"fundamental realities" is correct and usable in written English.
It can be used to refer to concepts or truths that are elemental or essential. For example, "The fundamental realities of life are that we all must die someday."
Bono's laudable crusade glosses overtwo fundamental realities.
Other times it asserts that certain metaphysical or transcendental entities — Plato's archetypes, for example — are the fundamental realities.
Thirteen games into the Stoudemire-Anthony experiment — and 15 games from the finish line — the Knicks are straddling the uncomfortable space between expectations and fundamental realities.
When we understand that all humans share these fundamental realities and that we all have a responsibility to ensure their availability for everyone, then everything is possible.
By the time literature appears in the development of a culture, the society has already come to share a whole system of stereotypes and archetypes: major symbols standing for the fundamental realities of the human condition, including the kind of symbolic realities that are enshrined in religion and myth.
No one bothered to examine the fundamental realities of the business; no one asked the right questions.
What has yet to be made explicit, however, are the even more fundamental underlying realities: women are relying on their sexual prowess largely in the absence of alternative forms of income generation.
"Supply is never guaranteed and all Israelis understand this fundamental reality".
And there is the fundamental reality that the Democratic Party's platform explicitly embraces abortion rights.
The last paragraph illustrates a fundamental reality of religion that Mr. Eshleman probably did not intend.
A fundamental reality of technology spending is that it is cyclical.
