Yes, I believe student loans are becoming the next economic bubble.

stock prices being higher than their real value :)

Economic interdependence can cause chain reaction such as the situation we are in right now. America's economy crashed due to the housing bubble and the other economys of the world crashed with America's.

A stock market bubble can be defined as an economic cycle in which there is a rapid expansion, which is followed by contraction. Basically, too many investors become too eager to buy. When they realize the value of the stock is going down, and sell off to save some of their money. The crash usually happens because when there is a bubble, the investment class gets to a point when prices don't justify the underlying value.

Double bubble!