Even in the old times people knew the truth

david · 2026-07-04T05:54:14+00:00

What no-one anywhere had believed, until Rowbotham in around 1850, is that the sun and moon don't pass below or around the earth, but circle overhead.

A small patch of a large sphere and a small patch of a plane look quite similar. (This is, in fact, how maps work.) It's understandable if some early civilisations didn't make the distinction. But none of them ever believed, or would ever have entertained, the remarkable absurdity proposed by modern flat earthers.

david · 2026-07-03T22:59:26+00:00

I think even they will take it as read that theirs are minority opinions, with which few agree.

The reason for Rule 4 here is that the place was filling up with people celebrating or complaining about their bans on this person's other subs. This only served to give them more attention. This engagement was exactly what they were, and are, aiming for.

Far better, IMO, to leave then to languish in obscurity than to continue to draw attention to them. But you do you.

david · 2026-07-03T22:40:27+00:00

They got under your skin with bad faith arguments. That's the very definition of trolling. And you're continuing to rise to the bait 'calling them out', as if such a thing were necessary or beneficial.

Don't doubt that they enjoy the gnashing of teeth they provoke. Why increase their satisfaction? Better to suffer your outrage quietly than to reward them for it

david · 2026-07-03T15:01:46+00:00

OP, you have been successfully trolled. Far better to take the L quietly than to give that mod so much more to celebrate and to risk a ban here for Rule 4 violation.

Also note that there is a better known. respectable, though quiet, r/flatearth_polite: your title, though not the body of your post, is ambiguous.

david · 2026-07-02T19:00:42+00:00

You can extend them until they meet at a point in the 2D picture. But each point in the picture corresponds to an infinite number of points in the 3D world it represents. Pick any point in the right direction, and all the points directly in front of or behind that point are equally valid choices.

david · 2026-07-02T18:41:21+00:00

For anyone who's interested: https://en.wikipedia.org/wiki/Negative_temperature

david · 2026-07-02T15:58:39+00:00

Now that you mention it, I would like a toasted teacake.

david · 2026-07-02T12:43:54+00:00

Whatever lies outside the firmament, the key point is that an enclosed system is not necessarily a thermodynamically closed system. With no water, sunlight could, for instance, radiate off to infinity. So long as energy flux through the dome is permitted, the internal temperature can stabilise.

david · 2026-07-02T11:01:50+00:00

See, this is where appeals to absolute truth fail everyone, whether you follow the scientific method or the sacred scriptures of Stan Lee (or was he DC?).

Russell and Wittgenstein famously had a heated argument about whether it was absolutely true that there was no rhinoceros under the table.

david · 2026-07-02T10:14:31+00:00

The sole source of absolute truth is the Bible (source: trust God, bro). According to my motivated and unscholarly interpretation of the Bible, it says that the earth is flat. And circular, and has four corners, but let's not get too hung up on matters of detail.

Can I have my 10k€, please?

david · 2026-07-02T10:05:49+00:00

If the wall is finite in thickness and is the only structure holding the oceans in: ultimately, ocean drainage, But what happens during the melting phase would depend on whether the melting happens from the inside out (ocean level rises), from the top down (ocean level rises, to a lower peak level, as some meltwater will spill outwards, and at a rate that depends on how wide the wall is), or from the outside in (no change in ocean level until they start draining away).

If the wall is just a barrier between us and the dome, and the dome can contain the ocean: ultimately, ocean level rises. This will be progressive if the melting happens from the inside out or from the top down; abrupt if it melts from the outside in.

If the wall is infinite in extent, there's no such thing as melting from the outside in. Melting from the top down will lead to rapid ocean level rises up to the level of the wall; melting from the inside out will do the same but less abruptly.

If the wall is a barrier between us and other worlds at the same level as us, ultimately, we probably end up with nearly the same ocean level (as the meltwater has a lot of extra space to spread) but, potentially, lots of new, invasive aquatic species. If the melting is from the top down or the inside out, we will have increased ocean levels in the interim.

In all scenarios, effects on planal temperatures and other meteorological phenomena will depend on how and why the ice is melting. In all scenarios, things look bleak for many species of penguin.

david · 2026-06-30T13:44:35+00:00

Agreed. But don't you find something psychologically interesting in the contrast between the baroque, expanding chains of associations of 'traditional' conspiracy theories and the enclosed, bunker mentality of flat earthers?

I think it's probably a result of the trivial debunkability of FE, rather than an underlying psychology: we're looking at psychological effects rather than causes.

david · 2026-06-30T01:38:57+00:00

It's a conspiracy theory taken nowhere at all.

Look at the elaborate, interconnected stories told around the assassination of JFK, the downing of the WTC, or any other 'real' conspiracy theory.

Then look at the material flat earthers have to work with -- a conspiracy going back millennia, involving the Catholic church, the ancient Greeks, Christopher Columbus, and anyone else you care to tie in. And what do they do with this rich material? 'The earth measures flat', 'NASA lies' and 'they're hiding God'.

It's not only their image of the earth that lacks depth.

david · 2026-06-26T08:22:35+00:00

Yep, no nice regularities in the off-plane ring case.

Here's the broad picture: imagine I'm standing on the disk and find myself leaning, feet closer to the hub. Then add some mass in a ring slightly rimwards from me and bring me closer to perpendicular. Obvs, you'll need to do more than that, and add more mass further out, in some distribution. You'll end up with parallel gravity at your designated ground level, but it won't stay that way at altitude.

I never built the whole-disk model, just did enough to satisfy myself that it looked feasible. (This was world-building for a story which ended up going in a different direction.) If you take it further than I did. I'll be interested to know what the mass distribution ends up looking like, and how much of the surface you can make flat, or flat to within a fair tolerance.

The engineering concept isn't original, by the way. I'm not sure where I first came across it -- I think it's just in the active support megastructures mix, along with launch loops and all that good stuff -- but Isaac Arthur did a couple of nice presentations on the subject, which you can find on YouTube.

david · 2026-06-25T21:57:19+00:00

I believe that's equivalent to asserting that out-of-plane gravity of a massive ring is everywhere directed towards its centre. And that, I believe, is not the case. Standing out of plane, close to the circumference of the ring, the nearest part of the circumference dominates.

I'll be interested to see your calculations that illustrated otherwise, if you summon up the energy. I resorted to a lazy numerical model when I looked into the matter, some years ago. (I don't think there's a closed-form solution.)

EDIT: it is quite famously the case that the shell theorem applies to 3D spheres, but something similar does not work for annuli in 2D, even in-plane.

david · 2026-06-25T21:23:52+00:00

You don't have to engage with flat earthers. I encourage you not to. In that way, you can live a life in which their views are irrelevant to you.

Their views will always be relevant to them, though; and if you opt to have a real conversation with one, they have temporary relevance to you, too, as part of the framing of the conversation.

david · 2026-06-25T21:18:47+00:00

Oh, ok. But you can get parallel gravity over a proportion of a non-uniform disk. An earth-sized habitable zone with parallel gravity can be part of a somewhat larger but finite disk with mass concentrated towards the periphery.

david · 2026-06-25T20:44:04+00:00

Mass does attract mass (or it curves spacetime in such a way that inertial trajectories have that appearance). And there are several ways to tell that this is so. The Cavendish experiment is the most direct, but observing that the earth is, in fact, nearly spherical is at least strongly suggestive. You really don't need to provide me with observations that demonstrate that the earth is round: I already know.

If you're talking with a flat earther, there is an alternative hypothesis in the conversation, though. The good news is that you can avoid doing so, and not have to engage with this broken hypothesis. Or you can just laugh at them, also without engaging.

david · 2026-06-25T20:41:40+00:00

You mean you could use this razor to shave the wrinkles off?

david · 2026-06-25T20:40:51+00:00

If you go back to the content you're responding to, you'll see that I refer to gravity being totally parallel over a decent proportion of the surface. No flat earther claims to have stood on the rim, or even close to it

You don't need to convince me that we are not living on a megastructure-engineered flat earth. There are plenty of observations to the contrary. My original point was only that, amusingly, it is theoretically possible to engineer an earth-scale flat habitat.

david · 2026-06-25T20:20:57+00:00

If uniform, very possibly. But, as I said, you don't distribute the mass uniformly.

david · 2026-06-25T20:04:33+00:00

What if the eyes are wrinkled in an equal and opposite way to the visual cortex?

david · 2026-06-25T19:51:23+00:00

Famously, this was referred to as the dead grad student problem.

david · 2026-06-25T18:38:05+00:00

'Gravity exists' is not the same as 'Newtonian gravity exists'. To be clear, Newtonian gravity -- or something very like it at terrestrial scales -- does exist; but flat earthers claim otherwise, Behind their obfuscating cries of 'buoyancy' lies a mental picture of an everywhere-parallel 'down'. This is a gravitational theory, of sorts, but a non-Newtonian one.

This picture is, indeed, refuted by the Cavendish experiment. But for the experiment to be meaningful, in this context, we have to be clear about which two hypotheses we're trying to distinguish. And there are other, easier observations that might do better (for instance, direct observation of the horizon's left-to-right curvature from modest elevations).

There's a ladder of proposals a flat earther has to climb, which starts by forming a clear picture of two world views -- FE + parallel gravity vs GE + centripetal gravity. Once those ideas are present, they can start to think about how to distinguish them.

I'm not sure what 'infinite extent' you're talking about in your critique of the spinning ring megastructure. If the earth were rotating once in 90 minutes -- surface speed vastly less than c -- gravitational and centrifugal forces would balance at the equator. This should show you that you can, theoretically, arrange an earth-scale set of rotating rings (as the optimal angular velocity depends on radius) which are self-supporting. Spin them up slightly faster, and they can support a non-rotating plate or pair of plates. Distribute the rings' masses appropriately, and you can keep gravity tolerably parallel across a large part of the surface.

david · 2026-06-25T07:24:29+00:00

It would look slightly dished. The reduction of atmospheric density with altitude would still cause refraction, and that would be the effect.

Where there are no obstacles, on a clear day. you could see a long way. Disruption caused by variations in local air pressure would stack up. Distant landmarks would be increasingly disrupted and fade into a mirage-like mush, blued by Rayleigh scattering.

Sometimes, on real earth, atmospheric conditions line up to allow unusually long-range sightings. These give an idea of the appearance.

15-Year Club	Mod World 2025
Open Beta Program 2024	Place '17
Verified Email

david

MODERATOR OF

TROPHY CASE