Two-Fluid Snap Off

At what point does a drop of fluid pinch off into two droplets? University
of Chicago professor of physics Sidney
snapped the photo of such an event:

How does one fluid body become two? At what point do the two separate,
but still hold together? For Sidney Nagel, it was is not enough just
to ask these questions, it was necessary to see exactly what this moment
looks like. This image, titled “Two-Fluid Snap Off” was
created by Nagel, a professor in the department of physics at the University
of Chicago. It shows one drop of glycerol breaking apart inside the
surrounding oil (Polydimethylsiloxane). Nagel writes that since the
viscous fluids were both transparent, it was difficult to show the details
of the shape at the breaking point. Using customized dark-field lighting,
he was able to make even the narrowest point of contact clearly visible.

Discover’s Visual Science has the post: Link