We here examine some assertions made by Troy, a young earth creationist who has made some very unorthodox claims about conditions before the Genesis flood.  He believes that the length of a day was much shorter before the flood, only 18 to 20 hours per day, and that the flood somehow changed this.  As errors go, this is a fairly mild one, and there is nothing heretical or theologically damaging about such a speculation. But the way in which Troy attempted to defend his conjectures involved serious errors in reasoning, in science, and in biblical interpretation.  And these are the same kinds of errors that often lead to bad theology and even heresy.  It is crucial that Christians “accurately handle the Word of Truth” (2 Timothy 2:15).  And sometimes the best way to learn to reason properly, and to interpret the Scriptures correctly, is to see how someone else fails to do these things properly.  Thus, by examining Troy’s many errors, we can become better thinkers, and more accurately handle the Word of Truth.

The two most important principles of reasoning are (1) we must have a good reason for our beliefs, and (2) our reasoning must be self-consistent.  We will see that Troy fails both of these conditions.  He doesn’t provide any actual reasons why the days must be 4 to 6 hours shorter in the past.  The closest he gets to providing a reason is to simply say that no verse in the Bible says that the days before the flood were 24 hours long.  Students of logic will recognize this as the fallacy of the appeal to ignorance: namely, claiming that something must be true because it hasn’t been proved false.  Such a fallacy is always reversable (i.e. the days must be 24 hours since no one has proved otherwise).   When such a fallacy is committed in the context of hermeneutics, it is called the appeal to silence.  This is the error of drawing strong conclusions based on what the text does not say.  This is a fallacy because texts do not record everything.

An example of the appeal to ignorance/silence would be to argue, “John the Baptist never went to sleep because the Bible never mentions him sleeping.”  But just because the text doesn’t say that John slept, we can still conclude that he did because this is part of human nature and there is no basis – no reason – for thinking that this has ever changed.

In fact, there is no biblical or scientific reason to assume that the days before the flood were substantially shorter than our days today, and there are both biblical and scientific reasons to believe they were essentially the same, as we will see.

Troy: To YEC, what verse supports a 24 hour day for each day of creation vs a 20 hour day for each day of creation?

Lisle: Another person on the thread rightly pointed out that we have 24 hours in a day today: this is normative.  God upholds His creation in a consistent fashion for our benefit, and this includes the consistency in the day-night cycle.  God can supernaturally interrupt that pattern, but there would have to be Scriptural support in order to substantiate such an extraordinary miracle (e.g. Joshua 10:12-14; 2 Kings 20:10).  And such miracles would be temporary, with nature reverting to its God-ordained cycle after the miracle.  But, of course, there is no biblical evidence whatsoever that the days were substantially different before the flood, let alone 20 hours long.  So the belief is unwarranted and unjustified. 

I would also add that there is biblical evidence for continuity in the day-night cycle.  It is something that God promised (Genesis 8:22) and was established at creation (Genesis 1:14-19).  Indeed, the day-night cycle is a covenant promise from God and part of the fixed pattern of the universe according to Jeremiah 33:25.  It is not something that God will alter because God doesn’t go back on His Word.  Thus, any interruption in that cycle would be (1) supernatural and (2) temporary.  We will see below that there was an apparent disruption of that cycle during the flood year, but we have a promise from God that such a pattern will not cease until judgment day. 

In any case, 24-hour solar days are normative, and therefore a person who holds to any other position must provide compelling evidence to the contrary.

Troy responded as follows:

Troy: False.  We have 23 hours 56 minutes and 4.1 seconds.  And earth’s rotational velocity is slowing.

Lisle: Troy has confused a sidereal day with a solar day.  A sidereal day is the amount of time the earth takes to rotate as seen from a distant star.  Alternatively, it is the amount of time it takes the stars from earth’s perspective to make a complete cycle.  A sidereal day is about 23 hours 56 minutes long and is the reason we see different constellations in the summer evening sky than in the winter evening sky; the stars rise four minutes earlier every evening. 

But a “day” without the “sidereal” prefix refers to a solar day – the average amount of time it takes the earth to rotate relative to the sun.  Since most people prefer to be awake during the daylight hours, we base our time on the solar day, which is indeed 24 hours long. 

With regard to the rotation of the earth slowing, this is true.  Tidal effects from the moon gradually slow the earth’s rotation, causing the moon to recede.  The rate at which this occurs can be computed from first principles of physics.  It is highly non-linear, and is quite small over the biblical timescale.  I have done this computation in my book Taking Back Astronomy, and shown that the moon was only 750 feet closer to earth by the end of the creation week.  When we go through the math [as I will demonstrate in the next article], we find that the duration of a day during the creation week was within one second of its current duration.  It was certainly not four hours shorter.   

Several people asked Troy to justify his conjecture that the days of the creation week were only 20 hours each, but Troy was either unable or unwilling to provide any rational support for that notion.  At best he gave some examples of things that could, hypothetically, affect the rotation rate.  But he provided no quantitative evidence for a 4-6 hour difference.  Secularists believe the earth rotated much faster billions of years ago because they believe that tidal recession has been taking place for billions of years.  Perhaps Troy accepted their claims without realizing that such claims assume billions of years of tidal interaction which is contrary to the biblical timescale. 

Troy: Many things alter the rotational velocity of the Earth. Such as asteroid impacts volcanic activity tectonic plate movements and earthquakes and primarily lunar gravitational force. We don’t even have a 24-hour day. Today it is 23 hours 56 minutes and 4.1 seconds. And the Earth is slowing its rotational velocity because of lunar gravitational force. So you go back in time the Earth spun faster. …   The Moon is receding away from the earth because it is taking angular momentum away from the spin of the earth. Therefore as you go back in time the moon was closer causing greater ocean tide and slowed the Earth to a greater extent in the past. The further back in time you go the faster the Earth spun which equals a shorter day. Hence you cannot say 24-hour days for each day of creation. You can only say a literal Six-Day creation and perhaps the duration of the day was closer to 18 hours then it was to 24 hours.

Lisle: In my first response directly to Troy, I stated the following: 

FYI, that there are 24 hours in a day is an analytic truth because an hour is defined as 1/24th of a day. Logically, there are necessarily 24 1/24ths of a day for each day of the creation week – not 20.

We would not expect to find a reference to “hours” in the creation account because they had not been invented yet. The Egyptians invented the practice of dividing the day into 24 hours. Specifically, they divided the daylight portion into 12 hours, and the night portion into 12 hours. A day can refer to either the 12-hour daylight portion, or the 24-hour cycle, as in Genesis 1:5.

This system was in use at the time of Christ’s earthly ministry. So, what verse supports this use of the Egyptian system? John 11:9. Jesus affirms that there are 12 hours in the day (the light portion) and hence 24 hours in the full cycle.  [Jesus did not say, “Well, currently, there are 12 hours in day and 12 in a night.  But boy were things different at creation!”  No, Jesus takes the 24-hour day-night cycle as normative.  So should we.]

We do indeed have a 24-hour day today – not 23 hours 56 minutes. The latter refers to a “sidereal day” which is different. The Scriptures do not use sidereal days, and when no prefix is specified, “day” refers to a solar day (a 24-hour day) or the light portion thereof – not a sidereal day.  So, there are indeed 24 hours in a day.  By the way, there are exactly 24 sidereal hours in a sidereal day, just as there are 24 (solar) hours in a (solar) day. Be careful not to confuse categories.

The tidal angular momentum transfer to the moon does indeed slow earth’s rotation. But the effect can be calculated and is very small on the biblical timescale. The difference in the objective length of a day between creation and now is less than one second.  [We will go through the math later and demonstrate this.] 

I hope this helps.

Troy then responded as follows:

Troy: The earth is not exactly 24,000 mi. in cicumference [sic].

Lisle: I never said otherwise.  The equatorial circumference of the Earth is closer to 24,900 miles, but that is not relevant to length of the day.  Were you thinking that the 24 hours came from 24,000 miles?  It doesn’t. 

Troy: And the duration of the earth is not 24 hours. It is 23 hours, 56 minutes, 4.1 seconds.

Lisle: What makes you think that?  In any case, it is still wrong.  You are still confusing a (solar) day with a sidereal day.  With respect, you clearly do not know what a sidereal day is.  When the word “day” is used without the prefix “sidereal”, it refers to a solar day, which is 24 hours.  The Scriptures define a “day” either as the light portion of a day, or as a full day-night cycle in Genesis 1:5.  This is – by definition – a solar day, which is – by definition – 24 hours long.  The Scriptures never use sidereal days, only solar days.

It is easy to demonstrate that a (solar) day is 24 hours long, not 23 hours and 56 minutes.  If the day were 23 hours, 56 minutes, then the sun would rise four minutes earlier every day.  Thus, after three months, the sun would rise around midnight!  It doesn’t.

Troy: Science and evidence has [sic] revealed that many things slow the spin of the earth. Such as asteroid impacts, volcanoes, earthquakes, tsunamis, and moon’s gravity.

Lisle: No.  Volcanoes and earthquakes may cause an infinitesimal shift in earth’s distribution of mass, but they do not affect the angular momentum of earth, and so they don’t have any net effect on the rotation rate.  Asteroid impacts transfer momentum, but it is infinitesimal and so they don’t produce any measurable change in the rotation rate.  [Moreover, statistically just as many asteroids would add angular momentum to earth as subtract it, leaving a net zero sum over time.]  The only significant effect on earth’s rotation rate is due to tidal forces from the moon.  And over 6000 years, this effect adds up to less than a one second difference in today’s length of day as compared to the days of the creation week.  I have done this computation myself.  Have you?

Troy: The earth’s 23 degree tilt was from asteroid impacts.

Lisle: No, it isn’t.  Secularists believe that because the nebular hypothesis (the secular origins story of the solar system) requires all planets to be formed with zero tilt due to conservation of angular momentum.  But biblical creationists reject such an unbiblical hypothesis.  Any impact strong enough to tilt the earth by 23 degrees would vaporize the surface and destroy all life.   The earth’s tilt is a design feature.  The Lord created a tilted earth because this produces seasons, and it maximizes the habitable zones of the earth. 

[Notice that Troy gave absolutely no reason/evidence for his conjecture that the tilt of earth was caused by asteroid impacts.  He may have heard this claim from a secular source and thought that it was based on evidence.  It isn’t.  It is based on the secular assumption that the solar system formed from a collapsing nebula, billions of years ago.  Also, notice that I did provide evidence that the earth was already tilted at creation because (1) it is a design feature that maximizes the habitable regions of the earth, and (2) any asteroid impact large enough to change earth’s rotation axis by 23 degrees would also deliver enough energy to destroy all life (as I will demonstrate mathematically below).  Since all life was not destroyed, this did not happen since the creation of life.  (Secularists believe that such an event happened before life evolved.)]

Troy: Therefore, the earth spun faster in the past. Which means the duration of the earth was closer to 18 hours than 24 hours.

Lisle: No.  (Where are you getting that number?)  [Troy has made an enormous mistake in reasoning here.  He begins with the premise that the earth rotated faster in the past (which is true, although it is less than a one-second difference from today), and then erroneously concludes that it must have been six hours faster in the past.  But there is no logical connection between “faster” and “six hours faster.”  Just because something is faster does not imply that it is six hours faster.  If I win a race because I am faster than my opponents, it does not follow that I must have won by six hours!]

The angular momentum transfer from earth to the moon over the course of 6000 years adds up to less than a one second difference between today’s solar day and the solar days during the creation week.  Secularists believe that earth’s rotation rate was much faster in the past because they believe the moon has been tidally slowing the earth for nearly 4.5 billion years.  Indeed, it would take more than a billion years of tidal dragging to slow the earth’s rotation by hours.  But over 6000 years, the effect is less than one second of slowing.  [Troy had mistakenly accepted the secular view of 18-20 hour days in earth’s past without realizing that this computation assumes 4.5 billion years for the age of the earth and moon.]

Troy: The Bible creation account never mentions 24 hours.

Lisle: It doesn’t mention e-mail or computers either.  That’s because they had not been invented yet.  I explained that previously, but perhaps you missed it.  But since we now define an hour as 1/24th of a day, it follows (for those of us who embrace logical reasoning) that the creation days were 24 hours long.  [The question Troy should have been asking is whether hours during the creation week would have been of the same duration as hours today.  Of course, they are identical to within a tiny fraction of a percent.  Moreover, Troy’s reasoning is self-refuting.  The Bible never mentions a day being 18 or 20 hours long either, yet Troy insists that it was].

[If the days before the flood were only 20 hours, then there would be 438 days in a year.  Hence, the calendar would be completely different.  Yet, Moses uses the standard calendar to refer to days, months, and years for events both before the flood and after (e.g. Genesis 7:11, 8:4-5, 14).  That would make no sense if the calendar changed so drastically.]

Troy: You are thinking lunar recession is linear. It is not because of the inverse square law. It is parabolic recession.

Lisle: First, I was not thinking that lunar recession is linear; I am on record as affirming that the rate is inversely proportional to the sixth power of distance (see Taking Back Astronomy, p. 57).    [Troy clearly has not done his homework on this issue.]  Second, lunar recession is due to dipole interactions.  A dipole is an inverse cube relation.  And since the dipole is both inducing tides and responding to them, the rate of recession is proportional to the inverse sixth power of distance.  Third, over six thousand years, the change in distance of the moon is only 750 feet, and the rotation of earth is slowed by less than 1 second per day.  Because this is such a small change, the rate of change is actually well approximated by a linear interpolation over this region [as shown below].  Again, the mathematical details of lunar recession are on p. 57 of Taking Back Astronomy.

Troy: Since the invention of the 24 hour day did not start until the Egyptians, then why are you using it and why are the other young Earth creationists so dogmatic about a 24-hour day if it’s not even biblical?

Lisle: Fist, your question is like asking, “since the English language wasn’t invented until relatively recently, why do you use English to dogmatically talk about what happened during the creation week?”  Of course, the answer is that it is appropriate to use modern words and logic to describe what the Bible teaches.  [Again, Troy’s reasoning is self-refuting because he is insisting dogmatically that the days were only 18-20 hours long, when hours had not yet been invented].

Second, the 24-hour day is indeed biblical.  It’s just not found in the Old Testament because the word had not yet been invented (as I explained previously).  But the New Testament does use the Egyptian definition of hours (e.g. Matthew 20:3,5,6,9,12, 24:36, 40, 27:45,46; Mark 13:32, 14:35-36, 15:25, 33,34, etc.)  Jesus affirms the Egyptian use of hours as dividing the day into 12 parts (John 11:9) and the night into 12 parts, such that a complete day is 24 hours by definition.    

It’s basic logic. 

1. A day is 24-hours long.  (12 hours day [John 11:9] + 12 hours night)
2. The creation days were days.
3. Therefore, the creation days were 24 hours long.

Troy: “Asteroid impacts transfer momemtum, but it is infinetesimal and so they don’t produce any measurable change in the rotation rate.”[sic] Isaiah 24 and Revelation 16 disagrees with you.

Lisle: Hardly.  Isaiah 24 and Revelation 16 do not mention “asteroids” nor do they mention any change in the rotation rate of the earth.  (Did Troy think I wouldn’t check?)  The Hebrew word for “day” is only used in verses 21 and 22 of Isaiah 24, and neither verse gives the slightest hint that the length of the day is being altered.  Likewise, the Greek word for “day” is only used in verse 14 of Revelation chapter 16, where it is used metaphorically to describe the “day of God.”  There is not the slightest hint in this chapter that the length of a literal day has changed.  Troy is adding to God’s Word in violation of Deuteronomy 4:2. That is not exegesis.  It is eisegesis – reading into the text what is not there.

Troy:  “For the windows above are opened, and the foundations of the earth shake.  19The earth is broken apart, The earth is split through, The earth is shaken violently. 20 The earth trembles like a heavy drinker And sways like a hut.”

Lisle: And where does it say the length of a day was 18-20 hours?  It doesn’t.  In fact, there is no mention of “day” at all in those verses, and no mention of asteroids either, or anything that could be interpreted as an asteroid.  Clearly, Troy is reading into the text what is not there.

Troy:   “The seventh angel poured out his bowl upon the air, and a loud voice came out of the [h]temple from the throne, saying, “It is done.” 18And there were flashes of lightning and sounds and peals of thunder; and there was a great earthquake, such as there had not been since mankind came to be upon the earth, so great an earthquake was it, and so mighty. 19The great city [i]was split into three parts, and the cities of the [j]nations fell. Babylon the great was remembered in the sight of God, to give her the cup of the wine of [k]His fierce wrath. 20And every island fled, and no mountains were found. 21And huge [l]hailstones, weighing about [m]a talent each, *came down from heaven upon people; and people blasphemed God because of the plague of the hail, because [n]the hailstone plague *was extremely [o]severe.”

Lisle: Again, there is not the slightest hint in any of these verses that the length of a day has changed or will change.  Indeed, the word ‘day’ is not even mentioned in the passages Troy cited.  His mention of these verses is simply a red herring. 

Troy: God is not done using asteroids.

Lisle: Perhaps.  But there is no scriptural evidence to support Troy’s speculations.

Troy: The earth will be restored to how it was before sin entered creation.

Lisle: Yes, although with some differences (e.g. more people).  But this has no bearing on the length of a solar day.

Troy: Regarding the moon’s gravity. I have done the math.

Lisle: At this point, Troy is simply lying.  I know this because I have done the math, and the accumulated tidal recession over 6000 years amounts to about 750 feet, which conserving angular momentum amounts to a 0.105 second difference between the earth’s rotational period at creation and its period now [I will demonstrate this in the next article].  I had asked Troy repeatedly to show his calculations, and he was unable to provide any evidence that he had done any.

Troy: Your calculations are not factoring a change in lunar recession rates.  The inverse square law may help you.  Redo your math using a parabolic rate of recession.

Lisle: Here Troy attempted to continue his bluff, but he demonstrates that hasn’t studied the physics of tidal recession or he would know that the inverse square law is for point sources.  For extended objects (like the earth and the moon) we must also include the effect of tidal forces for long-term computations, and these are approximated as a dipole which is an inverse cube relationship.  This is something that would be covered in a freshman level college physics class.  It is also explained in my book Taking Back Astronomy in which the lunar recession rate over time is computed mathematically. 

Troy: As we go back in time, the moon was closer, which caused larger ocean tides, which resulted in more energy taken out of the spin of the earth. This resulted in an acceleration of lunar recession.

Lisle: That is true; it’s just that when we actually go through the math, we find that the change in lunar recession rate over 6000 years is negligible.  The moon was only 750 feet closer to earth during the creation week.  Therefore, the rate of lunar recession (going inversely with the sixth power of distance) would have been faster than the current rate by only 4×10-4 percent.  In other words, the rate was about an inch and a half per year then, and it is about an inch and a half per year now. 

Let’s look at the math.  As shown on pages 96-97 in Taking Back Astronomy, the recession rate of the moon will be approximately inversely proportional to the sixth power of distance.  Integrating the recession over time gives the formula on the top right of p. 57 in Taking Back Astronomy.  That formula integrates over R from zero to the current earth-moon distance, giving the maximum possible age of the earth-moon system of 1.5 billion years.  But we want to know how much the moon has receded in only ~6025 years, so we integrate from R0 (the unknown original distance from the earth to the moon at creation) to R1 (their current separation).  We then solve for R0 giving the following:

R0 = (R17 – 7k 6025 years)1/7

Here, k is the tidal breaking constant which equals 1.226×1029 km7/year.  Substituting the actual values reveals that the moon has receded by (R1-R0) = 751 feet since creation.  This is such a small change in distance that the lunar recession rate – even though it is non-linear – has remained very nearly constant during this interval.  So, if we simply used the current recession rate of 3.8 cm/year and multiplied this by 6025 years and convert to feet we get: 751 feet.  It’s the same answer! 

So, Troy’s bluff about needing to take into consideration the changing lunar recession rate is a red-herring because (1) I already did that and (2) it wouldn’t matter anyway because the change is so small over ~6000 years.  It is only when we consider how lunar recession would progress on a hypothetical millions-or-billions of years timescale that the non-linear effects become substantial.

Troy: I never said one earthquake or one event significantly slowed the spin of the earth. I am suggesting that many events and one catastrophic global flood changed the spin velocity of Earth.

Lisle: No combination of earthquakes, volcanoes, or a global flood will alter the rotation rate of the earth.  This is due to a principle in physics called the conservation of angular momentum.  Basically, any spinning object will continue to spin at the same rate with constant angular momentum unless acted upon by an external torque. Earthquakes, volcanoes, and the global flood are not external.  Therefore, they cannot affect the angular momentum of earth. 

The only way to slow the earth’s rotation is therefore to transfer some of its angular momentum to an external object. [1]  Volcanoes, earthquakes, and floods are not external to earth and therefore no combination of them can slow earth’s rotation at all.  The only significant external torque being applied to earth is tidal torquing due to earth’s moon.  This causes the moon to move away from earth, which increases the moon’s (orbital) angular momentum and simultaneously decreases earth’s rotational angular momentum by the same amount.  Thus, the total angular momentum of the earth-moon system is conserved. 

Troy: Your ending logic does not connect because you are missing the catastrophic global flood.

Lisle: On the contrary, Troy’s logic does not connect because the global flood is not an external torque.  It therefore cannot change the angular momentum of earth, and hence cannot slow earth’s rotation.  Troy’s speculation violates the law of conservation of angular momentum.

Troy: Using a verse that is roughly 2,400 years after the global flood is equivalent to secularists using the Uniformitarian theory to support an old earth.

Lisle: Students of logic will recognize Troy’s error as the fallacy of false analogy – making a comparison between two things that are not really alike in any way relevant to the argument.  When the Apostle Peter (writing under the inspiration of the Holy Spirit) writes about the global flood in 2 Peter 3:6, he is writing about 2,400 years after the global flood.  Does this make his point any less valid?  Does it make him “equivalent” to the very uniformitarianists that he is criticizing?  Hardly. 

Troy seems to be confusing uniformitarianism with uniformity.  The former is an unbiblical assumption that rates and conditions are comparable to today when there is good reason to think otherwise – such as historical records.  So, a denial of the global flood would be an example of uniformitarianism because it denies what the Bible affirms.  Conversely, uniformity is the biblical principle that God upholds His creation in a generally consistent way for our benefit.  This continuity is what makes science possible.  It means that – barring a supernatural miracle which would be temporary – the laws of physics and chemistry do not change over time.  This is what allows us to predict eclipses, and also to compute when eclipses occurred in the past.  God has promised us that certain things will be in the future as they were in the past – this includes seasons and also the day and night cycle (Genesis 8:22).  Thus, we have biblical reasons to believe that the day-night cycle was basically the same before the flood as after; it is part of the continuity God imposes on His creation.    

Troy:  You wrote “The Lord created a tilted Earth because this produces seasons.”  The four seasons did not begin until the global flood.

Lisle: What Scripture states that the four seasons did not begin until the global flood?  Of course, there isn’t any.  Again, Troy simply makes a bald assertion without any supporting evidence.  That’s not exegesis.  On the contrary, there is compelling biblical (and scientific) evidence that seasons existed before the flood as we will examine below.

Troy: This is a common mistake of only reading the English versions and not knowing what the Hebrew word “seasons” means on the fourth day. It is so mankind will know times for gatherings and festivals. Not winter, fall, and so forth.

Lisle: Here Troy makes another false assumption.  He has assumed that the reason that informed biblical creationists believe in seasons before the flood is based on Genesis 1:14.  It isn’t.  It’s a shame he didn’t bother to research this.  In any case, there are both scientific and biblical reasons to believe in seasons before the flood.

The first stems from a natural, exegetical reading of Genesis 8:22.  The context of this verse is the end of the global flood.  God has just promised to never again flood the entire earth.  Hence, He promises, “While the earth remains, Seedtime and harvest, And cold and heat, And summer and winter, And day and night Shall not cease.”   The Hebrews divided the year into six seasons, rather than just the four we use today: seedtime (spring), summer, heat (the hottest part of our summer), harvest (autumn), winter, and cold (the coldest part of our winter). 

So, God mentions these seasons in Genesis 8:22 as something that had already existed, along with the day & night cycle.  He did not say, “I am now creating something new: seedtime, harvest….”  Rather, after promising to never again flood the world, He promises that these cycles of nature will not cease.  The implication is that they did at least appear to cease during the flood year.  After all, there was no seedtime or harvest during the flood year.  If the ark had been carried near the polar regions at any point, even day and night may have been difficult to track, and may have seemed to cease (e.g. as within the arctic circle). 

Notice that God mentions these seasons right along with the day and night cycle – something that existed from creation (Genesis 1:5, 14).  The implication of Genesis 8:22 is that the day and night cycle and the seasons were apparently interrupted by the flood, and God is promising that He will never again do that.  These things will continue just as they did before the flood. 

Scientifically, we have every reason to believe that there were seasons before the flood.  Fossils of pre-flood trees show quasi-annual growth rings just like trees today that are due primarily to the changing seasons.  Furthermore, the tilt of the earth is held constant due to the conservation of angular momentum.[2]  Again, only an outside torque can change this, and therefore the flood could not.  (I will come back to Troy’s claim that an asteroid changed earth’s tilt by 23 degrees).  Furthermore, earth’s tilt is a design feature: it maximizes the habitability of earth.  If the earth were tilted significantly more, then the seasons would become extreme, making life difficult.  If the earth were tilted less, then the habitable latitudes would be reduced (the equator would be hotter and the poles much colder). 

Troy seems to have accepted secular claims without recognizing that they are anti-biblical.  Secularists believe that all the planets originally had a tilt of zero when the solar system supposedly first collapsed from a nebula 4.5 billion years ago.  This is because of the principle of conservation of angular momentum; the sun and all the planets should rotate and orbit in the same plane if they formed from a collapsing nebula.  But most planets are tilted.  Thus, secularists have invented rescuing devices in an attempt to save their secular model from what appears to be evidence to the contrary.  Therefore, they claim that many of the planets were struck by some enormous planetary body in the past, causing the planet to be tilted.  The energy of such an impact would destroy all life on earth, so secularists believe this happened before life evolved on earth.  They also believe that a large, Mars-sized protoplanet struck the earth, and that such material formed the moon.  As creationists, we reject such stories in light of recorded history.

Troy: Autumn and winter signify death and burial.

Lisle: Where does the Bible say that?  Where does the Bible even hint at such a concept?  Or is this Troy again reading into the text what is not there?  Biblically, the autumn harvest was a time of gladness and celebration, when the people finally were able to enjoy the fruit of their labor (Isaiah 9:3; Exodus 34:22).

Troy: Two things that were not part of creation until sin and the global flood.

Lisle: No death or burial before the global flood?  Troy’s reasoning here is simply terrible – it is both arbitrary and inconsistent.  He asserts that autumn and winter signify death and burial, for which I can find no biblical evidence.  He asserts that there was no death or burial before sin and the global flood.  There was no death before sin, but there was certainly death before the flood.  Cain killed Abel long before the flood.  Then Troy arbitrarily asserts that there would not be things that (came to) symbolize death before the entrance of sin and the global flood.  But in fact, the Scriptures sometimes use sleep as a symbol of death (John 11:11-13; 1 Corinthians 11:30, 15:51; Daniel 12:2).  And sleep did exist before sin (Genesis 2:21).  

Troy: Asteroids impacting the earth to commence the global flood and cause a 23 degree tilt would not vaporize the surface and destroy all life because the fountains of the deep and rain from the canopy dissipated the heat.

Lisle: What calculation did Troy do to establish his claim that the “fountains of the deep and rain from the canopy” were sufficient to dissipate all the heat produced by an impact capable of torquing the earth’s rotation axis by 23 degrees?  Of course, there are none.  It’s another bald assertion.  So let’s actually do the math to see how much energy would be released by such an impact, and how much energy could be reasonably dissipated. 

A solid sphere has a moment of inertia I = (2/5)Mr2, where M is the mass and r is the radius.[3]  The angular momentum is simply the moment of inertia multiplied by the angular velocity: L = Iω.  So, the angular momentum of earth is about 7×1033 kg m2/s, in the direction of the north pole.  To rotate this vector by 23 degrees, we would need to add an angular momentum vector of [L(cos(23) – 1), L(sin(23))] which has a magnitude of L √((cos(23)-1)2 + sin(23)2) = 0.399 L, which is 2.8×1033 kg m2/s.  In other words, an asteroid would have to deliver about 40% of earth’s current angular momentum to tilt the axis by 23 degrees. 

For maximum effectiveness, the asteroid would have to hit at a glancing angle, so r = earth’s radius (6.37×106 m).  And the momentum of the asteroid would be 0.339 L / r, which works out to 4.4×1026 kg m/s.  That is, the product of the mass and velocity of the asteroid must equal or exceed this value in order to tilt the earth by 23 degrees.  How much energy would this deliver?  The minimum energy would be delivered by a slower-moving asteroid, which must therefore be very large in order to have such momentum.[4]  The largest asteroid in our solar system (by far) is Ceres, which has a mass of 9.1×1020 kg.  Hence, its velocity would be 490 km/s, and the energy (½mv2) of the collision would therefore be 1.1×1032 joules, roughly the equivalent of 2.5 million billion hydrogen bombs. 

Troy claims (without any mathematical support) that water falling from a vapor canopy along with the fountains of the deep can somehow dissipate all that heat.  First, water falling from an alleged canopy actually makes the problem worse because it increases the temperature.  When an object falls, its gravitational potential energy is converted into kinetic energy, resulting in heat.  So that’s not going to help dissipate heat. 

However, water itself can absorb a great deal of thermal energy because it has a high specific heat.  So, could the fountains of the great deep refer to spots where water is vaporized, carrying some heat with it?  It’s certainly possible.  But is the effect large enough to dissipate the energy produced by an asteroid that tilts earth by 23 degrees?  Let’s do the math.

The average temperature on earth is around 61 degrees Fahrenheit or 16 degrees Celsius.  Water has a specific heat of 4,184 Joules per kilogram per Kelvin.  So, it takes 4,184 Joules to raise 1 kilogram of water by 1 degree Celsius (or Kelvin), and hence 351,456 Joules to raise 1 kg of water from 16 degrees Celsius to boiling point.  The heat of vaporization of water is 2,260,000 Joules per kilogram.  So, to both heat and vaporize 1 kg of water starting at 16 degrees Celsius would take 2,610,000 Joules.  The earth has about 1.4×1021 kilograms of water.  Hence, to heat and vaporize all water on earth takes 3.7×1027 Joules.  But, recall, the minimum energy delivered by an asteroid capable of tilting the earth by 23 degrees is 1.1×1032 Joules, which is thirty thousand times greater than the energy needed to completely vaporize earth’s oceans

So, any asteroid capable of tilting the earth by 23 degrees would not only completely vaporize earth’s oceans, but that vaporization would dissipate less than one hundredth of one percent of the heat energy.  The oceans would need to be vaporized 30,000 times to dump all that energy.  Since there was obviously water on earth’s surface during the global flood, we can be confident that the earth was not impacted by an asteroid that tilted it its rotation axis by 23 degrees. 

Working the problem in the other direction, what is the maximum amount an asteroid impact (or multiple asteroid impacts) during the flood year could change earth’s tilt axis?   Since the oceans did not vaporize, the energy of the impact must be 30,000 times less than the one necessary for a 23-degree change in tilt.  The momentum goes as the square root of energy. Hence, the maximum possible change in earth’s tilt axis due to asteroid impacts at the time of the flood would be only 0.13 degrees. 

It’s easy to make sweeping qualitative claims with no mathematical support.  But when we do our homework, such claims do not stand up to scrutiny.  In the next installment, we will look at further details of Troy’s claims and see if they stand up to mathematical scrutiny.  In particular, we will look at the rotation of the earth over time, and how this is affected by lunar recession, as well as asteroid impacts.


[1] For the physics students who may read this and ask, “What about a change in the earth’s moment of inertia?”  A redistribution of earth’s mass in the radial direction could change the moment of inertia, resulting in a different rotation rate while keeping the angular momentum constant – like a skater who spins faster as she pulls her arms in.  But (1), the nature of gravity is such that the denser objects would tend to move toward the core, while the less dense objects move away from the core due to buoyancy.  So, this would reduce the moment of inertia, resulting in the earth spinning faster – not slower as Troy has conjectured.  (2) The effect is likely to be very small since the flood mainly involved plate tectonics on the crust, and perhaps some of the upper mantle.   

[2] Although the magnitude of earth’s tilt remains nearly constant at approximately 23 degrees relative to the ecliptic, the direction of that tilt slowly precesses due to tidal interaction with the moon.  This process is cyclic, but less than one fourth of a cycle has occurred since creation. 

[3] Specifically, this refers to a sphere of constant density.  The earth’s density increases somewhat near the core.  But the approximation is sufficient for our purposes.

[4] The kinetic energy of an object is half its mass multiplied by the square of its velocity.  So, a less massive asteroid has higher kinetic energy than a more massive asteroid of the same momentum.  Hence, smaller asteroids (faster) would deliver more kinetic energy than our computation here.