Flat Earth

Hey Mission!I have always assumed that they would think it to be a circle, but then I can't really say I've ever given this specific question a lot of thought so...I must say, I'm surprised to hear about your friend (acquaintance?); I thought the flat-earthers were pretty much extinct. I know the moon-hoax crowd are for real but are you sure this guy is serious about the Earth being flat?Is he a member of the Flat Earth Society? I've been told that the only people in it now are there as a joke. I don't know if this is true, of course, but that's what I've heard.In fact, it was some time back in this thread as I recall. If memory serves, I believe Sylas said that the last confirmed flat-earther was Charles K. Johnson, who was president of the society until his death. Oh listen to the arrogance! You don't know any such thing you closed minded...Heh, just kidding.Seriously though, are you sure this guy is for real? I'm not saying he isn't, I'm actually asking. I've never come across a flat-earther as far as I know so I wouldn't really know how to tell if they were sincere or not. It seems pretty unbelievable but as I said in the other thread, when it comes to what some people will believe, I stopped saying "never" a long time ago.

Des was a flat-earther? Seriously?Well, I know she had some...uh...interesting perspectives on things but I must admit I missed that one. Perhaps by that stage I'd simply become numb to her posts and didn't take it in.What did I say about never dismissing anything when it comes to the things that some people will believe?Well, there you go; that's two of them...Anyone else?

Me: I'll lock in option number 2.Host: Is that your final answer?

If you take into account more than our four dimensions of spacetime, then yes, the Earth is flat along the axis of the extra dimension (or dimensions). Excluding time for the sake of simplicity, the Earth is three dimensional. As such, it has zero size along the fourth dimensional axis and is therefore flat in that direction. Of course we have no perception of this flatness because we are unable to step out of the 3D confines of our space.The way to understand higher dimensions is to come down a level. Instead of trying to imagine a 3D object's flatness in 4D space, visualize a 2D object's flatness in 3D space. The principle is exactly the same.Two dimensional beings living in a 2D universe would have no perception of 3D space. Their planet would be two dimensional (a circle) but since they could only perceive their own space, they would only see the round part (the edge-on view) of their planet.We however can see that their planet is flat in three dimensions by simply looking down on it from outside of their plane of existence. We can see it from a perspective that they never can. It has length and width but it lacks a third axis; it has zero size along the third perpendicular axis and is therefore flat in that direction even though the beings who live there are unable to comprehend it.So it is with our planet.We are confined to the three spatial dimensions of our universe. Therefore we can only see the round part of our three dimensional planet, which in four dimensions of space, is the edge-on view.However four dimensional beings could see that our planet is flat in 4D space by simply looking "down" on it from outside of its three dimensional confines. They could see it from a perspective that we never can. It has length, width, and height but it lacks a fourth axis; it has zero size along the fourth perpendicular axis and is therefore flat in that direction even though the beings who live here (us ) are unable to comprehend it.Hope this helps.

That's a good point, Lam. In colloquial speech, we tend to think of "flat" as being defined by a level, two dimensional surface.Perhaps it would be more accurate to say that the Earth simply lacks any size along the fourth axis. This would apply regardless of the number of dimensions involved. For example, a two dimensional circle lacks any size along the third axis.You're correct that it's a bit of a play on words. Technically, "flat" does describe the state of the Earth along the fourth axis but that's not what people generally think of when they hear the word "flat", so it can be somewhat misleading.I guess the point which should be made clear is that Andya's physicist friend is not saying that the Earth is "flat" in the common vernacular i.e. like a circle or any other two dimensional shape.

Well for what it's worth, you have my condolences. You're quite welcome, Mission. And thank you for the compliment! I never imagined that I would be teaching something to anyone on EvC; I feel so privileged! Yes, I understand that. My explanation was for Andya Primanda. Andya knows a physicist who made the statement about the Earth being "flat" with regard to higher dimensions so I thought I'd jump in as it's my area of expertise...*cough*...NOT!No, actually it's just a topic I love and find fascinating. Well that rules just about everything out, but then, maybe that's the point.I agree with Jar's suggestion, but personally, I wouldn't get my hopes up; if this guy believes that NASA, satellites, etc are all a big conspiracy I'm sure he'll find a way to "explain" the retroreflectors. And if he honestly believes the Earth is flat, he may be unreachable.Sorry, I hope I'm not coming off as a total pessimist, I just don't like the odds of trying to reason with someone who believes the Earth is flat.But by all means, give it a shot! Good luck!