What is the Physics?

phys‧ics [uncountable]

the science concerned with the study of physical objects and substances, and of natural forces such as light, heat, and movement

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This is "Express Tour for Modern Science".

I show genres of physics and one authority in it.

Mechanics & Lagrange

There are many mechanics, do you know?

Mechanics is most popular physics. And it is most likely to mechanics is first physics.

I could say mechanics is mother of physics.

Lagrange mechanics, Newton mechanics... Lagrange is one of persons who made mechanics. His full name is "Joseph-Louis Lagrange", 1736-1813. 

Newton mechanics is not ultimate in classical mechanics. There are principles those Newton mechanics and others based on. Newton mechanics and Lagrange Mechanics is parallel. These two says same thing!! Why, they based on same principle.

Maybe we can discover two ultimate theories about universe......

Thermodynamics & Maxwell

Can we make perpetual motion?

"James Clerk Maxwell"(1831-1879) made a ideal daemon.

It is "Maxwell Daemon".

Before talk about Daemon, I explain this principle, the first low of thermodynamics.

The first law of thermodynamics means,  "In all cases in which work is produced by the agency of heat, a quantity of heat is consumed which is proportional to the work done; and conversely, by the expenditure of an equal quantity of work an equal quantity of heat is produced." (Clausius)

There are two boxes A and B. In A,  there are warm molecule (=have more momentum), In b, there are  cold molecule (=have lesser momentum). A and B is connected, and there is a door between A and B that "Maxwell Daemon" can open and close. Then , "Maxwell Daemon" can decide which molecule can go to the other box. So if Daemon decide only warm molecule can go other side, the other box will hotter and hotter without energy! This means there are perpetual motion. 

It is the paradox! Which is true? 

"Maxwell Daemon" can't exit?

Or, principle is not true?

Electronics & Maxwell 

Maxwell again! He is great physician.

He made "Maxwell equation", it describe about electromagnetic field. This indicate the principle of constancy of speed of the light.Newton dynamics caused paradox in 19th. In Newton dynamics show speed of light is not constant.Then, Einstein's "Special relativity" shows speed of light is constant.

Newton dynamics must be modified!

There are more physics genre, but it is hard to describe those, because it is too difficult!

Physics is close to math, and if you want to learn physics, you have to learn math now.

It is very difficult to say when physics started. Because I don't know what physics is!

In early age, there are no line between any studies. 

Sophist is also physician, and physician is also sophist. (e.g. Demokritos)

It is theological, philosophical, and scientific term usually translated into English as "nature".