ABSTRACT: The book of Genesis was not written to teach us the age of the earth, and so it can legitimately support either a young-earth or an old-earth view. Evidence from astronomy and various earth sciences, however, suggests that our universe and our earth are billions of years old. In the absence of a clear biblical stance on the issue, Christians should be willing to consider interpretations of Genesis 1 that fit with an old creation.
We asked professors Wayne Grudem and Jason DeRouchie to offer arguments for their respective old-earth and young-earth views, and then respond to each other. Access the full set of articles and responses on the “How Old Is the Earth?” series page.
I do not believe that God intended in Scripture to tell us the age of the earth. In the following material, I will explain the factors that led me to this conclusion about Scripture and then summarize some scientific indications of the age of the earth.1
Meaning of the Word Day
The word day as used in Genesis 1 translates the Hebrew word yôm, which often refers to 24-hour days, but in other contexts clearly refers to an unspecified period of time. We see this in the immediate context, in Genesis 2:4: “. . . in the day that the Lord God made the earth and the heavens.” Here, day refers to the entire creative work of the six days of creation.
Other examples of the word day to mean a period of time include Psalm 20:1 (“May the Lord answer you in the day of trouble!”), Proverbs 24:10 (“If you faint in the day of adversity, your strength is small”), Proverbs 25:13 (“Like the cold of snow in the time [yôm] of harvest . . .”), and Ecclesiastes 7:14 (“In the day of prosperity be joyful, and in the day of adversity consider”).
Even the first use of the word day in Genesis 1 does not mean a day of 24 hours but simply the daylight hours: “God called the light Day, and the darkness he called Night” (Genesis 1:5).
Genesis 1 in Light of Science
The context of Genesis 1 does not clearly require one meaning of day over another, and if scientific data, drawn from many different disciplines and giving similar answers, convinces us that the earth is billions of years old, then this possible interpretation of day as a long period of time may be the best interpretation to adopt.
For those who hold to an old earth, the situation is something like that faced by Christians who first held that the earth rotates on its axis and revolves about the sun. They needed an explanation for verses about the sun “rising” or “going down,” like Ecclesiastes 1:5: “The sun rises, and the sun goes down, and hastens to the place where it rises.” (See also Psalm 104:22; James 1:11; and others.) They did not have to claim that the passages require us to believe in a heliocentric (sun-centered) solar system, nor did they have to say that this was the most natural or the easiest interpretation, but only that this is a possible legitimate understanding of the texts, seeing these verses as speaking from the standpoint of the observer. From there, observational evidence taken from science shows us that this is, in fact, the correct way to interpret those texts.
Each of the days of Genesis 1 ends with an expression such as, “And there was evening and there was morning, the first day” (Genesis 1:5). Does this require us to conclude that the days must be 24-hour days? Not necessarily, because the phrase may be simply the author’s way of telling us that the end of the first creative “day” (that is, a long period of time) occurred, and the beginning of the next creative “day” had come. In addition, alert readers would recognize that the first three creative “days” could not have been marked by evening and morning as caused by the sun shining on the earth, for the sun does not appear until the fourth day (Genesis 1:14–19). Therefore, Genesis 1 itself shows that references to “evening and morning” in the chapter do not refer to the ordinary evening and morning of days as we know them now.
Does it matter that the days are numbered? Supporters of a young-earth position sometimes argue that, while the Hebrew yôm can elsewhere refer to a longer period of time, its use in Genesis 1 is different because numbers are attached, and whenever yôm has a number attached, it refers to 24-hour days.
I do not find this argument persuasive because the requirement to consider only cases of the Hebrew yôm with a number attached acts as a filter to preselect the desired “24-hour day” answer. This is because, in the course of ordinary human life, the usual kinds of “days” that people count are 24-hour days, not longer periods of time. The creation narrative just happens to be the only context where longer periods of time are counted.
Nevertheless, interpreters who have decided that the days of Genesis 1 must be 24-hour days have another option available to them. The creation days might be 24 hours long, with many millions of years between the days. I think this must be considered another possible way to understand Genesis 1 in a manner that is consistent with an old earth.
Gaps in the Genealogies
In the 1650s, Irish archbishop James Ussher, a distinguished historian and biblical scholar, argued from the genealogies in Genesis 5 and 11 that the date of God’s creative work in Genesis 1 was October 22, 4004 BC. To arrive at this conclusion, he used both the genealogies in Genesis 5 and 11 and extrabiblical historical sources.
However, it is doubtful that God’s purpose in these genealogies was to enable us to calculate the date of creation. If that had been God’s intention, he could have done so clearly by having Moses write, “So all the years from Adam to Abraham were 2004 years” (or some similar number). But there is no such summary statement in Genesis 5 or Genesis 11.
It is certainly possible, on the other hand, that the genealogies in Genesis 5 and 11 contain gaps. For instance, the genealogy in Matthew 1 tells us that Joram was “the father of Uzziah, and Uzziah the father of Jotham” (Matthew 1:8–9). But from 1 Chronicles 3:10–12 (which uses the alternate name Azariah for Uzziah), we learn that three generations have been omitted by Matthew: Joash, Amaziah, and Azariah.
So when Genesis 5 says, “When Seth had lived 105 years, he fathered Enosh,” it could mean that Seth fathered someone whose descendent was Enosh. Thus Enosh in Genesis 5:6–8 could in fact be someone who came many generations after Seth. In that case, the large number of years is not meant to give us a chronology that can be added together to get the age of humanity, but rather it is given to show us the health and longevity of someone who could still beget children at more than 100 years old and could even live to 912 years.
For the God who lives forever, for whom “one day is as a thousand years, and a thousand years as one day” (2 Peter 3:8), and who delights in gradually working out his purposes over time, perhaps 13.8 billion years was just the right amount of time to wait for light from vastly distant stars to reach the earth, so that as we discover the age and size of the universe, we would be amazed at the greatness of our Creator, who made such an immense universe and whose eternal existence is far greater than even 13.8 billion years.
Scientific Evidence for an Old Earth
Different kinds of observational (or scientific) evidence from astronomy and the earth sciences seem to indicate that both the earth and the universe are extremely old (13.8 billion years for the universe and 4.5 billion years for the earth).2
Expansion Rate of the Universe
Astronomers can measure the distance from earth to various stars and galaxies. They can also measure the speed at which they are moving away from us. With those two values, they can “back up” the process to find how long the universe has been expanding. After summarizing three different methods of measuring such expansion, Hugh Ross says they show an average age of the universe of “13.79 ± 0.06 billion years,” and he adds, “The consistency of the three independent methods is remarkable.”3
Starlight from Events in the Distant Past
Many stars are so far from the earth that it would take millions or even billions of years for their light to reach us. They give us evidence that requires a brief discussion of the speed of light.
The speed of light (in a vacuum) is approximately 186,000 miles per second, and the sun is about 92,960,000 miles from the earth. That means it takes just over eight minutes for light from the sun to reach us. Therefore, when we see a sunrise or sunset, we are not seeing the sun as it is at that very moment, but we are seeing the sun as it was eight minutes ago.
This principle also applies to light from other stars. When we look through a telescope at Alpha Centauri (the star that is closest to us, after the sun), we are looking at a star that is 4.4 light-years away, which means the light from that star took 4.4 years to reach us. Therefore, what we see is Alpha Centauri as it existed 4.4 years ago. In the same way, some of the stars we can observe are so distant that their light would take 13,800,000,000 years to reach us. This indicates a very old universe.
Young-earth supporters may respond that perhaps God created the universe with light rays already in place, so that Adam and Eve would see thousands of stars on the first night after they were created. This of course is possible. Certainly Adam and Eve themselves had an “appearance of age” (God created them as adults, not as infants), as did all the animals that God created as “grown-up” animals.
But there are difficulties with this suggestion. First, there is the existence of white dwarfs, which are formed when stars reach the end of their lifetimes and run out of nuclear fuel.4 But “a star takes millions of years, minimum, to burn up all of its nuclear fuel and become a white dwarf.”5 If the universe is only 10,000 years old, and if God created stars with light rays in place, why would he also create optical illusions that look like material from stars that died billions of years ago, when in fact those stars never even existed?
The same is true for other events that astronomers observe in space, such as the existence of supernovas, which are massive, extremely bright explosions, lasting several weeks or months, that happen when stars are about to burn out. But according to young-earth advocates, as Ross notes, “The supernova eruption astronomers claim to see in the Large Magellanic Cloud 163,000 light-years away did not occur 163,000 years ago.” In fact, according to a young-earth view, it never occurred, since nothing existed before 10,000 years ago. When astronomers see such supernovas that explode and then quickly die out, these would be optical illusions placed in outer space to make us think (wrongly) that supernovas happened hundreds of thousands of years ago. It would seem contrary to God’s character to deceive us like this.6
Some young-earth advocates have responded that perhaps the speed of light has changed, and perhaps light traveled much faster a few thousand years ago. But the speed of light is one of the most universal constants in physics, and the need to speculate that it might have been vastly different (a million times faster?) seems to me to cast doubt on the entire young-earth viewpoint.
Scientists have drilled deep into the ice layers in the central parts of Antarctica and northern parts of Greenland. They have found that “three ice cores from Antarctica . . . provide a continuous record of the past 800,000, 720,000, and 420,000 years, respectively.”7 A young-earth advocate might respond that multiple layers could be laid down within a single year, but Ross notes that “within the layers are dust signatures of known volcanic eruptions,” including eruptions of Mount Vesuvius in AD 79, 472, 512, 968, 1037, 1139, 1631, and 1944. “Counting the layers between layers that contain the dust signatures of these eruption events, researchers have confirmed that each layer indeed corresponds to one year.”8
Sediment Layers at the Bottom of Lakes
Geologists Gregg Davidson and Ken Wolgemuth have written an extensively documented article showing that “finely layered sediments from Lake Suigetsu [in Japan] were deposited annually going back more than 50,000 years.” They also show that the most recent of these layers of sediment correspond closely with tree rings that go back more than 14,000 years, and that carbon-14 decay rates (measured by various samples taken at various depths of the sediment layers) “have remained unchanged.”9
Radiometric Dating of Rocks
Igneous rocks are formed when lava or magma (very hot molten material found beneath the earth) cools and changes from a liquid to a solid. Some igneous rocks consist partly of radioactive material that begins to decay as soon as a rock solidifies, and when it decays it changes into another element. For example, uranium-238 decays and turns into lead-206. But uranium-235 becomes lead-207, and thorium-232 becomes lead-208.10 For every type of radioactive substance, the rate of such decay can be measured. With that information, geologists can measure the amount of each kind of uranium and thorium isotope and the amount of each kind of lead isotope in a rock, and with that information they can determine six independent measures of the age of a rock.
Since each of the uranium and thorium isotopes decays at a different rate, if a rock sample has all three of the uranium and thorium isotopes and all three isotopes of the resulting lead, the proportion of each kind of uranium, thorium, and lead gives us six different independent measures of the age of the rock. Ross reports that “ratios of different radiometric elements relative to the lead end products and the ratios of the different lead end products relative to one another provide consistent, accurate dates — all saying that the earth is billions of years old.”11
Fossil-bearing rock fields near the coasts of Africa and South America were apparently previously joined together and then separated by continental drift as the continents gradually moved apart. In fact, anyone who looks at a globe can see that, if the continents of North and South America could be moved eastward and the continents of Europe and Africa could be moved westward, with slight rotation the continental shelves would fit together. In addition, underneath the Atlantic Ocean there is a large mountain ridge called the Mid-Atlantic Ridge that follows the curved pattern of a line halfway between these continents. All this is evidence of plate tectonics, the scientific study that explains movements of the plates on which the continents rest.
Now, there are two separate methods to determine how long ago the continents separated. Taking samples from the crust of the Atlantic Ocean at the edges of the continents, “maximum ages of about 180 million years for the Atlantic Ocean crust are obtained.”12 This suggests that the continents separated about 180 million years ago, leaving the Atlantic Ocean between them. If we measure the distance from a point on the North American coastline to the corresponding point on the African coastline, the distance is 3,480 miles. If we divide 3,480 miles by 180,000,000 years, it “yields an average rate of 1.2 inches per year.”13 Repeated calculations at different points vary only slightly, from 1.1 to 1.7 inches per year.
But are these continents actually moving apart at that rate? Long-term precise satellite “measurements of the relative positions of North America and North Africa document a current spreading rate of approximately 1 inch per year, a value in remarkable agreement with the radiometrically determined rates.”14 This confirms that the continents began to move apart 180,000,000 years ago — but that is impossible if the earth is less than 10,000 years old.
Conclusion: Old Earth
I realize that young-earth advocates will disagree with my assessment of this evidence. They will claim that maybe the speed of light was vastly different, maybe the rate of sediment deposit in lakes was vastly different, maybe the speed of movement of the earth’s tectonic plates was vastly different, maybe the rate of decay of radiometric elements in rocks was vastly different, and so forth. Eventually this begins to sound to me like, “If the facts were different, they would support my position.” But that kind of argument is just an admission that the facts do not support one’s position.
As for the biblical evidence, I think it can be legitimately and honestly understood to allow for either an old-earth or a young-earth view. I do not think the Bible tells us or intends to tell us the age of the earth or the age of the universe.
For more detailed arguments for the old-earth position, see my Systematic Theology, 2nd ed. (Grand Rapids: Zondervan, 2020), 385–413. ↩
Much of the following material, plus the relevant documentation, comes from the Christian astronomer Hugh Ross, in the much-expanded 2015 edition of his book A Matter of Days: Resolving a Creation Controversy, 2nd ed. (Covina, CA: RTB Press, 2015). Ross interacts repeatedly and specifically with young-earth objections to his arguments. ↩
Ross, A Matter of Days, 147, 150. ↩
“White dwarfs are the final state of all stars possessing less than enough mass to become either black holes or neutron stars” (Ross, A Matter of Days, 156). ↩
Ross, A Matter of Days, 156. ↩
I am glad to see that the ministry Answers in Genesis, though holding to a young earth, rejects the idea that God created the universe with light rays from stars and the earth already in place; see Jason Lisle, “Does Distant Starlight Prove the Universe Is Old?” December 13, 2007, https://answersingenesis.org/astronomy/starlight/does-distant-starlight-prove-the-universe-is-old/. ↩
Ross, A Matter of Days, 190. ↩
Ross, A Matter of Days, 190. ↩
Gregg Davidson and Ken Wolgemuth, “Testing and Verifying Old Age Evidence: Lake Suigtsu, Varves, Tree Rings, and Carbon-14,” Perspectives on Science and Christian Faith 70, no. 2 (June 2018): 75–89. ↩
Ross, A Matter of Days, 187. ↩
Ross, A Matter of Days, 187. ↩
Roger Wiens, “So Just How Old Is That Rock?” in The Grand Canyon: Monument to an Ancient Earth, ed. Carrol Hill, Gregg Davidson, Tim Helble, and Wayne Ranney (Grand Rapids: Kregel, 2016), 94. ↩
Wiens, “So Just How Old,” 94. ↩
Wiens, “So Just How Old,” 94. ↩