The National Association of Realtors reported this morning that existing home sales rose 1 percent in March, easily beating most expectations. Such numbers also indicate the current strength of the so-called real estate bubble.

Following the report, Jeffrey Otteau of the Otteau Appraisal Group, told CNBC that the real estate market has real legs and will continue to be strong for the next five years. Ultimately, demand is far greater than supply, Mr. Otteau believes, and market fundamentals, including job growth and lower levels of home construction, should keep it that way. While the rate of appreciation will slow, home values will continue to rise.

On the other hand, Professor Shiller of Columbia countered that bubbles are psychologically-driven and have nothing to do with real estate market fundamentals. Real estate buyer expectations are becoming unrealistic and will eventually force the bubble to pop according to Shiller. Nonetheless, citing March's strong existing home sales, Mr. Shiller noted that it could still take a few years before the bubble shows any signs of depreciation.