"You hardly have postdoctoral positions in math, physics and social sciences."
I don't know anything about the social sciences. In physics, I know that postdocs are absolutely necessary and expected, to the same degree that they are in the life sciences.
Mathematics is a little different. There are a very small minority of prodigy-types that go right from graduate school to the tenure track. However, post-doc's are still the norm, although they don't go by the name 'postdoc.' Usually they are pronounced 'visiting assistant professor' or 'instructor.'
Here's an example of a 'postdoc' in mathematics. All of the big universities have them:
I don't know anything about the social sciences. In physics, I know that postdocs are absolutely necessary and expected, to the same degree that they are in the life sciences.
Mathematics is a little different. There are a very small minority of prodigy-types that go right from graduate school to the tenure track. However, post-doc's are still the norm, although they don't go by the name 'postdoc.' Usually they are pronounced 'visiting assistant professor' or 'instructor.'
Here's an example of a 'postdoc' in mathematics. All of the big universities have them:
http://www.mathjobs.org/jobs/jobs/1815