State of the World

[vakkotaur]

First, let's get this taken care of. A while ago I wrote, not all that well, about some of the events of a certain day a couple years ago. There are plenty of people affected by those events, but I do hope someday that while it may be remembered, that the date of September 11 is more just another day again.

Now, on to the state of the world. I do

Comments

[vakkotaur]

Simple travel in and of itself proves nothing. I do expect travel to be involved somehow for some methods though. Measurement of some kind at different places, that sort of thing. Not that I'd mind a world trip - well, there are parts I'd steer clear of - but that's a bit of an expense in both money and time.

[jdm314]

As for the Lunar Eclipse, the critical point is that the shadow is always round, no matter where the sun and moon happen to be in relation to the earth. If the earth were disk shaped, we would sometimes get a line shaped, or at least cat-pupil shaped shadow on the moon. Of course that might be a bit elaborate to prove, since most people don't see dozens of eclipses.

The other standard item cited as evidence is the horizon. In ancient Greek sources the example given is a boat saling away on the open sea. As it gets farther and farther away it appears to get smaller and smaller, without changing shape. But instead of continuing to shrink until it is too small to see, as we might expect if the earth were flat, after a certain point the bottom of the ship starts to disapear under the horizon, and slowly this continues until the whole thing is gone. This is because the curvature of the earth is getting between the observer and the ship. And trust me, the ship hasn't fallen off the edge of the earth- I've seen many of them come back ;)

[vakkotaur]

Yes, that would do very nicely. Not to be obstructionist, but I don't happen to have an ocean handy here on the plains. Perhaps I should rephrase the question: How would you teach this lesson to kids (pick an age) where they figure out the result for themselves?

[pharwarner]

I would also suggest the method of watching a ship sail over the horizon. I find seeing a square rigger coming towards you over the horizon to be the best (and most spectacular!) way to show up the curvature of the earth. But then that does need more than one person... Maybe walking towards a steep mountain range would allow you to see the same effect with no input from other humans at all.