Whether one answers “yes”, “no”, or “maybe” depends on what one understands by the phrase “24-hour days.”
If one considers the phrase a synonym for “ordinary days”, then, yes. The Bible record and the Hebrew language are quite clear on this point. The days of creation were ordinary days, marked and defined by evening and morning, periods of dark and light. They corresponded to the days at the time of Moses when God’s Third Commandment (Fourth in Evanglical and Jewish reckoning) was given, for it cites the days of creation as the basis for the Sabbath law. There is absolutely no room for “long days” of thousands or millions of years for each, as some have tried to argue, thinking that they can thereby reconcile “science” with the Bible. (Any “science” that disagrees with the Bible is not really science, but an opposing religion.) Trying to explain divine creation over years of time rejects not only the Biblical use of the word “day” but also the whole arrangement revealed in Scripture with the earth and plants being created before the sun, moon, and stars.
If, however, one understands exactly twenty-four hours as we use and measure them today compared to the vibration of a quartz crystal vibrating at a specific frequency, or the amount of time the earth rotates on its axis compared to the sun and a pendulum of a set length, then one cannot be so quick to think the matter settled. The Bible does not use the words hours, minutes, or seconds to mark creation time. Only days. Were we to insist that a day then was exactly the same as it is today, we would be guilty of the same error made by the evolutionary uniformitarians: “As it is, so it has always been.”
One could, of course, define “hour” as one twenty-fourth of the time it takes for a solar day. Then, however long it would take, it would still be exactly a twenty-four day. But that evades the question. Even so, it does not admit “days” made of long eons of time, for that would leave one side of the earth facing toward the sun for half eons, too long for life to continue, let along arise.
There are many who speak of the relationship between the earth and the sun as being so perfectly precise as to be like a well made and tuned watch. But when one conducts precise measurements one finds that things are a bit off. A day is not exactly twenty-four hours, even now. A year is not exactly three hundred sixty-five days. The earth wobbles on its axis. The shape of its orbit varies and the orientation of perihelion and aphelion change relative to the backgound of stars. I therefore think it unwise to assert that the earth’s relationship with the sun is perfect. To insist it is gives room to argue against divine creation on the basis of its obvious lack of perfection today.
But, one might argue, doesn’t that go against the teaching that when God created the earth everything was perfect? Not at all. And one doesn’t have to say that the earth’s movement today has a perfection that we cannot yet see, even though that is a possibility. The earth was perfect. But perfection was lost by the fall into sin. Sin did not affect only man’s relationship with God, but the whole earth. (See Romans 8:22) Weeds were not a problem until after the fall. Death did not exist anywhere, not even for plants and animals, until after the fall. The Bible is clear: sin brought death. It does not violate Scripure one iota to contemplate the possibilty that the earth’s motion today is not exactly what it was at creation.
There is Biblical evidence of a great upheaval of mountains going up and valleys going down, of waters coming up from the great deep, of torrents of water falling from the sky, of the sun appearing to stand still for a whole day and of the shadow of the sun going backward ten steps. We would go beyond Scripture were we to insist, even if they were pure miracles and involved no natural phenomena, that everything about the earth’s movement was exactly the same both before and after each of these events. We also have science to show us what happens when moving bodies collide, as well as evidence – some historical – that extra-terrestrial bodies of various sizes have impacted the earth. We have the evidence that the rock structure of the earth has been torn to pieces and rearranged (probably during Noah’s flood), and even evidence that seems to suggest that the locations of the continental plates are not permanent. Has the redistribution of mass been only horizontal and neither toward the center (which would cause an increase in rotational speed) nor away (which would cause a slowing)? The impact of a large meteor or comet could very well have changed the speed of the earth’s rotation, up or down, and introduced a wobble to its axis that wasn’t there at creation. We also have measurements that show that the earth’s rotation is constantly slowing, due to the drag of the lunar induced tides.
How long might a creation day have been? As addressed already in the first paragraph, whatever it was, if was different than now, it was still in the range of what people commonly understand (and understood at the time of Moses) as an ordinary day. We can only speculate at this point. Exactly 24 hours instead of about 24 hours as today? Fewer? More” Thirty of our hours? There’s no way to tell.
Interestingly, there is another bit of information in the Bible that gives room not only for a different length of day but also for a different kind of year than we have today. It’s not that the earth and moon would have had a drastically different orbit, just that it might have had a slightly different orbit. Genesis 6-9 speaks of only ten months. There might have been twelve, with two not being mentioned, but the highest number applied to months there is ten. That gives room for a ten-month year, and even ten thirty-day months of 30 hours each. Does the Bible lead us to that conclusion? Absolutely not. But it leaves room for that kind of arrangement, which some might consider a kind of perfection.
Outside the Bible there are other things that suggest changes in the earth’s orbit in the past. Where did the convention of there being 360 degrees in a circle come from? Apparently from the Babylonians, who were avid students of the sun, moon, and stars. Did a year once last exactly 360 days? Did something upset their calendar so that they had to add intercalary days from then on? What happened about 800 B.C. to motivate the mass migrations that seem to have occurred at the time? When God caused the shadow to go backward ten steps (also about 800 B.C.) did he perform a pure miracle, or did he, as he has done at times, use also some natural means to accomplish it? If he did use some natural event, could that have changed the earth’s motion? What about the long day of Joshua? Were there ten months before the Flood and twelve months each year after?
A highly respected colleague of mine does not like the argument that creation days might not have been exactly twenty-four hours long. In his mind, opening the doors to the possiblity of additional hours opens the doors also to the possiblity of eons of time. I don’t agree, so long as one makes it clear that creation days must still be “ordinary” days. I think insisting on exactly twenty-four hours as we measure them today opens to door to those who would argue against God’s record on the basis of the earth’s obvious imperfection. Yes, the earth’s location with respect to the sun is right where it needs to be for life and is part of the evidence that points to its divine creation. But that “just right” location is not so precise as to be measured in inches. There is room for some variation over time. God’s creation was perfect. It isn’t any more.
So, did God create everything in six twenty-four days? If by that you mean simply ordinary days, then yes. If by that you mean exactly twenty-four hours as we measure them today, maybe yes, maybe no.