Astrophysicists managed to record an example of overcoming the superluminal velocity barrier, in the form of a pulse emitted by a pulsar.
Theoretical calculations and laboratory experiments made it possible to assume that the object can be overcome without violating the principle of the theory of relativity. Now astrophysicists have managed to note a real example of this phenomenon by studying the propagation of radio pulses from pulsars.
Superluminal velocity can be achieved under the condition of anomalous dispersion, that is, under the condition that the refractive index of the medium will increase during the passage of a light wave through it. Suppose that a single pulse, consisting of light waves of different lengths, passes through space. In this case, the overall speed of the pulse can be greater than the speed of each individual wave, although the pulse energy continues to move at the speed of light. That is, the principles of the theory of relativity will not be violated.
The experiments were carried out by a group of scientists led by Frederick Janet at an observatory located in Puerto Rico. For three days, scientists monitored the radiation from the pulsar PSR B1937 + 21, located at a distance of 10,000 light years from Earth. The measurements were carried out at a frequency of 1420.4 MHz with a bandwidth of 1.5 MHz. Observations showed that the central impulses arrived earlier than the estimated time, that is, they moved at a speed exceeding the speed of light.
A pulsar is a neutron star that rotates at a tremendous speed and periodically emits pulses of energy. The speed of passage of pulses in space can be influenced by several different factors... For example, hitting a magnetic field, pulses can change the plane of polarization, when colliding with free electrons, the pulse decays, and "meeting" with neutral hydrogen will result in the absorption of the pulse.
Janet believes that anomalous dispersion also has a significant effect on the speed of the impulses. According to scientists, the pulses pass through a hydrogen cloud with a resonant frequency of 1420.4 MHz. Under the influence of dispersion, the group radiation velocity changed, reaching superluminal values. And impulses with frequencies close to resonant ones arrived to the Earth faster than others. It is like changing the speed when you replenish your account with Beeline and any other operator.
According to scientists, the achievement of superluminal speeds became possible with the "interaction of the time scales of the medium and the pulse itself." Such a phenomenon has already been observed in laboratory conditions, but in a natural environment such an observation was made for the first time. The discovery will allow astronomers to study the composition of interstellar matter, in particular clouds of non-ionized hydrogen, located in our galaxy.
Science fiction or science fact?
It's not too hard to navigate within solar system... Despite the fact that the distances here are measured in billions of kilometers, this can be called local flights. But interstellar travel is another matter entirely. “One of the most difficult problems that physics poses to us is the limitation on the speed of light,” - Pamela L. Gay. When it comes to exceeding the speed of light, physicists unanimously declare that this is impossible, we have to agree.
Is superluminal speed possible?
But why is the speed of light the ultimate in the universe? You simply cannot travel from one point to another faster than light, unless your mass is less. There is one as yet unsolvable problem, the faster you move, the more your mass and more and more energy is required to increase the speed. Only photons of light, which have no mass, can move at the speed of light. But anything with mass requires an infinite amount of energy to reach this speed, it is simply impossible.Superluminal speed in science fiction
In science fiction, overcoming the speed of light is not a problem, this kind of technology has many names: warp drive, hyperdrive, superluminal drive, stargate, etc. Fewer and fewer scientists who have grown up watching their heroes zip through the galaxy tend to deny the possibility of flying at faster than light speeds.Superluminal Velocity - Bold Ideas
A scientist named Miguel Alcubier has formulated some concept of how a superluminal engine starts, expanding and contracting the space in front of the ship. And there was nothing like that, neither in Einstein's theory, nor in anyone else's, which would say that space cannot stretch or contract faster than the speed of light. Actually, we think that it was so at the birth of the universe. Space expanded much faster than the speed of light microseconds after the big bang, resulting in our universe."If you had enough energy, you could expand and contract the space in front of you at a speed of a hundred times the speed of light to fly at superluminal speed, even though you would not have reached it in your own space bubble."
The speed of light propagation is equal to 299 792 458 meters per second, but it is no longer a limiting value. "Futurist" collected 4 theories, where light is no longer Michael Schumacher.
An American scientist of Japanese origin, an expert in the field of theoretical physics Michio Kaku is sure that the speed of light can be overcome.
Big Bang
The most famous example of when the light barrier was overcome, Michio Kaku calls the Big Bang - an ultra-fast "pop" that became the beginning of the expansion of the Universe, to which it was in a singular state.
“No material object can penetrate the light barrier. But empty space can certainly move faster than light. Nothing can be more empty than a vacuum, which means it can expand faster than the speed of light, "the scientist is sure.
Flashlight in the night sky
If you shine a lantern in the night sky, then, in principle, a ray that goes from one part of the Universe to another, located at a distance of many light years, can move faster than the speed of light. The problem is that in this case there will be no material object that really moves faster than light. Imagine that you are surrounded by a giant sphere one light year in diameter. An image of a beam of light will sweep across this sphere in a matter of seconds, despite its size. But only the image of a ray can move through the night sky faster than light, and not information or material object.
Quantum entanglement
Faster than the speed of light may be not an object, but a whole phenomenon, or rather a relationship called quantum entanglement. This is a quantum mechanical phenomenon in which the quantum states of two or more objects are interdependent. To obtain a pair of entangled photons, you can shine a laser at a specific frequency and intensity onto a nonlinear crystal. As a result of the scattering of the laser beam, photons will appear in two different polarization cones, the connection between which will be called quantum entanglement. So, quantum entanglement is one way subatomic particles interact, and the process of this connection can be faster than light.
“If two electrons are brought together, they will vibrate in unison, according to quantum theory. But if you then split these electrons by many light-years, they will still communicate with each other. If you shake one electron, the other will feel this vibration, and this will happen faster than the speed of light. Albert Einstein thought this phenomenon would refute quantum theorybecause nothing can travel faster than light, but in fact he was wrong, ”says Michio Kaku.
Wormholes
The theme of overcoming the speed of light is played up in many science fiction films. Now even those who are far from astrophysics hear the phrase "wormhole", thanks to the film "Interstellar". This is a special curvature in the space-time system, a tunnel in space that allows you to overcome huge distances in negligible time.
Such distortions are discussed not only by film scriptwriters, but also by scientists. Michio Kaku believes that a wormhole, or as it is also called, a wormhole, is one of the two most realistic ways to transmit information faster than the speed of light.
The second way, also associated with changes in matter, is the contraction of space in front of you and expansion behind you. In this deformed space, a wave is generated that travels faster than the speed of light if controlled by dark matter.
Thus, the only real chance for a person to learn to overcome the light barrier may be hidden in general relativity and the curvature of space and time. However, everything rests against the very same dark matter: no one knows if it exists for sure, and whether wormholes are stable.
Doctor of Technical Sciences A. GOLUBEV.
In the middle of last year, a sensational report appeared in magazines. A group of American researchers found that a very short laser pulse travels in a specially selected medium hundreds of times faster than in a vacuum. This phenomenon seemed completely incredible (the speed of light in a medium is always less than in a vacuum) and even raised doubts about the validity of the special theory of relativity. Meanwhile, a superluminal physical object - a laser pulse in an amplifying medium - was first discovered not in 2000, but 35 years earlier, in 1965, and the possibility of superluminal motion was widely discussed until the early 70s. Today the discussion around this strange phenomenon has flared up with renewed vigor.
Examples of "superluminal" motion.
In the early 1960s, high-power short light pulses began to be obtained by passing a laser flash through a quantum amplifier (medium with inverse population).
In an amplifying medium, the initial region of a light pulse causes stimulated emission of atoms in the amplifier medium, and its final region causes energy absorption by them. As a result, it will appear to the observer that the pulse is moving faster than light.
Lijun Wong's experiment.
A light beam passing through a prism made of a transparent material (eg glass) is refracted, that is, undergoes dispersion.
A light pulse is a set of vibrations of different frequencies.
Probably everyone - even people far from physics - knows that the maximum possible speed of movement of material objects or the propagation of any signals is the speed of light in a vacuum. It is indicated by the letter from and is almost 300 thousand kilometers per second; exact value from \u003d 299 792 458 m / s. The speed of light in a vacuum is one of the fundamental physical constants. Impossibility to reach speeds exceeding from, follows from Einstein's special theory of relativity (SRT). If it were possible to prove that signals can be transmitted at superluminal speeds, the theory of relativity would fall. So far, this has not happened, despite numerous attempts to refute the ban on the existence of speeds large from... However, in recent experimental studies, some very interesting phenomena have been discovered, indicating that under specially created conditions, one can observe superluminal velocities without violating the principles of the theory of relativity.
First, let us recall the main aspects related to the problem of the speed of light. First of all: why is it impossible (under normal conditions) to exceed the light limit? Because then the fundamental law of our world is violated - the law of causality, according to which the effect cannot outstrip the cause. No one has ever observed, for example, that first a bear fell dead, and then a hunter fired. At speeds exceeding from, the sequence of events is reversed, the tape of time is rewound. This is easy to verify from the following simple reasoning.
Suppose that we are on some kind of space miracle ship, moving faster than light. Then we would gradually catch up with the light emitted by the source at earlier and earlier points in time. First we would catch up with the photons emitted, say, yesterday, then the ones emitted the day before yesterday, then a week, a month, a year ago, and so on. If the light source were a mirror reflecting life, then we would first see the events of yesterday, then the day before yesterday, and so on. We could see, say, an old man who gradually turns into a middle-aged man, then into a young man, into a youth, into a child ... That is, time would turn back, we would move from the present to the past. The causes and effects would be reversed.
Although this reasoning completely ignores the technical details of the process of observing light, from a fundamental point of view, it clearly demonstrates that movement with superluminal speed leads to an impossible situation in our world. However, nature has set even more stringent conditions: motion is unattainable not only with superluminal speed, but also with speed, equal speed light - you can only approach it. From the theory of relativity it follows that with an increase in the speed of movement, three circumstances arise: the mass of a moving object increases, its size decreases in the direction of motion, and the flow of time on this object slows down (from the point of view of an external "resting" observer). At ordinary speeds, these changes are negligible, but as they approach the speed of light, they become more noticeable, and in the limit - at a speed equal to from, - the mass becomes infinitely large, the object completely loses its size in the direction of motion and time stops on it. Therefore, no material body can reach the speed of light. Only light itself has such speed! (And also a "all-pervading" particle - a neutrino, which, like a photon, cannot move at a speed lower than from.)
Now about the signal transmission speed. It is appropriate here to use the representation of light in the form of electromagnetic waves. What is a signal? This is some kind of information to be transmitted. An ideal electromagnetic wave is an infinite sinusoid of strictly one frequency, and it cannot carry any information, because each period of such a sinusoid exactly repeats the previous one. The speed at which the phase of the sine wave moves - the so-called phase speed - can in a medium under certain conditions exceed the speed of light in a vacuum. There are no restrictions here, since the phase velocity is not the signal velocity - it is not there yet. To create a signal, you need to make some kind of "mark" on the wave. Such a mark can be, for example, a change in any of the wave parameters - amplitude, frequency or initial phase. But as soon as the mark is made, the wave loses its sinusoidality. It becomes modulated, consisting of a set of simple sinusoidal waves with different amplitudes, frequencies and initial phases - a group of waves. The speed at which the mark moves in the modulated wave is the speed of the signal. When propagating in a medium, this speed usually coincides with the group speed, which characterizes the propagation of the above-mentioned group of waves as a whole (see Science and Life, No. 2, 2000). Under normal conditions, the group velocity, and hence the signal velocity, is less than the speed of light in a vacuum. It is not by chance that the expression "under normal conditions" is used, because in some cases the group velocity can also exceed from or even lose its meaning, but then it does not apply to signal propagation. In the service station it is established that it is impossible to transmit a signal at a speed greater than from.
Why is this so? Because an obstacle to the transmission of any signal with a speed greater fromthe same law of causality serves. Let's imagine the following situation. At some point A, a light flash (event 1) turns on a device that sends a certain radio signal, and at a remote point B, an explosion occurs under the action of this radio signal (event 2). It is clear that event 1 (flash) is a cause, and event 2 (explosion) is a consequence that occurs later than the cause. But if the radio signal propagated at a superluminal speed, an observer near point B would first see an explosion, and only then reach it with a speed from light flash, cause of explosion. In other words, for this observer, event 2 would occur earlier than event 1, that is, the effect would be ahead of the cause.
It is appropriate to emphasize that the "superluminal prohibition" of the theory of relativity is imposed only on the movement of material bodies and transmission of signals. In many situations, movement at any speed is possible, but it will not be movement of material objects or signals. For example, imagine two fairly long rulers lying in the same plane, one of which is horizontal, and the other intersects it at a small angle. If the first ruler is moved down (in the direction indicated by the arrow) at high speed, the point of intersection of the rulers can be made to run as fast as you want, but this point is not a material body. Another example: if you take a flashlight (or, say, a laser giving a narrow beam) and quickly describe an arc in the air with it, then the linear velocity of the light spot will increase with distance and at a sufficiently large distance will exceed from.The light spot will move between points A and B at a superluminal speed, but this will not be a signal transmission from A to B, since such a light spot does not carry any information about point A.
It would seem that the question of superluminal velocities has been resolved. But in the 60s of the twentieth century, theoretical physicists put forward a hypothesis of the existence of superluminal particles called tachyons. These are very strange particles: theoretically they are possible, but in order to avoid contradictions with the theory of relativity, they had to ascribe an imaginary rest mass. Physically imaginary mass does not exist, it is a purely mathematical abstraction. However, this did not cause much alarm, since tachyons cannot be at rest - they exist (if they exist!) Only at speeds exceeding the speed of light in a vacuum, and in this case the mass of the tachyon turns out to be real. There is some analogy here with photons: a photon has zero rest mass, but this simply means that a photon cannot be at rest - light cannot be stopped.
As expected, the most difficult thing was to reconcile the tachyon hypothesis with the law of causality. Attempts in this direction, although they were quite ingenious, did not lead to obvious success. Nobody succeeded in registering tachyons experimentally either. As a result, interest in tachyons as superluminal elementary particles gradually faded away.
However, in the 60s, a phenomenon was experimentally discovered that initially confused physicists. This is described in detail in the article by A. N. Oraevsky "Superluminal Waves in Amplifying Media" (Phys. Phys. No. 12, 1998). Here we briefly summarize the matter, referring the reader interested in details to the specified article.
Soon after the discovery of lasers - in the early 60s - the problem arose of obtaining short (about 1 ns \u003d 10 -9 s) high-power light pulses. For this, a short laser pulse was passed through an optical quantum amplifier. The pulse was split into two parts by a beam-splitting mirror. One of them, more powerful, was directed to the amplifier, while the other propagated in the air and served as a reference pulse with which it was possible to compare the pulse that passed through the amplifier. Both pulses were fed to photodetectors, and their output signals could be visually observed on the oscilloscope screen. It was expected that the light pulse passing through the amplifier will experience a certain delay in it compared to the reference pulse, that is, the speed of propagation of light in the amplifier will be less than in air. Imagine the surprise of the researchers when they discovered that the pulse propagated through the amplifier with a speed not only greater than in air, but also several times faster than the speed of light in a vacuum!
Having recovered from the first shock, physicists began to look for the reason for such an unexpected result. No one had even the slightest doubt about the principles of the special theory of relativity, and it was this that helped to find the correct explanation: if the principles of special relativity are preserved, then the answer should be sought in the properties of the amplifying medium.
Without going into details here, we only point out that detailed analysis the mechanism of action of the amplifying medium has completely clarified the situation. The matter consisted in a change in the concentration of photons during pulse propagation - a change due to a change in the gain of the medium up to a negative value during the passage of the rear of the pulse, when the medium already absorbs energy, because its own reserve has already been spent due to its transmission to the light pulse. Absorption causes not amplification, but a weakening of the impulse, and thus the impulse is enhanced in the front and weakened in the rear. Imagine that we are observing a pulse with the help of a device moving at the speed of light in an amplifier medium. If the medium were transparent, we would see an impulse frozen in immobility. In the environment in which the above-mentioned process takes place, the amplification of the leading and weakening of the trailing edge of the pulse will appear to the observer in such a way that the environment, as it were, moved the pulse forward. But since the device (observer) moves at the speed of light, and the pulse overtakes it, then the speed of the pulse exceeds the speed of light! It is this effect that was registered by the experimenters. And here there really is no contradiction with the theory of relativity: just the amplification process is such that the concentration of photons that came out earlier turns out to be more than those that came out later. It is not photons that move with superluminal speed, but the pulse envelope, in particular, its maximum, which is observed on the oscilloscope.
Thus, while in ordinary media there is always an attenuation of light and a decrease in its speed, determined by the refractive index, in active laser media, not only light amplification is observed, but also pulse propagation with superluminal velocity.
Some physicists have tried to experimentally prove the existence of superluminal motion in the tunneling effect - one of the most amazing phenomena in quantum mechanics. This effect consists in the fact that a microparticle (more precisely, a micro-object, exhibiting both the properties of a particle and the properties of a wave under different conditions) is able to penetrate through the so-called potential barrier - a phenomenon that is completely impossible in classical mechanics (in which the analogue would be the following situation: the ball thrown into the wall would be on the other side of the wall, or the undulating motion imparted to the rope tied to the wall would be transmitted to the rope tied to the wall on the other side). The essence of the tunneling effect in quantum mechanics is as follows. If a micro-object with a certain energy meets on its way a region with a potential energy that exceeds the energy of the micro-object, this region is a barrier for it, the height of which is determined by the energy difference. But the micro-object "seeps" through the barrier! This possibility is given to him by the well-known Heisenberg uncertainty relation, written for the energy and interaction time. If the interaction of the micro-object with the barrier occurs for a sufficiently definite time, then the energy of the micro-object will, on the contrary, be characterized by uncertainty, and if this uncertainty is of the order of the barrier height, then the latter ceases to be an insurmountable obstacle for the micro-object. This is the rate of penetration through a potential barrier and has become the subject of research by a number of physicists, who believe that it can exceed from.
In June 1998, an international symposium on FTL problems took place in Cologne, where the results obtained in four laboratories were discussed - in Berkeley, Vienna, Cologne and Florence.
And finally, in 2000, there were reports of two new experiments in which the effects of superluminal propagation appeared. One of them was performed by Lijun Wong with employees in research institute in Princeton (USA). Its result is that the light pulse entering the chamber filled with cesium vapor increases its speed 300 times. It turned out that the main part of the pulse leaves the far wall of the chamber even earlier than the pulse enters the chamber through the front wall. This situation contradicts not only common sense, but, in essence, the theory of relativity.
L. Wong's message provoked intense discussion among physicists, most of whom are not inclined to see in the results obtained a violation of the principles of relativity. The challenge, they believe, is to correctly explain this experiment.
In L. Wong's experiment, the light pulse entering the chamber with cesium vapor had a duration of about 3 μs. Cesium atoms can be in sixteen possible quantum-mechanical states called "magnetic hyperfine ground state sublevels." With the help of optical laser pumping, almost all atoms were brought to only one of these sixteen states, corresponding to almost absolute zero temperature on the Kelvin scale (-273.15 o C). The cesium chamber was 6 centimeters long. In a vacuum, light travels 6 centimeters in 0.2 ns. The measurements showed that the light pulse passed through the chamber with cesium in 62 ns less time than in vacuum. In other words, the transit time of the pulse through the cesium medium has a minus sign! Indeed, if 62 ns is subtracted from 0.2 ns, we get a "negative" time. This "negative delay" in the medium - an incomprehensible time jump - is equal to the time during which the pulse would have made 310 passes through the chamber in a vacuum. The consequence of this "temporary coup" was that the pulse leaving the chamber had time to move away from it by 19 meters before the incoming pulse reached the near wall of the chamber. How can such an incredible situation be explained (if, of course, there is no doubt about the purity of the experiment)?
Judging by the unfolding discussion, an exact explanation has not yet been found, but there is no doubt that unusual dispersion properties of the medium play a role here: cesium vapors, consisting of atoms excited by laser light, are a medium with anomalous dispersion. Let us briefly recall what it is.
The dispersion of a substance is the dependence of the phase (ordinary) refractive index non the wavelength of light l. With normal dispersion, the refractive index increases with decreasing wavelength, and this occurs in glass, water, air, and all other substances transparent to light. In substances that strongly absorb light, the course of the refractive index changes to the opposite with a change in the wavelength and becomes much steeper: with decreasing l (increasing the frequency w), the refractive index sharply decreases and in a certain region of wavelengths it becomes less than unity (the phase velocity V f\u003e from). This is the anomalous dispersion, in which the picture of the propagation of light in matter changes radically. Group speed V gr becomes greater than the phase velocity of waves and can exceed the speed of light in vacuum (and also become negative). L. Wong points to this circumstance as the reason underlying the possibility of explaining the results of his experiment. However, it should be noted that the condition V gr\u003e fromis purely formal, since the concept of group velocity was introduced for the case of small (normal) dispersion, for transparent media, when a group of waves almost does not change its shape during propagation. In regions of anomalous dispersion, on the other hand, the light pulse is rapidly deformed and the concept of group velocity loses its meaning; in this case, the concepts of signal velocity and energy propagation velocity are introduced, which in transparent media coincide with the group velocity, and in media with absorption remain less than the speed of light in vacuum. But here's what is interesting in Wong's experiment: a light pulse, having passed through a medium with anomalous dispersion, is not deformed - it retains its exact shape! And this corresponds to the assumption about the propagation of the pulse with the group velocity. But if so, then it turns out that there is no absorption in the medium, although the anomalous dispersion of the medium is due precisely to absorption! Wong himself, admitting that much is still unclear, believes that what is happening in his experimental setup can, in a first approximation, be clearly explained as follows.
A light pulse consists of many components with different wavelengths (frequencies). The figure shows three of these components (waves 1-3). At some point, all three waves are in phase (their maxima coincide); here they, adding up, reinforce each other and form an impulse. As they further propagate in space, the waves are out of phase and thereby "extinguish" each other.
In the region of anomalous dispersion (inside the cesium cell), the wave that was shorter (wave 1) becomes longer. Conversely, the wave that was the longest of the three (wave 3) becomes the shortest.
Consequently, the phases of the waves change accordingly. When the waves have passed through the cesium cell, their wavefronts are restored. Having undergone unusual phase modulation in a substance with anomalous dispersion, the three waves under consideration are again in phase at a certain point. Here they fold again and form a pulse of exactly the same shape as entering the cesium medium.
Usually in air and in virtually any transparent medium with normal dispersion, a light pulse cannot accurately maintain its shape when propagating over a distant distance, that is, all its components cannot be phased at any distant point along the propagation path. And under normal conditions, a light pulse at such a distant point appears after some time. However, due to the anomalous properties of the medium used in the experiment, the pulse at a distant point turned out to be phased in the same way as when entering this medium. Thus, the light pulse behaves as if it had a negative time delay on its way to a distant point, that is, it would arrive at it not later, but earlier than it has passed the environment!
Most physicists are inclined to associate this result with the appearance of a low-intensity precursor in the dispersive medium of the chamber. The fact is that in the spectral decomposition of a pulse, the spectrum contains components of arbitrarily high frequencies with negligible amplitude, the so-called precursor that goes ahead of the "main part" of the pulse. The nature of the establishment and the form of the precursor depend on the dispersion law in the medium. With this in mind, the sequence of events in Wong's experiment is proposed to be interpreted as follows. The incoming wave, "extending" the harbinger in front of itself, approaches the camera. Before the peak of the incoming wave hits the near wall of the chamber, the precursor initiates a pulse in the chamber, which reaches the far wall and is reflected from it, forming a "backward wave". This wave, spreading 300 times faster from, reaches the near wall and meets the incoming wave. The peaks of one wave meet the troughs of another, so they destroy each other and nothing is left as a result. It turns out that the incoming wave "returns the debt" to the cesium atoms, which "lent" energy to it at the other end of the chamber. Anyone who watched only the beginning and end of the experiment would see only a pulse of light that "jumped" forward in time, moving faster from.
L. Wong believes that his experiment does not agree with the theory of relativity. The statement about the unattainability of superluminal speed, he believes, is applicable only to objects with rest mass. Light can be represented either in the form of waves, to which the concept of mass is generally inapplicable, or in the form of photons with a rest mass, as is known, equal to zero. Therefore, the speed of light in a vacuum, Wong believes, is not the limit. Nevertheless, Wong admits that the effect he discovered does not make it possible to transfer information at a faster speed. from.
"The information here is already in the leading edge of the pulse," says P. Milonny, a physicist at the US Los Alamos National Laboratory. "And you can get the impression of sending information faster than light even when you are not sending it."
Most physicists believe that new job does not deal a crushing blow to fundamental principles. But not all physicists believe the problem is solved. Professor A. Ranfagni of the Italian research group, which carried out another interesting experiment in 2000, believes that the question remains open. This experiment, conducted by Daniel Mugnai, Anedio Ranfagni and Rocco Ruggeri, found that centimeter-band radio waves in normal air travel at a speed exceeding from by 25%.
Summarizing, we can say the following. Work recent years show that under certain conditions, superluminal speed can actually take place. But what exactly is traveling at superluminal speed? The theory of relativity, as already mentioned, forbids such a speed for material bodies and for signals carrying information. Nevertheless, some researchers are very persistently trying to demonstrate how to overcome the light barrier for signals. The reason for this lies in the fact that in the special theory of relativity there is no rigorous mathematical justification (based, say, on Maxwell's equations for the electromagnetic field) of the impossibility of transmitting signals at a speed greater than from... This impossibility in SRT is established, one might say, purely arithmetically, proceeding from the Einstein formula for the addition of velocities, but this is fundamentally confirmed by the principle of causality. Einstein himself, considering the question of superluminal signal transmission, wrote that in this case "... we are forced to consider a signal transmission mechanism, when using which the achieved action precedes the cause. But, although this result from a purely logical point of view does not contain to myself, in my opinion, no contradictions, it still contradicts the nature of all our experience so much that the impossibility of assuming V\u003e c seems to be sufficiently proven. ”The principle of causality is the cornerstone that underlies the impossibility of superluminal signal transmission. , for this is the nature of our world.
In conclusion, it should be emphasized that all of the above refers specifically to our world, to our Universe. This reservation was made because in recent times in astrophysics and cosmology, new hypotheses appear that allow the existence of a multitude of universes hidden from us, connected by topological bridging tunnels. For example, the famous astrophysicist NS Kardashev adheres to this point of view. For an outside observer, the entrances to these tunnels are marked by anomalous gravitational fields, like black holes. Movements in such tunnels, as hypothesized by the authors of the hypotheses, will make it possible to bypass the speed limit imposed in ordinary space by the speed of light, and, consequently, to realize the idea of \u200b\u200bcreating a time machine ... things. And although so far such hypotheses are too reminiscent of plots from science fiction, one should hardly categorically reject the fundamental possibility of a multi-element model of the structure of the material world. It's another matter that all these other Universes are likely to remain purely mathematical constructions of theoretical physicists living in our Universe and trying to find worlds that are closed to us by the power of their thoughts ...
See the issue on the same topic
The theme is "An engine that allows you to fly at superluminal speed", "Travel to multidimensional space"And everything that is related to the topic of flight with a speed exceeding the speed of light, so far does not go beyond speculation, although in some aspects it comes into contact with the world of science. Today we are at the stage where we know that we know something and we don’t know something, but we certainly don’t know if it is possible to move at a speed exceeding the speed of light.
The bad news is that the foundations of modern scientific knowledge accumulated up to this point indicate that movement at speeds exceeding light speed is impossible. It is an artifact of Einstein's Special Theory of Relativity. Yes, there are other concepts - superluminal particles, wormholes ( tunnels in space - approx. transl.), inflationary universe, deformation of space and time, quantum paradoxes... All these ideas are discussed in serious scientific literature, but it is too early to talk about their reality.
One of the questions that comes up with superluminal motion is temporal paradoxes: a breakdown in causality and what is meant by time travel. As if the theme of superluminal flight is not enough, so is it also realistic to develop a scenario in which superluminal speed will enable time travel. Time travel is considered much more impossible than light flight.
What is the main difference?
Barely breaking the sound barrier, people asked the question: "Why don't we also overcome the light barrier now, is it so different?" It’s too early to talk about breaking the light barrier, but something is already known for sure — this is a completely different problem than breaking the sound barrier. The sound barrier was broken by an object made of material, not sound. Atoms and molecules of material are connected electromagnetic fieldsthat is what light is made of. In the case of overcoming the barrier of the speed of light, the object trying to overcome this barrier consists of the same as the barrier itself. How can an object move faster than the one that binds its atoms? As we have already noted, this is a completely different problem than breaking the sound barrier.
The "Special Theory of Relativity" can be summarized very briefly. It's actually very simple in design ... Start with two simple rules.
Rule # 1: the distance you have traveled (d) depends on your speed (v) and your travel time (t). If you are driving 55 miles per hour, you will travel 55 miles in an hour. Just.
Rule # 2: This is an amazing thing - no matter how fast you move, you will constantly notice that the speed of light remains the same.
Put them together and compare what one traveler "sees" versus one who is moving at a different speed - this is where problems arise. Let's try a different picture. Close your eyes. Imagine that of all your senses, only hearing is involved. You only perceive sounds. You only identify objects by the sound they make. So, if a steam locomotive has passed, its whistle has somehow changed? We know that it sounds on a certain note, but due to the movement of the train, it changes due to the action of the so-called Doppler effect. The same thing happens with light. We know everything around us thanks to the presence of light or, to summarize, electromagnetism. What we see, feel (air molecules bounce off our skin), hear (molecules hit each other under the pressure of waves), even the passage of time - all this is controlled by electromagnetic forces. So if we start moving at speeds approaching the speed through which we receive all information, our information is distorted. In general, it's as simple as that. Understanding this is enough if you try to do something about it. But that's another question.
The light speed barrier is one of the consequences of Special Relativity. You can look at it differently. To move faster, you need to add energy. But when you start approaching the speed of light, the amount of energy required to move soars up to infinity. It takes infinite energy to move mass at the speed of light. It turns out you are facing a real barrier here.
Is it possible to bypass Special Relativity? Probably.
Are there any studies in this direction? Yes, but on a small scale.
In addition to the individual theoretical work of physicists such as Matt Visser, Michael Morris, Miguel Alcubierre and others, there is qualitatively new program NASA in jet physics.
InoSMI materials contain assessments exclusively of foreign mass media and do not reflect the position of the Inosmi editorial board.