Genesis 1:1: Heaven or Heavens?

In the beginning God created the heaven and the earth. (KJV)

In the beginning, God created the heavens and the earth. (ESV)

One thing that you learn early in studying Biblical Hebrew is that the Hebrew noun for "heaven" is שָׁמַיִם (shā-ma-YIM), and שָׁמַיִם appears only in the plural form[E1][E2], yet seems to be referring to a single thing. So naturally I have wondered often if it is better to translate it as "heaven" or "heavens". Most modern translations present it as "heavens", whereas the KJV, most older translations, and a few modern translations, present it as "heaven".[E3] And if "heavens" is correct, to how many heavens is this verse referring?

The answer given by my best scholarly resources is that this is an example of the "plural of extension". Williams 1.A.11 (pg. 3):

Plural of extension. A plural word may refer to a single object that consists of several parts; for example, פָּנִים 'face,' צַוָּארִים 'neck,' and שָׁמַיִם 'heaven' or 'sky.' This is also called the compounding plural, the complex plural, or the plural of a compound object.

One of the scholarly references Williams sites is BHRG 24.3.3.iv, and I happen to have a copy of that. BHRG puts it this way:

The plural forms of some nouns indicate that the referent of the noun is large, complex or manifold (the so-called plurals of extension).

BHRG gives examples מַיִם (ma-YIM, water) and אֹהָלִים (˒ō-hā-LỊM, camp or dwelling).

HALOT, in the entry for שָׁמַיִם, also makes a brief reference to the "plural of spatial extension".

Now, for שָׁמַיִם, from the information above, I am not certain if the focus here is on the vastness (largeness) of the "heavens", or the complexity (many parts) of the heavens. I would at least say that anyone can be impressed by both truths, even without the benefit of telescopes or other modern technology: viewing the "heavens above", we are profoundly affected by the vastness of this great space far above us, filled with sun and moon, a multitude of stars in various brightnesses and patterns, including wandering stars (planets) and falling stars (meteors), and the milky glow of our galaxy.

So, is "heaven" or "heavens" correct? I believe the exact meaning of the Hebrew word here is somewhere in-between these two English words. As a matter of preference, I would lean toward "heavens". The plural seems to capture a little better the vastness and wonder of that great thing above which God has created.

Psalm 19:1-6 (ESV):

The heavens declare the glory of God,
    and the sky above proclaims his handiwork.
Day to day pours out speech,
    and night to night reveals knowledge.
There is no speech, nor are there words,
    whose voice is not heard.
Their voice goes out through all the earth,
    and their words to the end of the world.
In them he has set a tent for the sun,
    which comes out like a bridegroom leaving his chamber,
    and, like a strong man, runs its course with joy.
Its rising is from the end of the heavens,
    and its circuit to the end of them,
    and there is nothing hidden from its heat.

End Notes

[E1] שָׁמַיִם also has construct form שְׁמֵי, suffix forms such as שָׁמֶיךָ (Deuteronomy 28:23), and locative forms. (See HALOT.)

[E2] Williams' (p. 3) states: "שָׁמַיִם looks like it is dual, but it is actually the plural of שׁמי. Similarly, מַיִם is the plural of מי." HALOT gives a similar note.

[E3] See https://www.biblehub.com/parallel/genesis/1-1.htm, accessed Oct 15 2021.