Previously, we examined some unusual claims made by Troy, who asserted that the days before the global flood were four to six hours shorter than days today.  We found that Troy gave no biblical or quantitative scientific evidence to support his claim.  His only argument in terms of Scripture was that the Bible does not say that the days before the flood were 24-hour days.  This is a hermeneutical error called an argument from silence.  It’s the equivalent of claiming that people had six arms before the flood since the Bible doesn’t say they had only two.

Furthermore, Troy had made a number of scientifically unsupportable claims: that volcanoes, earthquakes, asteroid impacts, and lunar recession were what caused the earth to switch from an 18-20-hour day to our current 24-hour day (he had confused a solar day with a 23-hour 56-minute sidereal day) during the flood year.  But, volcanoes and earthquakes cannot significantly affect the length of a day due to conservation of angular momentum.  Today we will examine Troy’s claims that asteroid impacts and/or lunar recession have reduced earth’s rotation period by 4-6 hours per day since creation.  In responding to me, Troy stated the following:

Troy: You say asteroids cannot alter the spin of the Earth.

Lisle: This is a straw-man fallacy – a misrepresentation of my position.  I did not say that asteroids “cannot alter the spin of the earth.”  Rather, I stated, “Asteroid impacts transfer momentum, but it is infinitesimal and so they don’t produce any measurable change in the rotation rate.”  That is, the asteroids that have actually impacted the earth have far too little momentum to significantly affect the rotation rate of earth on the biblical timescale

But I never said it “cannot” happen in principle.  It’s just that any asteroid impact powerful enough to affect earth’s rotation significantly within the biblical timescale would deliver so much energy that the surface of earth would be vaporized, as I will show below.  So, we know this has not happened on earth since the creation of life.  Secularists believe that the earth was struck by massive asteroids nearly 4.5 billion years ago before life supposedly evolved and that these did indeed reduce earth’s primitive crust to magma.  But this is not consistent with the biblical account.

Troy: However, many disagree with you. [Troy linked to a secular article on the tilt of the planet Uranus.]

Lisle: This is a continuation of Troy’s straw-man fallacy.  First, his referenced article is about Uranus, not earth.  Second, the article is secular, not biblical.  Secularists cannot easily explain why most of the planets in our solar system are tilted relative to the ecliptic because they assume the secular nebular collapse model.  So, they appeal to imagined massive asteroid impacts.  Conversely, biblical creationists recognize the tilt of the earth as a design feature, and the tilt of the other planets exhibits God’s creativity.  Third, (as will be demonstrated below) such impacts (on earth) would vaporize earth’s oceans completely and liquify the crust.  Secularists believe this happened on earth before the oceans formed and before life evolved.  It could not have happened since then because it would destroy all life.  And I am not aware of any Ph.D. physicists who would disagree with that. 

Troy: You admit that many contend the tilt of the earth was from asteroid impacts. And you admit that asteroid impacts slow the spin of the earth. And you admit the moon slows the spin of the earth.

Lisle: This is another straw-man fallacy which includes a mixture of truth and error.  Let’s separate them.  Do “many contend” that the tilt of the earth was from asteroid impacts?  Yes – secularists believe this happened billions of years ago, vaporizing the primate surface of the earth before life supposedly evolved.  But no one holds to Troy’s view, that this happened within the biblical timeline and somehow managed not to wipe out all life.  Biblical creation physicists rightly recognize earth’s tile as a design feature.  Troy has accepted a secular view apparently without realizing that it requires the secular timeline. 

Do I “admit that asteroid impacts slow the spin of the earth?”  No.  First, (as I will demonstrate below) any asteroid impacts capable of substantially changing earth’s rotation rate (which is what Troy needs to explain his supposed 18-20-hour day) would produce sufficient heat to destroy all life on the surface.  Since this has not happened, we must conclude that such an event has not transpired.  Second, asteroid impacts are just as likely to add angular momentum to earth over time as they are to reduce it.  So, the net sum over time should be close to zero.  Therefore, asteroids impacts cannot have significantly altered earth’s rotation rate since the creation week.

Do I admit that “the moon has slowed the earth?”  Yes – by 0.105 seconds per day since creation – not by 4-6 hours per day!  Troy has imagined that this effect is enormous on the biblical timescale, but the math shows that it isn’t, as I will demonstrate below. 

Troy: You just disagree on the amounts of those changes. You say they are all infinitesimal.

Lisle: Yes, because I have done the math and Troy has not.  Any asteroid impact large enough to alter earth’s rotation axis by more than 0.13 degrees would have more than enough energy to completely vaporize all of earth’s oceans, as we calculated in the previous article.  That would obviously destroy all aquatic life.  And since all aquatic life hasn’t been destroyed, we can conclude that no asteroid that large has impacted earth since day 5 of the creation week.  Certainly, it did not happen during the flood or there would have been no water for the flood. 

What about the slowing of earth’s rotation due to lunar recession?  Let’s do the math. 

The orbital speed of the moon is given by √(GM/R), where M is the mass of earth (5.972×1024 kg), R is the distance to the moon (384,401 km), and G is the gravitational constant (6.67408×10-11 m3kg-1s-2).  The angular velocity (ω) is therefore: ω = √(GM)/R3/2.  The angular momentum of the moon’s orbit is the product of its mass (m=7.346×1022 kg), angular velocity, and the square of its distance from earth.  So, we have:  Lm = mR2ω = m√(GMR).  We could also include the angular momentum due to the moon’s rotation ((2/5)mr2ω, where r is the radius of the moon).  But this is 12 million times smaller than its orbital angular momentum, and is therefore negligeable for our purposes.

The change in the moon’s angular momentum (ΔL) as it receded over ~6025 years is therefore simply the difference between its angular momentum now (L1) and its angular momentum at creation (L0), as the radius of its orbit increased by 751 feet (ΔR = 229 m).  So we have:

ΔL = L1 – L0 = m√(GMR1) – m√(GMR0) = m√(GMR1) – m√(GM(R1-ΔR))

Here, R1 is the current distance between the earth and moon, and R0 was the distance at creation.  So ΔR  = R1 – R0, and we already found in the previous article that ΔR = 751 feet (229 m).  We can use the binomial theorem to expand the right-hand term, truncating the higher order terms.  This results in the following:

ΔL = m √(GM)(1/2)ΔR/√R1 = 8.56×1027 kg m2/s

This is the angular momentum that the moon gained due to its tidal interaction with earth since creation.  Since angular momentum is a conserved quantity, this is also exactly the amount of angular momentum that the earth lost in this time, slowing the rotation.  But since the current angular momentum of earth is 7.05×1033 kg m2/s, we can already see that the change in rotation rate will be very small.  But how small quantitatively? 

Recall, the angular velocity (ω) is the angular momentum (L) divided by the moment of inertia (I) which we computed for earth in the previous article.  So, the angular velocity of earth decreased since creation by ΔL/I = 8.83×10-11 rad/s.  The period of rotation is then 2π/ω.  But we are looking for the change in the rotational period which is 2π/ω1 – 2π/ω0.  To express this in terms of the change in angular velocity (Δω = ω0 – ω1 = 8.83×10-11 rad/s) we again use the binomial theorem to express the change in period as:

 ΔP = 2π Δω/ω12 = 0.105 seconds.

So, yes, the days were shorter during the creation week – by one tenth of a second!  When we do our homework, we can see that lunar recession over ~6000 years does slow earth’s rotation, but only by a tiny amount.  For Troy’s claims to be substantiated, lunar recession would have to be 137,000 times stronger than it actually is. 

Could an asteroid impact slow earth’s rotation rate by four hours per day?  Let’s again examine the math:

Since L = Iω, an asteroid reducing earth’s rotation period by four hours would result in a reduction of earth’s angular momentum from 8.46×1033 kg m2/s down to its current value of 7.05×1033 kg m2/s, a difference of 1.41×1033 kg m2/s.  Interestingly, that is almost exactly half the angular momentum needed to tilt the earth’s rotation by 23 degrees (as computed in the previous article).  Since momentum is linearly proportional to velocity, and since energy is proportional to the square of velocity, the minimum energy of the asteroid impact would be one fourth (1/2 squared) of that necessary to tilt the earth by 23 degrees, which we computed previously.

Thus, an asteroid impact sufficient to slow earth’s rotation by four hours per day would release a minimum energy of 2.7×1031 joules, the equivalent of six hundred billion hydrogen bombs.  From our previous computation, this is enough energy to completely vaporize earth’s oceans 7,500 times! 

Hence, any asteroid impact sufficient to reduce earth’s rotation period by four hours would destroy all life on the surface.  Therefore, this has not happened since the creation of life.

So, again, it is easy for people who don’t know physics or mathematics to make sweeping qualitative claims.  But it is necessary to know something about physics and mathematics to evaluate whether such claims are quantitatively possible.  This is why new scientific models are published in peer-reviewed literature where they can be vetted by people with education in the relevant field. 

Troy: Perhaps you are unaware of the Bible’s mentioning of an asteroid impact that splits the earth asunder, causes it to wobble, and shakes every mountain and island till they are gone. See Isaiah 24 and Revelation 16 (7th seal).

Lisle: So many problems here.  First, and most importantly, these chapters say absolutely nothing about a change in the length of days at the time of the flood, nor a change in earth’s rotational axis.  Again, Troy is reading into the text what is not there. 

Second, Troy does not seem to understand the genre of literature he is attempting to interpret.  Isaiah and Revelation are not newspaper articles.  Rather, both books are prophetic literature, and employ a very different style from the more straightforward narrative of the Pentateuch and historical books.  Isaiah, for example, uses the characteristic Hebrew poetic form: parallelism.  To understand the imagery, the parallels need to be interpreted as a unit.  Troy has failed to do so.

Third, neither passage is about the global flood or past events!  Rather, each passage describes a time in the author’s future.

Fourth, no “asteroid” is mentioned in either passage.  There is no hint of anything even remotely resembling an asteroid in Isaiah 24.  Troy might think that the hailstones in Revelation 16:21 are asteroids, but this goes beyond the text.

Fifth, even if we did interpret Revelation 16 in a wooden-literal sense contrary to its context, it does not say that the days changed length or that the earth changed its tilt.  So, this doesn’t support Troy’s claims in the slightest.  This is merely a red-herring fallacy – a distraction that has nothing to do with the issue at hand.

Troy: You say it’s impossible. The Bible and many studied individuals says [sic] differently than [sic] you.

Lisle: We have already seen that the Bible doesn’t remotely support Troy’s conjectures.  As for “many studied individuals,” please show me one Ph.D. physicist who believes that an asteroid impact changed the tilt of the earth by 23 degrees or slowed its rotation by 4 hours within the biblical timescale.

Troy: Maybe you should do some self re-evaluation instead of pointing out grammar and arguing your opinion over someone elses [sic].

Lisle: Here Troy attempts an ad-hominem fallacy.  When a person’s claim cannot be defended by any rational argument, he often attempts to attack the character of his opponent.  While this may have an emotional impact, it is irrelevant to the argument.  It’s also self-refuting.  What has Troy been doing except “arguing [his] opinion over someone else’s?”  The difference is that Troy’s opinion is not supportable by science or hermeneutics.

Troy: You repeatedly point out that Jesus said “12 hours in a day.” Your argument is that ever since the fathers have fallen asleep, 24 hours remains the same. Essentually [sic] saying that the rate of today is the same rate its [sic] always been. That is the same mistake the Uniformitarian proponents make. You both overlook the destruction and subsequent environmental changes that occurred from the global, catastrophic flood.

Lisle: Here Troy confuses uniformitarianism with uniformity/continuity.  The former is the assumption that conditions have always been as they are now, particularly when there is evidence to the contrary.  So, to deny the global flood on the basis that there is no global flood today would be a uniformitarian assumption because there is evidence (both biblical and scientific) to the contrary.  Conditions, such as weather, change from day to day.  Thus, we can have sunshine on Monday, but a flood on Tuesday.  These conditions God allows to change with time.  The global flood is a spectacular example of weather conditions that were extreme and unlike today.

However, there are some things that God does not allow to change.  For example, God has promised us a degree of uniformity/continuity in nature (Genesis 8:22) – including the day and night cycle.  There are underlying laws of physics that do not arbitrarily change with time because they are demonstrations of God’s unchanging power.  The law of gravity is one example.  So is conservation of energy and momentum.  Since these underlying cycles do not arbitrarily change with time, we can and should apply them to the past and the future.  This is the principle by which we learn from past experience because in terms of basic principles, the future is like the past.  Notice that Jesus endorses this principle in Matthew 16:2-3, when He points out that people can make short-term weather predictions by noticing the appearance of the sky.  We can only do that because of past experience and the underlying assumption that God upholds the universe in a consistent way

To be consistent Troy should disagree with Jesus and say, “You are wrong Jesus.  You are assuming uniformitarianism!  Just because in the past when the sky was red we had fair weather does not mean that in the future it will be that way.  You are assuming that ‘all things continue as they were from the beginning of creation!’”  But in fact, Troy would be mistaken because Jesus was rightly claiming that some things really do remain constant – including laws of physics upon which meteorology is based.  The recession of the moon is based on laws of physics – not on conditions like erosion or rainfall that would have been different during the global flood.

Jesus again confirms that some things do not change in Luke 17:26 where He says, “And just as it happened in the days of Noah, so it will be also in the days of the Son of Man.”  He does not say, “the days will be four hours longer than the days of Noah.”  Rather, He emphasizes the similarity.  My point is not to emphasize the length of those days specifically, but to point out that it would be absurd to accuse Jesus of promoting uniformitarianism when Jesus rightly believes that some things have not changed since creation.

Troy:   Your ilk is mentioned in 2 Peter 3:3-5 as one of the mockers that say things remain the same since the fathers fell asleep, discounting the changes that occurred from the Flood.

Lisle: The problem of course is that there is absolutely no biblical or scientific evidence that the flood would affect (1) the tilt of the earth or (2) the length of days.  None. 

Let’s apply Troy’s reasoning to a silly example that should highlight the error.  Suppose someone claimed, “Before the global flood, human beings had six arms each instead of just two, and they could fly by flapping those arms.  At the flood, God removed their extra four arms so that they could not fly away and escape it.  We know this is true.  After all, what Bible verse says that people only had two arms before the flood?  None!  And what Bible verse says that people couldn’t fly before the flood?  That’s right – none!  So, clearly I’m right!” 

Of course, any rational person would point out that having two arms is normative for a healthy human, and there is no reason to think that the flood would affect that.  But then suppose the person responded, “Your ilk is mentioned in 2 Peter 3:3-5 as one of the mockers that say things remain the same since the fathers fell asleep, discounting the changes that occurred from the Flood.  Your argument is that ever since the fathers have fallen asleep, [people having only two arms each] remains the same.”  Of course, that is exactly Troy’s argumentation.  But no rational person would accept that. 

In a very real sense, science is all about separating those things that God holds constant (underlying laws of nature) form those things that God allows to change (local conditions, erosion rates, sediment formation rates, etc.).  Things like lunar recession are based on laws of physics, such as the dipole inverse cube relation and conservation of angular momentum.  God does not allow these physical principles to change.  This is why we can predict eclipses down to the second even centuries in advance.  The movement of the earth and the moon is based on very basic laws of physics which God holds constant for our benefit. 

However, plate tectonics, erosion rates, sediment deposition – things that today are very dependent on local conditions, are obviously things that God allows to change.  And we would expect drastic changes in such conditions during a global flood.  But, we can only reasonably draw that conclusion because we assume continuity in basic principles!  In other words, we presume that gravity, and the laws of motion and chemistry worked the same way during the flood year as they do today which is why we can compute some things about the increased erosion and sedimentation that took place then.  If everything changed during the global flood, even laws of nature, then we could not conclude anything about erosion rates, or tectonics, etc., since these are physical processes that are subject to laws of nature.    

Troy: In your calculations, what rate of lunar recession did you calculate around 6,000 years ago?

Lisle: Since lunar recession is inversely proportional to the sixth power of distance, and since the current rate is 3.8 cm/year, the distance 6025 years ago would have been 751 feet (229 m) closer.  Thus, the rate of recession would have been faster than our current rate by ((384,401 – 0.229)/384,401)-6 – 1 which is 0.0004%.  So, the recession rate was still essentially 3.8 cm/year.  This is what I meant when I said that on the biblical timescale, the recession is well-approximated by a linear interpolation. 

Troy: Also, what do you have as the cause that commenced the Flood and fractured Pangaea?

Lisle: The leading hypothesis is that God used accelerated radioactive decay which created sufficient heat to start runaway subduction of the original oceanic crust.  Hot spots may be where the fountains of the great deep burst forth. There is some evidence to support this, but we don’t really know.  If you want to believe that an asteroid impact delivered such heat, that may be plausible too, but it would not significantly affect earth’s rotation rate or tilt without vaporizing the oceans thousands of times over. 

Troy: Do you also reject a literal ice/water canopy existing around the atmosphere from creation till the Flood?

Lisle: That sounds like the canopy hypothesis, which I have discussed elsewhere.  The Bible mentions waters upon/above the expanse, but it uses the word for liquid water (mayim).  So this would not be ice or a vapor canopy (which use different words).  Rather it could well be water droplets in suspension.  Whatever these waters above are, they are not something that collapsed at the time of the flood because they are mentioned later in Scripture.  Psalm 148:4 mentions the waters above as still existing at the time that Psalm was written – many centuries after the flood.

Troy: Thanks

Lisle: You are welcome.

The main error in Troy’s claims is the fallacy of the appeal to ignorance – asserting that something must be (or is very likely) true purely on the basis that it has not been proved false.  In reality, Troy’s claims have been proved false.  We can calculate the effects of lunar recession from physics principles and show that it has slowed the earth by only 0.105 seconds per day since creation.  Furthermore, we can demonstrate that the earth has not experienced any significant change in tilt or in rotation rate due to asteroid impacts within the biblical time frame since these would have vaporized earth’s oceans many times over.  Troy could appeal to supernatural intervention, but that would require Scriptural justification.  And we find none.

From a hermeneutics perspective, Troy’s error is the appeal to silence: arguing that something must be (or is very likely) true on the basis that the Scriptures don’t explicitly state the opposite.  It is tantamount to claiming that all people before the flood had six arms each since the Bible never specifies that they had only two.  But such a claim is baseless.  Having exactly two arms is normative for healthy people today, just as 24 hours is normative for solar days.  Thus, we would need powerful biblical or scientific evidence to believe that such things were otherwise in the past, and we have no such evidence.  None.  On the contrary, God has promised to uphold His creation in a (basically) uniform way for our benefit, promising certain repeating cycles in nature.  God specifically includes the day and night cycle as part of His creation covenant (Genesis 8:22, Jeremiah 33:25).