Science is a process to pursue truth, and skeptical spirit is its motivation and essence. For all aspects of the phenomenon in the universe, we continue to doubt, continue to explore, continue to confirm and disprove. Therefore, we are able to continuously discovery, create and move forward.

　Dr. Danny H. Y. Li, the chief designer of NCA, has been working on the study for fundamental science of light. In 2008, Dr. Li published the paper in Frontier Science, has first proposed the Light Group Field theory, in this theory the essence of light and its motion characteristics have been re-recognized. Dr. Li also gave the mathematical justification for light motion law that coincide with the result of experiments. Completely different from Classical Physics, Quantum Physics and other optical theories, the Light Group Field theory suggests that:

　1. The theory of Photon is flawed. The Light Group Field theory specifies that under the micro condition light is Light Group formed by Light Particles Subgroup which is regularly composed of Light Particles with different features. The theory of Photon (or Quantum), which has been used for a long time, is just a hypothesis, and its description and interpretation for the essence of light and the motion characteristics are imperfect.

　2. Light's wave - particle duality is not the essence of light. Repeated experiments show that the wave - particle duality of light is just a performance of light, not the essence. The performance is not uncertain and occasional, but certain and regular. Light exhibits properties of particles because Light Particles Subgroup does, while light exhibits properties of waves because Light Particles Subgroup have Primary and secondary waves. Therefore, Light Group ("light") has always exhibited properties of waves, for example optical interference, diffraction and polarization, etc. Light Group exhibits partly properties of particles only when interact with some substances that exhibit properties of particles, for example the photoelectric effect, Compton effect, etc. Different light sources have different Light Group Filed, and the performance of light's wave - particle properties are different.

　3. The speed of light in vacuum is a variable. Referenced to the volume of light source, as the Light Group moves, the density of Light Particles Subgroup tends infinitely low (the limit is zero), and therefore Light Group ("light") tends to disappear eventually. Because the speed of light is only a physical quantities that describe the motion state of light, and cannot exist independently of the Light Group. Therefore, relative to the volume of space, the speed of light in vacuum (or free space) is clearly a variable that tends infinitely low and the limit is zero.

　4. The light motion law verified by experiments is coincident with the mathematical justification, the characteristics is：

　where represents the distribution density of the Light Particles Subgroup at light source surface, that's the primary distribution density of the Light Particles Subgroup, represents the distance from an area at three-dimensional space to the light source, represents the distribution density of Light Particles Subgroups per unit area (or per unit volume) at this area. When is zero, the Light Particles Subgroup (or light) is of non-existence. When tends to infinity, the amount of Light Particles Subgroups at light group field tends to zero, which means Light Group tends to zero. During the decreasing process of the distribution density of Light Particles Subgroups, the energy of Light Particles Subgroups faded gradually.

　The distribution density of Light Particles Subgroups is an important indicator reflecting the state of Light Group, it is also a basic parameter for explanations of lights. The primary distribution density of Light Particles Subgroups at light source surface depends on the physical or chemical properties of light source, light-generating condition, and the amount of Light Particles Subgroups per unit area in unit time. The different substances of light-generating have different distribution density of Light Particles Subgroups at the surface of light source, and the same properties of light sources under different condition have different distribution density too.

　In above characteristics, represents "light source constants" which is an important parameter indicating the luminescence properties of substances that generate light (light source substances) and Light Group motion law. The constants depends on the ingredients of light source substances, light-generating environment and condition, the types of Light Particles Subgroups, and the combination of different light particles, etc. In nature, all substances generating light under certain condition, such as physical or chemical light, have a corresponding light source constants which could be determined experimentally.

　The method for determining and calculating of light source constants .

　When is the primary distribution density of Light Particles Subgroups at a light source, and is the distance to the light source, take n random (or deliberate) samples of the primary distribution density of Light Particles Subgroups, then convert the equation from

　

　to

　

　thus

　

　Measure the of the samples with a distribution density meter for Light Particles Subgroups, obtain the distribution density , thereby calculate light source constants of the samples . Use mathematic statistical analysis to educe the light source constant of the light source in its environment.

　The present cognition is subject to many conditions, for example "the uncertainty principle" bring out "the uncertainty" results. Though the consensus in science is that "it is the main purpose of science to give the widest results with the fewest hypotheses", Dr. Li considers that the search for truth should not be discontinued for some widespread theories of microscopic domains. Because the idealistic subjective consciousness may make it hazy to understand the microscopic domains, and we will be misled by the unknown physical world.

　It is a hypothesis that the speed of light is constant, the theory could be disproved but couldn't be confirmed. Many physicists have tried to measure the speed of light, but the experimental range is close relative to the universe, and therefore the measurements and results are not typical. It is impossible to measure the speed of light on the sun or on the edge of the galaxy... At this stage, it is obviously not strict to insist that the speed of light is constant.

　It is not enough to infer the true state of substance in micro world on the basis of mathematical logic, which is also the reason why explores on essence of light and its motion law has no breakthrough. If we want to explore continually the substance's micro world, we have to find a new way to approach and find out the truth, and we cannot be limited by mathematical logic or subjective imagination. Fortunately, in recent years, many researchers in the world have detected the changes in the speed of light in a vacuum, which was a turning point for the advancement of light science in the 21st century.

　The innovations and applications based on

　Light Group Field effect is significant and its applications will greatly benefit many fields, especially in optical industry, for example, device for enhancing photovoltaic generating, recycle unit for various light (nature light or illumination light), product for increasing the efficiency of Li-Fi (optical wireless communications), anti-stealth optical radar detection device, etc. Besides, Light Group Field theory has great significance in calculating the influence of other objects when astrophysical phenomena and substance in three-dimensional space expands rapidly, this theory is also of great importance to lighting layout in different environment.