# Why isn't the world flat ? (Are you sure )

1. May 28, 2007

### Langbein

One thing I think is a little bit funny (among a lot of other things).

All the time I have learned and heard that the world is round, and when I travel with aircraft I can actually se it is at last courved. But when planning long distance travels I understand that it is quite round as it is possible to travel arount it.

But as I observe the earth most of the time it is completely flat.

I dont live on a ball, I dont walk on a ball, I'm not sleeping or working on a ball, it is completely flat, as observed by me. As I have learned to know the earth it is completely flat all the time.

I understand this - that if I were a astronaut the "roundness" of the earth would be something important. Even if I were a pilot on a jet airplane "roundness" might be something important.

But thing I observe everyday is "flattness".

What will be the earth as observed by a farmer or a footballplayer, will it be round or will it be flat ? (The Earth.)

What if you go down to the level of athoms for observing the earth ? - It will be a sky of "emptiness".

So ther should be at least tree way to see the earth, "roundness", "flatness" and "emptiness".

Why do I have to chose "roundness" as the dominant or significant property of the earth all the time, when what I actually see is "flatness".

Why do I have to think about the earth like as observed by an astronaut and not as observed from an farmer or an footballplayer "the flat earth variant".

So isn't then more correct to say it just like it is: "The world is flat"

Why not ?

2. May 28, 2007

### loseyourname

Staff Emeritus
Come on, man, this isn't a philosophical question. If you want to have a real discussion about local flatness in a globally curved space, check out the cosmology forums.

But don't ask this question there! You'll get me crucified!

3. May 28, 2007

### chroot

Staff Emeritus
What you're looking for is the word locally, as in, the surface of the Earth is a two-sphere, and like all manifolds, is a set made up of pieces which individually look like open subsets of $\bb{R}^N$ such that these pieces can be sewn together smoothly.

In other words, the Earth is a two-sphere, but it looks locally flat. We don't need any philosophical discussion on the topic; you simply need an education.

- Warren