A Simple and Fun Introduction to Modern Physics

Physics is the study of matter, energy, and the interactions between them. It explains many phenomena in the natural world, such as gravity, light, sound, electricity, and magnetism. But what is contemporary physics?Contemporary physics is the branch of physics that deals with the most recent and advanced topics in the field. It includes topics such as quantum mechanics, relativity, cosmology, particle physics, and string theory.

What are those things?

Quantum mechanics is the theory that describes the behavior of very small things, such as atoms, electrons, photons, and quarks. It shows that these things can behave in strange and unpredictable ways, such as being in two places at once, or changing their state when observed.

How can something be in two places at once?

Physicist: It's hard to explain, but it has to do with the fact that these things are not really particles, but waves. And waves can interfere with each other and form patterns. Sometimes these patterns look like particles are in two places at once, but they are really just probabilities of where they might be.

What is relativity?

Relativity is the theory that describes the behavior of very fast things, such as rockets, satellites, and light. It shows that these things can experience time and space differently than we do. For example, time can slow down or speed up depending on how fast you are moving or how strong the gravity is around you.

So if I go on a rocket to space, I will age slower than my friends on Earth? Yes, that's true. But the difference will be very small unless you go very close to the speed of light or near a black hole.

What is a black hole?

A black hole is an object that has so much mass and gravity that nothing can escape from it, not even light. It is formed when a very massive star collapses at the end of its life. It is called a black hole because it absorbs all the light that falls into it and makes it look black.

Can a black hole swallow the Earth?

The nearest black hole to Earth is thousands of light-years away and poses no threat to us. Besides, black holes are not like vacuum cleaners that suck everything in. They only affect things that come very close to them.

What is cosmology?

Cosmology is the study of the origin, structure, and evolution of the universe as a whole. It tries to answer questions such as how did the universe begin? What is it made of? How old is it? How big is it? How will it end?

How did the universe begin?

The most widely accepted theory is called the Big Bang theory. It says that about 13.8 billion years ago, the universe was very small, hot, and dense. Then it suddenly expanded rapidly in a huge explosion. This created space and time and filled them with matter and energy. Since then, the universe has been expanding and cooling down.

 We know this from observing the universe with various instruments such as telescopes, satellites, and detectors. We also use mathematics and computer simulations to test our theories and make predictions.

What is particle physics?

Particle physics is the study of the smallest and most fundamental building blocks of matter and energy. It tries to answer questions such as what are the basic particles that make up everything? How do they interact with each other? What are the forces that govern them?

What are the basic particles?

The basic particles are called elementary particles. There are two types of elementary particles: fermions and bosons. Fermions are the matter particles that make up atoms, such as electrons, protons, and neutrons. Bosons are the force particles that mediate interactions between fermions, such as photons, gluons, and the Higgs boson.

What is the Higgs boson?

The Higgs boson is a very special particle that was discovered in 2012 at the Large Hadron Collider, the world's largest and most powerful particle accelerator. It is responsible for giving mass to other particles by interacting with a field that fills the whole universe. It is also called the God particle because it is essential for the existence of matter.

What is string theory?

String theory is a very ambitious and controversial theory that tries to unify all the forces and particles in nature into a single framework. It says that the elementary particles are not really point-like, but tiny vibrating strings of energy. These strings can have different shapes and modes of vibration, which determine their properties and interactions. String theory also predicts that there are more dimensions than the four we know (three of space and one of time), but they are curled up and hidden from us.

How can there be more dimensions than we see?

It's hard to imagine, but you can think of it like this: imagine a very thin wire that looks like a line from far away, but if you look closer, you can see that it has a circular cross-section. That circle is another dimension that is too small to notice. Similarly, there could be other dimensions that are too small or too twisted to see.