In the sun's core, nuclear fusion creates a large number of photons. On the way from the core to the surface of the Sun, photons are constantly bumping into electrons and protons. It wasn't until hundreds of thousands of years later that they had a chance to leave the surface of the Sun and head straight for Earth.
Although we can feel the warmth of the sun every day, few people will think, what is light? Until the 17th century, Newton was in a room and managed to pass the light from the sun through the prism. Newton discovered that what was thought of as white light in the past could actually be broken down into different colors of light, thus unveiling the colorful side of light. Since Newton's time, more people have begun to think about what the nature of light really is.
The Infrared Life of Mark McColling
Today, thanks to the efforts of many, we know that light is not only composed of particles, i.e., photons, but it is also a kind of wave. The visible light observed by Newton is actually only a part of the entire electromagnetic spectrum. Light invisible to the naked eye also includes gamma rays, X-rays, ultraviolet rays and so on.
There are many different objects in the universe that emit different wavelengths of light. Mark McColin is a senior consultant to science and exploration at the European Space Agency, and he is most interested in the infrared band in the electromagnetic spectrum. Through the infrared telescope, he saw many beautiful landscapes that could not be seen in the optical band.
Image source: Becoming a Scientist
Wang Yifang and ghost particles
In fact, nuclear fusion in the sun's core produces not only photons, but also a large number of other particles, neutrinos. But unlike photons, neutrinos can fly out of their cores unhindered and straight to the sun's surface because they hardly interact with matter. In our daily lives, there are countless solar neutrinos passing through our bodies every second, but we are unaware.
Neutrinos, like photons and electrons, are elementary particles. To describe the interactions between elementary particles, physicists developed the Standard Model of particle physics in the 1970s. Although the Standard Model has been extremely successful in the past, it is incomplete and has many problems that it cannot explain. Through neutrino experiments, physicists may be able to find clues to break through the Standard Model.
Among all the neutrino "catchers", Wang Yifang, an academician of the Chinese Academy of Sciences, is very representative. Because the team he led discovered a third mode of oscillation for neutrinos.
Lisa Randall's Journey to Dimensions
Another problem with the Standard Model is that it only describes three fundamental forces in nature— electromagnetic, weak, and strong— and does not include gravity. Gravity is the fundamental force we experience every day and are most familiar with. In the context of a weak gravitational field, we only need to apply Newton's law of universal gravitation; but in some extreme gravitational environments, we need Einstein's general theory of relativity. General relativity tells us that gravity is the result of the curvature of space-time, and predicts other wonderful phenomena such as gravitational waves, black holes, and so on. Still, we don't know enough about gravity.
One question that puzzles physicists is why gravity is so weak compared to the other three fundamental forces. Lisa Randall, a tenured professor at Harvard University, thinks the answer may be hidden in an extra dimension. We live in a four-dimensional space-time of three-dimensional space + one-dimensional time, but that doesn't mean there aren't more dimensions. The theory of extra dimensions predicts a type of particle known as the Kaluza-Klein particle (KK particle). Physicists pin their hopes on the collider, hoping to experimentally prove the theory of extra dimensions by colliding high-energy particles to produce such hypothetical particles.
Exploring the dark side of the universe
In addition to her gravitational studies, Lisa has proposed that 66 million years ago, the culprit of the dinosaur mass extinction was actually dark matter.
Astronomical observations of the last century suggest that there should be a lot of dark matter in the universe. But what exactly is dark matter? No one knows. It may be one or more particles, and since it doesn't participate in electromagnetic interactions, we can't see it, it's a presence that the Standard Model can't describe.
For decades, scientists have painstakingly come up with a variety of methods to find dark matter particles. At the end of the last century, Chang Jin, an academician of the Chinese Academy of Sciences, proposed a new method to find dark matter through high-energy electron and gamma ray detection. In 2015, The dark matter exploration satellite "Wukong" led by Changjin was launched, indicating that the era of space science belonging to China has arrived.
Chase the light together
More than 300 years ago, Huygens and Newton began to think about the nature of light and proposed the wave theory and the particle theory, respectively. More than 100 years ago, Einstein subverted Newton's view of gravity and thus rewrote our understanding of the universe. More than 90 years ago, in order to explain the problem of energy conservation β decay, Pauli proposed neutrinos that he himself thought could not be found. More than 50 years ago, Rubin discovered that galaxies rotated too fast while studying their rotation, thus postulating the existence of dark matter in the universe, further validating Zwicky's suspicions more than 80 years ago. It is under the contemplation of these masters that we have a deeper understanding of the universe and have triggered revolutions one after another. They are like light, illuminating the way forward for generations to come.
#创作团队:
Text: Hara
Typography: Wenwen
#参考来源:
The illustrations and some of the text in this article are compiled from Becoming a Scientist (by Tencent Youth Development Committee, CITIC Publishing Group) and are used with permission.