I would like to be the first to advocate that if you ever meet a flat earther in real life - do them a favor and give them a lobotomy since they aren't using their brains anyways it won't be missed.

and it totally makes sense...

Question:

What is the maximum distance we should be able to see out across the flat planet, given no intervening obstructions? Consider as you answer this that we are capable of viewing visible light cast from objects in space that are approximately 13 billion light years (a quite unfathomable number of miles) distant, so clearly light travels pretty far.

Even if the earth wasn't flat, it is totally possible GPS isn't real. I mean we don't know, we've never seen it.

You can observe satellites with your naked eye.

You can observe satellites specs of light of unknown origin with your naked eye.

FTFY.

They don't look like specs of light when they transverse the moon.

They do. Maybe you should get a telescope.

Can I have yours?

Why would you want his? It's so inadequate that it can't even focus enough on the ISS as it traverses the moon to see that it's not just a random round blob.

Free telescope? I mean, come on.

Ignore him. Butthurt Flat Earther.

No. Get your own.

Maybe YOU should get a telescope to see that you are lying.

If you can't propose an actual working model that could reconcile the behavior of gps with a ground based transmitter system, then this is all totally pointless. It is blatantly obvious that you have no technical knowledge regarding the operation of satellite based communications and therefore have no insight to offer on the subject.
We can all come up with a metric shit ton of 'what if?' scenarios, but without any actual supporting evidence they are all USELESS. Your idea is preposterous and no one is going to be interested in it unless you do some actual research and develop a theory to actually EXPLAIN how it could be possible.

I can't see radio waves either, but sure as shit when there's a baseball game on and I pull out my little yellow transistor radio, I hear the broadcast team calling the game.

That pretty much works just like the GPS I've used as just a GPS device and now on my phone. I pull out the device and poof magical waves of energy communicate to the device, which changes those magical waves of energy into something I can comprehend.

Are radio waves not real? Did they find a way to stuff Dan & Jim into that little 1.5" by 6" by 3.5" yellow box to talk to me every now and again?

Oh, and you didn't answer my question. Here it is again:

What is the maximum distance we should be able to see out across the flat planet, given no intervening obstructions?

You might want to look up vanishing point. It goes out into infinity, but to the eye it exponentially decreases and resolves into a line we see as the horizon.

You didn't give me a number. Please give me a number.

Please also assume I have at my disposal the absolute best optics available - the best telescope here on the planet.

Give me a number in miles or kilometers - how far should I be able to see?

Thanks.

The Philadelphia skyline from 60 miles away: https://www.youtube.com/watch?v=Mgur5EKboLY

So we know you should be able to see at least 60 miles away.

https://www.youtube.com/watch?v=aLlNKy5j_O8

It's 36 miles between Apple Pie Hill and Philly, and Apple Pie Hill is 205 feet tall with a 60-metre tall tower on top, which that photograph could easily have been taken from.

Doing the maths on height and the curvature of the earth you can easily see this far from this high.

Have you ever seen an emotion? Have you ever seen love or hate? No. What you've seen are the effects and manifestations of it.

Have we ever seen an atom, let alone a quark? No. Do we know they exist? Yes.

We often know about the existence of things not because of our having actually seen the things themselves, but because of our understanding of the effects those things are having on the things around them.

So every planet we see and the sun, moon, etc are round. Except the earth? How does that make sense?

I believe that they are meant to be lights. Or something

If we haven't even been to the moon, you have to doubt even if just a little.

Not really

This can't be serious.

GPS uses ground based technology designed by the military.

https://www.youtube.com/watch?v=RNHnU48E-MI

Probably s̶t̶o̶l̶e̶n̶ borrowed from Nicola Tesla.

Then how does it work in the middle of the ocean ?

I definitely don't have all the answers. But if navigational systems were around before GPS, then you could say that GPS is just an enhanced ground system. A computerized ground system with great graphics.

https://www.youtube.com/watch?v=byTJk9E4_Bc

Sure, just like I could say that cars are just enhanced horses. What are they hiding from us about the secret equine nature of automobiles? How did they twist horses into this unnatural shape? I definitely don't have all the answers. I bet it was flouride though.