The blame has been pinned, squarely and often, on inadequate oversight of U.S. financial institutions, which created ever more complex and risky mortgage instruments, lured people to buy homes they could not afford, and brought the economy crashing to the ground.
Motion on the Earth does not take place in a vacuum. When one thing moves, it moves through or across another. When a wheel turns on an axle, the two surfaces rub against one another. This is called dry friction. Grease can be used to separate the solid metal parts, but this just reduces the problem to layers within the grease sliding past one another.
In layman's terms, friction is a force that resists one surface from sliding or rolling over another. Therefore, it can be said that friction only occurs when two surfaces are in relative motion, such as when a crankshaft is rotating in a journal bearing or when a ball bearing is rolling along its raceway.