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.
A lossy dielectric, on the other hand, is one that irretrievably absorbs some of that energy (and eventually converts it into heat). Thereâs no such thing as a perfectly lossless dielectric, but many materials (ceramics, glasses, some plastics) have very low loss and can be considered to be effectively lossless.