This happens a lot: I am reading a paper, as usual going directly to the results and skipping the introduction, related literature, discussion, preliminaries, formal model etc. And then there is some \alpha which I have no idea what it stands for. I would like to search for `\alpha’ in the pdf document, but if there is a way to do it then I have never heard about it.

So, imagine my delight when I heard of Springer’s LaTeX Search tool, which does something that I never even dared to wish — search in their database for an equation that contains a given latex code. Pretty awesome, isn’t it ?

I tried some arbitrary code

i\hbar\frac{\partial}{\partial t}\Psi=\hat H\Psi

(which translates to i\hbar\frac{\partial}{\partial t}\Psi=\hat H\Psi)
but apparently nobody has used this equation before.

So I tried something else: E=mc^2. Again no exact matches but this time there are a couple of similar results

Well, as Jeffrey Shallit said, it is, at least, a start.