceed one atom per cubic centimeter, hydrogen scattered in space can acquire the properties of intense radiation bombardment. Hydrogen will begin to decompose into subatomic particles that will penetrate the ship and expose radiation to both crew and equipment. At a speed equal to 95% of the speed of light, exposure to such radiation would mean almost instantaneous death. , will immediately boil. "These are all extremely unpleasant problems," remarks Edelstein with grim humor. He and his father roughly calculated that in order to create some kind of hypothetical magnetic protection system that could protect the ship and its people from the deadly hydrogen rain, the starship could move at a speed less than half the speed of sound. Then the people on board have a chance to survive. Mark Millis, a translational physicist and former head of NASA's Breakthrough Motion Physics Program, warns that this potential speed limit for spaceflight remains a problem for the distant future. "Based on of physical knowledge accumulated to date, it can be said that it will be extremely difficult to develop a speed of more than 10% of the speed of light, "says Millis. "We are not in danger yet. A simple analogy: why worry that we can drown, if we still did not enter the water. Faster than light? If we assume that we, so to speak, have learned to swim, can we then master the gliding through space time - if we develop this analogy further - and fly at a superluminal speed? The hypothesis of an innate ability to survive in a superluminal environment, although doubtful, is not without certain glimpses of educated enlightenment in pitch darkness. One of these intriguing modes of transportation is based on technologies similar to those used in the "warp drive" or "warp drive" from the Star Trek series. The principle of operation of this propulsion system, also known as The "Alcubierre engine"* (named after the Mexican theoretical physicist Miguel Alcubierre) is that it allows the ship to compress the normal space-time described by Albert Einstein in front of it and expand it behind it. Essentially, the ship moves in some volume of space-time, a kind of "curvature bubble" that moves faster than the speed of light. Thus, the ship remains stationary in normal spacetime in this "bubble" without being deformed and avoiding violations of the universal speed limit of light. like a surfer rushing on a board along the crest of a wave. "There is a certain catch here. To implement this idea, an exotic form of matter with negative mass is needed to compress and expand space-time. "Physics does not contain any contraindications regarding negative mass," says Davis, "but there are no examples of it, and we have never seen it in nature. ".There is another catch. In a paper published in 2012, researchers at the University of Sydney speculated that the "warp bubble" would accumulate high-energy cosmic particles as it inevitably began to interact with the contents of the universe. Some of the particles would penetrate the bubble itself and pump the ship with radiation. Stuck at sub-light speeds? Are we really doomed to get stuck at sub-light speeds because of our delicate biology?! It's not so much about setting a new world (galactic?) speed record for humans, but about the prospect of humanity turning into an interstellar society .At half the speed of light - which is the limit that Edelstein's research suggests our bodies can withstand - a round-trip journey to the nearest star would take more than 16 years. (The effects of time dilation, which would cause the crew of a starship to pass less time in their coordinate system than people left on Earth in their coordinate system would not be dramatic at half the speed of light.) Mark Millis is full of hope. Considering that humanity has developed anti-g suits and protection against micrometeorites, allowing people to safely travel in the great blue distance and the star-studded blackness of space, he is confident that we can find ways to survive, no matter how high-speed frontiers we reach in the future. "Te the very technologies that can help us achieve incredible new speeds of movement, Millis muses, will provide us with new, as yet unknown capabilities for protecting crews. And in 1995, Russian theoretical physicist Sergei Krasnikov proposed the concept of a device for space travel faster than the speed of sound. The idea was called "Krasnikov's pipes". This is an artificial curvature of space-time according to the principle of the so-called wormhole. Hypothetically, the ship will move in a straight line from the Earth to a given star through curved space-time, passing through other dimensions. According to Krasnikov's theory, the space traveler will return back at the same time that he set off.
The 20th century was marked by the greatest discoveries in the field of physics and cosmology. The foundations of these discoveries were theories developed by a galaxy of prominent physicists. The most famous of them is Albert Einstein, on whose work modern physics is largely based. From the scientist's theories it follows that the speed of light in vacuum is the limiting speed of particles and interaction. And the time paradoxes arising from these theories are completely amazing: for moving objects, time flows more slowly relative to those at rest, and the closer to the speed of light, the more time slows down. It turns out that for an object flying at the speed of light, time will completely stop.
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This gives us hope that with the right level of technology, theoretically, a person is able to reach the most remote corners of the Universe within the life of one generation. At the same time, the flight time in the earth's reference frame will be millions of years, while on a ship flying at near-light speed, only a few days will pass ... Such possibilities are impressive, and at the same time the question arises: if physicists and engineers of the future will somehow accelerate the spacecraft to enormous values, even theoretically up to the speed of light (although our physics denies such a possibility), will we be able to reach not only the most distant galaxies and stars, but also the edge of our Universe, to look beyond the border of the unknown, about which scientists have no idea?
We know that the Universe was formed about 13.79 billion years ago and has been continuously expanding ever since. It could be assumed that its radius at the moment should be 13.79 billion light years, and the diameter, respectively, 27.58 billion light years. And this would be true if the universe was expanding uniformly at the speed of light - the fastest possible speed. But the data obtained tell us that the universe is expanding with acceleration.
We observe that the galaxies farthest from us are moving away from us faster than those nearby - the space of our world is constantly expanding. At the same time, there is a part of the Universe that is moving away from us faster than the speed of light. At the same time, no postulates and conclusions of the theory of relativity are violated - inside the Universe, objects have sub-light velocities. This part of the Universe cannot be seen - the speed of photons emitted by radiation sources is simply not enough to overcome the speed of expansion of space.
Calculations show that the part of our world visible to us has a diameter of about 93 billion light years and is called Metagalaxy. What is beyond this boundary and how far the Universe extends, we can only guess. It is logical to assume that the edge of the universe is moving away from us the fastest and far exceeds the speed of light. And this speed is constantly increasing. It becomes obvious that even if some object flies at the speed of light, it will never reach the edge of the Universe, because the edge of the Universe will move away from it faster.
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