Quote Originally Posted by Gilrandir View Post
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.

Quote Originally Posted by Fragony View Post
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.