From Wikipedia
Human societies are characterized by patterns of relationships between individuals sharing a distinctive culture and institutions. Without an article, the term refers either to the entirety of humanity or a contextually specific subset of people.
I would restate one part of the original question as
'"society" (without "the") refers to human society in general'
and, the example should read
"socialization is the process of learning to live in society"
The phrase "the society" is used in areas of study such as anthropology, political science and sociology when referring to specific groups.
Again from the Wikipedia article, discussing a particular group
This nobility organized warriors to protect the society from invasion.
In this case, "the society" is used to limit the scope to the group under discussion, and not all of humanity.
Edited to respond to OP's edit of original question
In "Soldiers protect society" the lack of an article preceding "society" makes it a statement about human society in general. As such it can stand alone without other context.
"Soldiers protect the society" seems taken out of context. It begs the question which society?
(Note: The following example statements are not meant to be historically accurate.)
In general, soldiers protect (human) society.
In ancient Rome, soldiers called centurions protected the (Roman) society.
In ancient Japan, soldiers called samurai protected the (Japanese) society.
It's not two verbs, cracked and open. It's one phrasal verb, crack open. Open is the particle (open can be an adjective and an adverb, as well as a verb), and crack is the verb.
To crack means to make a crack, or opening, in something, which can be literal, like crack an egg, or figurative, like crack the books (which means study) or crack another bottle of scotch, which means to open a sealed bottle.
The phrasal verb crack open means to open something sealed (like a door) a very small amount ("only a crack"), so that one can see inside. It refers to the very beginning of an opening.
In this case, it's metaphoric, and refers to the first "opening" of scientific knowledge of the atom, which was due to Curie's work.
Best Answer
Merriam-Webster's Dictionary of Synonyms (1984) includes explicate and expound—together with elucidate, interpret, and construe—in a group under the heading word explain. Here is its treatment of expound and explicate:
An earlier edition of Webster's Dictionary of Synonyms (1942) has an identical treatment of the two words, except that also says that explicate means "literally, to unfold."
S.I. Hayakawa, Choose the Right Word (1968), on the other hand, groups explicate with elucidate, explain, and interpret under the heading word clarify, but doesn't address expound at all. Here is Hayakawa's commentary on explicate:
Putting the two discussions together, I would surmise that, although both terms imply a carefully developed (and usually, scholarly) investigation and presentation of a subject, explicate has a stronger sense of a line-by-line or point-by-point analysis of the subject, whereas expound is just as learned but perhaps a bit more general in its treatment and more inclined to elaborate on the implications of the broader subject.