The Field Of Physics

   Suddenly, I want to improve my English skills especially, writing and speaking. Why I want to improve my English is that The final goal is to discuss expert physical topics in English. There are some ways to improve my English, I'm going to use this blog. What I'll write is about physics.

   Today, I want to talk about The Field Of Physics. Physics has a wide range of fields so, I'll talk about this in turn.

   First, I talk about MECHANICS or DYNAMICS(these two wards in the same mean). In the ordinary school of physics, students learn mechanics at first after enrolling in college. Mechanics consists of three fundamental laws called Newton's law of motion.NO.1The law of inertia.NO.2 The law of motion. NO.3 The law of action and reaction. 

   Let's look at NO.1. Probably, you think the laws mean that moving objects will be still moving if there is no force. But this interpretation is wrong because that concept is contained NO.2. The true interpretation is that there is one inertia coordinate system at least. 

   Next, look at NO.2.This law means object acceleration is proportional to the force that works it and proportional constant is object mass. In the mathematical expression, $ m\overrightarrow{a}=\overrightarrow{F}$ (m is mass, a is acceleration, F is force) 

 Finally, look at NO.3.This law means that When two objects are interacting with each other, There arise action and reaction force whose direction is  opposite and magnitude is the same

   Second, I talk about ELECTROMAGNETICS. In electromagnetics, We study the property of electricity and magnet, and finally, we will study electromagnetic waves. Like mechanics, electromagnetics consists of a four plus one equation. The first and second are called Coulomb's law (electric charge version and magnetic charge version). Third, is called Faraday's law. Forth is Ampere-Maxwell's law. These four equations are called Maxwell's equations. One more thing is the Lorentz force relationship.

  If we use Maxwell's equation in specific situations, we can lead that light is an electromagnetic wave and its structure is that Electric and magnetic fields are the right angle.

   Third, I talk about THERMODYNAMICS. Modern people believe that any substance is made from a very small particle called an atom and temperature is caused by molecular motion. In thermodynamics, these hypotheses are not necessary because, in the stage of thermodynamics being complete, the theory of substance made by the atom is not perfect so, in the starting point for discussion of thermodynamics, this theory is not in as requested.

   These three physics field is what is called fundamental physics. Next, I'll talk about modern physics but I have not studied modern physics enough yet, so I'll introduce you less than I wrote above.

   By the way, when we describe phenomena around us, we use classical mechanics but the laws of classical mechanics can apply for objects around us being fully big. In the case of quantum, we can't apply the principle of classical mechanics law so, to describe quantum phenomena, quantum mechanics is born. 

   I talk about quantum mechanics as one of the two major fields of modern physics, the other is relativity. As you well know, who built the theory of relativity is Einstein. Relativity consists of special relativity and general relativity. The discussion of special relativity is started as the principle of light speed invariance and the principle of relativity. After some easy calculation, we obtain these results that if you get on a very very high speed specifically, near the light speed vehicle, the time which you feel in the vehicle is slower than you feel it when you stand still and if you look at very very high speed specifically, near the light speed vehicle, you find that the vehicle is shorter (the direction of travel is getting shorter) than you look at it is still. What I write above is the main topic in special relativity and the difference between special relativity and general relativity is whether these contain gravity or don't. General relativity contains gravity and to understand it, we have to use very difficult mathematics such as the tensor field.

   Other modern physics is Statistical Mechanics, continuum mechanics, Solid State Physics, quantum field theory, astrophysics, and so on.