Posted by: William | May 19, 2017

Moment of Inertia Factor is also a BIG PROBLEM for the UM

This is part of a series of articles responding to the claims made in Dean Sessions’ Universal Model.  Click the link to see the introduction to the series.  This article was contributed by Will Meservy.

One portion of the “discoveries” part of the Universal Model website states, “the concept that Earth is a Hydroplanet instead of a magmaplanet is one of the key components of the UM.” It also includes a fancy illustration (below) depicting what that means—you’ll notice that the Earth is depicted with a liquid water outer core and solid ice inner core:


On the other hand, the scientific consensus is that the outer and inner cores of the Earth are mostly liquid and solid iron—something more like this:


Iron is much denser than any known phase of H2O, so Sessions’ “hydroplanet” belief requires that the overall density and mass of the Earth be considerably reduced in order to fit his model. Without any empirical or mathematical basis, he confidently asserts that the Earth’s new mass is roughly 1/3 the actual mass that modern physics dictates.

His arguments rapidly fell apart when asked about the major problems a new mass of the Earth poses to orbital mechanics (I was a little encouraged, personally, to hear that he doesn’t dismiss satellites as a government hoax). And Dr. Barry Bickmore extensively covers Sessions’ false claims about the Earth’s mass in this blog post.

A few weeks ago, I had the opportunity to speak over the phone with Jarom Sessions (Dean’s son) about this issue, and he hung up on me as soon as I started into the particulars about the Earth’s mass. Russ Barlow (one of Sessions’ closest UM associates) called me later that evening, and he also could not offer any viable explanation for orbiting satellites under the current UM model except to repeat that Volume III of the Universal Model would somehow explain the discrepancy. I have learned that the repeated answer you will get from any die-hard UMer is this: “It will all be cleared up in Volume III.” If you don’t believe me, call them up and ask.

But…they haven’t released Volume III yet, so we will have to take it on faith that they will be able to rework modern physics to fit their claim (I guess starting with conclusions and working backwards is the new science). However, my bet is that Sessions cannot provide the mathematics necessary to prove his biased, ill-conceived conclusions.

Actually, I believe that Dean Sessions will, at some point in his life, come to the realization that the Earth’s mass has already been correctly described with modern physics. It’s pretty hard to argue against the simple reality that each new satellite we put into orbit stays there as a testament to the fact that we already know, reliably well, the Earth’s actual mass. They wouldn’t be in that orbital sweet spot if this weren’t true.


When Sessions and his followers finally do admit the Earth’s mass is already correct, I am confident that their next step will be to make something akin to this argument: The mantle must be much denser than is generally thought. That’s the only way to maintain our “hydroplanet” model and acknowledge that the Earth’s mass is already correct because…THERE MUST BE A WATER CORE!

I am confident this will be their eventual reaction because another (former?) UMer that I spoke with acknowledged to me that Sessions was wrong about the Earth’s mass and brought this same hypothesis up to me instead.

But I want to preemptively stop that line of reasoning before more UMers jump on that ill-judged train. The problem is that any “hydroplanet” model (I think of it as the “core(s)-light” model for obvious reasons) completely ignores the Earth’s moment of inertia factor, a useful clue to what the interior structure of any spinning sphere is.

In general, moment of inertia is just a measure of how hard it is to get something rotating. More precisely, according to merriam-webster, it can be defined as “a measure of the resistance of a body to angular acceleration about a given axis that is equal to the sum of the products of each element of mass in the body and the square of the element’s distance from the axis.” In mathematical terms, for a rigid sphere with a uniform density, then I=0.4mr^2 (where I is the moment of inertia, m is the mass, and r is the radius).

453233_animation-physics-moment-wikipedia-inertiaMoment of inertia demonstration with objects of same mass. Note that the red sphere is hollow.

Moment of inertia factor is related to moment of inertia and is used to describe the radial density distribution of all major planetary bodies in our solar system based on their spin precession, gravity quantities, mass, and radius. This PowerPoint by Francis Nimmo gives a detailed explanation of what moment of inertia factor is and how it’s calculated.

Generally put, if a celestial sphere has a moment of inertia factor less than 0.4, then its mass must be distributed more towards its core, and it will be denser at its core. If it has a moment of inertia factor greater than 0.4, then its mass must be distributed more towards its outer layers, and it will be denser toward its surface.

No planetary bodies (not even the moon) in our solar system have a moment of inertia factor greater than 0.4, meaning they are all denser towards their centers than they are towards their exteriors.


In fact, moment of inertia factor offers scientists a large clue about the interior makeup of nearly any nearby planetary body. Based on moment of inertia factors, we know that all major planetary bodies in our solar system have differentiated to some level, meaning that denser materials have sunk to their centers.

In short, the Earth’s inner and outer cores, which extend nearly halfway from its center, cannot be less dense than the Earth’s mantle. If this were true, then the Earth’s moment of inertia factor would be much higher. So, there is no core(s)-light model for the Earth, or really for any major planetary body in our solar system. The Sun and all the planets in our solar system are densest at their cores.



  1. That’s a brilliant bit of argumentation. I had not considered that it would be possible to measure the moment of inertia but I can see that precession of the polar axis gives a clue, or so it seems to me.

  2. […] outer core is liquid water, and the mantle/crust are a mixture of rock and water.  (Will Meservy recently pointed out that this can easily be disproven by referring to the Earth’s measured moment of inertia, […]

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