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When did modern flat-Earth movements revive and which figures (e.g., Eric Dubay, Mark Sargent) promote horizon/flight arguments?

Checked on November 17, 2025
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Executive summary

The modern flat‑Earth revival has roots in 19th‑century zetetic work and several 20th‑century revivals, but it surged again after the 2000s with online forums, a 2009 relaunch of the Flat Earth Society and viral YouTube personalities; reporting and summaries cite revivals in the 1840s (Rowbotham), mid‑20th century revivals [1] [2] [3] and a relaunch around 2009 that fed the social‑media explosion [4] [5] [6]. Two prominent contemporary promoters who push horizon‑and‑flight style arguments are Eric Dubay — author and video creator behind “The Flat‑Earth Conspiracy” and “200 Proofs…” — and Mark Sargent — the producer of the Flat Earth Clues series and a public face of the movement [7] [8] [9] [10].

1. How historians locate the “modern” revival

Historians trace today’s movement back to Samuel Birley Rowbotham in the 1840s — the so‑called zetetic method — which spawned the Universal Zetetic Society and later organizations; scholars and research compendia note revivals of that society in 1956, 1972 and 2004 and an early‑21st‑century acceleration as social media spread the ideas [4] [5]. Encyclopedias and research starters emphasize continuity: a nineteenth‑century intellectual strand that never vanished and later institutional relaunches that provided organizational anchors [5] [11].

2. The internet and conferences: the 2000s tipping point

Multiple accounts single out the 2010s as when flat‑Earth belief expanded markedly, aided by YouTube, Facebook groups and local meetups; the Flat Earth Society was relaunched online in October 2009 and annual conferences began to grow, which journalists say helped turn a fringe curiosity into a global online subculture [6] [11]. Analysts underline that social platforms amplify storytellers and influencers, letting persuasive non‑experts recruit followers more effectively than traditional institutions [12].

3. Eric Dubay: text, video and conspiracy framing

Eric Dubay is widely identified in documentary and press coverage as a leading voice who packages historical claims, long video “proof” lists and conspiracy framing; Dubay authored The Flat‑Earth Conspiracy and produced long videos such as “200 Proofs that Earth is Not a Spinning Ball,” which the New Yorker and other outlets cite as central artifacts of the online revival [7] [8]. Dubay’s output mixes purported empirical claims (horizon/flight anecdotes) with broader conspiracy narratives about NASA, Freemasonry and modern science — a pattern visible across his books and videos [13] [14].

4. Mark Sargent: the “enclosed world” and horizon arguments

Mark Sargent emerged as a public recruiter for flat‑Earth ideas through his Flat Earth Clues series and appearances in media and the documentary Behind the Curve; reporting calls him a de facto leader of the recent revival and highlights his “enclosed world” model — a flat disk with a surrounding ice wall and a dome that explains why space footage must be faked — and his repeated appeals to horizon and line‑of‑sight observations [9] [10]. Sargent often points to what he calls failures of perspective or “table‑top flat” footage from high‑altitude videos as evidence, a style that resonates on social media [15] [16].

5. The specific “horizon/flight” arguments used by promoters

Both Dubay and Sargent lean on similar, observable‑sounding claims: that horizons appear flat from everyday altitudes, that camera distortion or CGI explain contra‑evidence, and that pilots or high‑altitude videos supposedly corroborate a flat appearance; these are described in interviews, documentaries and their online content [7] [15] [13]. Journalistic coverage and academic commentators stress that these claims are amplified by selective viewing, rhetorical reframing and community reinforcement on platforms [12] [17].

6. What mainstream reporting and researchers add as context

Major outlets and encyclopedias place the movement in a larger pattern of mistrust of official science, community bonding and social‑media dynamics; Britannica and Scientific American say the revival is driven by distrust, conspiracy theory networks and influencers who are better storytellers than scientists on social platforms [11] [18]. Documentary coverage (Behind the Curve) and critics note that the movement’s internal experiments sometimes actually contradict its claims, yet the social mechanisms preserve belief [10].

7. Limits of available sources and open questions

Available sources document key personalities (Dubay, Sargent), dates of organizational relaunches [1] [2] [3] [19] and the internet’s role, but they do not provide a single, agreed‑upon date for a “final” revival moment — reporting instead emphasizes waves of resurgence and a sharp online growth in the 2010s [4] [6] [18]. Precise quantitative measures of follower counts over time or internal movement structure are not consistently reported in these sources [4] [20].

If you want, I can compile a short timeline of key milestones with direct source quotes, or extract a list of Dubay’s and Sargent’s most cited videos and where they made the horizon/flight arguments (with direct citations).

Want to dive deeper?
When did the contemporary flat-Earth revival begin and what events sparked its growth?
What roles did Eric Dubay and Mark Sargent play in popularizing flat-Earth horizon and flight arguments?
How do flat-Earth proponents use horizon observations and airplane behavior to support their claims?
What social-media platforms and algorithms amplified modern flat-Earth influencers since the 2000s?
How have scientists, pilots, and educators effectively debunked the horizon and flight arguments used by flat-Earth advocates?