A problem with this is that the river presumably goes all the way around the earth. Otherwise you could just travel west until you found its end. You really need a donut shaped earth, a sphere doesn’t help much
Surely it a river doesn’t go all the way around the earth. Rivers typically have one (or many) start points, where they are surrounded on three sides by land, meaning it’s possible to cross from one side to the other. Otherwise it’s just a strait or channel.
However, that assumes you are not on the land in between a fork in the river. In which case you would have to cross a bridge outside of Königsberg, and we might have to expand the problem to crossing every bridge on the continent once.
I mean that might be theoretically possible with some geothermal energy input at some point, but practically speaking all rivers I’ve observed do not do this.
It seems likely that there is land between the source and the mouth.
It should be fairly easy for someone to visit the sources of the Elbe to test this presumption with real science.
A problem with this is that the river presumably goes all the way around the earth. Otherwise you could just travel west until you found its end. You really need a donut shaped earth, a sphere doesn’t help much
But the river running round the whole planet does not matter in this case.
You run into it on the planet backside and then need another bridge, right?
What about an opposite bridge where you cross under the river? Some sort of tubular subterranean structure. We could call them opposite bridges.
That would make the earth a donut lol and would work!
Won’t be in Königsberg anymore though, so that bridge won’t count
Surely it a river doesn’t go all the way around the earth. Rivers typically have one (or many) start points, where they are surrounded on three sides by land, meaning it’s possible to cross from one side to the other. Otherwise it’s just a strait or channel.
However, that assumes you are not on the land in between a fork in the river. In which case you would have to cross a bridge outside of Königsberg, and we might have to expand the problem to crossing every bridge on the continent once.
I mean that might be theoretically possible with some geothermal energy input at some point, but practically speaking all rivers I’ve observed do not do this.
It seems likely that there is land between the source and the mouth.
It should be fairly easy for someone to visit the sources of the Elbe to test this presumption with real science.