Principles and experimental phenomena of holography

Holography refers to a new photography technology, which records all the information of the amplitude and phase of the reflected wave of the object being photographed. Ordinary photography records the light intensity distribution on the surface of the object, but it can't record the phase information of the reflected light of the object, so it loses its three-dimensional sense. Holography uses laser as the illumination source, and divides the light emitted by the light source into two beams, one of which is directly directed at the photosensitive plate, and the other is reflected by the subject and then directed at the photosensitive plate. The superposition of two beams of light on the photosensitive plate produces interference, and the sensitivity of each point on the photosensitive plate changes not only with the intensity, but also with the phase correlation of the two beams of light. Therefore, holography not only records the reflection intensity on the object, but also records the phase information. When the human eye directly looks at this photosensitive film, it can only see interference fringes like fingerprints, but if it is irradiated by laser, the human eye can see the three-dimensional image of the original object through the film. Even if only a small part of the holographic image remains, it can still reproduce the whole scene. Holography can be applied to nondestructive testing, ultrasonic holography, holographic microscope, holographic storage, holographic film and television and many other aspects in industry. The principle of generating holograms can be traced back to 300 years ago, and some people have done experiments with poor coherent light sources, but it was not until 1960 that laser, the best coherent light source, was invented that holography developed rapidly.

Laser holography is a brand-new technology, which is known as the miracle of the 20th century. Its principle was discovered by Hungarian British physicist dennis gabor in 1947, which is completely different from ordinary photography. It was not until 10 years later that American physicists Rafe and Rupert Nyx invented the laser and holography was put into practical application. It can be said that holography is a combination of information storage and laser technology.

Laser holography includes two steps: recording and copying.

1. The holographic recording process is: the laser beam is divided into two beams; A laser beam is directly projected on the photosensitive film, which is called reference beam; Another laser beam is projected on an object, and after being reflected or transmitted by the object, it carries the relevant information of the object, which is called object beam. After processing, the object beam is also projected to the same area of the photosensitive film. On the photosensitive film, the object beam and the reference beam are coherently superimposed to form interference fringes, thus completing the hologram.

2. The method of holographic reconstruction is to irradiate the hologram with a laser beam. The frequency and propagation direction of the laser beam should be exactly the same as the reference beam, so that the three-dimensional image of the object can be reproduced. People can see different sides of the object from different angles, just like seeing the real thing, but they can't touch the real thing.

Holographic imaging is a sophisticated technology. Holography is different from traditional photography. What is recorded on the negative is not the plane image of a three-dimensional object, but the light field itself. Conventional photography only records the change of light intensity on the surface of the reported object, that is, only records the amplitude of light, while holographic photography records all the information of light waves, forgetting to record the phase of light waves except amplitude. That is to say, all the information of the optical wave field of the three-dimensional object is stored in the recording medium.

Holographic principle is that "a system can be completely described by some degrees of freedom on its boundary", which is a new basic principle based on the quantum properties of black holes. In fact, this basic principle is related to the quantum theory of combining quantum elements and quantum bits. Its mathematical proof is that there are as many quantum elements as there are dimensions of time and space; There are as many qubits as there are. Together, they form a finite set of time and space similar to a matrix, that is, their permutation and combination set. Holographic incompleteness means that there is duality among the selected permutation number, the selected empty set and the selected full permutation. That is, the holography of a certain dimension of space-time is completely equivalent to the holography with one less quantum bit arrangement number; This is similar to the "quantum error-avoiding coding principle", which fundamentally solves the problem of systematic calculation error caused by coding error in quantum calculation. The quantum computation of space-time is similar to the double conjugate coding of biological DNA, and it is a quantum computer that organizes real and imaginary, positive and negative double conjugate coding together. This can be called "biological spatio-temporal science", in which "entropy" is similar to "macro entropy", which refers not only to the degree of chaos, but also to a range. Does time mean a range? From "from life", it should mean. Therefore, all positions and times are ranges. Position entropy is area entropy and time entropy is thermodynamic arrow entropy. Secondly, the binary arrangement similar to the binary arrangement of n elements and n bits is similar to the determinant or matrix of n rows and n sequences. One of the differences is that a determinant or matrix has one less quantum bit than a binary arrangement of n elements and n bits. Is this similar to the holographic principle? The binary arrangement of n elements and n bits is an integrable system, and its dynamics can be similar to the determinant of n rows and n sequences with one qubit lower. Mathematically, it may be proved or explored.

1, anti-De Sitter space, that is, point, line and in-plane space, is integrable, because the junction of point, line, in-plane space and point, line and out-of-plane space tends to be "super zero" or "zero point energy" zero, so it is an integrable system, and any dynamics of it can be realized by a low-dimensional field theory. That is to say, due to the symmetry of anti-De Sitter space, the symmetry in the field theory of point, line and in-plane space is greater than the Lorentz symmetry of the origin, line and out-of-plane space. This larger symmetric group is called conformal symmetric group. Of course, this symmetry can be eliminated by changing the geometry inside the anti-De Sitter space, so that the equivalent field theory has no conformal symmetry. This is called new conformal conformal conformal. If Madsina space is regarded as "out-of-point space", then the general "out-of-point space" or "in-point space" can also be regarded as spherical space. Anti-de sitter space, that is, "space within a point", is a special limit in field theory. The calculation of classical gravity and quantum fluctuation effect in "space within a point" is very complicated and can only be calculated under a limit. For example, the inflation rate of the cosmic mass orbit circle similar to the above anti-De Sitter space is 8.88 times of the speed of light, which is made under a limit. Under this limit, the "in-point space" transits to a new space-time, or called pp wave background, so that the spectra of various states of cosmic strings can be accurately calculated and reflected in the dual field theory, and we can get the abnormal scale indexes of some operators in the mass spectrum calculation of matter families.

2. The trick is that strings are not composed of a limited number of spherical quantum micro-units. In order to get strings in the usual sense, we must take the limit of loop quantum string theory. Under this limit, the length does not tend to zero, and each string that is coupled into a loop quantum by line rotation can be divided into -33 cm microcells 10, so that the number of microcells does not tend to infinity, so that the physical quantities corresponding to the string itself, such as energy and momentum, are limited. In the operator construction of field theory, we only need to take this limit to get the string state under the background of pp wave. In this way, the microscopic cell model is a universal structure and clear. Under the special background of pp wave, the corresponding field theory description is also an integrable system.