Talk:Preliminary reference Earth model

Newtonian methodology

This theoretical chart is incorrect.

Acceleration does not go to zero within the center of a gravity well. Acceleration will be highest at the core

The author's are confused about newtonian notions of mass attracting mass equating to some kind of balanced zero g state at the core.

This is hopelessly incorrect. It's not about weight, it's about time.

General Relativity explains how mass tells space time how to curve. For our frame of reference motionless on the earth, our straightest path through curved space time is a line entering the top of our head, out our feet and straight to the core. The deeper it goes the greater the acceleration experienced and the greater the time dilation.

As you descend, the accumulation of less dense matter directly above you is negligible when compared to all the mass that comprises the gravity well

as a thought experiment, even with two identical earth's in binary orbit of each other, the presence of one above may make you weigh less, but your acceleration and hence your time dilation at your location is unchanged

Gravity Wells are stratified by density with the densest matter in the core and helium and hydrogen in the upper atmosphere

There's a theoretical paper (not handy, Google it) on the age of the core of the earth being younger than the crust. This is due to the increased acceleration there causing time to run slower than at the surface.

As modeled in the above chart, a clock would run faster at the core than it would in orbit, that's silly. You can't use a 300 year old methodology that is ignorant of time in place of the more accurate, more difficult to work with GR.

acceleration is definitely higher at the core than at the surface

Thanks Joe 2605:59C8:41D:2010:D054:3FF:FE32:767 (talk) 14:01, 1 August 2024 (UTC)

You may be confusing free-fall speed with acceleration. If there was a narrow airless hole going through the Earth, and you fell from the surface into the hole, your speed would indeed be maximized as you passed through the center of the Earth. But that is exactly what you would get if the acceleration was 0 at the center (and then negative, i.e., pulling you in the opposite direction) past the center.

Now you might argue that if you were at rest at the center of the Earth, you'd be accelerated (in what direction?) faster than the ~9.8 m/s^2 at the surface. (I'd say you're wrong, but ok.) But that's not what the chart shows; it shows how fast you'd fall if you were at rest at the center of the Earth (and at other points) in these three models. You seem to believe that none of these models reflect reality, but that's not only unsourced speculation but not particularly relevant to this article.

CRGreathouse (t | c) 01:41, 3 August 2024 (UTC)