The Seebeck effect is really interesting and the reasoning behind the phenomenon does seem to make sense, that is, that electrons move from the hotter areas to the colder areas. What I don't understand is the need for two conductors. I don't see why electrons couldn't move around in a circle of copper wire. In fact, wouldn't a strand of straight copper wire produce voltage for a brief moment as the available electrons move (but they can't come go back, so no more voltage)?
I've spent a fair bit of time researching and it seems like the reason is something to do with how electrons diffuse between the different materials which causes a potential difference, that would otherwise be cancelled out when using the same metal, but I don't quite understand the reasoning behind this. I would greatly appreciate if the need for dissimilar conductors was explained.