Disregarding String Theory, which says that electrons and quarks are 1-dimensional, why are electrons and quarks 0-dimensional?
The way I look at it is that they have mass, and if we were the same size as an up quark and looked at another up quark, it would look like a 3-dimensional object. So why do we say particles are 0-dimensional as opposed to 3-dimensional?
I hope I'm correcting in saying they are regarded as 0-dimensional, the reason I think it is because of this quote from Wikipedia:
String theory posits that the electrons and quarks within an atom are not 0-dimensional objects, but rather 1-dimensional...