The subprime mortgage crisis was caused by hedge funds, banks, and insurance companies. The first two created mortgage-backed securities. The insurance companies covered them with credit default swaps. Demand for mortgages led to an asset bubble in housing.
The field of dielectrics is a branch of physics that covers how insulating materials separate different electrical charges in a capacitor. A capacitor is a device with two metal plates of opposite charges, with a dielectric insulating material in between the keeps the charges separate.
Dielectric unions are used to separate two dissimilar metal pipes (such as copper pipes and galvanized steel). Purpose of dielectric unions is to prevent galvanic corrosion, which is caused by electrolysis.