All objects with temperatures above absolute zero can generate thermal radiation. The higher the temperature, the greater the total energy radiated. When the temperature is low, the main form of thermal radiation is infrared light that is invisible to the human eye; When the temperature is high, the main form of thermal radiation changes to visible light visible to the human eye. ——Cai Yifu, a professor at the Astronomy Department of the School of Physics at the University of Science and Technology of China, is one of the oldest Chinese characters. In oracle bone inscriptions, the glyph shows a person with a fire on their head, indicating that the flame brings light to humanity. However, where does the light in the universe come from? This issue still causes scientists to argue endlessly. In a new study, researchers believe that light in the universe comes from strong gravity. What is strong gravity? Where exactly did the first ray of light in the universe come from? Why has the first ray of light not yet reached Earth, more than 13 billion years after the birth of the universe? With these questions in mind, a reporter from Science and Technology Daily interviewed relevant experts. The origin of light is the origin of matter. To understand where light in the universe comes from, one first needs to understand the essence of light. Cai Yifu, a professor at the Astronomy Department of the School of Physics at the University of Science and Technology of China, introduced to reporters that as early as ancient times, humans began to study light. The ancient Chinese "Mojing" recorded 8 pieces of knowledge related to light, including the linear propagation of light and pinhole imaging, but the definition of light has not yet been clearly defined. Since the 17th century, with the continuous expansion of scientific research, the understanding of the essence of light can be divided into two opposing theories: wave theory and particle theory. In 1925, French physicist de Broglie proposed the theory that all matter has wave particle duality. Subsequently, German physicist Planck and other digital scientists established the theory of quantum physics, greatly expanding human understanding of light. "At present, it is generally believed that light has wave particle duality. In essence, light is both an electromagnetic wave and a particle photon. Therefore, light has some characteristics of electromagnetic waves and particles at the same time." Cai Yifu said, "In geometrical optics, the path of light propagation is straight; in wave optics, light propagates in the form of waves; in quantum optics, the existence of light energy is quantization." Today, With the continuous deepening of research on light, people's understanding of light is also deepening. In Cai Yifu's view, studying the origin of light is essentially studying the origin of matter. Generally speaking, as long as there is matter in the universe, there will be temperature. As long as there is temperature, thermal radiation will be generated, which in turn generates light, "said Cai Yifu. According to the introduction, thermal radiation refers to the phenomenon of an object radiating electromagnetic waves due to its temperature. All objects with temperatures above absolute zero can generate thermal radiation. The higher the temperature, the greater the total energy emitted. "Cai Yifu said," When the temperature is low, the main form of thermal radiation is infrared light that is invisible to the human eye; when the temperature is high, the main form of thermal radiation changes to visible light that is visible to the human eye, The light in the universe comes from strong gravity. Experts pointed out that the new research proposed a possible theoretical mechanism and approach for the conversion of graviton into photons.