[Dragon]

I think there is one thing that could throw everything away. If I can walk in a "straight" line from one point and eventually make it back to that same point, how is the Earth flat? If it is, I would fall of the Earth. Explain to me how NASA does live streams from satelites?
You can look it up on YouTube too. It shows curvature on the Earth. Am I not supposed to believe an unedited video? I watched it live too. I will be adding things over time to this post.

[markjo]

How do you propose to walk across the various large bodies of water along the way?

[Bad Puppy]

I think there is one thing that could throw everything away. If I can walk in a "straight" line from one point and eventually make it back to that same point, how is the Earth flat? If it is, I would fall of the Earth. That is just one. Please ask me more things to disprove.

First you'd have to get past the wiki's claim that you can't walk in a straight line without turning.

Q. Can't we just circumnavigate the earth by traveling in a straight line without a navigational aid?

A. It is not possible to travel in a perfectly straight line for very long without a navigational aid.

It's not even possible to drive down a long length of highway without turning the steering wheel left or right. Get in a car and see if you can drive down a long stretch of highway without turning the wheel left or right. It's a near impossible thing to do.

Of course, the second part is just a silly statement which is misleading.  If the road were absolutely level, straight and smooth, with no environmental or atmospheric effects such as wind, exact tire pressure, tread specifications, drag on bearings, perfect symmetry in a vehicle's internal parts including the driver (which isn't possible), etc.....the car will go straight....forever....without a navigational aid.  But, those conditions do not exist on a flat or round earth.  So, the car analogy is a terrible one and adds no value to the argument.

[Tom Bishop]

It sounds like you just demonstrated the point of the car analogy. The conditions to travel in a perfectly straight line without navigational aid are impractical.

[Tim Alphabeaver]

Tom's spot on here.  Even if it's possible to walk in a perfectly straight line in theory, in reality it's basically impossible. I think if you really wanted to know for sure that you were walking in a straight line, you could use the aether as a reference frame, which would be kind of hard since it's never been detected.

[AATW]

Yeah. I'm going to give Tom this one. Newton says that an object will remain at rest or continue at a constant velocity (velocity includes direction in physics, that's the distinction between velocity and speed) unless acted on by a force.
But in real life there are all kinds of forces acting on a car or other vehicle, friction, bumps in the road, mechanical factors.
And, fun fact, if you blindfold someone and ask them to go in a straight line they end up going in a circle. Without a point of reference we aren't able to go in a straight line.

When it comes to circumnavigation East to West this actually works on a FE. You'd actually be going round in a big circle but so gradually you wouldn't actually notice.
The issue for FE is North to South circumnavigation. Much less common as it involves going over both poles which is obviously problematic, but it has been done.

[TheNormalOne]

Yeah. I'm going to give Tom this one. Newton says that an object will remain at rest or continue at a constant velocity (velocity includes direction in physics, that's the distinction between velocity and speed) unless acted on by a force.
But in real life there are all kinds of forces acting on a car or other vehicle, friction, bumps in the road, mechanical factors.
And, fun fact, if you blindfold someone and ask them to go in a straight line they end up going in a circle. Without a point of reference we aren't able to go in a straight line.

When it comes to circumnavigation East to West this actually works on a FE. You'd actually be going round in a big circle but so gradually you wouldn't actually notice.
The issue for FE is North to South circumnavigation. Much less common as it involves going over both poles which is obviously problematic, but it has been done.

First one was the great Sir Ranulph Fiennes in 1982 I think

[spherical]

Of course there is a way, involves technology and a speedy vehicle, better if it flies.
You can not use star locking navigation, since on FE stars also make a circle, if you follow a star you make a circle around North Pole.

But you can use the old and good magnetic compass, even electronic ones (much more precise), and also, you can use electronic accelerometers, electronic gyros, they are very very good, much better than the old mechanical ones used on rockets.  One of my jobs is develop field products using those little high tech devices, they work very very good.  As a matter of fact your own Android of iPhone has all of the above and even more of those little gizmos that you never heard about.

You don't need too much, just depart from New York, for example, towards North+330° (30°NW), calculate a formula (based on RE) to go straight around the globe, so you would return to New York from the South.  The formula will be a simple navigation based on magnetic North deviation versus distance traveled, that is very simple, used for centuries.   That circumnavigation straight line will cut the globe in two, slicing close to the North and South Pole.

Why use de 30°NW instead of flying directly over the North and South Pole in a straight line?  Because, by doing so you can keep track of where is the North all the time, no matter where you would be.  If you fly over the North Pole you can not compute your bearings very well when over the poles, some may say "oh, you make a turn and don't even noticed" .

Following 30°NW from New York, you will fly over Canada, probably China, Australia, South Pole (FE ice wall), then magically appears over the tip of South America - Argentina or Uruguay, then over Brazil, back to New York.   The "magic"  here is the fly distance and time from Australia to South America over the South Pole would be much shorter than one can see on FE map.  And that is not from winds, light refraction or any other magic you can pull up from the sleeve, it is plain real distance.   May be you can use the to plot this trip.

The problem is that you can not have a fly object that can do such trip in one fuel tank.  I think only a B-52 can do 14~15000 km between refuels on flight, and complete the circumference with at least 3 refills. 

But wait, thousands of orbital satellites do it all the time, but no, FEs don't recognize the existence of orbiting satellites.

But there are an easy way, a flight from Sydney to Montevideo (Uruguay), 11862km, 25 hours flight (wristwatch time), one stop in Arturo Merino Benitez Airport in Santiago Chile.  The tarmac waiting time in Chile is 11 hours, so the Qantas flight time is a little bit short of 15 hours, average speed of 790km/h (493mph).
https://www.prokerala.com/travel/flight-time/from-sydney/to-montevideo/

On FE world, it would be more than 35000km, to make it in 15 hours, the average speed would be 2333km/h, it would required a Mach2 airplane to complete such trip in that time.  Even the Concord at 2180km/h at 60000 ft (18000m altitude) would not do it in 15 hours, with a maximum range of 7200km with the 210000 lbs of fuel, it would need 5 refueling stops during the trip.

FEs would say that flight doesn't exist, it is a lie promoted by governments and the potential travelers aboard were paid off to lie.
If you want to book such flight, click here:
https://www.tripadvisor.com/Flights-g255060-o294323-Montevideo_to_Sydney.html

[iamcpc]

I think there is one thing that could throw everything away. If I can walk in a "straight" line from one point and eventually make it back to that same point, how is the Earth flat? If it is, I would fall of the Earth. That is just one. Please ask me more things to disprove.

 On the round earth model your path curves along the sphere to put you back where you started.

On the flat disk  models your path curves around the flat disk to put you back where you started.

In the infinite repeating plane models you might be able to walk in a straight line to arrive back where you started.

There are several other models that I've heard of and I don't know how they work on those models

There are maybe a dozen or so flat earth models

[stack]

I think there is one thing that could throw everything away. If I can walk in a "straight" line from one point and eventually make it back to that same point, how is the Earth flat? If it is, I would fall of the Earth. That is just one. Please ask me more things to disprove.

On the round earth model your path curves along the sphere to put you back where you started.

Correct.

On the flat disk  models your path curves around the flat disk to put you back where you started.

If using the North Pole centered model (probably the most common model) and 'straight line' east to west or west to east, correct. If going north to south, south to north, you would ultimately dead-end in the south at presumably the ice wall.

In the infinite repeating plane models you might be able to walk in a straight line to arrive back where you started.

In any direction, I'm not sure what happens. I guess you would sort of teleport or 'pac-man' at some point. If not and you just kept moving in a given direction without pac-manning and let's say someone went in the opposite direction, you would never see each other again. 

There are several other models that I've heard of and I don't know how they work on those models

There are maybe a dozen or so flat earth models

Agreed.

[Bad Puppy]

It sounds like you just demonstrated the point of the car analogy. The conditions to travel in a perfectly straight line without navigational aid are impractical.

Fair enough.  Now, if only we had a navigational tool which would aid us in maintaining a straight path regardless of the shape of the earth, we'd get somewhere.  Obviously a compass won't work here.