objections to the roundness of Earth

[Wiploc]

I have heard about the cattle being thought of as growing as you walked closer.

I also read long ago that before gravity was discovered to exist. People thought things were stuck to the ground not because some force was pulling you down but because the Earth was moving up.

Speaking of gravity.....

If you lived before the discovery of gravity how do you explain that if Earth was a ball why doesn't all of the water fall off.

Why would you need to demonstrate that? Gravity is apparent, maybe not explained, but stuff settles down... for whatever reason. No one would live parallel to the surface of Earth.

A flat earth fellow living before gravity was discovered--

"If you pour water onto a ball 10 to the zillion billionth times the water falls off . Therefore the earth cannot be a ball"

This is way too scientific of an argument. A person that long ago is arguing the earth is flat, because the ground around them is as flat as the eye can see.

Where would one live to have the ground be flat all around them as far as the eye could see?

Diskworld.

 

[Loren Pechtel]

Where would one live to have the ground be flat all around them as far as the eye could see?

Diskworld.

I've never understood how that is supposed to be remotely feasible. Assuming an unobtainium structure to support it you still have the big problem that down isn't straight down no matter how massive the disk. It's always going to be tipped towards the center and your atmosphere will follow. A spill wall could contain it but wouldn't mean the outer parts weren't in hard vacuum. If you spin the ring you have the same problem on the outside, but you still don't get even atmosphere. It's always unstable, there's always a point that everything closer wants to fall in and (assuming spin) anything farther wants to fall out.

There is a remotely viable structure in splitting it into many, many bands balanced so one band wants to throw it's air out and the next one wants to throw it in. But each band is moving relative to it's neighbor, you can't just walk across.

Let's add Ringworld (you can see the arch in the distance, you can't see the curvature) and Dyson Sphere. In both cases you'll get occlusion by the atmosphere before you see the curvature.

 

[Bronzeage]

For most of humanity's existence, whether the world was flat or round was of absolutely no consequence. It only began to matter on a practical basis when it became possible to sail a ship beyond the horizon, and more importantly, sail back home. The concept of gravity was just a philosopher's brain teaser. The idea of gravity was so trivial that when Aristotle said a heavier object would fall faster than a lighter object, everybody shrugged and said, "Sounds right." Nobody thought to check. It wasn't until artillery became a thing that gravity became a serious enough problem to merit real questioning.

People thought the Earth was flat mostly because it looks flat. They thought the Sun revolved around the Earth because that's what it looks like.
Neither mistaken belief had any effect on anyone's everyday life.

Flat Eartherism is a fairly modern idea, because it can only exist after there is general acceptance of a spherical Earth. Scientists, of as they were called back then, "Natural Philosophers", collected enough indirect evidence to create a crude model of the solar system that was simpler than the Geocentric model, and did a better job of explaining stuff like eclipses and the motions of the other planets. Any time you present evidence to convince people to believe something contrary to what they can see with their own eyes, there will always be those who refuse to accept the evidence. To compound the problem, there will be plenty of people who think it's funny to feign ignorance and apply folk science to create alternative theories of the universe. I saw an interview with a man who held a model airplane over a globe and asked the interviewer why passengers don't fall from their seats and hit the ceiling of the plane as it approaches Argentina, as it is obviously now upside down. Maybe he was serious, maybe it was a joke. I couldn't tell.

If he was serious, in the words of the great philosopher Mendacious, "Such ignorance is damnable."

 

[Bomb#20]

Where would one live to have the ground be flat all around them as far as the eye could see?

Diskworld.

I've never understood how that is supposed to be remotely feasible. Assuming an unobtainium structure to support it you still have the big problem that down isn't straight down no matter how massive the disk. It's always going to be tipped towards the center and your atmosphere will follow. ...

I don't think you're taking into account the mass of the four giant elephants the Diskworld is sitting on.

 

[bilby]

The idea of gravity was so trivial that when Aristotle said a heavier object would fall faster than a lighter object, everybody shrugged and said, "Sounds right." Nobody thought to check.

Lots of people checked. It's very easy to drop a stone and a feather, and see for yourself that the stone falls much faster. Aristotle was correct.

 

[bilby]

Where would one live to have the ground be flat all around them as far as the eye could see?

Diskworld.

I've never understood how that is supposed to be remotely feasible. Assuming an unobtainium structure to support it you still have the big problem that down isn't straight down no matter how massive the disk. It's always going to be tipped towards the center and your atmosphere will follow. ...

I don't think you're taking into account the mass of the four giant elephants the Diskworld is sitting on.

It's easier* to build a lightweight discworld, without appreciable gravity, and just accelerate it upwards at a constant 1g.

Turtles are capable of adjusting their bouyancy, to rise in the water column without significant expenditure of energy.







*for a given value of 'easy'

 

[pood]

The idea of gravity was so trivial that when Aristotle said a heavier object would fall faster than a lighter object, everybody shrugged and said, "Sounds right." Nobody thought to check.

Lots of people checked. It's very easy to drop a stone and a feather, and see for yourself that the stone falls much faster. Aristotle was correct.

Yes, he was correct. With air interference. What nobody suspected was two objects dropped in a vacuum would fall at the same rate.

 

[steve_bank]

This is a weighty subject.

Good NOVA video. How Galileo measured gravitational acceleration.

Galileo's Falling Bodies | PBS LearningMedia

Learn how Galileo mathematically described the physics of falling objects in this video from NOVA: The Great Math Mystery. For thousands of years, people erroneously thought that heavier objects fell faster than lighter ones. It was not until Galileo studied the motion of falling objects that it...

kcts9.pbslearningmedia.org

Learn how Galileo mathematically described the physics of falling objects in this video from NOVA: The Great Math Mystery. For thousands of years, people erroneously thought that heavier objects fell faster than lighter ones. It was not until Galileo studied the motion of falling objects that it became clear that, in the absence of air resistance, gravity causes all objects to fall at the same rate. Galileo used ramps to slow down the speed of falling objects so that he could carefully observe and collect data about their motion. Ultimately, he recognized that all falling objects accelerate at the same rate and showed that the distance a falling object travels is directly proportional to the square of the time it takes to fall.

In a vacuum two objects of different mass accelerate at the same rate, but the force and kinetic energy are different.

 

[Spacetime Inhabitant]

The idea of gravity was so trivial that when Aristotle said a heavier object would fall faster than a lighter object, everybody shrugged and said, "Sounds right." Nobody thought to check.

Lots of people checked. It's very easy to drop a stone and a feather, and see for yourself that the stone falls much faster. Aristotle was correct.

I think there is a problem with the claim that Aristotle said something, and everyone believed. Aristotle was a philosopher (and also tutor to Alexander the Great), so most of the people who would know his beliefs would be other philosophers, scholars and nobles.
There were probably lots of anonymous people in the world who observed that if they dropped two objects say off a cliff they would land at same time, for example the body and head of a defeated enemy. Or kids just dropping various sized stones.
What most people knew or didn't know isn't recorded by history.

 

[bilby]

The idea of gravity was so trivial that when Aristotle said a heavier object would fall faster than a lighter object, everybody shrugged and said, "Sounds right." Nobody thought to check.

Lots of people checked. It's very easy to drop a stone and a feather, and see for yourself that the stone falls much faster. Aristotle was correct.

Yes, he was correct. With air interference. What nobody suspected was two objects dropped in a vacuum would fall at the same rate.

Why would they care? Nature abhors a vacuum.

 

[Loren Pechtel]

Where would one live to have the ground be flat all around them as far as the eye could see?

Diskworld.

I've never understood how that is supposed to be remotely feasible. Assuming an unobtainium structure to support it you still have the big problem that down isn't straight down no matter how massive the disk. It's always going to be tipped towards the center and your atmosphere will follow. ...

I don't think you're taking into account the mass of the four giant elephants the Diskworld is sitting on.

Are we perhaps thinking of different diskworlds?

Because I'm thinking of the Alderson disk. Big washer around a star, perhaps with the star bobbing.

 

[Loren Pechtel]

The idea of gravity was so trivial that when Aristotle said a heavier object would fall faster than a lighter object, everybody shrugged and said, "Sounds right." Nobody thought to check.

Lots of people checked. It's very easy to drop a stone and a feather, and see for yourself that the stone falls much faster. Aristotle was correct.

I've seen a feather fall fast. It's truly nuts to see, feathers don't do that! The tube looked just the same as before he pumped the air out. (It doesn't bother me as a demonstration on TV, but it was wrong when it was in the classroom.)

 

[Bronzeage]

The idea of gravity was so trivial that when Aristotle said a heavier object would fall faster than a lighter object, everybody shrugged and said, "Sounds right." Nobody thought to check.

Lots of people checked. It's very easy to drop a stone and a feather, and see for yourself that the stone falls much faster. Aristotle was correct.

Yes, he was correct. With air interference. What nobody suspected was two objects dropped in a vacuum would fall at the same rate.

The idea of gravity was so trivial that when Aristotle said a heavier object would fall faster than a lighter object, everybody shrugged and said, "Sounds right." Nobody thought to check.

Lots of people checked. It's very easy to drop a stone and a feather, and see for yourself that the stone falls much faster. Aristotle was correct.

The idea of gravity was so trivial that when Aristotle said a heavier object would fall faster than a lighter object, everybody shrugged and said, "Sounds right." Nobody thought to check.

Lots of people checked. It's very easy to drop a stone and a feather, and see for yourself that the stone falls much faster. Aristotle was correct.

Yes, he was correct. With air interference. What nobody suspected was two objects dropped in a vacuum would fall at the same rate.

Why would they care? Nature abhors a vacuum.

Are you saying Nature is a vaccuumist?
.

 

[Swammerdami]

Where would one live to have the ground be flat all around them as far as the eye could see?

I once saw a "scientific paper" with analysis showing that Kansas, as a certain meme tells us, is indeed "flatter than a pancake."

 

[Swammerdami]

The idea of gravity was so trivial that when Aristotle said a heavier object would fall faster than a lighter object, everybody shrugged and said, "Sounds right." Nobody thought to check.

Lots of people checked. It's very easy to drop a stone and a feather, and see for yourself that the stone falls much faster. Aristotle was correct.

Yes, he was correct. With air interference. What nobody suspected was two objects dropped in a vacuum would fall at the same rate.

"Nobody"?? Surely you're not joining the contingent who thinks important historic persons were "nobodies."

There may have been very FEW ancient people who made the guess about equal speeds but (supposedly) there was at least one: Archimedes of Syracuse. I can't remember exactly where I read this claim, and the dumbed-down Internet/Google doesn't find it now (unless it's considered a corollary of Archimedes Principle of Buoyancy).

(I think there were also some medieval thinkers, e.g. Jean Buridan, who understood most of Galileo's solution long before Galileo.)

 

[bilby]

Where would one live to have the ground be flat all around them as far as the eye could see?

I once saw a "scientific paper" with analysis showing that Kansas, as a certain meme tells us, is indeed "flatter than a pancake."

Wow. Someone ahould probably have posted a link to that in this thread.

Oh, wait...

Kansas.

https://www.aps.org/publications/apsnews/200310/pancake-kansas.cfm

 

[lpetrich]

 John Philoponus (c. 490 - c. 570, Alexandria, Egypt) -- John Philoponus | Byzantine Philosopher & Theologian | Britannica -- John Philoponus (Stanford Encyclopedia of Philosophy)
Wiki:

But this [view of Aristotle] is completely erroneous, and our view may be completely corroborated by actual observation more effectively than by any sort of verbal argument. For if you let fall from the same height two weights, one many times heavier than the other you will see that the ratio of the times required for the motion does not depend [solely] on the weights, but that the difference in time is very small. ... — John Philoponus' refutation of the Aristotelian claim that the elapsed time for a falling body is inversely proportional to its weight

SEP:

As regards the natural motion of bodies falling through a medium, it was Aristotle’s contention that the speed is proportional to the weight of the moving bodies and indirectly proportional to the density of the medium. Philoponus repudiates this view by appeal to the same kind of experiment that Galileo was to carry out centuries later (In Phys. 682–84).

So John Philoponus beat Galileo by over a millennium.

The difference is air resistance. Compare a leaf and a wadded-up leaf. Or a sheet of paper and a wadded-up one. Beyond a certain mass per cross-section area, air resistance is negligible, and that threshold is low by the standards of familiar objects. I dropped a ruler and a filled water bottle onto my bed - they fell at the same rate.

Leaves and sheets of paper have the further complication of their shape. When released horizontally, they do not fall vertically but in a zigzag motion because of which sort of direction they most easily move.

 

[Shadowy Man]

The difference is air resistance. Compare a leaf and a wadded-up leaf. Or a sheet of paper and a wadded-up one.

 

[Shadowy Man]

Yeah, Bilby, you weren’t this wrong!