“I think I can safely say that no one understands quantum mechanics,” said Richard Feynman, a famous physicist Some of the most puzzling topics in physics almost all revolve around quantum theory, among which the most famous problems may be “Schrodinger’s cat” and the information loss in the process of black hole evaporation. Most physicists are used to this. There is no doubt that quantum theory is successful at the practical level, but serious conceptual problems arise when quantum theory is no longer just a probabilistic tool for calculating possible experimental results, but a basic description of the “outside world.”. The basic problem with quantum theory is that it seems that quantum theory is only about what we measure, not about what exists in the world. It’s just that “the information about the world is likely to be good for us.”. But that makes sense only if there is something in the world that we can be told; in general, such information must be specified by quantum theory. < / P > < p > according to quantum theory, the general state (position or velocity of particles) of the system has no definite value. This uncertainty is called “quantum uncertainty”, also known as “quantum fluctuation”. The quantum theory in the standard textbook involves two different rules of the state evolution of physical systems: one is the “U-process” mentioned by British mathematical physicist Roger Penrose. The U-process is represented by the Schrodinger equation, which allows accurate determination of the system state at any time in the future (deterministic prediction), or at any time in the past (completely reversible), given the current state of the system. However, this rule only applies when the system is not “observed.”. < / P > < p > the second rule is a random rule, which is called “r-process” by Penrose. According to this rule, as a result of the measurement, the system state will jump to one of the states where the query attribute has a well-defined value. Generally speaking, this rule does not allow accurate prediction of the state to occur, nor does it allow inversion of the state prior to measurement or observation. The r-process can be used to accurately predict the probability, and to estimate the average value produced by a large number of repeated experiments, as well as the statistical dispersion of the results, which are numerically consistent with the above level of uncertainty. Another problem is that quantum theory is vague about the nature of the world without observers. Does this theory require the participation of consciousness to be meaningful, and if so, does it include the consciousness of mice or flies? In particular, it should be pointed out that the specific elements of measurement in quantum theory are also very vague and almost irreparable. Maybe all we need is a device big enough, but how big is enough? What happens at the border? All of these problems are called measurement problems. Such conceptual difficulties are often ignored by physicists in practice. The famous physicist David Bohm offers an exception. He rediscovered a theory initiated by Louis de Broglie and endowed it with different characteristics. He believed that point particles had definite position and velocity at any time, while quantum state only guided them to evolve over time (and a cat would never be in a state of both death and life). Another notable exception comes from researchers who support the modified quantum theory, which unifies the U-process and r-process into a single rule, eliminating the need to introduce the concept of “measurement” at the basic level. In this case, the unfortunate Schrodinger cat will be either dead or alive, even if no one is watching it. This method forms the basis of spontaneous collapse theory. The characteristic of these theories is that some kind of microscopic collapse is triggered throughout space and time, similar to the spontaneous r process of all particles; that is, no measurement is required. More advanced theories include many worlds interpretation, which was proposed by Hugh Everett. In multi world interpretation, each measurement is associated with one or more branches of reality, which are similar to parallel coexisting worlds. Careful analysis shows that these theories are essentially three possible logical ways to deal with the above problems: modifying the quantum theory by adding something other than quantum states (de Broglie Bohm theory in the hidden variable theory); modifying the state evolution rules in the theory by allowing the measurement event to occur at all times (such as spontaneous collapse theory); Or completely eliminate the R process (such as multi world interpretation). < / P > < p > many quantum physicists believe that this problem, or the approach that people may take in this area, is not related to the challenges in their field, but a few researchers hold quite different views and believe that “spontaneous collapse” is the most promising path to solve some of the most serious difficulties encountered in understanding the laws of the universe Those that have to deal with both gravity and quantum theory. The study of inflation period is one of the central topics of cosmology. Scientists believe that inflation occurred in a very short period of time after the Planck period. The Planck period itself is very inconceivable. It is considered to be the earliest time stage in the history of the universe, from 0 to about 10 ^ – 43 seconds. In Planck’s time, quantum gravity should play a leading role, and the concept of space-time itself may no longer be relevant or useful (quantum gravity theory is a theory that harmoniously combines the basic principles of general relativity, gravity theory and quantum theory). Under the mechanism of inflation, the usual concept of time and space is considered sufficient. Moreover, gravity is thought to be well described by general relativity, and matter can be explained by the same kind of theory that we use to study the physical phenomena of conventional particles (such as the Large Hadron Collider at CERN, or the study of high-energy cosmic rays). The main difference is considered to be that the dominant substance (inflation) in the period of inflation is in the so-called “inflation field”. The inflation field is a bit like an electromagnetic field, but it’s much simpler because there’s no fixed direction or spin for the Bulger. The main feature of the inflation period is that, due to the gravitational effect of the inflation field, the universe expands rapidly in an accelerated way (the total expansion coefficient is at least a factor of 10 ^ 30). As a result, the space curvature of the universe is driven to zero, and all deviations from perfect uniformity and isotropy are completely diluted (the remaining 10 ^ – 90 order deviation, so small, can be simply taken as zero). < / P > < p > at the end of the inflationary period, the inflationary field decays, and the universe is filled with all the matter we can see today: ordinary matter, which makes up ourselves, is also the matter that makes up the earth and the solar system; with the powerful particle accelerator of CERN, scientists have produced some more exotic substances in a fraction of a second; it is even difficult The elusive dark matter seems to make up the vast majority of galaxies and clusters. In other words, the universe after the end of the period of inflation should be in line with the description of the earlier, more traditional and more empirical theory of the big bang. At this time, an expanding universe is filled with thermal plasma composed of various particles, whose abundance is mainly determined by thermodynamic factors. The universe cooled as it expanded, forming light nuclei (the temperature dropped to 1 billion Kelvin); long after, the first atoms (about 3000 Kelvin) were formed. The latter stage corresponds to the photons emitted by the cosmic microwave background radiation. < / P > < p > in the small changes in the temperature pattern of the cosmic microwave background radiation, we can see the imprints from the homogeneity and isotropy of the original deviations, which will continue to grow until now and constitute the galaxies, stars and planets of our current universe. The point is, for a long time, the universe is heterogeneous and anisotropic. On the other hand, according to the inflation theory, the violent expansion of the universe completely dilutes all the heterogeneity (differences in different space conditions) and anisotropy (differences between different directions). This situation is described in terms of space-time and inflation field in a completely homogeneous and isotropic state. < / P > < p > causes the inhomogeneity in the formation of all cosmic structures, and the imprints we see in the cosmic microwave background, where do they all come from? According to the current cosmological orthodoxy theory, they come into being from the “quantum fluctuations” and space-time measurement in the period of inflation. In fact, the field of a certain quantum state, the so-called “bunch Davies vacuum”, also appears with inflation. This state, like the vacuum state in flat space-time, is 100% homogeneous and isotropic; but we should have thought of the quantum uncertainty of this state as the cause of the inhomogeneity of the universe today. < / P > < p > most cosmologists don’t see a problem at this point, because they can easily confuse “quantum uncertainty” with “statistical dispersion” (in both cases, the word “fluctuation” tends to mask conceptual bias). However, this view is reasonable only when it comes to measurement. The key is that, according to the r-process, the measurement may indeed change the state of the system, resulting in the system no longer as homogeneous and isotropic as the initial state. < / P > < p > so what could be used as a measure in the early universe before galaxies, planets, and conscious life were formed? Some cosmologists will reply that we are using satellites to make the necessary measurements today. After a little thinking, we can find the problem of this view: human beings and human measuring devices are the reasons for the perfect uniformity of the early universe, which changed the formation of cosmic structure (including galaxies, stars, planets, etc.), which in turn are necessary conditions for the emergence of life (and call itself “intelligence”)! In a way, we are the reason for our existence! This can not help but remind people of an old country folk song, “I am my own grandfather.”. < p > < p > after considering the existing path to solve the “granddad” problem, researchers such as Professor Daniel sudarsky of the Institute of nuclear science of the National Autonomous University of Mexico proposed to add a new element: spontaneous collapse of the quantum state of the inflation field. This is a version of the r-process, which occurs continuously and usually leads to small and random changes in the quantum state of the inflation field. The randomness of this process can explain the destruction of homogeneity and isotropy in the early universe without the use of any observer or measuring equipment. In addition, if the spontaneous collapse satisfies some simple requirements, the prediction of these inhomogeneities can reproduce the temperature distribution characteristics seen in the cosmic microwave background. < / P > < p > at first, this new method did not seem to cause any significant deviation from the standard forecast