Einstein versus Peer Review...
scitation.aip.org
scitation.aip.org
Yeah, I mean, who doesn't know that. That's like middle school stuff right there.
Anyway, this paper publishing business has become an industry, which has little to do with exposing/exchanging ideas/thoughts on a given topic. It has become an industry for justifying applications for grants, as most people rather game the system then be left without a paycheck. See the story behind the Bose-Einstein condensate: Einstein had hardly anything to do with it -- except to open the door to the publisher (who btw has also nothing to do with it, still owning the copyright to Bose's work)
It's shorthand for "Most people in the field or capable of understanding an explanation of this already know it".
Sorry, but it is well known to physicists.
In any case I think it's safe to assume that Einstein understood it. He was pretty good at the whole general relativity thing.
Consider the curve x=y^2. This curve is just a parabola, rotated 90 degrees clockwise, and is completely smooth. No angles, no jumps, no nothing.
You can parameterize this curve in the following way:
(x(t),y(t))=(t, sqrt(t))
This coordinate system is singular at t=0: sqrt(t) has no derivative there. But the curve itself is smooth. This is the type of singularity Einstein et al found.
In this simple example the singularity can be removed with the parameterization (t^2,t).
A standard result of GR (I think Tipler proved it) says that gravitational waves always have this type of singularity. But it's really not a physical singularity, since you can change it's location by changing coordinates.