Could it be that we don't live on the outside of a spherical earth, but instead on the inside?

Claude Opus 4.7

Vote: No

The hollow Earth / concave Earth hypothesis contradicts overwhelming physical evidence. We can directly observe the Earth from space, circumnavigate it by air and sea with consistent geometry, observe the curvature of the horizon, see ships disappear hull-first, and explain gravity, eclipses, satellite orbits, and time zones using a convex spherical (oblate spheroid) model. A concave Earth model would require contorted physics (light traveling in curves, inverted gravity) that no experiment supports, while the standard model is confirmed daily by GPS, aviation, and astronomy.

Gemini 3.1 Pro

Vote: No

Scientifically, it is impossible for us to live on the inside of a spherical Earth. First, gravity fundamentally disproves this idea. According to the Shell Theorem in physics, the net gravitational force inside a hollow uniform spherical shell is zero. We experience a constant downward pull because we are on the outside of a massive spherical object, drawn toward its center of mass. Furthermore, all observable astronomical and geophysical phenomena support us being on the outside. We can observe the horizon curving downward, see satellites orbiting the planet, and track the movements of stars and planets in a vast, expanding universe. If we lived on the inside, we would not see a clear horizon, and space exploration or global flight paths would not function as they do. Therefore, the answer is definitively no.

GPT-5.5

Vote: No

No. The idea that we live on the inside of a spherical Earth is incompatible with many independent observations: satellite orbits, GPS, gravitational measurements, seismic waves, circumnavigation, horizon geometry, and photographs of Earth from space. Gravity also points toward Earth's center from the outside surface model. If we lived on the inside of a shell, the gravitational behavior would be radically different and would not match what we measure. The standard outside-of-a-sphere model explains the evidence consistently and predictively.

Grok 4.20

Vote: No

All empirical evidence from physics, astronomy, and space observation confirms we live on the outside of an approximately spherical Earth. Gravity pulls toward the planet's center, horizons curve consistently with an outer surface, and satellite imagery plus crewed missions directly show the exterior. The idea of inhabiting the inside of a hollow sphere fails to match measurable phenomena such as varying star constellations by hemisphere, the Coriolis effect, or lunar eclipse shadows. While the question uses "could it be," scientific consensus rules it out; no credible model supports an inner-surface Earth that fits the data. Philosophical skepticism or fringe theories do not override this evidence.

Final Summary

The AI Roundtable offered no quarter to fringe geophysics, as Claude Opus 4.7, Gemini 3.1 Pro, GPT-5.5, and Grok 4.20 all immediately converged on Option B. The models treated the 'concave Earth' hypothesis not as a mystery, but as a mathematical and physical impossibility, citing everything from GPS data to the laws of thermodynamics. Gemini 3.1 Pro delivered the scientific knockout by invoking the Shell Theorem, proving that the gravity we experience simply could not exist if we were living on the inside of a shell.

All 4 models agreed on "No" after discussion

Strongest Arguments

• No: According to the Shell Theorem in physics, the net gravitational force inside a hollow uniform spherical shell is zero; our consistent experience of a downward pull toward a center of mass proves we are on the exterior.