Language
Country/Area
No result found
The mysterious origin of the positron: Why did Dirac's prediction in 1928 revolutionize the scientific community?
In 1928, British physicist Paul Dirac proposed a theory that not only changed the landscape of particle physics, but also had a profound impact on the development of quantum mechanics. In this paper, he introduced the Dirac equation, which allows us to now understand that electrons not only have negative energy solutions, but may also have positive energy solutions. The subsequent impact of this discovery eventually led to the prediction of the anti-electron, or positron.
A positron is the antiparticle of an electron, with the same mass and spin but a charge of +1e. When it collides with an electron, an annihilation reaction occurs.
Theoretical foundations
The birth of the Dirac equation is a landmark unification of quantum mechanics and special relativity. When Dirac derived the solution for negative energy, he did not immediately conclude it until he clarified its significance in a subsequent paper in 1929. He assumed that all negative energy states were "filled," meaning that it was impossible for electrons to jump between positive and negative energy states at will. This hypothesis also introduced a more revolutionary idea: space is an "ocean" filled with negative energy electrons.
Dirac claimed in his paper: "...an electron with negative energy moving in an external electromagnetic field looks just like one with positive charge."
The idea sparked an academic debate that was challenged by scientists from Oppenheimer to Weill, providing important mathematical insights into predictions for future theories. In his 1931 paper, Dirac predicted the existence of a particle called the "anti-electron," which has the same mass as an electron but an opposite charge. Further experiments proved the credibility of this theory and unveiled the mystery of antimatter. .
The dawn of experimental discovery
The experimental discovery of the positron was not simple. Although Dmitri Skobeltsyn first observed the possible existence of the positron in 1923, he was unable to determine its identity. In 1932, Carl David Anderson observed charged particles in a cloud chamber that were eventually confirmed to be positrons, a discovery that won him the 1936 Nobel Prize. He discovered the anti-electron by placing a magnetic field inside a cloud chamber to discern the charge of the particles. This moment is considered a milestone in particle physics and antimatter research.
"The discovery of the anti-electron made me realize that this was not just a theoretical concept but a real entity that existed in nature," Anderson wrote.
Positrons in life
Positrons don't just exist in laboratories; they can also be found in nature. The beta decay of some radioactive isotopes (such as potassium-40) produces positrons, which naturally generate some positrons in the human body. About 4,000 positrons per second die in the human body and produce electrons by annihilation. Gamma rays. The process is related to the medical use of positron emission tomography (PET), which helps doctors obtain three-dimensional images of a patient's metabolic activity.
The existence of positrons in the universe
In addition to being produced on Earth, astronomical research shows that positrons also exist in the universe. Satellite experiments have observed positrons from primordial cosmic rays, which has sparked much discussion about the origin of antimatter. Some researchers have suggested that the generation of positrons may be related to the annihilation of dark matter, which could deepen our understanding of the universe.
Scientists speculate that the source of positrons may come from the interaction between cosmic rays and dark matter, rather than from undetected areas of antimatter.
Artificial production of positrons and future prospects
With the advancement of technology, scientists have begun to be able to produce high amounts of positrons in artificial environments. For example, at the Lawrence Liverpool National Laboratory in the United States, scientists used powerful lasers to irradiate a target to produce more than 100 billion positrons. In addition, the collaborative research between CERN and Oxford University achieved a breakthrough in producing 10 trillion electron-positron pairs in the experiment. This progress has opened up a new way to study the behavior of particles in extreme environments in the universe.
The study of positrons is not only crucial to the exploration of fundamental physics, but will also open up unlimited possibilities in medical imaging, materials science, and future experiments in particle physics. As we gradually unravel the mystery of the positron, perhaps we are also wondering: How many unsolved mysteries are there in this ocean of antimatter waiting for us to explore?
