Axion facts for kids
| Interactions | Gravity, electromagnetic |
|---|---|
| Status | Hypothetical |
| Symbol | A0 |
| Theorized | 1977, Peccei and Quinn |
| Mass | 10−5 to 10−3 eV/c2 |
| Electric charge | 0 |
| Spin | 0 |
An axion is a tiny, theoretical elementary particle that scientists believe might exist. It was first suggested in 1977 by two scientists, Roberto Peccei and Helen Quinn. They proposed the axion to help solve a big puzzle in quantum chromodynamics (QCD), which is a theory about how tiny particles interact. This puzzle is called the strong CP problem.
If axions really do exist and have a certain mass, they could be a part of cold dark matter. Dark matter is a mysterious substance that scientists think makes up a large part of our universe, but we can't see it directly. There's also some evidence that axions might come from the Sun. Some theories even suggest that axions could travel faster than the speed of light, which would be a huge discovery!
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What is an Axion?
An axion is a type of boson, which is a fundamental particle. Unlike some other particles, axions are thought to have no electric charge and no spin. This means they wouldn't interact much with light or other charged particles. They are also very light, much lighter than an electron.
Why Do Scientists Think Axions Exist?
Scientists often propose new particles to explain things they observe or to fix problems in their theories. The axion was suggested to solve a specific problem in quantum chromodynamics (QCD). QCD describes the strong force, which holds the tiny parts of atoms together.
The Strong CP Problem Explained
The "strong CP problem" is a puzzle in physics. It has to do with how the strong force should behave. Based on our current understanding, the strong force should allow for something called "CP violation." This means that certain processes involving the strong force should look different if you flip them in a mirror and reverse time. However, experiments show that this CP violation doesn't happen for the strong force, or it's extremely small. This is a mystery! The Peccei–Quinn theory suggests that if axions exist, they would naturally prevent this CP violation from happening, solving the puzzle.
Axions and Dark Matter
One of the most exciting possibilities for axions is that they could be a major part of dark matter. Dark matter is invisible and doesn't interact with light, making it very hard to detect. However, scientists know it's there because of its gravitational pull on galaxies. If axions are very light and don't interact much, they would be perfect candidates for cold dark matter. Many experiments are trying to find axions to see if this is true.
Looking for Axions
Scientists are actively searching for axions using different methods. Some experiments look for axions coming from the Sun, as the Sun's hot core might produce them. Other experiments try to detect axions that could be part of the dark matter in our galaxy. These experiments often involve strong magnetic fields, hoping to convert axions into tiny flashes of light that can be detected. Finding an axion would be a huge step forward in understanding both particle physics and the universe.
See also
In Spanish: Axión para niños
