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How did positrons change the world of physics? The shocking theories and experiments behind this!
In the history of physics, the discovery of the positron is undoubtedly a landmark event. As the antimatter partner of the electron, the positron played a key role in the development of particle physics and cosmology and has had a profound impact on our understanding of the nature of the universe.
Shocking theoretical background
In 1928, physicist Paul Dirac proposed the "Dirac equation", a mathematical formula that combines quantum mechanics, relativity and electron spin. The core of this theory is to propose that electrons can exist not only with positive energy, but also with negative energy. Dirac's research made scientists realize for the first time that electrons may correspond to a kind of "anti-electron", namely a positron.
"The possibility that electrons have negative energy forces us to rethink the structure of the entire universe."
Although Dirac's theory caused a lot of controversy, it provided guidance for subsequent experimental discoveries. In 1931, Dirac took this prediction further and formally predicted for the first time the existence of positrons, particles that annihilate when interacting with electrons.
Experimental discovery of positrons
The discovery of the positron did not happen overnight. Many scientists have hypothesized its existence before. Although as early as 1923, the Russian physicist Dmitri Skobeltsyn had observed electron-like particles while studying the Compton effect, this result failed to arouse scientific interest at the time. world's attention. Later, Lorenz Gansha (Carl David Anderson) successfully captured the existence of positrons in a cloud chamber experiment using cosmic rays in 1932, for which he won the 1936 Nobel Prize in Physics.
"I observed traces of positrons for the first time in the experiment. The shock at that moment cannot be described in words."
The discovery of the positron not only confirmed Dirac's theory, but also became the first instance of antimatter being observed by humans, completely changing our view of the universe.
Positron generation in nature
In nature, the generation of positrons mainly comes from the β+ decay process, such as the decay of radioactive isotopes such as potassium-40. In addition, cosmic rays also contain positrons. A 2011 study showed a combination of positron and gamma-ray flashes above thunderclouds.
The content of potassium-40 in the human body is also sufficient to release numerous positrons every day. These positrons will eventually annihilate with electrons to form high-energy gamma rays.
Applications of positrons in current physics
Today, positrons are used in many fields, including particle accelerator experiments, positron emission tomography (PET), and materials science. The collision of positrons and electrons can be used to produce a variety of elementary particles, which is of great significance for testing physical theories and discovering new particles.
"The application of positrons gives us a deeper understanding of the nature of matter."
In the medical field, PET scanners use gamma rays released by positrons to create three-dimensional images of the inside of the human body to help doctors diagnose diseases. In addition, positron annihilation spectroscopy (PAS) technology has also become a powerful tool in materials research, capable of detecting defects and voids inside solid materials.
Future research directions
With the continuous advancement of science and technology, scientists have launched more in-depth explorations in positron research. Some large laboratories have begun to try to generate and observe positrons under extreme conditions, hoping to uncover the mystery between antimatter and matter in the early days of the universe.
In future research, the analysis of positrons will not only be limited to the properties of elementary particles, but will also be expanded to explore other physical phenomena such as dark matter. Therefore, the study of positrons is not only a scientific issue, but also an in-depth exploration of the nature of the universe.
In the exploration of positrons, we can't help but think: How will we further reveal the deep connections and interactions between matter and antimatter in the vast mysteries of the universe?
