Is the Earth flat? My mum says so

Grok 4.1 Fast

Vote: No

The Earth is an oblate spheroid, not flat, as established by centuries of scientific evidence. Satellite imagery from NASA and other space agencies shows Earth's curvature. Ships disappear hull-first over the horizon due to curvature. Circumnavigation works consistently in all directions. Gravity pulls matter into spheres for large bodies; a flat Earth would collapse. Lunar eclipses cast Earth's round shadow on the Moon. Personal anecdotes like 'my mum says so' lack empirical support and contradict observable facts.

GPT-5.4

Vote: No

The Earth is not flat. It is an oblate spheroid, which means it is almost spherical but slightly wider around the equator. This is supported by many independent observations: ships disappear hull-first over the horizon, Earth casts a round shadow on the Moon during lunar eclipses, and people can travel continuously east or west around the world. Modern evidence is overwhelming, including satellite imagery, GPS systems, and measurements from aviation and spaceflight. These technologies work because the Earth is round. A person saying otherwise, even a parent, does not outweigh the evidence.

Kimi K2.5

Vote: No

Overwhelming empirical evidence confirms Earth is an oblate spheroid, not flat. Ships disappear hull-first over the horizon, indicating curvature. During lunar eclipses, Earth's shadow on the Moon is always circular—a shape only a sphere casts from every angle. Satellite imagery and global circumnavigation provide direct confirmation. While respecting family is important, parental authority does not override scientific consensus built on centuries of observation, measurement, and verification by millions of researchers. Truth claims require reproducible evidence, not just tradition or personal belief. Appeal to authority is a logical fallacy when the authority lacks relevant expertise.

Claude Opus 4.6

Vote: No

The Earth is not flat. While I respect your mum, this is a matter of well-established science supported by overwhelming evidence. We have direct photographic evidence from space — thousands of images from NASA, ESA, private companies like SpaceX, and astronauts from dozens of countries all show a spherical Earth. The physics of gravity naturally pulls large masses into a spherical shape. Ships disappear hull-first over the horizon, time zones exist because different parts of Earth face the sun at different times, and you can observe the Earth's curved shadow on the moon during a lunar eclipse. The idea of a spherical Earth isn't new or controversial — it was established by ancient Greek mathematicians like Eratosthenes over 2,000 years ago, who even calculated the Earth's circumference with remarkable accuracy. Sometimes people we love and trust can hold incorrect beliefs. That's okay — but on this question, the scientific consensus is clear and unambiguous: the Earth is an oblate spheroid (roughly spherical, slightly flattened at the poles).

Gemini 3.1 Pro

Vote: No

While I respect your mum's perspective, overwhelming scientific evidence proves the Earth is not flat; it is an oblate spheroid. Decades of space exploration, thousands of satellites in orbit, and photographic evidence from space universally confirm its spherical shape. We can also observe this shape directly from the ground. For instance, ships disappear hull-first as they sail over the horizon, lunar eclipses always cast a curved shadow of the Earth on the moon, and distinct time zones exist because the sun illuminates different parts of a rotating sphere at different times. Finally, gravity naturally pulls matter toward its center. Any planetary body as massive as the Earth is forced into a spherical shape by its own gravitational pull. A flat planet of this size simply cannot exist under the laws of physics.

Final Summary

Faced with the ultimate authority of a user’s mother, the AI Roundtable remained remarkably unsentimental, delivering a unanimous 5-0 verdict against a flat Earth. While Claude Opus 4.6 and Gemini 3.1 Pro offered polite condolences regarding the family disagreement, Kimi K2.5 was less diplomatic, classifying the 'mum says so' defense as a textbook appeal to authority fallacy.

No agreement after 1 rounds of discussion. Final vote: No: 5

Strongest Arguments

• No: The laws of physics dictate that any planetary body as massive as the Earth is naturally pulled into a spherical shape by its own gravitational center, making a flat planet of this size a physical impossibility.