Most of the controversy concerning Genesis 1 centers on the meaning of the Hebrew word “yom” (pronounced yome) for day. In Biblical Hebrew it can mean a 24-hour day, the daylight hours, or a finite period of time of indefinite duration. Its most common meaning is “daylight”. It is only rarely used to represent a 24-hour day. Unlike English, the original Biblical Hebrew had no other word to express a finite period of time of unspecified duration. Some writers have suggested that the Hebrew word “olam” could have been used for that purpose. However, this word only came to mean an age or era in post biblical writings. In Biblical times “olam” meant forever, always, eternity, etc., i.e. periods of time without a beginning or end. The following are some examples in which “yom” refers to a finite period of time.
Numbers 3:1 These are the generations of Aaron and Moses in theyomthat the Lord spoke with Moses in mount Sinai. ( From Exodus 34:28 we have “So he was with the Lord forty days and forty nights”)
Genesis 2:4 These are the generations of the heavens and of the earth when they were created, in theyomthat the Lord made the earth and the heavens.
Genesis 2:17 But of the trees of the knowledge of good and evil, thou shall not eat of it: for in theyomthat thou eatest thereof thou shalt surely die. ( Genesis 5:5 states that Adam lived 930 years)
Psalm 90:4 (attributed to Moses) For a thousand years in thy sight are butyomwhen it is past and as a watch in the night.
Isaiah 34:8 For it is theyomof the Lord's vengeance, and the year of recompenses for the controversy of Zion.
Hosea 6:2 After twoyomhe [God] will restore us [Israel]; on the third day he will restore us.
The seventh “yom” in Genesis 1 is often taken to be a long period of time (possibly extending to the present) since the phrase “and there was evening and there was morning” is omitted.
Hebrews 4:4–11 For somewhere [God] has spoken about the seventh day in these words: “And on the seventh day God rested from all his work.” …
It still remains that some will enter that rest. … There remains, then, a sabbath-rest for the people of God; for anyone who enters God's rest also rests from his own work, just as God did from his. Let us, therefore, make every effort to enter that rest.
It is possible that the seven days in Genesis 1 are, at least in part, a literary device. Ancient Near Eastern literature, particularly from Mesopotamia and Canaan, provides numerous examples of the use of seven days as a literary framework to circumscribe the completion of a significant or catastrophic event . The pattern in these works runs uniformly as follows: “One day, a second day, so and so happens; a third day, a fourth day, such and such occurs; a fifth day, a sixth day, so and so takes place; then, on the seventh day, the story comes to its exciting conclusion.” Genesis 1:1–2:3 modifies this pattern from three sets of two days followed by a concluding day to two sets of three days followed by a concluding day. On days 1–3 God gives form to the universe. The characteristic verbs used in these three days are separate and gather. On days 4–6 God fills his creation. The characteristic verbs here are teem, fill, be fruitful, increase.
In some translations we find the phrases “the first day”, “the second day”, “the third day”, “the fourth day”, “the fifth day”, and “the sixth day” associated with the days of creation. Actually, the definite article ‘the’ is not present in the Hebrew for the first five days. In Hebrew the article ‘the’ is expressed by prefixing a word with the letter ‘heh’. Elsewhere in the Old Testament where expressions such as “the first day”, “the second day”, etc. are used, both the number and the word ‘day’ are prefixed with ‘heh’. In Genesis one, only the sixth day has the prefix ‘heh’ and it only on the number. Although Hebrew has a word for ‘first‘, the word ‘one’ is used instead. Thus, the use of numbers with the word ‘day’ in Genesis chapter one has a very unusual construction. A more literal rendering of the Hebrew is “day one”, “a second day”, “a third day”, “a fourth day”, “a fifth day”, and “the sixth day.” The omission of the definite article “the” in all but the sixth day allows for the possibility of a literary ordering of the days as well as a strictly chronological order. It would also seem to allow for the possibility of gaps between the days. The use of the article on the sixth day seems to provide a special emphasis.
Each of the six days ends with the phrase “and there was evening and there was morning …” Authors Mark Van Bebber and Paul Taylor  wrote, “This phrase [evening and morning] is used 38 times in the Old Testament, not counting Genesis 1. Each time, without exception, the phrase refers to a normal 24-hour day.” However, it has been pointed out by others that
- The word “day” appears in none of these references.
- In only a few of these do the words “evening” and “morning” even occur in the same sentence.
- The phrase “evening and morning” occurs only once. In Psalm 55:17 David said, “Evening, and morning, and at noon will I pray.”
- 24-hour days were usually marked by “evening to evening” and occasionally “morning to morning.”. Strictly speaking, evening followed by morning delimits the nighttime.
- The exact phrase “and there was evening and there was morning” occurs only in Genesis 1.
You sweep men away in the sleep of death; they are like the new grass of the morning — though in the morning it springs up new, by evening it is dry and withered. Psalms 90:5–6
are an example of where “evening” and “morning” are used figuratively to delimit a period of time. It is also interesting what is not said in relation to the evening and the morning. The Egyptians believed that the setting of the sun was when the sun god descended into the underworld. He battled with the gods of the underworld throughout the night. The sunrise in the morning represented the victory of the sun god over the gods of the underworld. In the Genesis account there is nothing special that happens during the night. Everything is under God's control.
Van Bebber and Taylor also said that 358 out of the 359 times “yom” is used with an ordinal number modifier, it represents a 24-hour day. However,
- There is no rule in Hebrew grammar that requires this interpretation.
- All of the 358 cases mentioned refer to human activity where the 24-hour meaning would be natural. Genesis 1 and Hosea 6:2 refer to God's activity.
It is often argued that the required Sabbath observance indicates that the days were ordinary 24-hour days.
Exodus 20:9,11 Six days you shall labor …, but the seventh day is a Sabbath. … For in six days the Lord made the heavens and the earth …, but he rested on the seventh day.
Hebrew scholar Gleason Archer noted, “By no means does this [Exodus 20:9–11] demonstrate that 24-hour intervals were involved in the first six ‘days,’ any more than the eight-day celebration of the Feast of Tabernacles proves that the wilderness wanderings under Moses occupied only eight days.” In addition, Leviticus 25 speaks of a Sabbath year. Thus, it could be argued that the Sabbath is not tied to a particular time duration, but to the pattern of one in seven. It should also be noted that the preposition “in” preceding “six days” in Exodus 20:11 is not present in the Hebrew. Also, the verb translated as “made” is the Hebrew verb “asah” that doesn't necessarily imply the creation of something new. The creation verbs will be discussed later on.