Particle Stars Grocery Store: A Book on Particle Astrophysics

By Jingyu Xiang

Particle Star Grocery Store: A Popular Science Book on Particle Astrophysics is a book that introduces the basic concepts, latest developments and future prospects of particle physics and astrophysics to the readers in a lively and interesting way. Do you want to know what the universe is made of? Do you want to understand the mysteries of black holes, dark matter and gravitational waves? Do you want to explore the history and methods of human's knowledge and exploration of the universe? If you are interested in these questions, then this book is for you. In this book, you will feel like walking into a particle and star grocery store, where you can freely choose the topics that interest you, and enjoy the wonder and charm of particle physics and astrophysics. Whether you are a science enthusiast or a science professional, you will find something suitable and fun for you in this book.

• Language: English
• Publisher: Jingyu Xiang
• Release date: May 1, 2023
• ISBN: 9798223311898

Book preview

Modern Physics Travel Guide

Two major theories of modern physics

Quantum mechanics

Relativity (Special Relativity)

Relativity (General Relativity)

Atomic Model

Four basic forces

The Standard Model of Elementary Particles

1.Fermion

2. Boson

Common rays, radiation and waves

Common decay

General Introduction to Particle Astrophysics

Discovery of cosmic rays

Prediction and discovery of positrons

Uncovering the reason why stars glow and glow

Neutrino prediction and discovery

Big Bang Theory and Cosmic Microwave Background Radiation

Discovery of pulsars

Discovery of gravitational waves (indirectly)

Detection of extrasolar neutrinos

Accelerated expansion of the universe and dark energy

Discovery of neutrino oscillations

Discovery of the Higgs boson

Direct detection of gravitational waves (direct)

Early Universe and Cosmic Evolution

Stellar evolution and high-energy objects

Electromagnetic waves

Cosmic rays

Gravitational Waves

Neutrino

Cosmic rays

Detection of neutrinos and dark matter

Particle Cosmology

Final Chapter

Modern Physics Travel Guide

Before starting the real microcosm and space travel, we need to read the travel guide carefully to ensure that our travel process is smoother and can also prevent our brains from overloading during the trip.

Two major theories of modern physics

Quantum mechanics

THE BASIC IDEA OF QUANTUM mechanics is to consider microscopic particles of matter (such as electrons, photons, etc.) as quanta with wave-particle duality, i.e., they can behave as both particles and waves. Quantum mechanics attempts to describe the laws of motion of quanta and their interactions with other physical quantities in mathematical terms.

It is difficult for me to introduce you clearly all the contents of quantum mechanics in a very short space, but I can use a few of the most critical facts or principles inside quantum mechanics to let you establish the basic ideas of quantum mechanics.

1. Quantum state

YOU CAN THINK OF A quantum state as a snapshot of a quantum system, which records all the information about the system at a given moment, such as its energy, position, momentum and spin. However, this information is not definite, but has a certain probability distribution, that is, you cannot read the specific values of the system directly from the quantum state, but can only calculate the probability of their appearance. This is different from the macroscopic world, for example, in the macroscopic world, a car can only be in a certain place, it may be parked in the garage at home or speeding on the road, but its state is unique, it cannot be parked in the garage and speeding on the road at the same time. But in the microscopic world, it happens that even if the exact same environment and situation acts on the same car (the exact same experiment is repeated), we may observe it in the garage one time and on the road the next time, and this has been shown to be determined not by some implicit variable, but by its own probability. More precisely, given the initial conditions and the external environment, we cannot predict what choice a microscopic particle will make, but can only calculate the probability that it will make various choices. This is the meaning of the famous uncertainty principle in quantum mechanics. This possibility is not caused by our lack of information or technology, but is an inherent property of the microscopic particle itself. This means that, in a sense, microscopic particles have their own will and are not bound by determinism. But this is actually a comforting thing for us. Once I was thinking that if everything in a world is certain, then the next moment, and even every moment in the future, can be predicted, then our life is in a sense already decided, but the microscopic randomness caused by quantum mechanics prevents this view from holding true, that is, each of our minds, our life is not already decided. This is, of course, just a little reflection of the author.

2. Wave-particle duality

LET'S TAKE LIGHT AS an example. Maybe you have heard the expression light wave or photon, which one is correct? In fact, they are both correct statements, light has both particle and fluctuation, I use two experiments to explain its fluctuation and particle nature.

Fluctuation of light: Double slit interference experiment, you can see the light through the two slits, the formation of light and dark stripes on the screen, indicating that light has the characteristics of coherent superposition and interference. Just like when two beams of water waves meet, they will stir up bigger waves in some positions, and in some positions two water waves cancel each other out, which is interference.

The particle nature of light: the photoelectric effect experiment, you can see that when light shines on a metal surface, it causes the metal to emit electrons, indicating that light has energy and momentum and can collide with matter.

So what else has wave-particle duality besides light? In fact, electrons, protons, and all other microscopic particles have wave-particle duality. But are they the only ones? The book you are reading, the drink you are drinking, and even you, all have wave-particle duality, and we are both a physical particle and a wave. But why don't we usually feel or observe the properties of our waves? Because according to De Broglie's formula, a 60kg person walking at 1m/s has a wavelength of only 10 minus 35 meters, which is much smaller than the nucleus of an atom, so in the macroscopic world, it is almost impossible to observe the volatility of objects, and they show more of their particle nature.

3. Uncertainty principle

THE UNCERTAINTY PRINCIPLE is an important principle of quantum mechanics, which shows that a pair of conjugate physical quantities of a particle cannot be measured or determined precisely at the same time. For example, position and momentum are a pair of conjugate physical quantities; the smaller the uncertainty of position, the larger the uncertainty of momentum, and vice versa. It indicates that some physical quantities of a quantum system (such as position and momentum) cannot be measured exactly at the same time and there is a minimum uncertainty between them.

It is worth noting that the uncertainty principle is not caused by the limitations of measurement methods or technical capabilities, but by the wave-particle duality and superposition of quantum states in the quantum system itself.

When we measure a quantum system in a superposition state, we observe that one of the determined states disappears while the other states disappear, which is called wave function collapse.

4. Quantification

IN QUANTUM MECHANICS, quantization means that certain physical quantities can only take on discrete values, not continuous arbitrary values. For example, the electron energies in an atom are quantized in that they can only be an integer multiple of some smallest unit. This smallest unit is the quantum. This is not quite in line with our common knowledge that the energy of light, for example, is actually one part at a time, rather than continuous, with each photon carrying a fixed amount of energy. A common example is that when we go to the store to buy water to drink, we can only buy one or more bottles of water, not half a bottle.

5. Quantum entanglement

QUANTUM ENTANGLEMENT is a quantum mechanical phenomenon in which two or more quanta in an entangled state, no matter how far apart they are, are associated in such a way that if one of them changes its state, the state of the other one changes instantaneously, regardless of the spatial constraints, and the association is superluminal. This phenomenon was called ghostly hypergravity by Einstein because it seems to violate the relativistic law of cause and effect. However, quantum entanglement cannot be used to transmit information because the measurements are random and classical communication is required to compare the results at both ends. Quantum entanglement is an important resource for quantum information processing, and it can be used for applications such as quantum invisible transfer, quantum key distribution, and quantum computing.

To use a more interesting analogy as an example, suppose there are two magicians, A and B, who are at opposite ends of the earth, and they have a special magic trick that allows them to create entanglements with two identical hats. They put two hats together, then put one on each, and then they can fly to anywhere. At this point, the two hats are in a state of entanglement, and their color is indeterminate; it could be red or blue, but it must be the opposite. If A takes her hat off and sees that it is red, then she knows that B's hat must be blue, and vice versa. This is the effect of quantum entanglement, a mysterious connection between two hats that makes them always the opposite color, and no matter how far apart they are. But A and B can't use this method to send messages, because they can't control the color of their hats or know when the other person has looked at their hat. They can only tell each other what color they saw by phone or other means. This is why quantum entanglement cannot violate the law of cause and effect.

Relativity (Special Relativity)

SPECIAL RELATIVITY is a theory that describes the physical laws of objects moving at high speeds in the absence of gravity. It was proposed by Albert Einstein in 1905 and is based on two fundamental principles: the principle of relativity and the principle of invariance of the speed of light.

1. Principle of relativity

The principle of relativity means that the laws of physics are the same in any reference system moving at a constant speed, and that no one reference system is more specific or superior to another. This means that if you are on a train, and the train is moving at a constant speed on the tracks, then you are observing the same physical phenomena as you would observe on the ground. For example, you can play ping pong on the train, or measure things with a ruler, or keep time with a clock, and you will find that these are no different than if you were doing these things on the ground.

2. The speed of light is constant

The speed of light invariance principle means that the speed of light in a vacuum is constant in any reference system, about 300,000 kilometers per second. This means that no matter how fast you are moving, the speed of light you see is the same. For example, if you are on a train