Editing Hollow Earth (section)

== Contrary evidence ==
=== Density of the Earth ===
{{Main|Schiehallion experiment|Cavendish experiment}}
In 1735, [[Pierre Bouguer]] and [[Charles Marie de La Condamine]] chartered an expedition from France to the [[Chimborazo]] volcano in Ecuador. Arriving and climbing the volcano in 1738, they conducted a [[vertical deflection]] experiment at two different altitudes to determine how local mass anomalies affected gravitational pull. In a paper written a little over ten years later, Bouguer commented that his results had at least falsified the Hollow Earth Theory. In 1772, [[Nevil Maskelyne]] proposed to repeat the same experiment to the Royal Society. Within the same year, the Committee of Attraction was formed and they sent [[Charles Mason]] to find the perfect candidate for the vertical deflection experiment. Mason found the Schiehallion mountain, where the experiment took place<ref>Davies, R. D. "A Commemoration of Maskelyne at Schiehallion." Quarterly Journal of the Royal Astronomical Society, Vol. 26, NO. 3/SEP, P. 289, 1985 26 (1985): 289.</ref> and not only supported the earlier Chimborazo Experiment but yielded far greater results.

In 1798, [[Henry Cavendish]] published a measurement of the density of the Earth based on a [[torsion balance]]. These results were later repurposed into a measurement of the [[gravitational constant]].<ref>{{Cite book |last=Zee |first=Anthony |title=Einstein Gravity in a Nutshell |date=2013 |publisher=Princeton University Press |isbn=978-0-691-14558-7 |edition=1st |series=In a Nutshell Series |location=Princeton}}</ref>{{rp|33}}

Based upon the size of the Earth and the force of gravity on its surface, the average density of the planet Earth is 5.515&nbsp;g/cm<sup>3</sup>, and typical densities of surface rocks are only half that (about 2.75&nbsp;g/cm<sup>3</sup>). If any significant portion of the Earth were hollow, the average density would be much lower than that of surface rocks. The only way for Earth to have the force of gravity that it does is for much more dense material to make up a large part of the interior. Nickel-iron alloy under the conditions expected in a non-hollow Earth would have densities ranging from about 10 to 13&nbsp;g/cm<sup>3</sup>, which brings the average density of Earth to its observed value.<ref>Lowrie, W., & Fichtner, A. (2020). Fundamentals of geophysics. Cambridge university press.</ref>{{rp|186}}

=== Seismic ===
The picture of the [[Structure of Earth|structure of the Earth]] that has been arrived at through the study of [[seismic waves]]<ref name="press">{{Cite book | last1 = Press | first1 = Frank | last2 = Siever | first2 = Raymond
| last3 = Grotzinger | first3 = John | last4 = Jordan | first4 = Tom
| author-link = Frank Press | title = Understanding Earth | publisher = W. H. Freeman
| edition = 4 | year = 2003 | location = New York | pages = 484–487
| url = https://books.google.com/books?id=P8iEVK1yGKwC&q=%22structure+of+earth%22++%22seismic+waves%22&pg=PA484
| isbn = 978-0-7167-9617-6 }}</ref> is quite different from a fully hollow Earth. The time it takes for seismic waves to travel through and around the Earth directly contradicts a fully hollow sphere. The evidence indicates the Earth is mostly filled with solid rock (mantle and crust), liquid nickel-iron alloy (outer core), and solid nickel-iron (inner core).<ref name="usgs">{{cite web|url=http://pubs.usgs.gov/gip/interior/ |title=The Interior of the Earth |publisher=pubs.usgs.gov|access-date=1 November 2015}}</ref>

=== Planetary creation===
Another set of scientific arguments against a Hollow Earth or any hollow planet comes from [[gravity]]. Massive objects tend to clump together gravitationally, creating non-hollow spherical objects such as stars and planets. The solid spheroid is the best way to minimize the [[gravitational potential energy]] of a rotating physical object; having hollowness is unfavorable in the energetic sense. In addition, ordinary matter is not strong enough to support a hollow shape of planetary size against the force of gravity; a planet-sized hollow shell with the known, observed thickness of the Earth's crust would not be able to achieve [[hydrostatic equilibrium]] with its own mass and would collapse.{{citation needed|date=November 2024}}

=== Direct observation ===
Drilling holes does not provide direct evidence against the hypothesis. The deepest hole drilled to date is the [[Kola Superdeep Borehole]],<ref>{{Cite web|url=http://www.iflscience.com/environment/deepest-hole-world/|title=What's At The Bottom Of The Deepest Hole On Earth?|date=11 March 2016 |access-date=2016-08-17}}</ref> with a true vertical drill-depth of around {{convert|12|km|mi|abbr=on}}. However, the distance to the center of the Earth is nearly {{convert|6400|km|mi|abbr=on}}.<ref name="...">{{Cite arXiv |eprint=1510.07674 |last1=Mamajek |first1=E. E. |last2=Prsa |first2=A. |last3=Torres |first3=G. |last4=Harmanec |first4=P. |last5=Asplund |first5=M. |last6=Bennett |first6=P. D. |last7=Capitaine |first7=N. |last8=Christensen-Dalsgaard |first8=J. |last9=Depagne |first9=E. |last10=Folkner |first10=W. M. |last11=Haberreiter |first11=M. |last12=Hekker |first12=S. |last13=Hilton |first13=J. L. |last14=Kostov |first14=V. |last15=Kurtz |first15=D. W. |last16=Laskar |first16=J. |last17=Mason |first17=B. D. |last18=Milone |first18=E. F. |last19=Montgomery |first19=M. M. |last20=Richards |first20=M. T. |last21=Schou |first21=J. |last22=Stewart |first22=S. G. |title=IAU 2015 Resolution B3 on Recommended Nominal Conversion Constants for Selected Solar and Planetary Properties |date=2015 |class=astro-ph.SR }}</ref>