Flat Earthers

[Husar]

I though the big crunch theory was that all matter would eventually start falling back towards the big bang's ignition point and form a great ball of matter that would form a unimaginably massive black hole which would then apparantly explode into a new universe.

That's also a theory, these theories are not like Highlanders, there can be more than one as long as we can't definitely prove that one of them is correct. There is also the one where the universe expands until everything freezes. The crunch and the freeze are terrible for our offspring though unless they can one day escape to a parallel universe (provided there even is one) before they get burnt or freeze. I know, before that we will have to get off this planet either way, it's just why bother with children if it all just ends in a few billion trillion years or so anyway?

Before posting this I would like to make a reservation:
1. I'm in no way a mathematician, so don't try to start an argument after you have read the following information.
2. I just remembered the statement about converging parallel lines and found this corroboration. If it is no corroboration (to your mind) see #1.

https://en.wikipedia.org/wiki/Line_at_infinity

In projective geometry, any pair of lines always intersects at some point, but parallel lines do not intersect in the real plane. The line at infinity is added to the real plane. This completes the plane, because now parallel lines intersect at a point which lies on the line at infinity. Also, if any pair of lines intersect at a point on the line at infinity, then the pair of lines are parallel.

I think that is more a thought construct than actually true for real parallel lines.
See this related article for reference: https://en.wikipedia.org/wiki/Projective_plane

As it says, it relates to painting, where you actually do let parallel lines cross in one point to create the illusion of three dimensions and so on. It is merely a matter of perspective though, take the following picture. You can see several lines that appear to meet in the middle if you'd draw them on and on, that appears to be the point at infinty. In reality they would not meet though if they are actually parallel, it is a matter of perspective. The guy in my last video seems to turn this into a related mistake when he paints a triangle over some light rays to "prove" that the sun is just hovering a few thousand meters above earth.
In mathematics it seems to serve some purposes that I won't research now because it would take too much time, it does not seem very relevant for the wrong "explanation" given by flat earthers though.



I will also apologize for not being good at explaining or understanding this in English, the terms are all different from the ones I learned in German so some concepts seem new at first but really aren't, or are they?

[Gilrandir]

I think that is more a thought construct than actually true for real parallel lines.

In mathematics it seems to serve some purposes

Mathematics IS a thought construct, so in its world anything may be true when it serves some purpose and nothing is real.

[Fragony]

Mathematics IS a thought construct, so in its world anything may be true when it serves some purpose and nothing is real.

That's why I suspect Einstein had a very naughty sense of humour when he said the sun is actually circling around earth. Everything can be made impossible to dismiss if you are really good at doing that. Someone who has no idea of formulas whatsoever can conclude that the earth is round just by watching a ship dissapearing at the horizon, you cant see it anymore it's gone. I wish I was smart enough to join the fun but I'm not. We can be creative with blunt tools that's all

[Husar]

Mathematics IS a thought construct, so in its world anything may be true when it serves some purpose and nothing is real.

Some of it can be applied to real world phenomena though, about some other parts I'm not so sure, that was the difference I tried to make.
I'm not the expert to ask when it comes to translating physical models to mathematics though.

That's why I suspect Einstein had a very naughty sense of humour when he said the sun is actually circling around earth. Everything can be made impossible to dismiss if you are really good at doing that. Someone who has no idea of formulas whatsoever can conclude that the earth is round just by watching a ship dissapearing at the horizon, you cant see it anymore it's gone. I wish I was smart enough to join the fun but I'm not. We can be creative with blunt tools that's all

As Wooly Mammoth already said, the idea was that movement is a relative thing that can depend on the observer.
Consider this:


Now IMO the video is not entirely correct, because the "old" solar model is not wrong just because it does not take the movement of the solar system in the galaxy into account, it is simply a model from a different point of view, which is what Einstein meant. I'd also say the idea that the sun is dragging the planets along with it is fals because the entire galaxy and everything in it were probably spinning around from the start, so the planets would keep moving at 70k km/h if the sun suddenly disappeared, they'd just move in completely different directions based on the next stronger gravitational pull etc. I also didn't check whether the movement through the galaxy is at a 90° angle compared tothe "planetary disc" around the sun.

That said, it illustrates that movement is always relative to the observer. From a fixed point in the universe, the solar system moves really fast, when you look at earth from the sun, you see it spinning around, when you look from earth, you can easily think the entire universe spins around you, which is true if you define yourself as the central point of reference. Or in other words, when you run around in a computer game, what really moves on your screen is not your character, but the entire level around it. Because you are used to it, your brain thinks you move around in a world, but your character always stay at the same point of your monitor while the world around your character rotates and moves based on your inputs.
It is like in a train, where from your point of view, the train does not move, but everything outside does. For someone outside the train it looks the other way around. So in the same way, from our spinning earth it looks as though the sun revolves around us, but that's only because we don't feel that our planet moves since we move with it. I think that is what Einstein meant, if that is clear enough. I'm sure Montmorency, Seamus or someone else can say it more eloquently in three sentences.

[Fragony]

Train is a nice example, if you ride a train that moves at the speed of time and you walk forward, are you really getting ahead of time then, or just the perception of time which is alsways relative. In the end our perception of time is only what we can see, that doesn't make it real it's only what we percieve. My socially cripled but incredibly intelligent brother could make sense to that, I really can't, he thinks I am just as smart as him but I'm not. What is time, I don'tknow

[Sigurd]

So.. you would basically need to gather a few of the more vocal flat earthers and fly them into space and circumnavigate the globe - and let them "experience" for them selves the roundness they so hate.

[Fragony]

Not a bad idea, but I kinda like it that someone who is smart enough can actually prove that the earth is in fact flat and get away with it, it's like a very clever heist