how do we know if the earth is really round?

Question

for instance all of us reading this have not been to space. how do we know that the earth is round? how do we know that we are actually living on earth? maybe people told us that we live on earth and showed us pictures of it from space. but in reality we could be living on god knows what and have no idea about it and most of us will never get the opportunity to go to space and see it for real. kinda scary isnt it. we could all be told one thing but in reality have no idea what is really going on. we all just belive it is round becasue thats what they have told us, but no one really knows unless you have been to space and seen it first hand.

Answer 1

Sounds much like the cause and effect ideals from a philosophical point of view:

Say you play snooker. You pull back your cue, hit the white ball, the white ball rolls, hits a black ball which then rolls off and often the white balls then is deflected in another direction. Scientists will explain that it is because of the kinetic energy or whatever (not sure on the exact terms, my science is a little hazy lol).

But just because we see the ball roll, it does not mean we actually perceive the action in itself, just the result. We cannot see the very molecules/atoms/whatever or the way it interacts, the vibrations on such a small level or otherwise, we cannot see the very scientific actions we are told to, we just assume it is so.

As for the earth being round...no, virtually none of us know the earth is round. Afterall, say 700 years ago, it was common knowledge that the earth was flat. Not even five years ago it was common knowledge we have 9 recognisable planets in our solar system (when according to newer astronomy definitions of a planet, Pluto does not constitute as a planet but a moon instead as its' orbit crosses the orbit of other planets).

Even when those few have been into space, do they "know" the earth is round? They have excellent justified belief to accept it is round. However, it could be another shape just seen differently, there's nothing to say it isn't, just justifiable belief.

Carry on that train of thought, the possibilities are endless and frightening for most. How do we know anything to be knowledge whatsoever?

Ultimately we have to draw the line somewhere and just believe because it makes sense though, especially seeing as our "knowledge" always changes. Things that once seemed as "common knowledge" could well be false in a few years time, we just don't know.

But your comments are incredibly valid... ;)

Toodles

Answer 2

You don't have to go into space. Go to a port some time, and watch a ship sailing out to sea, out of your line of sight.

What happens when the ship disappears? Does it just get smaller and smaller until it is out of sight? No. Something more interesting happens. The bottom of the ship disappears from your view first.

In terms of old-fashioned sailing ships (like, say, the Nina, the Pinta, and the Santa Maria -- this is Columbus Day weekend after all) the wooden portion would disappear first and the sails themselves would remain in view.

This strongly suggests that the ship is travelling away from us along the surface of a sphere, and that when it begins to disappear, this is because part of the globe has interposed itself between the bottomof the ship and our line of sight.

There might be other possible explanations of the way the ship disappears, but the one I've just given is by far the simplest one. So if you've ever done this experiment (which is, as I say, a heck of a lot cheaper than getting a ride on a space shuttle!) you are warranted in believing that you live on a globe.

Answer 3

Imagine a sail boat at sea. When you see it come over the horizon you first notice the top of the mast, the sail, then rest of the vessel. This can only happen if the earth is round. I have witnessed this first hand.

Lunar eclipses, when the earth is between the sun and the moon. You see the earth's shadow on the moon. Kind of round in shape, is it not?

I have also flown aROUND the world. I don't think I could that if the earth was flat.

Answer 4

Well, there was this guy named Magallion. He got a bunch of people to travel in one direction (around the world). After a while, the few survivors came back from the opposite direction.

And somebody else (even farther back) noticed that shadow length varies with latitude. After some math, he calculated the radius of the earth.

A little farther ahead, a couple more people had the bright idea of strapping themselves to big burning cans. After a bunch of smoke, they looked behind themselves, took some pictures, and noticed the Earth was round.

Anybody can prove it with a little trig and a compass. Or even just looking at a live TV channel and measuring shadows.

Answer 5

The Egyptians/Greeks knew the world was round thousands of years before flight. They even estimated its diameter pretty accurately. Check out the works of Ptolemy.

It can be proven from Earth. It involves deep, narrow holes some distance apart, shadows, and the ability to observe both at identical times.

Unfortunately, we can't draw pictures on this forum, or I'd show you the technique.

Answer 6

You can see it's round because of the horizon - if it was flat, we would be able to see a whole lot further than we can.

Ta da! It's so easy isn't it?

Answer 7

Not me, I know it`s round because my world atlas globe looks like a basketball !!

Answer 8

even then, how do they know it's real?

It all boils down to this. Does it make a difference?

Answer 9

They claimed it was. It just didn't seem to make any sense to me either. You drive across the US, and it still seem flat.

Answer 10

because some dope science guy said so and we believed him