That moves faster than the speed of light. Is superluminal flight possible? See in a room on the same topic
The speed of light is one of the universal physical constants, it does not depend on the choice of inertial reference frame and describes the properties of space-time as a whole. The speed of light in vacuum is 299,792,458 meters per second, and this is the limiting speed of particles and propagation of interactions. This is what school books on physics teach us. You can also remember that the mass of a body is just not constant and tends to infinity as the speed approaches the speed of light. That is why photons move at the speed of light - particles without mass, and it is much more difficult for particles with mass.
However, the international team of scientists from the large-scale OPERA experiment, located near Rome, is ready to argue with the elementary truth.
He managed to detect neutrinos, which, as experiments have shown, move at a speed greater than the speed of light,
the press service of the European Organization for Nuclear Research (CERN).
The OPERA experiment (Oscillation Project with Emulsion-tRacking Apparatus) studies the most inert particles in the Universe - neutrinos. They are so inert that they can fly through the entire globe, stars and planets, and in order for them to hit an iron barrier, the size of this barrier must be from the Sun to Jupiter. Every second, about 10 14 neutrinos emitted by the Sun pass through the body of every person on Earth. The probability that at least one of them will hit the tissues of a person throughout his life tends to zero. For these reasons, it is extremely difficult to register and study neutrinos. The laboratories that do this are located deep under the mountains and even under the ice of Antarctica.
OPERA receives a beam of neutrinos from CERN, where the Large Hadron Collider is located. Its "little brother" - the superproton synchrotron (SPS) - directs the beam directly underground towards Rome. The resulting neutrino beam passes through the thickness of the earth's crust, thereby being cleansed of other particles that the substance of the crust retains, and goes straight to the laboratory in Gran Sasso, hidden under 1200 m of rock.
An underground path of 732 km is overcome by neutrinos in 2.5 milliseconds.
The detector of the OPERA project, consisting of about 150 thousand elements and weighing 1300 tons, "catches" neutrinos and studies them. In particular, the main goal is to study the so-called neutrino oscillations - transitions from one type of neutrino to another.
The stunning results of exceeding the speed of light are supported by serious statistics: the laboratory in Gran Sasso observed about 15 thousand neutrinos. Scientists have found that
neutrinos travel at 20 millionths faster than the speed of light - the "infallible" speed limit.
This result came as a surprise to them, its explanation has not yet been proposed. Naturally, to refute or confirm it, independent experiments carried out by other groups on other equipment are required - this principle of "double-blind control" is also implemented at the CERN Large Hadron Collider. The OPERA collaboration immediately published its results to enable colleagues around the world to verify them. A detailed description of the work is available on the preprint website Archive.Org.
The official presentation of the results will take place today at a seminar at CERN at 18.00 Moscow time, will be conducted online streaming.
“This data came as a complete surprise. After months of collecting, analyzing and cleaning data, as well as cross-checking, we did not find a possible source of system error in either the data processing algorithm or the detector. Therefore, we publish our results, continue our work, and also hope that independent measurements of other groups will help to understand the nature of this observation, ”said Antonio Ereditato, head of the OPERA experiment from the University of Bern, quoted by the CERN press service.
“When experimental scientists discover some implausible result and cannot find an artifact that would explain it, they turn to their colleagues from other groups to begin a wider study of the issue. This is a good scientific tradition, and the OPERA collaboration is now following it.
If the observations of the speed of light are confirmed, this may change our understanding of physics, but we must make sure that they do not have another, more banal explanation.
This is what independent experiments are for,” said CERN scientific director Sergio Bertolucci.
The measurements carried out in OPERA are extremely accurate. Thus, the distance from the point of neutrino launch to the point of their registration (more than 730 km) is known with an accuracy of 20 cm, and the time of flight is measured with an accuracy of 10 nanoseconds.
The OPERA experiment has been running since 2006. Approximately 200 physicists from 36 institutes and 13 countries, including Russia, take part in it.
Dedicated to direct measurement of the speed of neutrinos. The results sound sensational: the speed of the neutrino turned out to be slightly - but statistically significant! - more than the speed of light. The collaboration article contains an analysis of various sources of errors and uncertainties, however, the reaction of the vast majority of physicists remains very skeptical, primarily because such a result does not agree with other experimental data on the properties of neutrinos.
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Experiment Details
The idea of the experiment (see OPERA experiment) is very simple. The neutrino beam is born at CERN, flies through the Earth to the Italian laboratory Gran Sasso and passes through a special OPERA neutrino detector there. Neutrinos interact very weakly with matter, but due to the fact that their flux from CERN is very large, some neutrinos still collide with atoms inside the detector. There they generate a cascade of charged particles and thus leave their signal in the detector. Neutrinos at CERN are not born continuously, but in "bursts", and if we know the moment of birth of a neutrino and the moment of its absorption in the detector, as well as the distance between the two laboratories, we can calculate the speed of the neutrino.
The distance between the source and the detector in a straight line is about 730 km and it was measured with an accuracy of 20 cm (the exact distance between the reference points is 730534.61 ± 0.20 meters). True, the process leading to the birth of a neutrino is not at all localized with such accuracy. At CERN, a beam of high-energy protons flies out of the SPS accelerator, is dropped onto a graphite target and generates secondary particles in it, including mesons. They continue to fly forward at near-light speed and decay into muons on the fly with the emission of neutrinos. Muons also decay and give rise to additional neutrinos. Then all particles, except for neutrinos, are absorbed in the thickness of the substance, and they freely reach the place of detection. The general scheme of this part of the experiment is shown in fig. one.
The entire cascade leading to the appearance of a neutrino beam can stretch for hundreds of meters. However, since all the particles in this bunch fly forward at near-light speed, for the detection time there is practically no difference whether the neutrino was born immediately or after a kilometer of the way (however, it is of great importance when exactly the original proton that led to the birth of this neutrino flew out of the accelerator). As a result, the produced neutrinos by and large simply repeat the profile of the original proton beam. Therefore, the key parameter here is precisely the time profile of the proton beam emitted from the accelerator, in particular, the exact position of its leading and trailing edges, and this profile is measured with good time s m resolution (see Fig. 2).
Each session of dropping a proton beam onto a target (in English such a session is called spill, "splash") lasts about 10 microseconds and leads to the birth of a huge number of neutrinos. However, almost all of them fly through the Earth (and the detector) without interaction. In the same rare cases when the detector does register a neutrino, it is impossible to say at what exact moment during the 10-microsecond interval it was emitted. The analysis can be carried out only statistically, that is, to accumulate many cases of neutrino detection and construct their time distribution relative to the starting point for each session. In the detector, the point of time is taken as the origin when the conditional signal moving at the speed of light and emitted exactly at the moment of the leading edge of the proton beam reaches the detector. Accurate measurement of this moment was made possible by synchronizing the clocks in the two laboratories to within a few nanoseconds.
On fig. 3 shows an example of such a distribution. The black dots are real neutrino data recorded by the detector and summed over a large number of sessions. The red curve shows a conventional "reference" signal that would move at the speed of light. You can see that the data starts at about 1048.5 ns. before reference signal. This, however, does not yet mean that the neutrino is actually ahead of the light by a microsecond, but is only a reason to carefully measure all cable lengths, equipment response speeds, electronics delay times, and so on. This recheck was done and found to shift the "reference" moment by 988 ns. Thus, it turns out that the neutrino signal actually outruns the reference one, but only by about 60 nanoseconds. In terms of the neutrino speed, this corresponds to an excess of the speed of light by about 0.0025%.
The error of this measurement was estimated by the authors of the analysis at 10 nanoseconds, which includes both statistical and systematic errors. Thus, the authors claim that they "see" the superluminal motion of neutrinos at a statistical confidence level of six standard deviations.
The difference between the results and expectations by six standard deviations is already quite large and is called in physics elementary particles loud word "discovery". However, this number must be understood correctly: it only means that the probability statistical fluctuations in the data is very small, but does not indicate how reliable the data processing technique is and how well physicists have taken into account all instrumental errors. After all, there are many examples in elementary particle physics where unusual signals with exceptionally high statistical certainty have not been confirmed by other experiments.
What do superluminal neutrinos contradict?
Contrary to popular belief, special relativity does not in itself prohibit the existence of particles moving at superluminal speeds. However, for such particles (they are generally called "tachyons"), the speed of light is also a limit, but only from below - they cannot move slower than it. In this case, the dependence of the energy of particles on the speed turns out to be inverse: the greater the energy, the closer the speed of tachyons to the speed of light.
Much more serious problems begin in quantum field theory. This theory replaces quantum mechanics when we are talking about quantum particles with high energies. In this theory, particles are not points, but, relatively speaking, clumps of the material field, and they cannot be considered separately from the field. It turns out that tachyons lower the energy of the field, which means they make the vacuum unstable. It is then more profitable for the void to spontaneously break up into a huge number of these particles, and therefore it is simply meaningless to consider the movement of one tachyon in ordinary empty space. We can say that a tachyon is not a particle, but an instability of the vacuum.
In the case of tachyon-fermions, the situation is somewhat more complicated, but even there, comparable difficulties arise that hinder the creation of a self-consistent tachyon quantum field theory, which includes the usual theory of relativity.
However, this is also not the last word in theory. Just as experimenters measure everything that can be measured, theorists also test all possible hypothetical models that do not contradict the available data. In particular, there are theories in which a slight, not yet noticed deviation from the postulates of the theory of relativity is allowed - for example, the speed of light itself can be a variable. Such theories do not yet have direct experimental support, but they have not yet been closed.
This brief sketch of the theoretical possibilities can be summed up as follows: despite the fact that in some theoretical models the movement with superluminal speed is possible, they remain only hypothetical constructions. All currently available experimental data are described by standard theories without superluminal motion. Therefore, if it were reliably confirmed for at least some particles, quantum field theory would have to be radically redone.
Is it worth considering the result of OPERA in this sense as the "first sign"? Not yet. Perhaps the most important reason for skepticism is the fact that the OPERA result does not agree with other experimental data on neutrinos.
First, during the famous supernova SN1987A, neutrinos were also registered, which arrived a few hours before the light pulse. This does not mean that neutrinos were faster than light, but only reflects the fact that neutrinos are emitted at an earlier stage of nuclear collapse during a supernova explosion than light. However, since neutrinos and light, having spent 170,000 years on the road, did not separate for more than a few hours, it means that their speeds are very close and differ by no more than billionths. The OPERA experiment shows a thousand times stronger discrepancy.
Here, of course, we can say that neutrinos produced during supernova explosions and CERN neutrinos differ greatly in energy (several tens of MeV in supernovae and 10–40 GeV in the described experiment), and the neutrino velocity varies depending on energy. But this change in this case works in the “wrong” direction: after all, the higher the energy of tachyons, the closer their speed should be to the speed of light. Of course, even here one can come up with some kind of modification of the tachyon theory, in which this dependence would be completely different, but in this case it will be necessary to discuss the “double-hypothetical” model.
Further, from the set of experimental data on neutrino oscillations obtained for last years, it follows that the masses of all neutrinos differ from each other only by fractions of an electronvolt. If the result of OPERA is perceived as a manifestation of the superluminal motion of a neutrino, then the value of the square of the mass of at least one neutrino will be of the order of –(100 MeV) 2 (the negative square of the mass is the mathematical manifestation of the fact that the particle is considered a tachyon). Then you have to admit that all varieties of neutrinos are tachyons and have approximately the same mass. On the other hand, direct measurement of the neutrino mass in the beta decay of tritium nuclei shows that the neutrino mass (modulo) should not exceed 2 electron volts. In other words, it will not be possible to reconcile all these data with each other.
The conclusion from this can be drawn as follows: the declared result of the OPERA collaboration is difficult to fit into any, even the most exotic, theoretical models.
What's next?
In all large collaborations in elementary particle physics, it is normal practice for each specific analysis to be performed by a small group of participants, and only then the results be submitted for general discussion. In this case, apparently, this stage was too short, as a result of which not all the participants in the collaboration agreed to put their signature under the article (the full list includes 216 participants in the experiment, and the preprint has only 174 authors). Therefore, in the near future, most likely, many additional checks will be carried out within the collaboration, and only after that the article will be sent to print.
Of course, now one can also expect a stream of theoretical papers with various exotic explanations of this result. However, until the claimed result is reliably rechecked, it cannot be considered a full-fledged discovery.
In September 2011, physicist Antonio Ereditato shocked the world. His statement could have turned our understanding of the universe upside down. If the data collected by the 160 scientists of the OPERA project were correct, the unbelievable was observed. The particles - in this case neutrinos - were moving faster than light. According to Einstein's theory of relativity, this is impossible. And the consequences of such an observation would be incredible. Perhaps the very foundations of physics would have to be revised.
Although Ereditato said that he and his team were "extremely confident" in their results, they did not say that the data was completely accurate. Instead, they asked other scientists to help them figure out what was going on.
In the end, it turned out that OPERA's results were wrong. A badly connected cable caused a synchronization problem and the signals from the GPS satellites were inaccurate. There was an unexpected delay in the signal. As a result, measurements of the time it took a neutrino to travel a certain distance showed an extra 73 nanoseconds: it seemed that the neutrinos flew faster than light.
Despite months of careful checking before the start of the experiment and rechecking the data afterwards, the scientists were seriously mistaken. Ereditato resigned, despite the remarks of many that such errors always occurred due to the extreme complexity of particle accelerators.
Why would the suggestion - the mere suggestion - that something could travel faster than light cause such a fuss? How sure are we that nothing can overcome this barrier?
Let's deal with the second of these questions first. The speed of light in a vacuum is 299,792.458 kilometers per second - for convenience, this number is rounded up to 300,000 kilometers per second. It's quite fast. The Sun is 150 million kilometers from the Earth, and the light from it reaches the Earth in just eight minutes and twenty seconds.
Can any of our creations compete in the race with light? One of the fastest man-made objects ever built, the New Horizons space probe whizzed past Pluto and Charon in July 2015. He reached a speed relative to the Earth of 16 km / s. Much less than 300,000 km/s.
However, we had tiny particles that were moving quite fast. In the early 1960s, William Bertozzi at MIT experimented with accelerating electrons to even higher speeds.
Since electrons have a negative charge, they can be accelerated—more specifically, repelled—by applying the same negative charge to a material. The more energy is applied, the faster the electrons accelerate.
One would think that one would simply need to increase the applied energy in order to accelerate to a speed of 300,000 km/s. But it turns out that electrons just can't move that fast. Bertozzi's experiments showed that the use of more energy does not lead to a directly proportional increase in the speed of the electrons.
Instead, huge amounts of additional energy had to be applied to change the speed of the electrons even slightly. It got closer and closer to the speed of light, but never reached it.
Imagine moving towards the door in small steps, each one covering half the distance from your current position to the door. Strictly speaking, you will never reach the door, because after each step you take, you will have a distance to overcome. Bertozzi faced a similar problem when dealing with his electrons.
But light is made up of particles called photons. Why can these particles move at the speed of light, but electrons cannot?
"As objects go faster and faster, they get heavier - the heavier they get, the harder it is for them to accelerate, so you'll never reach the speed of light," says Roger Russoul, a physicist at the University of Melbourne in Australia. “A photon has no mass. If it had mass, it couldn't move at the speed of light."
Photons are special. They not only lack mass, which provides them with complete freedom of movement in the vacuum of space, they also do not need to accelerate. The natural energy they have at their disposal moves in waves, just like them, so at the time they are created, they already have maximum speed. In some ways, it's easier to think of light as energy rather than as a stream of particles, although, in truth, light is both.
However, light travels much more slowly than we might expect. While internet techs like to talk about communications that run "at the speed of light" in fiber, light travels 40% slower in fiber glass than it does in a vacuum.
In reality, the photons travel at 300,000 km/s, but they encounter a certain amount of interference caused by other photons that are emitted by the glass atoms as the main light wave passes. It may not be easy to understand, but at least we tried.
In the same way, within the framework of special experiments with individual photons, it was possible to slow them down quite impressively. But for most cases, 300,000 will be true. We have not seen or created anything that could move as fast or even faster. There are special points, but before we touch on them, let's touch on our other issue. Why is it so important that the speed of light rule be followed strictly?
The answer has to do with the person named, as is often the case in physics. His special theory of relativity explores the many implications of his universal speed limits. One of the most important elements of the theory is the idea that the speed of light is constant. No matter where you are or how fast you are moving, light always travels at the same speed.
But this raises several conceptual problems.
Imagine the light that falls from a flashlight onto a mirror on the ceiling of a stationary spacecraft. The light goes up, reflects off the mirror, and falls on the floor of the spacecraft. Let's say he covers a distance of 10 meters.
Now imagine that this spacecraft starts moving at a colossal speed of many thousands of kilometers per second. When you turn on the flashlight, the light behaves as before: it shines upward, hits the mirror, and reflects on the floor. But to do this, the light has to travel diagonally, not vertically. After all, the mirror is now rapidly moving along with the spacecraft.
Accordingly, the distance that the light overcomes increases. Let's say 5 meters. It turns out 15 meters in general, not 10.
And despite this, although the distance has increased, Einstein's theories state that light will still travel at the same speed. Since speed is distance divided by time, since the speed has remained the same and the distance has increased, the time must also increase. Yes, time itself must stretch. And although it sounds strange, it has been experimentally confirmed.
This phenomenon is called time dilation. Time moves more slowly for people who move in fast moving vehicles relative to those who are stationary.
For example, time is 0.007 seconds slower for astronauts on the International Space Station, which travels at 7.66 km/s relative to the Earth, compared to humans on the planet. Even more interesting is the situation with particles like the aforementioned electrons, which can move close to the speed of light. In the case of these particles, the degree of deceleration will be enormous.
Stephen Kolthammer, an experimental physicist at the University of Oxford in the UK, points to the example of particles called muons.
Muons are unstable: they quickly decay into simpler particles. So fast that most of the muons leaving the Sun must have decayed by the time they reach the Earth. But in reality, muons arrive on Earth from the Sun in colossal volumes. Physicists have long tried to understand why.
“The answer to this puzzle is that muons are generated with such energy that they move at a speed close to the speed of light,” says Kolthammer. “Their sense of time, so to speak, their internal clock is slow.”
Muons "stay alive" longer than expected relative to us, thanks to a true, natural time warp. When objects move quickly relative to other objects, their length also decreases, shrinks. These consequences, time dilation and length reduction, are examples of how space-time changes depending on the movement of things - me, you or a spacecraft - that have mass.
What is important, as Einstein said, light is not affected because it has no mass. That is why these principles go hand in hand. If objects could move faster than light, they would obey the fundamental laws that describe how the universe works. These are the key principles. Now we can talk about a few exceptions and digressions.
On the one hand, although we have not seen anything moving faster than light, this does not mean that this speed limit cannot be theoretically beaten under very specific conditions. Take, for example, the expansion of the universe itself. Galaxies in the universe are moving away from each other at a speed much faster than the speed of light.
Another interesting situation concerns particles that share the same properties at the same time, no matter how far apart they are. This is the so-called "quantum entanglement". A photon will spin up and down randomly choosing from two possible states, but the choice of direction of rotation will accurately reflect on another photon anywhere else if they are entangled.
Two scientists, each studying their own photon, will get the same result at the same time, faster than the speed of light could allow.
However, in both of these examples, it is important to note that no information travels faster than the speed of light between two objects. We can calculate the expansion of the universe, but we cannot observe faster-than-light objects in it: they have disappeared from view.
As for the two scientists with their photons, although they could get the same result at the same time, they could not let each other know about it faster than the light travels between them.
“That doesn't create any problems for us, because if you can send faster-than-light signals, you get bizarre paradoxes where information can somehow go back in time,” says Kolthammer.
There is another possible way make faster-than-light travel technically possible: rifts in space-time that allow the traveler to escape the rules of conventional travel.
Gerald Cleaver of Baylor University in Texas believes that one day we will be able to build a spacecraft that travels faster than light. Which moves through the wormhole. Wormholes are loops in space-time that fit nicely into Einstein's theories. They could allow an astronaut to jump from one end of the universe to the other using an anomaly in space-time, some form of cosmic shortcut.
An object traveling through a wormhole would not exceed the speed of light, but could theoretically reach its destination faster than light that follows the "normal" path. But wormholes may not be accessible at all. space travel. Could there be another way to actively warp spacetime to go faster than 300,000 km/s relative to anyone else?
Cleaver also explored the idea of an "Alcubierre engine", in 1994. It describes a situation in which space-time contracts in front of the spacecraft, pushing it forward, and expands behind it, also pushing it forward. “But then,” says Cleaver, “there were problems: how to do it and how much energy would be needed.”
In 2008, he and his graduate student Richard Obousi calculated how much energy would be needed.
"We imagined a 10m x 10m x 10m ship - 1,000 cubic meters - and calculated that the amount of energy needed to start the process would be equivalent to the mass of an entire Jupiter."
After that, the energy must be constantly "poured" so that the process does not end. No one knows if this will ever be possible, or what the required technologies will look like. “I don’t want to be quoted for centuries afterwards as if I predicted something that will never happen,” Cleaver says, “but so far I don’t see solutions.”
So, faster-than-light travel remains a fantasy for now. So far, the only way is to plunge into deep suspended animation. And yet, not everything is so bad. In most cases, we talked about visible light. But in reality, light is so much more. From radio waves and microwaves to visible light, ultraviolet radiation, x-rays and gamma rays emitted by atoms as they decay - all of these beautiful rays are made up of the same thing: photons.
The difference is in energy, and therefore in wavelength. Together, these rays make up the electromagnetic spectrum. The fact that radio waves travel at the speed of light, for example, is incredibly useful for communications.
In his research, Kolthammer creates a circuit that uses photons to send signals from one part of the circuit to another, so it deserves the right to comment on the usefulness of the incredible speed of light.
"The very fact that we've built the infrastructure of the Internet, for example, and before that light-based radio, has to do with the ease with which we can transmit it," he notes. And he adds that light acts as a communication force of the Universe. When the electrons in the cell phone start to jitter, photons fly out and cause the electrons in the other cell phone to jitter too. This is how a phone call is born. The shivering of electrons in the Sun also emits photons - in huge numbers - which, of course, form the light that gives life on Earth warmth and, ahem, light.
Light is the universal language of the universe. Its speed - 299,792.458 km/s - remains constant. Meanwhile, space and time are malleable. Perhaps we should think not about how to move faster than light, but how to move faster through this space and this time? Ripe to the root, so to speak?
The speed of light propagation is 299,792,458 meters per second, but it has long ceased to be the limiting value. "Futurist" has collected 4 theories, where the light is no longer Michael Schumacher.
An American scientist of Japanese origin, a specialist in the field of theoretical physics Michio Kaku is sure that the speed of light can be overcome.
Big Bang
The most famous example, when the light barrier was overcome, Michio Kaku calls the Big Bang - an ultra-fast "pop", which became the beginning of the expansion of the Universe, before which it was in a singular state.
“No material object can overcome the light barrier. But empty space can certainly travel 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 flashlight in the night sky, then in principle a beam that goes from one part of the universe to another, located at a distance of many light years, can travel faster than the speed of light. The problem is that in this case there will be no material object that actually moves faster than light. Imagine that you are surrounded by a giant sphere one light year in diameter. The image of a beam of light will rush through this sphere in a matter of seconds, despite its size. But only the image of the beam can move through the night sky faster than light, and not information or a material object.
quantum entanglement
Faster than the speed of light can be not some object, but the whole phenomenon, or rather the relationship, which is called quantum entanglement. This is a quantum mechanical phenomenon in which the quantum states of two or more objects are interdependent. To get a pair of quantum entangled photons, you can shine a laser on a nonlinear crystal with a certain frequency and intensity. As a result of the scattering of the laser beam, photons will appear in two different polarization cones, the relationship between which will be called quantum entanglement. So, quantum entanglement is one way for subatomic particles to interact, and the process of this connection can occur faster than light.
“If two electrons are brought together, they will vibrate in unison, according to quantum theory. But if these electrons are then separated by many light-years, they will still keep in touch 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 that this phenomenon would disprove the quantum theory, because 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 for those who are far from astrophysics, the phrase "wormhole" is heard, thanks to the movie "Interstellar". This is a special curvature in the space-time system, a tunnel in space that allows you to overcome huge distances in a negligible time.
Not only screenwriters of films, but also scientists speak about such curvature. Michio Kaku believes that a wormhole (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, which is also connected with changes in matter, is the contraction of the space in front of you and the expansion behind you. In this warped space, a wave arises that travels faster than the speed of light if driven by dark matter.
Thus, the only real chance for a person to learn to overcome the light barrier may lie in the general theory of relativity and the curvature of space and time. However, everything rests on the very dark matter: no one knows whether it exists exactly, and whether wormholes are stable.
The speed is greater than the speed of light in a vacuum - this is a reality. Einstein's theory of relativity prohibits only superluminal transmission of information. Therefore, there are quite a few cases where objects can move faster than light and not break anything. Let's start with shadows and sunbeams.
If you create a shadow on a distant wall from a finger on which you shine a flashlight, and then move your finger, then the shadow moves much faster than your finger. If the wall is very far away, then the movement of the shadow will lag behind the movement of the finger, since the light will still have to fly from the finger to the wall, but still the speed of the shadow will be as many times greater. That is, the speed of the shadow is not limited by the speed of light.
In addition to shadows, “sunbeams” can also move faster than light. For example, a speck from a laser beam aimed at the moon. The distance to the moon is 385,000 km. If you slightly move the laser, moving it by only 1 cm, then it will have time to run through the Moon at a speed of about a third more than the speed of light.
Similar things can happen in nature. For example, a light beam from a pulsar, a neutron star, can comb through a cloud of dust. A bright flash generates an expanding shell of light or other radiation. When it crosses the surface of the cloud, it creates a ring of light that grows faster than the speed of light.
All these are examples of things moving faster than light, but which were not physical bodies. With the help of a shadow or a bunny, it is impossible to transmit a superluminal message, so communication faster than light is not possible.
And here is an example that is connected with physical bodies. Looking ahead, let's say that, again, superluminal messages will not work.
In a frame of reference associated with a rotating body, distant objects can move at superluminal speeds. For example, Alpha Centauri, in a reference frame linked to the Earth, moves at more than 9,600 times the speed of light, "traversing" a distance of about 26 light-years per day. And exactly the same example with the Moon. Stand facing her and turn around your axis in a couple of seconds. During this time, it turned around you for about 2.4 million kilometers, that is, 4 times faster than the speed of light. Ha-ha, you say, it wasn't she who was spinning, but I ... And remember that in the theory of relativity all frames of reference are independent, including rotating ones. So which side to look at...
And what to do? Well, actually, there is no contradiction here, because again, this phenomenon cannot be used for FTL messages. In addition, note that in its vicinity the Moon does not exceed the speed of light. Namely, all prohibitions are imposed on exceeding the local speed of light in the general theory of relativity.
