Einstein's general theory of relativity is the correct theory to describe the evolution of the universe. In the framework of classical general relativity, Hawking and Penrose proved that under very general conditions, there must be singularities in space-time. The most famous singularities are the singularities in black holes and the singularities in the Big Bang. At the singularity, all laws and predictability fail. Singularity can be regarded as the edge or boundary of space and time. Only by giving the boundary conditions at the singularity can we get the evolution of the universe from Einstein's equation. Because the boundary conditions can only be given by the creator outside the universe? So the fate of the universe is manipulated in the hands of the creator. This is the first driving force that has troubled human wisdom since Newton's time. ?
Introduction pronunciation: qí? Dimi 65
This is a black hole simulation.
English: singularity/ singular? Point?
Physical singularity, the full name of singularity, is a point that exists or does not exist in physics.
Space-a time point with infinite curvature [1]. Space-time begins there and ends there. Einstein said that time and space are illusions of people's understanding. Time is the change of everything in the universe, which gives people the concept of time. At the singularity, with the birth of the universe, change began, and this is the beginning of the universe. Classical general relativity predicts the existence of singularity, but because the existing theory fails there, it can't be described by quantitative analysis. ?
Edit this cosmic singularity as "cosmic singularity", which is the point at which the universe was formed by explosion at the beginning. It has the potential energy of all matter, and this one?
Singularity-internal structure model diagram
Potential energy-the mass and energy that BIGBANG transformed into cosmic matter, and the "space" to express this mass and energy. Me?
Singularity Grand View (14 photos)
Scientists can imagine that singularity is an invisible, infinitesimal and wonderful existence. It is not the universe yet, but it is the origin and origin of our universe. As the beginning of a world, it should have all the potential energy that constitutes all the substances in the universe, and this potential energy is what we call energy. We can imagine that energy is invisible, so the singularity is invisible. In other words, the potential energy possessed by the singularity of the universe is intangible, and it is just a wonderful existence. At the same time, we can imagine that the potential energy balance of the singularity of the universe is broken at a certain point, so energy is continuously transformed into matter, and after a few years, our present universe-a * * * life body of matter and energy is formed. However, we can't imagine what caused the potential energy balance of this singularity to be destroyed. Singularity is a "geometric point" with no size, that is, a point that does not actually exist, which is very difficult to understand. It is also difficult to understand that strange matter without size is actually a matter with infinite energy level. These are inconsistent with our existing theories and concepts.
In general relativity, the study of singularity is an important subject, which is not only one of the earliest applications of energy conditions, but also an example of the whole method in general relativity. In the introduction of energy conditions, the classical solution of general relativity is mentioned, such as Schwarzenegger? Solution? -? There is a singularity. Part of this singularity? -? Like what? Schwarzschild? In solution? r=2m？ -? It can be eliminated by coordinate transformation, so it does not represent a physical singularity; ? And some singularity? -? Like what? Schwarzschild? In solution? r=0？ -? This is a real physical singularity. Obviously, in the study of singularity, the real physical singularity is the object of interest. ?
strange
Singularity is obviously that those spacetime structures have some pathological properties? (pathology? Behavior)? Time and space. But after a little scrutiny, you will find that there are many problems with this statement. First of all, "pathological" is a very vague concept. What kind of nature is pathological nature? Obviously, it needs to be precise. Secondly, general relativity is very different from other physical theories. That is to say, other physical theories are based on the existence of a background space-time, so what if those theories have singularities? -? For example, in electromagnetic theory, the singularity of the field strength where the point charge is located can clearly identify the position of the singularity in the background space-time. But general relativity describes the nature of space-time itself. So once the singularity of general relativity appears, it often means that the nature of space-time itself cannot be defined. On the other hand, physical spacetime is defined as a space with Lorentz? The metric four-dimensional manifold has good properties at every point. So there is no singularity in physical spacetime by definition, in other words, there is no singularity in physical spacetime. ?
Since there is no singularity in physical space-time, it can naturally be said that any time-space point is a singularity, so it is impossible to define a singularity as a time-space point with ill-conditioned space-time structure. But even so, like what? Schwarzschild? The obvious fact that the solution is singular is still undeniable. Therefore, the key is to find a suitable definition of singularity. If there is an incomplete non-spatial geodesic, the space-time manifold has a singularity. This is the definition of singularity adopted by most general relativity documents. This kind of non-spatial geodesic incomplete spacetime is called non-spatial geodesic incomplete spacetime, or geodesic incomplete spacetime for short? (geodesy? Incomplete? Time and space).
What exactly does the characteristic singularity of this paragraph look like? In this regard, people tried to give an intuitive description, but unfortunately, they failed to find an intuitive description covering all possible geodesic imperfections. People used to think that singularity refers to some geometric quantities? (e.g. curvature tensor)? Or physical quantity? (such as the density of matter)? Divergence, if so, then the test particles moving along the incomplete non-spatial geodesic will encounter tidal action or other divergent physical effects tending to infinity. Schwarzschild? Singularities and big bang singularities obviously have this property. But careful study shows that not all singularities are like this. One of the simplest counterexamples is conical spacetime: ds2? =? dt2？ -? dr2？ -? r2(dθ2？ +? sin2θdφ2)？ Among them? r & gt0,? 0 & ltφ。 ?
strange
Physicists have done a lot of research on the properties of singularities. Through these examples, we have some preliminary understanding of the complexity contained in the definition of singularity. Although its expression is simple, it subtly contains all kinds of complex space-time types that are difficult to enumerate completely. On the other hand, although this definition has a great coverage, it is still not enough to include all singular types. This is also caused by? Jeroche? It is pointed out that this person can be compared with Hawking in the study of singularity theorem. And then what? Penrose? An equally important person. 1968? In the same paper that puts forward the above counterexample, Jeroch? Give another space-time, which is geodesic, but contains an inextensible time-like curve with limited length (note that it is a time-like curve rather than a time-like geodesic curve), and the acceleration on this curve is bounded. Physically speaking, this means that in this space-time, the experimental particles carried by the rocket with limited fuel move along a specific time-like curve and can disappear from the space-time manifold in a limited time. Obviously, this is as serious as the disappearance of experimental particles in free fall from the space-time manifold (in fact, there is an extra rocket here! )。 So, if we think that the incompleteness of geodesic means singularity, then we must admit that Geroch? Space-time also has singularities. This counterexample shows? Like most other documents, the geodesic incompleteness adopted is only a sufficient condition to define the singularity, but not a necessary condition. In other words, a geodesically incomplete space-time must have a singularity, but conversely, a geodesically complete space-time does not necessarily have a singularity. ?
Another intuitive description of singularity is that singularity is a point (or point set) excavated in time and space. Like what? Schwarzschild? Are the singularity and cone singularity just mentioned dug up? R=0, the singularity of the big bang was dug up? T=0. But if this description is correct, then all geodesics leading to the singularity, whether time-like or light-like, must be incomplete. In other words, if the singularity is a point (or point set) that has been excavated in time and space, its existence will mean both time-like geodesic incompleteness and light-like geodesic incompleteness. The above examples all have this feature. But careful study shows that this description is not enough to cover all singularities. 1968? R years? p？ Jeroche? Give a * * * shape in Minkowski? Space-time (R4, ω 2 η ab),? Where the * * * shape factor ω 2? Spherically symmetric, in this area? r & gt 1? Constant is 1, at? r=0？ T 2 ω→ 0？ (t→∞). Obviously? Please prove it yourself. For such a space-time, time-like geodesic r=0? Along t→∞? It is incomplete, so this space-time manifold is time-like incomplete. On the other hand, all optical geodesics will pass through the region r≤ 1? And enter a flat space-time, so they are geodesics. It can be seen that this space-time has the incompleteness of time-like geodesy, but it does not have the incompleteness of light-like geodesy. This counterexample shows that not all singularities can be understood as points dug out of time and space? (or point set).
According to the current black hole theory, there is a singularity with infinite density and mass in the center of a black hole, so the singularity must be defined before defining a black hole. Using Einstein's rubber membrane analogy, if an object has enough energy or mass, it will pierce a hole in the rubber membrane, which is probably a singularity. Since the existence of a black hole has been proved, and the center of the black hole is determined as a singularity, here we start with a black hole. Obviously, light cannot escape from a black hole, which means that the gravitational acceleration and surface escape velocity of the black hole are superluminal. The existing theorem regards the matter hitting the singularity as "disappearing". In fact, when an object approaches the singularity, it will quickly accelerate above the speed of light. According to the previous proof, if it exceeds the speed of light, it will jump to another time and space, so there is absolutely no need to care about this poor object. Has nothing to do with the present time and space. According to the above reasoning, we can make a new definition of singularity, which is a breaking point in the existing time and space. In other words, the singularity is the entrance to the time tunnel. If you can stand the tidal force caused by acceleration, you can get out of here. (If you are in doubt about this, you can also understand it in another way, that is, matter has been converted into energy, and whether energy "exceeds the speed of light" is meaningless. )?
Now, let's discuss the life of the singularity. If it is naked singularity, the energy required to maintain it is basically zero. Because the singularity is a hole, its mass is basically 0. Using Einstein's equation e = MC 2 (e is energy, m is mass, and c is the speed of light), we can draw the above conclusions. In other words, a singularity is something similar to a blackbody, and it has many properties in common with a blackbody. First of all, because there is no absolute black body, it is assumed that a small hole in the closed box is a black body. Similarly, the assumption just now is similar to this. Considering the benefits of quantum, blackbody is radioactive. The quantum effect must be considered here, because in most cases, the singularity is a quantum dot. According to the uncertainty principle, it is easy to conclude that the singularity has tiny energy, which makes the singularity have a temperature (like a black hole) and something similar to blackbody radiation, which is temporarily called singularity energy radiation here. ?
Because of the great attraction of the singularity, it will not have a naked singularity, because it will soon be wrapped in matter and energy, forming a black hole. This has created a new problem. Assuming that this definition is one of the theoretical models that can best describe the real situation (it can't be said to be "correct"), then for an observer, the singularity energy radiation that he can observe from naked singularity is likely to be different from the theoretical value. Because based on the assumption that the singularity may connect with another time and space, the energy or radiation of another time and space can completely enter this time and space through this point. If you observe this effect, you can win the Nobel Prize. But unfortunately, in most cases, these radiations will be extremely weak (because the current assumed black hole radiation is unobservable, and the black hole radiation is stronger than this), and it is almost impossible to be measured in the cosmic background radiation close to 3K. However, in the special case discussed next, it is likely that this phenomenon can be roughly measured. ?
The above discussion actually assumes that the energy level of another spacetime connected by the singularity is lower than that of this spacetime. Now let's discuss other situations. Because the quantum effect is obvious here, it is easy to prove that it is impossible to show the same energy levels of two spacetime in observation. When the energy level of another time and space is higher than that of that time and space, the energy of that time and space will enter that time and space, which can be understood as the present white hole. It can be inferred that most white holes do not radiate matter. We can easily find that under this theoretical framework, many abnormal phenomena in actual observation can be easily explained, such as dark matter. To "prove" or disprove this hypothesis, it is necessary to determine whether it is a theoretical model that can best describe the current situation through actual observation. ?
Edit this main analysis 1. Physical singularity: the point of existence and non-existence in physics. Space-a time point with infinite curvature [1]. Space-time begins there and ends there. Classical general relativity predicts the existence of singularity, but because the existing theory fails there, it can't be described by quantitative analysis. ?
2. Cosmic singularity: As a "cosmological singularity", it is the point where the universe explodes at the beginning to form the universe. It has the potential energy of all matter, and this potential energy-the mass and energy transformed into cosmic matter by BIGBANG, and the "space" to express this mass and energy. As you can imagine, singularity is an invisible, infinitesimal and wonderful existence. Now it is not the universe, but the origin and origin of the universe. As the beginning of a world, it should have all the potential energy that constitutes all the substances in the universe, and this potential energy-just the energy mentioned, you can imagine that energy is an invisible thing, so the singularity is invisible. In other words, the potential energy possessed by the singularity of the universe is intangible, and it is just a wonderful existence. At the same time, it can be imagined that the potential energy balance of the singularity of the universe is broken at a certain point, so energy is continuously transformed into matter, and a few years later, the present universe-the * * body of matter and energy is formed. However, it is inconceivable what caused the potential energy balance of this singularity to be destroyed. Singularity is a "geometric point" with no size, that is, a point that does not actually exist, which is very difficult to understand. It is also difficult to understand that strange matter without size is actually a matter with infinite energy level. These are inconsistent with the existing theories and concepts. ?
3. Geometric Singularity: "Singularity in geometric sense" is also an infinitesimal and nonexistent "point". You can imagine a one-dimensional space (such as a straight line), a two-dimensional space (such as a surface), or a three-dimensional space. When it is infinite, take the last "point" with a small limit, which does not exist, that is, the singularity. ?
Attachment 1. In physics, singularities are also used to describe the center of black holes. At this time, due to the extremely high density of matter, space is infinitely compressed and bent, and matter is compressed at a very small point. At this time, the description of infinitesimal denominator will appear in the space-time equation, and then the laws of physics will be invalid. Conceptually, astrophysics thinks that singularity is the state before the universe came into being (that is, the "energy gathering place" before the Big Bang. )。 ?
Appendix 2, "Geometric Singularity?" , plus a dimension of time, is a four-dimensional "space", that is, there is a "singularity in the physical sense". ?
Appendix 3: Applying the "geometric singularity" and "physical singularity" to the Big Bang theory, that is, the "zero-starting point" of the universe exists but cannot be described, that is, the "singularity before the Big Bang". ?
It is generally believed that Einstein's general theory of relativity is the correct theory to describe the evolution of the universe. In the framework of classical general relativity, Hawking and Penrose proved that under very general conditions, there must be singularities in space-time. The most famous singularities are the singularities in black holes and the singularities in the Big Bang. At the singularity, all laws and predictability fail. Singularity can be regarded as the edge or boundary of space and time. Only by giving the boundary conditions at the singularity can we get the evolution of the universe from Einstein's equation. Because the boundary conditions can only be given by the creator outside the universe? So the fate of the universe is manipulated in the hands of the creator. This is the first driving force that has troubled human wisdom since Newton's time. ?
4. Mathematical Singularity: A mathematical singularity is usually an undefined point on a mathematical object, or when it cannot be completely ordered under special circumstances, it makes this point appear in the set of anomalies. Like derivatives. See? Geometry? Narration of several singularity theories in A Dream of Red Mansions. Example: Equation?
When a point in a real number looks like. "close" Where to? ∞? And an undefined point is a singularity? x？ =? 0。 Equation g(x)? =? |x| (see absolute value) also contains the singularity x? =? 0 (because it is not differentiable at this time). Similarly, in y? =? x？ There is a singularity (0,0) because this point contains a vertical tangent. Algebraic set is defined as y in (x, y) dimensional system. =? 1/x has a singularity (0,0) because tangents are not allowed here. ?
Gravity singularity (gravity? Singularity? ) is a "point" mentioned in the big bang cosmology, that is, the starting point of the big bang. According to this theory, the universe (space-time) was formed after the "big bang" of this "point". Singularity is a "point" with infinite density, infinite curvature of space-time height, infinite heat and infinitesimal volume, and all known physical laws fail at singularity. ?
Where the well-known laws of physics fail. Singularities are generally regarded as points, but in principle they can take the form of one-dimensional lines or even two-dimensional films. According to the equation of general relativity, as long as a schwarzschild black hole without rotation is formed, the matter in the horizon of the black hole will inevitably collapse into a point with infinite density under the action of gravity, which is a singularity (see Penlos, Roger). The uniform expansion of the universe since the Big Bang is the mirror image inversion of the collapse of this black hole, which means that the universe was born at a singularity. ?
In both cases, quantum theory is not considered in the equation. When the processed object is shorter than Planck length or Planck time, the known laws of physics, including general relativity, seem to really fail. This means that, at that scale, it is reasonable to assume that the matter that collapses to the singularity is affected by the quantum process and may "bounce" and expand outward to another set of dimensions. Some people think that the "singularity" of the Big Bang is actually such a rebound. ?
The theoretical basis for editing this paragraph is Hawking's singularity theory and the "black hole" after the singularity (that is, the pressure per square nanometer reaches hundreds of millions to tens of billions of tons. A singularity is just a point on a supermassive black hole. According to the inference provided by NRAO Observatory, an American VLBA astronomical website, in June 5438+October 20071October, the so-called supermassive black hole is millions to tens of millions times the mass of the sun. According to the calculation of the mass of the sun itself, the mass density of supermassive black holes is as high as several billion to tens of billions of tons per cubic centimeter. After calculation in the 1980s, scientists in the former Soviet Union thought that the density of matter at the singularity was as high as 10 45? Tons, the area at the singularity is 10-33? Square centimeters. And the matter at the singularity is only 10-5? G mass, and in this fetus just broke out at 10-35? Seconds, the temperature reaches 10 16? Degrees (equivalent to 1 trillion degrees), and at this time there are only various rays in the universe, such as β and γ rays. ), all kinds of "radiation", X-rays and so-called "antimatter fountains" have been unable to release "excess energy", and the temperature after the explosion may be so high that it is difficult to use today's computer to count 10 trillion times per second. Seconds, in today's 10 trillion times/second electronic computer and 58 million tons of TNT equivalent hydrogen bomb experiments are difficult to describe and count, resulting in particles with "high density and extremely high temperature". One second after the explosion, the "temperature" and "density" when particles are generated can already be used by computers on earth at the speed of 10 trillion times per second. ?
Is it the Big Bang 10-43? Seconds, or 10-35 of the big bang? The big bang of seconds and 1 second has every reason to think that the expansion speed of the universe at this time is the square of the speed of light. Since then, the universe has been expanding at superluminal speed until neutrons and protons appear. Then, in 1 100 million years, from the appearance of neutrons and protons to the appearance of atoms, the universe has been expanding at the speed of light, and the manufacturing process has continued until 138 years. According to A Brief History of Time translated by Stephen Hawking, Xu Mingxian and Wu, the temperature in the second after BIGBANG is 65.438+000 billion degrees, which is about 654.38+0000 times the temperature in the center of the sun, which is equivalent to the hydrogen bomb explosion experiment conducted by human beings. Particles continue to collide and collide at the speed of light under the original first square of the original "Big Bang" (in a cosmic vacuum, the power generated by nuclear fusion can easily make the movement speed or collision speed of particles and matter reach the speed of light. ?
The pipeline of the high-energy particle accelerator on the earth is not only filled with gas composed of special elements, but also connected with magnets and a power supply with very high voltage: the pipeline is generally vacuum, so that all kinds of particles and substances can be' accelerated to near the speed of light',' neutron cloud' and' proton cloud'. The temperature of the universe of neutron clouds and proton clouds may be quite high, and the generation of neutrons and protons may take tens of millions to hundreds of millions of years; At this time, the expansion speed of the universe may still be equivalent to 300 thousand km/s, otherwise according to Einstein's e = MC 2? According to the formula, in the expanding universe, the collision of neutrons and protons cannot produce atoms. Perhaps these neutron clouds and proton clouds, which still have extremely high temperature and energy, continue to "explode and shrink, releasing a lot of energy" in "collision" and "friction", which is very similar to the "hydrogen bomb experiment" conducted by human beings. Hawking, a British astrophysicist, believes that atoms were produced in 654.38 billion years after the "singularity" broke out. The temperature of the atomic universe may have dropped to about -270 degrees. According to the Deutsche Welle-Science and Technology Program (Russian)? Mary, a British astronomer, believes that the center of a galaxy is generally empty and its temperature is lower than the average temperature of the universe through long-term observation. Scientists believe that after the Big Bang, after a long time, the vacuum was full of neutrons and protons. This is the conclusion reached through nuclear and nuclear fusion experiments and long-term observation of stars and cosmic rays. ?
Scientists have found that the sun not only emits a lot of ultraviolet rays and neutrinos, but also emits a lot of high-energy protons and electromagnetic particles. As early as the beginning of the last century, British scientist Rutherford and his assistant discovered protons by bombarding the nucleus with particle A. In the 1930s, German physicist Heisenberg believed that neutrons and protons in the nucleus could be combined by exchanging electrons, and protons would become neutrons after losing an electron, and neutrons would become protons after gaining an electron. 1932, when Rutherford's student Charlie Wei bombarded the nucleus of beryllium with particle A, he found an uncharged particle-neutron. Chinese scientists pointed out through experiments in the 1970s that the so-called particle A was a nuclear cluster, consisting of two neutrons and two protons. June 5438+October 20071October, Ge Changchun, an academician of China Academy of Sciences, pointed out that the fusion of deuterium and tritium produced a large number of neutrons and A particles, as well as electromagnetic radiation. Because the experimental results in the laboratory are completely consistent with the observations and experimental results of astrophysics scientists on the properties of solar radiation, it is very certain that the source of solar energy is nuclear fusion.