Not so long ago, there was news in the media with an extremely panicky headline: physicists allegedly found out that the Higgs boson will cause the death of the Universe! A detailed description of what was actually meant can be found in our Newsletter Rumors of the death of the universe are greatly exaggerated. It is useful to complete this description with a task that - with a few hints - will be within the power of a good student. It will deal with nothing less than the quantum decay of the vacuum.
In the quantum world, there is such a thing as tunneling. This is the name of the movement of a quantum particle, which would be impossible within the framework of classical mechanics. For example, let's say we have a double potential well in which one minimum is slightly deeper than the other (Fig. 2). Classical mechanics says that if a particle is placed at the bottom of a less deep hole, then it will remain there forever. Quantum mechanics predicts that the particle will not stay there forever: after some time it can already be found in a deeper minimum. It tunneled despite not having enough energy to move smoothly over the potential barrier separating the two lows.
The simplest version of this situation is the "Higgs" field h(r) with the following potential energy density (it is also called "potential"):
Here r is a three-dimensional spatial coordinate, v- some energy dimension (for a real Higgs field, it is approximately equal to 246 GeV). The minimum energy will be when the field in the entire space h(r) will be equal to a constant: v or - v. Any space-varying field will necessarily result in more energy overall. The height of the potential barrier separating two minima is
In this form, both values of the vacuum average field are equal, since the potential is symmetric. But it turns out that in non-minimal versions of the Higgs mechanism, a situation resembling Fig. 2. In them, the potential is slightly skewed “in favor” of one of the minima (Fig. 3). In this case, the shape and height of the potential barrier practically do not change (so one can use the formula for δ ), but between the two minima there is a difference in the energy density ε . The fact that the skew is small means that δ /ε ≫ 1.
Now the most important point. The two "vacuums" are now different. The one that is deeper - the true vacuum - corresponds to the minimum energy density, and it is eternal. The one that is higher - a false vacuum - is not entirely stable. For the time being, it can look like a normal vacuum, and particles can also fly in it, interactions can occur, and stars and planets can form. But there is always the possibility that this vacuum will "break", that it will tunnel into a more stable true vacuum.
This quantum decay of vacuum looks like this. At some point in the Universe, which is in a state of "false vacuum", a bubble of true vacuum appears (Fig. 1). "Appears" is a conditional statement; this means that in this region of space the Higgs field has tunneled into the true vacuum. The transition between the region of true and false vacuum cannot be discontinuous, the theory does not allow such a possibility. Therefore, there is a thin intermediate zone (bubble wall) in which the Higgs field smoothly passes from one vacuum to another, overcoming a potential barrier along the way.
If this bubble is energetically favorable, then it will begin to expand, slowly at first, but then accelerate to the speed of light. With such a transition, the properties of particles will change dramatically, and a lot of additional energy will be released in the Universe, which was previously stored in a false vacuum. In other words, the consequences of such a collapse of the vacuum will be catastrophic for any structures that inhabited the "old" Universe. This process is in many ways reminiscent of the boiling up of a superheated liquid, only, of course, the scale here is not the same.
Task
Explanation about units of measurement and dimensions. In quantum mechanics, the so-called natural units of measurement are often used, in which everything is expressed in terms of energies, and Planck's constant ( ħ ) and the speed of light ( c) are included in the definition of the unit of measure. As a result, the length is expressed not in meters, but in reciprocal energy units, for example J -1 or eV -1. The transition factor is the combination ħc: for example, 1 GeV –1 corresponds to length = 1 GeV –1 · ħc= 0.197 fm. For this reason, the energy density, whose real dimension is J m -3 , is expressed here in units of energy to the fourth power. Accordingly, the surface tension coefficient with the dimension of J m -2 will be expressed in natural units in terms of the cubed energy.
Hint 1
Of course, an honest full-fledged solution is a serious scientific problem. However, a very rough estimate of the lifetime can be given from fairly simple arguments based on dimensional analysis. Let's say right away that the time before the collapse will be exponentially large, T ~ eB, and it is required to estimate how the quantity B depends on the relationship δ /ε .
Hint 2
Let us consider a motionless bubble of "true vacuum" of radius R in the Universe, which is in a state of "false vacuum". Let us estimate the total energy of this bubble relative to the false vacuum. The bubble is filled with a true vacuum which gives the bubble a negative energy. However, the bubble has thin walls in which the Higgs field smoothly transitions from true to false vacuum. These walls have positive energy, similar to the surface tension at the fluid boundary. Based on dimensional considerations, estimate the surface tension coefficient of the wall in this problem. After that, find the critical size of the bubble, which must appear somewhere in the Universe, so that the decay of the vacuum begins from it. In the last step, try to understand how the probability of such a bubble in the universe depends on its size. Then substitute the found size and get the answer.
Decision
Step 1. The total energy of a thin-walled bubble of radius R is equal to
The critical size of the bubble, from which the decay of the vacuum in the entire Universe will begin, is calculated in the same way as the critical size of the vapor bubble for the start of boiling of a superheated liquid. It is only necessary that the total energy of this bubble be negative. From this we obtain that the critical radius of the bubble is equal to
The surface tension σ can be estimated by dimension, but there is one subtlety. In general, estimates based on dimensions work when a dimensionless parameter does not appear in the problem. There is such an option here: δ /ε . Therefore, on the basis of dimensional considerations alone, it cannot be said whether σ order δ 3/4, or order ε 3/4 , or any combination of them of a suitable dimension.
But here an additional physical argument comes to the rescue. Value ε should not be included in this formula, at least as long as it remains small. Indeed, there is surface tension here because the Higgs field "rolls over the mountain." The presence of a small "elevation difference" does not play a significant role here; approximately the same surface tension will be at zero ε . Therefore, one can conclude from this that σ ~ δ 3/4 ~ v 3 (we do not pay attention to a possible numerical coefficient, we are only interested in the dependence between the quantities). Hence, we obtain that the critical bubble size is equal in order of magnitude to
Step 2 Now we need to get the probability of such a bubble in the Universe. Let's imagine that the entire space is "broken" into small volumes of size r = 1/v(in natural units!). Such a size was not chosen by chance: according to the uncertainty relation, quantum fluctuations with energies of the order v. This means that the potential energy density of the Higgs field fluctuates up to values of the order v 4 = δ . In other words, in such a volume, the Higgs field easily jumps back and forth, and can, in particular, go over a potential mountain.
Denote by p the probability that in this small volume in time τv = 1/v there will be a jump from a false vacuum to a true one. It is clear that this probability is high. The exact value is absolutely not important to us, it can be 99%, and 50%, and 1%, this will not affect the estimates. But it will be convenient for us to write this probability in exponential form: p = e – q, where the number q order of unity.
For a true vacuum bubble to occur, we need this jump to occur synchronously (that is, within the time τv) at once in the entire size bubble Rc. This bubble has
small volumes, and each of them jumps independently with probability p. So the probability that they all jump at once is
and the numerical coefficient q, which is of the order of unity, we have neglected here. Substituting the values found above, we obtain the probability of the birth of a bubble at a given location in space during the time τv:
Step 3 Now we take into account the dimensions of the visible part of the Universe, the radius of which is denoted by R U. The critical bubble can be born anywhere in the universe that contains ( R U/Rc) 3 such bubbles. If you wait for time T, then the universe will have T/τv attempts to create such a bubble. Therefore, if you wait a very long time and look at the entire Universe as a whole, then sooner or later it will happen somewhere. Typical waiting time will be of the order
It is seen that for δ /ε ≫ 1 this time can be very long.
In principle, this is already the desired answer. But here it is useful to say something else. A more accurate analysis shows that the value B also contains a rather large numerical coefficient:
Therefore, even if the relationship δ /ε is not so large, for example, equal to two, then the exponent B will still be large, so that the lifetime of the metastable vacuum will be huge, far exceeding the current age of the Universe.
Afterword
This type of estimate - not in relation to the Higgs boson, but in a broader context - was first given by Soviet physicists Kobzarev, Okun and Voloshin in 1974. Three years later, the problem was solved by Coleman in a much more rigorous way. This was followed by a series of papers with an even more accurate analysis of the decay of a metastable vacuum, in which, by the way, gravitational effects turned out to be very important. This process, and the very possibility of using a metastable vacuum, then firmly entered cosmology as a possible scenario for the evolution of the Universe at its earliest stages.
It is interesting that recently another zigzag happened in this story. A year and a half ago, suspicions were expressed that metastable vacuums cannot exist at all in our space-time, since they do not decay slowly, as was thought until now, but vice versa - infinitely fast. However, then a counter-objection was put forward to these suspicions: the conclusion about infinitely fast decay is based on an unjustified extrapolation of formulas beyond the limits of applicability of the laws of physics known to us. So the alarm turned out to be false, and metastable vacuum states, at least in theory, are acceptable.
Returning to the discussion of whether the Higgs vacuum of the Standard Model is stable or not, we emphasize that the situation there is slightly different (the potential looks different, and the numbers are very different). But the general “moral” remains the same: if the barrier is high, then it will take a very long time to decay; if the barrier is small, then the decay will be quite fast. Fortunately, this does not threaten us.
The most incredible end of the world would be the destruction of the world as a result of the collapse of a false vacuum. In this case, not only people, the planet, the Sun and the Milky Way, but the entire observable Universe would cease to exist. Scientists, in particular, the philosopher Nick Bostrom, the author of the work “Are you living in a computer simulation?”, have repeatedly frightened humanity with such a future. How dangerous is the true vacuum for life on Earth - in the material "Lenta.ru".
Vacuum in quantum field theory corresponds to the state of the system with the lowest possible energy. All physical processes in such a world occur with energies exceeding this zero value. Meanwhile, it is possible that the Universe or its observable part is in a metastable, or false, vacuum. This means that there is an even more favorable energy position into which the Universe can evolve - a true vacuum.
A quantitative description of the transition of a system from a false vacuum to a true vacuum was first proposed in the 1970s by Soviet physicists. Almost at the same time, these questions attracted the attention of American scientists. To date, a mathematical apparatus has been developed that makes it possible to estimate the probability of a system tunneling from an initial, metastable state to a second, more stable one. It is largely based on statistical physics and quantum field theory, which form the basis of the so-called cosmological bubble formalism.
In this approach, the observable world is considered to exist in a false vacuum. This state, most likely, is of a metastable nature - the entire Universe or that part of it that a person sees can be in a stable state for a huge cosmological time interval, which, however, is finite. A true vacuum bubble can form inside a false vacuum bubble. The evolution of the Universe in this case occurs due to the decay of the initial metastable state.
The bubble of true vacuum expands inside the bubble of false vacuum in accordance with the special theory of relativity, no faster than the speed of light, and destroys all the matter of the original world. Therefore, they talk about the possible death of the observable universe. However, the quantitative analysis of false vacuum decay is associated with great uncertainty.
The main thing to do is to estimate the probability of the birth of a bubble of a new cosmological phase. There are two main approaches that make it possible to simplify the problem as much as possible and obtain explicit expressions for the transition probability - thin and thick wall approximations. The Higgs potential (in other words - Ginzburg-Landau) of the Standard Model - the modern concept of elementary particle physics - acts as a basic object. It contains the Higgs field, which is responsible for the appearance of an inertial mass in particles.
The formation of a bubble of true vacuum in a bubble of false corresponds to a phase transition of the first kind, when the system undergoes an abrupt, and not continuous, as in a phase transition of the second kind, change. The main thing in both approximations is the height of the potential barrier separating the false and true vacuum. The thin wall approximation works when the difference between the false and true minima of the potential is much smaller than the height of the barrier between them.
If the wall thickness is much smaller than the bubble radius, the main contribution to the probability of its birth is made by the surface rather than the bulk energy. The definition of probability in this case is reduced to the calculation of the exponent. The thick wall approximation is much less frequently used in physically interesting theories. And it is clear why: in this case, the probability of the formation of bubbles of a new phase is exponentially suppressed - a false vacuum is practically indistinguishable from a true one.
The tunneling probability depends on quantum corrections to the Higgs potential, in particular, on the contribution of heavy particles. Currently, the top quark is considered the heaviest elementary particle - its mass exceeds 173 gigaelectronvolts. That is why the discovery of new heavy particles is so important for cosmological models - it can affect the predictions of the stability of the observed world.
A special role in the decay of vacuum in gravity - the curvature of space-time. In particular, microscopic black holes, which can arise from collisions of high-energy particles, increase the probability of the birth of bubbles with true vacuum in their vicinity by a factor of hundreds. The dynamics of cosmological bubbles is even more complicated if several bubbles form inside the original Universe - expanding and colliding with each other, they create a new world with a true vacuum.
Today it is not known what state the universe is in. If this is a true vacuum, then there is nothing to worry about. If false, then, most likely, too - the dimensions of the observable Universe are too large for a new bubble, expanding at the speed of light, to fill the whole world in any reasonable time by human standards. However, there is an exception - if a new phase somehow arises in the immediate vicinity of humanity. Then the Earth can die almost instantly.
"Can you make something out of nothing, uncle?" - "No, my friend, nothing will come of nothing."
Shakespeare, "King Lear" (translated by T.L. Shchepkina-Kupernik)
Vacuum is empty space. It is often used as a synonym for "nothing". This is why the idea of vacuum energy seemed so strange when it was first put forward by Einstein. However, under the influence of the achievements of the theory of elementary particles over the past three decades, the attitude of physicists to vacuum has changed radically. Vacuum research continues, and the more we learn about it, the more complex and surprising it seems.
According to modern theories of elementary particles, vacuum is a physical object; it can be charged with energy and can be in a variety of states. In the terminology of physicists, these states are called different vacuums. The types of elementary particles, their masses and interactions are determined by the underlying vacuum. The relationship between particles and vacuum is similar to that between sound waves and the material through which they propagate. The vacuum in which we live is in the lowest energy state, it is called "true vacuum". It is possible that our vacuum is not the lowest energy. String theory, which today is the main candidate for the role of the most fundamental physical theory, assumes the existence of vacuums with negative energy. If they really exist, then our vacuum will spontaneously disintegrate with catastrophic consequences for all the material objects contained in it.
Physicists have amassed a wealth of knowledge about the particles that inhabit this type of vacuum and the forces acting between them. The strong nuclear force, for example, binds protons and neutrons in atomic nuclei, electromagnetic forces keep electrons in their orbits around nuclei, and the weak force is responsible for the behavior of elusive light particles called neutrinos. As their names suggest, these three forces are of very different strengths, with the electromagnetic force being intermediate between strong and weak.
The properties of elementary particles in other vacuums can be completely different. It is not known how many different vacuums there are, but elementary particle physics suggests that there should probably be at least two more, moreover, with greater symmetry and a smaller variety of particles and interactions. The first of these is the so-called electroweak vacuum, in which the electromagnetic and weak interactions have the same strength and appear as components of one combined force. Electrons in this vacuum have zero mass and are indistinguishable from neutrinos. They move at the speed of light and cannot be held within atoms. No wonder we don't live in this type of vacuum.
The second is the vacuum of the Grand Unification, in which all three types of interactions between particles merge. In this highly symmetrical state, neutrinos, electrons, and quarks (which make up protons and neutrons) become interchangeable. If an electroweak vacuum almost certainly exists, then the Grand Unification vacuum is a much more speculative construct. The particle theories that predict its existence are theoretically attractive, but involve extremely high energies, and their observational evidence is sparse and mostly indirect.
Each cubic centimeter of electroweak vacuum contains colossal energy and - according to Einstein's relation between mass and energy - an enormous mass, about ten million trillion tons (about the mass of the moon). Faced with such huge numbers, physicists switch to an abbreviated notation of numbers, expressing them in powers of tens. A trillion is a one followed by 12 zeros; it is written as 10^12. Ten million trillion is a one followed by 19 zeros; that is, the mass density of the electroweak vacuum is 10^19 tons per cubic centimeter. For the vacuum of the Grand Unification, the mass density turns out to be even higher, and monstrously higher - by 10^48 times. Needless to say, this vacuum has never been created in a laboratory: it would require much more energy than is available with current technology.
Compared to these staggering quantities, the energy of an ordinary true vacuum is negligible. For a long time it was believed to be exactly zero, but recent observations indicate that the vacuum can have a small positive energy, which is equivalent to the mass of three hydrogen atoms per cubic meter. The significance of this discovery will become clear in chapters 9, 12, and 14. High-energy vacuums are called "false" because, unlike true vacuums, they are unstable. After a short time, usually a small fraction of a second, the false vacuum disintegrates, turning into a true one, and its excess energy is released in the form of a fireball of elementary particles. In the following chapters, we will look at the process of vacuum decay in much more detail.
If the vacuum has energy, then, according to Einstein, it must also have tension. This conclusion is easy to understand from simple energy considerations. Force always acts on a physical object in the direction of decreasing its energy. (More specifically, potential energy, which is the non-moving component of energy.) For example, gravity pulls objects downward, in the direction of decreasing energy. (Gravitational energy increases with height above the ground.) For a false vacuum, the energy is proportional to the volume it occupies and can only be reduced by shrinking the volume. Therefore, there must be a force that causes the vacuum to compress. This force is tension.
But the tension creates a repulsive gravitational effect. In the case of a vacuum, the repulsion is three times stronger than the gravitational attraction due to its mass, so the total is a very strong repulsion. Einstein used this vacuum anti-gravity to balance the gravitational pull of ordinary matter in his stationary model of the world. He found that balance is achieved when the mass density of matter is twice the vacuum. Guth proposed another plan: instead of balancing the universe, he wanted to inflate it. So he allowed the repulsive gravity of the false vacuum to dominate unopposed.
space inflation
Alan Guth in his office at MIT. Guth is the proud winner of the 1995 Boston Globe contest for the cluttered cabinet.
What would happen if, in the distant past, the space of the universe was in a state of false vacuum? If the density of matter in that era was less than required to balance the universe, then repulsive gravity would have dominated. This would cause the universe to expand, even if it did not initially expand.
To make our ideas more definite, we will assume that the Universe is closed. Then it inflates like the balloon in figure 3.1. As the volume of the Universe grows, matter becomes rarefied and its density decreases. However, the false vacuum mass density is a fixed constant; it always stays the same. So very quickly the density of matter becomes negligible, we are left with a uniform expanding sea of false vacuum.
The expansion is caused by the tension of the false vacuum, which is greater than the attraction associated with its mass density. Since none of these quantities change with time, the rate of expansion remains constant to a high degree of accuracy. This rate is characterized by the proportion in which the universe expands per unit of time (say, one second). In meaning, this value is very similar to the rate of inflation in the economy - the percentage increase in prices per year. In 1980, when Guth was teaching a seminar at Harvard, the US inflation rate was 14%. If this value remained unchanged, prices would double every 5.3 years. Similarly, a constant rate of expansion of the universe implies that there is a fixed interval of time during which the size of the universe doubles.
Growth that is characterized by a constant doubling time is called exponential growth. It is known to lead to gigantic numbers very quickly. If today a slice of pizza costs $1, then after 10 doubling cycles (53 years in our example), its price will be $1024, and after 330 cycles it will reach $10^100. This colossal number, one followed by 100 zeros, has a special name - googol. Guth suggested using the term inflation in cosmology to describe the exponential expansion of the universe.
The doubling time for a universe filled with a false vacuum is incredibly short. And the higher the vacuum energy, the shorter it is. In the case of an electroweak vacuum, the universe would expand by a factor of a googol in one-thirtieth of a microsecond, and in the presence of a Grand Unification vacuum, this would happen 10^26 times faster. In such a short fraction of a second, a region the size of an atom will inflate to a size far larger than the entire observable universe today.
Because the false vacuum is unstable, it eventually disintegrates and its energy ignites a fireball of particles. This event marks the end of inflation and the beginning of normal cosmological evolution. Thus, from a tiny initial embryo we get a huge hot expanding Universe. And as an added bonus, this scenario miraculously eliminates the horizon and flat geometry problems that are characteristic of Big Bang cosmology.
The essence of the horizon problem is that the distances between some parts of the observable universe are such that they seem to have always been greater than the distance traveled by light since the Big Bang. This suggests that they never interacted with each other, and then it is difficult to explain how they achieved almost exact equality of temperatures and densities. In the standard Big Bang theory, the path traveled by light grows in proportion to the age of the universe, while the distance between regions increases more slowly as cosmic expansion is slowed down by gravity. Areas that cannot interact today will be able to influence each other in the future, when the light finally covers the distance separating them. But in the past, the distance traveled by light becomes even shorter than it should be, so if the regions cannot interact today, they certainly were not able to do so before. The root of the problem, therefore, is related to the attractive nature of gravity, due to which the expansion gradually slows down.
However, in a false vacuum universe, gravity is repulsive, and instead of slowing down expansion, it speeds it up. In this case, the situation is reversed: areas that can exchange light signals will lose this opportunity in the future. And, more importantly, those areas that are inaccessible to each other today must have interacted in the past. The horizon problem is gone!
The problem of flat space is solved just as easily. It turns out that the Universe moves away from the critical density only if its expansion slows down. In the case of an accelerated inflationary expansion, the opposite is true: the Universe is approaching a critical density, which means it is becoming flatter. Because inflation enlarges the universe by a colossal factor, we only see a tiny fraction of it. This observable region appears flat, similar to our Earth, which also appears flat when viewed close to the surface. So, a short period of inflation makes the universe large, hot, uniform and flat, creating just the kind of initial conditions required for standard big bang cosmology...
Doomsday predictions are a new trend in popular culture of recent times. Futurologists and occultists of all stripes compete in describing the colorful finale of human history. Scientists do not lag behind world trends and believe that the cause of the death of the Earth will be the interaction of two entities - false and true vacuum. The plot is so interesting that it pulls on a Hollywood blockbuster.
Disambiguation
Before proceeding to decipher the concepts of quantum mechanics, it is necessary to inquire about what is invested in the concept of " vacuum' in different contexts:
- In the general case, it is considered that this space is devoid of matter. Translated from Latin, the word translates as "freedom" or "emptiness";
- In engineering and applied physics: any space in which the pressure is below atmospheric pressure. So, the English name for the vacuum cleaner is " vacuumcleaner”refers precisely to this interpretation;
- In the context of 19th-century natural science research: it is an environment filled with an omnipresent substance called aether;
- In electromagnetism: reference medium for electromagnetic action. It does not create obstacles for the propagation of radiation. In it, the principle of superposition of two electric potentials is only a simple addition of each potential.
Philosophical disputes regarding the concepts of "emptiness" and "nothing" have been going on for more than two thousand years. The first attempts to step on this unsteady kidney were made by Plato, but his ideas were immediately rejected: nothing can be perceived by the senses - which means that its existence cannot be proved.
What is true vacuum?
Most often, in laboratory and natural conditions, physicists deal with the so-called partial vacuum, which deviates from "sterile" conditions by some amount. Outer space can serve as an example of such a "under-vacuum":
- It has an extremely low density and pressure;
- However, even in interstellar space there are a few hydrogen atoms per cubic meter;
- Planets and stars are even further from ideal conditions: they have their atmospheres due to gravitational attraction;
- In fact, space is a rarefied plasma filled with charged particles and electromagnetic fields.
In contrast to such an imperfect model, there is the concept of an "ideal vacuum", which is the so-called ground state in quantum field theory:
- This is the state with the lowest possible (zero) energy;
- It cannot be achieved experimentally, it exists only "on the tip of a pen";
- Despite the average zero values of the electric and magnetic fields, their dispersions are not equal to zero;
- Occasionally, virtual particles appear and disappear in such a “void” (a phenomenon called fluctuation).
Physical theories
Within the framework of modern quantum physics, the theory of the true physical vacuum remains not fully developed. There are several approaches to the study of this phenomenon:
- Lots of particles with tiny energy;
- A cellular medium that has a negative pressure;
- A quantum liquid consisting of photonic particles. They are linked together in a mosaic resembling a crystalline chemical bond;
- Liquid of quasiparticles with superfluid properties;
- According to the English scientist Paul Dirac, this is an endless sea of particles with energies below zero.
The historically dominant interpretation of the Latin concept of "vacuum" as "emptiness" is not used today.
On the contrary, its ontological meaning has changed: instead of "nothing" (empty space) - "something" (containing the potential of all things). Physicists believe that vacuum can give rise to all phenomena of the external world and is the most basic entity in the universe. And therefore - not fully known.
What is a false vacuum?
One of the most popular hypotheses regarding the nature of "content emptiness" belongs to the American physicists Frank Wilczek and Michael Turner. They first put forward the theory of the so-called "false vacuum", which has the following properties:
- Its energy level is extremely small, but not equal to zero, in contrast to the true vacuum;
- Probably, such a state can arise when the maximum number of particles and energy is removed from ordinary space. Such an operation will lead to the appearance of quantum fields with a local energy minimum;
- The state is characterized by instability due to the “tunnel effect”, when elementary particles easily bypass the potential barrier and pass into lower energy states;
- An imaginary vacuum tends to turn into a true one. The mathematical model of this transition was developed back in the 1970s by Soviet scientists.
The phenomenon in wildlife has not yet been registered. There are only theoretical assumptions concerning the nature of the entire Universe, which will be discussed below.
existential threat
Insufficient knowledge of fundamental cosmological issues opens up wide scope for the wild imagination of physicists. One of the now popular scientific "horror stories" concerns the threat to the universe if the latter is in a state of minimal energy:
- Scientists Eric Max Tegmark and Nick Bostrom were the first to start a discussion on this topic. In 2005, in Nature, they published a sensational article in which they proclaimed the death of all things after a few hundred million years;
- Such a scenario is highly probable if the Universe is in an imaginary vacuum. This state will smoothly flow into the true vacuum, which will be accompanied by uncertain but fatal consequences;
- The birth of a new state can be described as the appearance of several new ones inside one cosmological bubble;
- These bubbles will collide with each other, uniting and giving birth to a new world;
- If the theory is correct, the bubble will expand at a monstrous rate and the death of life on Earth will be almost instantaneous.
The apocalyptic plot formed the basis of the novel Poseidon Wakes (2015) by British writer Alastair Reynolds.
The relativity of the scientific picture of the world can knock the ground out from under your feet. In addition to the concept of emptiness, understandable to every layman, physicists have put forward "almost-emptiness", which is infinitely close to it, but still contains a certain minimum of energy. So in simple words one can describe false and true vacuum. For a more detailed acquaintance with the phenomenon, a deep technical education is required.
Video: why a false vacuum can destroy the universe?
In this video, physicist Roberto Stevens will tell you how the universe can disappear in a matter of seconds:
If you all of a sudden follow scientific and near-scientific news, you may have come across another horror story from Stephen Hawking. He is there again threatening the whole world with Armageddon. More precisely, Hawking, of course, did not say anything like that, he is just promoting his new book Starmus, which will be released in October, and the media, as usual, picks up and spreads the message around the world - "Hawking said there are two vacuums in the world, false and true Soon everything false will become true and all will be finished."
Naturally, this is complete nonsense and you should not be afraid, Armageddon is postponed indefinitely. But what is a false vacuum and why you should not be afraid of it, I would like to tell you. Traditionally I will on fingers™.
The idea is quite old, by the way, and Hawking did not come up with it. It has been circulating in scientific circles since the 1970s. And Hawking seems to have found another tricky solution to this yet completely theoretical concepts. In order to understand what is false vacuum, you first need to figure out what a true, real vacuum is.
By the very meaning of the word "vacuum" it seems to be complete, absolute emptiness. But we have emptiness, so to speak, varying degrees of freshness let's go through each one.
Look at the room from the picture of the post, usually if there are no people in the room, they say about it that it is empty. But after all, besides people, there can be a bunch of different objects in the room, chairs, sofas, cabinets, carpets on the walls (and they should be on the floor!) And so on.
We will remove all objects from the room, and absolutely everything - we will twist the sockets from the walls, tear off the baseboards, remove the laminate, and rip up the window sills. Now the room is completely empty. But is it a vacuum? She's full of air! By the way, a cubic meter of air at sea level weighs about a kilogram, and a cubic meter of water weighs exactly a ton. This means that in a standard room of 3x5 meters there is a little less than 40 kilograms of air, given the standard Khrushchev ceilings.
But they also removed the air, i.e. all the molecules, all the substance that was inside, now we have a vacuum? No, there are still a lot of fields! If the room is bright (the light bulb, baldos, they forgot to remove it!), It means that photons of light fly back and forth around the room. If someone put a Wi-Fi access point next to the wall, Wi-Fi also sends us its electric waves into the room. Plus, the cellular network is caught from the nearest tower, plus the whole room is permeated with radio and TV frequencies, and I’m still silent that a supernova exploded in the nebula from the constellation Hercules and flooded our entire room, but what’s the room, the entire Earth with gamma radiation. We will remove all possible electromagnetic radiation from the room, shield it completely. Anyway, the room is full of CMB (good luck getting it out!) and pierced by trillions of neutrinos for every cubic millimeter of volume. A-a-a-a!!!
In short, they tensed up and removed everything, everything, everything, everything that was possible from the room. Protected from everything, and to protect against neutrinos they built lead walls 2-3 light years thick all around. Only now have we begun to approach the concept of absolute vacuum. This does not occur in nature, of course. But far, far from galaxies, in the voids of space, you can find something similar, although there is still nowhere to escape from the cosmic microwave background radiation. But even there, either a stray proton will slip through, or a neutrino, or a couple of photons from some nearest galaxy will arrive.
So, we removed everything, absolutely everything that is possible from the room, got absolutely clean, fresh, frosty vacuum temperature 0 Kelvin (because there is no matter, no fields - no temperature) and wondered what was the energy contained in the volume of this room. The logical answer will be exactly zero, and then immediately - yeah!
The fact is that there are things that we can remove from the room (vacuum), and there are things that cannot be removed from there. Fundamentally.
First, these are the so-called quantum vacuum fluctuations. What is it in detail to explain for a long time, on fingers™ we can say that even in an absolutely empty vacuum at the quantum level, some kind of movement is constantly happening. The vacuum boils at the quantum level, in it countless virtual particles are born and disappear without interruption, either jumping out of the Dirac sea, or diving back. It is impossible to shield from vacuum fluctuations, this is a property of the vacuum itself, they are always there.
Secondly, it so happened that in a vacuum someone spilled dark energy. This is the one that is responsible for the accelerated repulsion of galaxies. We have no idea what kind of energy this is, we used to think that these are vacuum fluctuations, but then we calculated - no, they are not. And something else. "Dark Energy" is just a name. Perhaps it is not dark at all, perhaps not even energy. But it is there, it cannot be. From that, it is still simply considered another property of the vacuum itself, like vacuum fluctuations, but somehow different.
Third, the recently discovered Higgs Boson. The meaning of this boson is that a certain Higgs field extends throughout the Universe, of which this boson is a quantum. This field, again, is everywhere and everywhere, you can’t hide from it (according to modern scientific concepts), which means that even in the most empty vacuum it is always present.
Fourth, others universal fields or regular dark shit about which we still do not know and do not know.
All this tells us that even the most wasteful cubic meter of vacuum still contains some energy (at least the sum of those already mentioned), i.e. It can be said, albeit very figuratively, that a cubic meter of vacuum weighs something, because if there is energy in it, then the emcekvadrat is the same!
From which it is officially accepted in science today to consider absolute vacuum not something "absolutely empty", but something that has, in principle, minimum possible energy value. If you draw an energy graph, you get this squiggle:
From the picture, several things are immediately clearly visible and understood (that's why I brought it up).
Our vacuum is at the lowest red point of the graph, the energy value there is minimal, but it is not equal to zero. The graph does not touch the zero axis, but is located a little above it.
And then all the ideas from the series are swept aside - "since the vacuum energy is not equal to zero, is it possible to put it into business somehow, say, build some kind of cunning power plant operating on vacuum?" It is evident that it is impossible. If you put the ball in the hole, no matter what you do with it, it will still return to its lowest point. Those. to build some kind of "engine on the energy of the vacuum", you need to take this energy from the vacuum and give it to the engine, but this is impossible to do, the energy of the vacuum is already at the very minimum.
Now let's move on to a false vacuum. As soon as scientists guessed the picture that I cited above, suspicion immediately arose, what if this not the whole picture but only part of it? Suddenly, if we take two steps away from it, then we will have a wider perspective and the full picture will actually look like this:
Those. what we call our true vacuum is just one of the pits (Vacuum A). When the real, real true vacuum lies even lower (Vacuum B). Maybe in that vacuum the Higgs field strength is lower, or there is less dark energy, or something. In this case, in our Universe, we get not a true, but a false vacuum. Well, false and false. For us, there is not much difference, we can live all our lives in this false vacuum and not blow our heads. And not even know that he in fact false, but exists somewhere much more true.
But there is always a chance that this freebie will suddenly end abruptly. Nature always tends to a minimum of energies. She herself cannot jump from a false vacuum into a true one (from a small hole to a larger one) she is not allowed and the walls interfere.
But what if "push the ball harder"? What if you hit the vacuum with such energy that it jumps up and rolls over into a state of another vacuum, more true? By the way, this one may also turn out to be false, next to which there will already be true true, but for us it is not important. It is important for us that some nonsense may happen, and our vacuum will jump from our state to the next, "lower".
Let me tell you right now it will be very bad. And to everyone and everything. A good non-fiction article is not complete without some little Armageddian at the end. And then the end of the world comes to everyone and total. The properties of all other particles and fields in it depend on the properties of the vacuum. All of our electrons and protons, of which we are made, will immediately change their properties, they will have different charges, or some spins or some other foolish crap. And this means that all atoms will immediately fall into pieces, or evaporate, or annihilate, stars will explode or go out, or ... in short, anything can happen, and according to the law of probabilities, something bad is sure to happen. The chance that everything will remain as before is minimal, because if you just tweak any of the constants of the existing Universe a little, the whole of it immediately collapses right away. Of course, another universe is being built right there in its place, but we, as living organisms consisting of specific compounds of chemical molecules, will not be happy about this change at all.
I can't resist the pleasure of describing how everything will happen. First, one piece ("particle", "atom", if I may say so) of the vacuum will jump from a false state to a true one, or at least a lower one. And then it will pull "for itself" all its neighbors. The calculations there are not very simple, but the gloomy geniuses have already calculated that one piece will not do it - it will drag everyone along with it. It will trample like water through a tube from the upper vessel to the lower one, scientifically speaking: the gradient will be directed towards the lower minimum. Around the point of the initial jump, in fact, at the speed of light, a ball of a different space, a different vacuum, will begin to swell. Everything that the ball touches, it immediately absorbs, turning into dust and a pair of elementary particles, or it becomes lead-heavy and is shackled by complete real estate, or it ignites with a million degrees, or even all atoms, all matter in an instant turns into a stream pure-radiant energy and at the speed of light scatters in all directions. Here it will not be possible to say in advance that anything can be, but obviously it does not remain the same. Since the boundaries of the ball are flying apart at almost the speed of light, it is impossible to see in advance and be warned of a catastrophe. Information that a death ball is rushing at you another vacuum propagates at almost the same speed as the balloon itself inflates. You just live your life, crunching on French bread, shitting in comments or running away from the wild bees of Mozambique and then - bam! Everything is gone, including you. It won't hurt, it won't be scary, just in a moment our world will end and that's it. And the wave will go further, absorb Cassiopeia, the Andromeda nebula, the triangle supercluster... It will be a very boring end of the world, and no one will be able to predict, not warn, or even feel it. Consider that the universe just turned off the light.
How can such an Armogeddian start? There are two options. Or something will push the "vacuum ball" so high that it will jump over the barrier separating different vacuum states. These calculations are all purely hypothetical, of course. Vaughn Hawking gave birth, gave birth, and gave birth, that such a trick would allegedly require energy of the order of 100 billion GeV or 100 million TeV. How he did it, no one knows. Most likely, Hawking played with world constants, divided something somewhere, multiplied, took the root and gave the answer. Well, like, with such an energy, some tricky Higgs boson should be born, which from the usual Higgs field will make another Higgs field, with different characteristics. And this means a different vacuum energy density, and then everything follows the scenario that I described above.
Drives Hawking or not - no one knows. He calculated something there and gave us the result. All the media immediately trumpeted - "Hawking predicted the end of the world, it is scheduled for next Friday!" Someone has already estimated the size of the collider needed to achieve such energies, it must be much larger than the planet Earth. But here's the thing.
Remember, before the launch of the LHC, there was a hysteria in the world (more, of course, in the press) that a terrible black hole would form from collisions at the collider, which would eat us all? Collision energies at the LHC, if you don’t know, you can look at Wikipedia - 14 TeV (14x10 12 electron volts). And the so-called "cosmic rays" periodically fall on the Earth directly on the head from above, in which some particles reach energies millions of times higher than such energies. Where these particles come from is unknown. Even worse, they shouldn't exist at all. There is the so-called GZK limit (the Greisen-Zatsepin-Kuzmin limit, after the names of the scientists who discovered it). He says that a particle with an energy higher than 50 EeV (exaelectronvolt, 5x10 19) cannot fly to the Earth. All particles with higher energies must literally "slow down on the background radiation" and not reach the earth. But come on, they fly, and with much higher energies. This is still an unsolved mystery of science, where they originate and how they reach us, hence the paradox of the same name.
So, these particles exist, they fly to us and release much higher orders of energy than pathetic people can even imagine with all their LHCs and synchrophasotrons. And nothing, no black holes are formed, the Universe does not die. So it’s too early to worry about this, most likely we shouldn’t be afraid of any cunning boson.
But there is another variant of vacuum jumping from a false state to a true one. Spontaneous. Not dependent on anything, not on any particles, energies and collisions. Purely due to the laws of quantum mechanics. In this mechanics, there is a so-called tunnel effect, when some particle can completely randomly "jump over a potential mountain" and end up behind it, in the literal sense - like a tunnel through and straight. In this case, this is not some kind of funny incident of theory, interesting only in the form of a cunning formula on paper. All of us, right now, are using this effect in our electronics, for example, in the computer or tablet with which you are reading the current post, there is also probably a tunnel diode, a transistor, or some other tricky microcircuit that directly uses this quantum mechanical effect for its own (t .e. our) direct benefit.
So in a situation with a false vacuum, it may happen that some kind of bastard will take it and jump over the mountain for no reason. And drag the rest of the universe with it. The chances of such an outcome are very, very small (in quantum mechanics, in general, anything can happen, but with a certain probability in each specific case). Here, the risks are generally incalculably small, the number of zeros after the decimal point in the probability of such an event will not fit in any galaxy even if they are printed in small print directly in a vacuum. However, the universe is also quite large (maybe infinite). Who knows, maybe somewhere this transition-jump has already occurred, and another Universe is moving at us with the sizzling sword of Nemesis at the speed of light, with new, improved(but, alas, not for us) by the laws of physics.
On the other hand, if this orb originated a billion light-years away, you don't have to worry. There will be a billion (or five or ten, who knows) years left. During this time, many more interesting and deadly events and cataclysms will surely occur, human civilization will have the opportunity to be destroyed a hundred times more - is it worth fearing the hundred and first, moreover, instantaneous and painless?
