The Moon’s Regression and Density Waves

Dr. Lisle’s comments on the secular regression of the moon’s distance and the winding of spiral arms are pure nonsense. In 1939 Harold Spencer Jones, in an article in Monthly Notices, showed that the regression is not constant and stated 4.6 billion years ago, in excellent agreement with the estimated age of the sun as given by stellar evolution calculations. The so-called winding problem of spiral arms is no problem because the arms are not material arms but rather density waves. This has been known since the 1960’s. Density waves no more wind up than ocean waves pile up an ocean on one side of a continent. Either Lisle is completely unfamiliar with the relevant literature, in which case he is incompetent, or he is lying to deceive the gullible. Either way reflects extremely poorly on the competence, better stated lack of comptetence, of so-called creation scientists.

—R.B., Argentina

Dr. Lisle’s comments on the secular regression of the moon’s distance and the winding of spiral arms are pure nonsense. In 1939 Harold Spencer Jones, in an article in Monthly Notices, showed that the regression is not constant

If you had done your homework on this issue, you would see that we have not assumed a constant rate. (Ironically, if the rate were constant, it would not be a problem for 4.5 billion years.) The rate is inversely proportional to the sixth power of distance. This is because both the force of the moon, which induces tides, and the force that the tides induce on the moon are dipoles, each of which goes as 1/r³. So, the combined tidal force on the moon goes as 1/r⁶. Integrating over r yields a maximum possible age much less than 4.5 billion years.1

and stated [sic] 4.6 billion years ago, in excellent agreement with the estimated age of the sun as given by stellar evolution calculations.

The actual calculation done correctly gives a maximum possible age of 1.5 billion years for the earth-moon system.2 By the way, the age of the sun is not estimated from stellar evolution calculations, nor could it be. Such calculations could only give a maximum possible age to any star based on its mass and luminosity. You might ask, “How then do secular astronomers estimate the age of the sun?” The answer comes from certain types of radiometric dating applied to meteorites. The sun is assumed to have formed at the same time as the earth and the meteoroids. You might be surprised to find how assumption-laden many age estimations are.

The so-called winding problem of spiral arms is no problem because the arms are not material arms but rather density waves.

That’s a very common speculation. But to my knowledge, there is absolutely no evidence for it, and there is significant evidence against it.

This has been known since the 1960’s.

It has been speculated since the mid-1960s. It has never been demonstrated, and there is much evidence to the contrary. For example, there are difficulties in getting such a wave started. There is observational evidence of galaxies with backward-wound spirals and observations of galaxies with a tightly-wound core (such as M51), both of which are contrary to the expectations of the spiral density wave hypothesis. The spiral density wave hypothesis presupposes abundant spontaneous star formation, which is problematic in its own right.

Perhaps most significantly, the magnetic fields of spiral galaxies are aligned with their spiral arms.3 This would not be the case if the arms were caused by density waves because plasma cannot cross a magnetic field line. The magnetic fields must travel with the material, not with a density wave.

Density waves no more wind up than ocean waves pile up an ocean on one side of a continent. Either Lisle is completely unfamiliar with the relevant literature, in which case he is incompetent, or he is lying to deceive the gullible.

That is the bifurcation fallacy. The unstated (and correct) third option is that you have not done your homework on this issue. Furthermore, you have unwittingly acknowledged the truth of biblical creation in your previous sentence. Only in a biblical creation worldview would it make sense to criticize someone for “lying to deceive the gullible” (because such an action is contrary to God’s command as revealed in the Bible).

However, in an evolutionary worldview why would lying be wrong—particularly if it benefits my survival? You may not personally like it, of course, but on what rational basis could you declare that anything is fundamentally, objectively wrong? Objective morality is only meaningful if biblical creation is true as shown here: Evolution and the Challenge of Morality.

Either way reflects extremely poorly on the competence, better stated lack of comptetence [sic], of so-called creation scientists.

Well, I hope you now see that this is not the case. It would be beneficial for you to study up on these issues before you accuse others of failing to do the same.

Dr. Jason Lisle