The cost of living in the United States is going up, notes writer Alissa Quart.As reported in the New York Post, Quart points to "the costs of housing, education, health care and child care in particular."At the same time, a new study found that half of Americans born in the 1980s are falling behind their parents economically.The study is a project of researchers at Stanford University, Harvard University, and the University of California, Berkeley.Their report is called "The Fading American Dream."Together, these findings show that many younger adults are experiencing "downward mobility."In other words, they are not doing as well, either socially or economically, as their parents were at the same age.The idea of downward mobility is especially troubling for Americans, writes Robert Samuelson in The Washington Post.He says most U.S. citizens believe that, over time, the amount of money they earn will rise and life will get easier.