Flat Earth

[An aspiring Thomist]

The fact that the distance of the earth from the sun changes with the seasons means that even if the sun goes around the earth the earth will oscillate back and forth around a central position.

Would that be true if the earth were at the center of mass of the whole universe and assuming the whole universe revolved around it?

[Greg]

Isn't the whole "world on some elephants on a turtle" thing from Hinduism?

The Universe is actually a giant saddle, strapped to back of a cosmic donkey and God is riding it up and down a deserted intergalactic highway giving it toffee-apple supernovas.

[GloriaPatri]

If the Earth were actually flat the horizon would be much farther away from you than it actually is. Face it y'all, the Earth is approximately a sphere. Anyone who says otherwise is a damn idiot.

[Quaremerepulisti]

The fact that the distance of the earth from the sun changes with the seasons means that even if the sun goes around the earth the earth will oscillate back and forth around a central position.

Would that be true if the earth were at the center of mass of the whole universe and assuming the whole universe revolved around it?

Yes.  (We can ignore the rotation of the universe here since centrifugal and Coriolis forces are zero along the axis of rotation, where the earth is.)  It's necessary to distinguish between the position of the center of mass itself not moving (which is indeed the case whenever there are no outside forces) and a body at the center of mass not moving (which is not always the case, there can be a nonzero net force at the center of mass).  Now, if the sun didn't move it would be possible that the gravitational attraction of the earth toward the sun would be exactly balanced out by forces from other masses.  But if the sun gets closer towards the earth the only way that could be balanced out is if there were another of sun of equal mass on the opposite side of the earth at the same distance moving in tandem with the first sun.  This is obviously not the case.

[An aspiring Thomist]

The fact that the distance of the earth from the sun changes with the seasons means that even if the sun goes around the earth the earth will oscillate back and forth around a central position.

Would that be true if the earth were at the center of mass of the whole universe and assuming the whole universe revolved around it?

Yes.  (We can ignore the rotation of the universe here since centrifugal and Coriolis forces are zero along the axis of rotation, where the earth is.)  It's necessary to distinguish between the position of the center of mass itself not moving (which is indeed the case whenever there are no outside forces) and a body at the center of mass not moving (which is not always the case, there can be a nonzero net force at the center of mass).  Now, if the sun didn't move it would be possible that the gravitational attraction of the earth toward the sun would be exactly balanced out by forces from other masses.  But if the sun gets closer towards the earth the only way that could be balanced out is if there were another of sun of equal mass on the opposite side of the earth at the same distance moving in tandem with the first sun.  This is obviously not the case.

Thanks for the explainstion. Couldn't there be a sun twice the distance away from the earth and four times the mass moving in tandem? And if so, couldn't there be any number of possible forces from objects which as long as their net forces and so forth were equal to the sun's then the earth would not move?

I still don't quite understand why if the sun moves around the earth, it would move assuming the earth were at the center of mass. I would think all of the forces would cancel out.

[Quaremerepulisti]

Thanks for the explainstion. Couldn't there be a sun twice the distance away from the earth and four times the mass moving in tandem?

But then the earth wouldn't be at the center of mass.  The center of mass would be closer to the heavier sun.  Unless you really mean barycenter and not center of mass.  But here's the problem; the suns can't actually move in tandem.  When the suns move you need to take the Coriolis force into account.  To keep the heavier star twice the distance away from the earth as the lighter one the radial velocity needs to be twice as big, resulting in a Coriolis acceleration twice as large.  That will not result in an angular velocity twice as large, which is necessary to keep the heavier star from canceling out the force of the lighter one.

And if so, couldn't there be any number of possible forces from objects which as long as their net forces and so forth were equal to the sun's then the earth would not move?

But the net force would not remain zero.

I still don't quite understand why if the sun moves around the earth, it would move assuming the earth were at the center of mass. I would think all of the forces would cancel out.

It's not necessarily true that there is zero net force at the center of mass.

[Kephapaulos]

To all Flat Earthers: So you're telling me this is flat?




Wouldn't I be able to see more land?

[red solo cup]

https://www.washingtonpost.com/news/speaking-of-science/wp/2017/11/21/this-man-is-about-to-launch-himself-in-his-homemade-rocket-to-prove-the-earth-is-flat/?utm_term=.f2d337ccedbd

[Greg]

Best comment

If the earth really was flat, cats would have pushed everything off by now.

[Greg]

Funny as hell.

[Livenotonevil]

My question is when and how did the idea of a flat earth come to prominence? Even the Romans, according to Ovid's Metamorphoses, had a clear if not scarily accurate idea of what the Earth was like (the Earth being spherical with two cold poles on opposite sides); and when geocentrism was usually modeled by Medieval scholars, the Earth was generally understood to be spherical. Where did the idea come from?

Was there a prominent theological opinion supported by the Bible that the Earth was flat?

[Tales]

https://en.m.wikipedia.org/wiki/Flat_Earth

tl;dr Many wise people over many centuries across many countries have thought the Earth to be flat, but it was generally known to be round.  The modern flat earth theory is a Protestant / "Enlightenment" hoax rewrite of history to paint the Catholic Church as foolish.

[Lumen Christi]

To reference something from another forum:



Looks pretty round to me.

[Jayne]

Was there a prominent theological opinion supported by the Bible that the Earth was flat?

I recently had a debate with the Cathinfo Flatearthers  (perhaps half a dozen people - most there disagree with them) about the historical and theological aspects of the question.

The standard understanding is that many of the Church Fathers believed  in a flat earth but over time a consensus developed among Catholics that the earth is spherical. By the time universities began being established in the Medieval period, virtually everyone accepted the sphere shape and this is what was taught. It is generally recognized that St Thomas Aquinas and St Albert the Great believed the earth is a globe.

The Flatearthers I talked to denied the accepted view and claimed that flat earth is the Catholic position taught by Scripture and the Fathers and held until the Reformation introduced it's errors.

They seemed to think they were better Catholics for believing in flat earth and one even referred to belief in a globe earth as heresy.

They tried to prove their position by using quotes from Scripture and the Fathers. When shown a papal encyclical which explicitly stated that these should not be used to determine natural science, they still clung to their view that they were the ones holding the real Catholic position.

I do not know much about science but in the fields I do know about I could see that these people were wilfully ignorant and they rejected Church teaching on Scriptural exegesis. If anyone wishes to see the thread it is here - https://www.cathinfo.com/the-earth-god-made-flat-earth-geocentrism/did-catholics-before-the-'reformation'-believe-in-fe/msg581137/#msg581137

[Tales]

Jayne,

That thread illuminates some peculiar aspects of human nature.  Pretty troubling stuff.  No matter how much evidence there is nor how much education a person has, if said person really wants to believe something false, then he will do so and rationalize it with whatever straws are available.

It always frustrates me how seemingly impossible it can be to change understandings.