Salesforce.com announced Database.com at Dreamforce. I realized that many could be wondering why they decided to do this and more so, why now? The answer is Data Gravity. As Data accumulates (builds mass) there is a greater likelihood that additional Services and Applications will be attracted to this data. This is the same effect Gravity has on objects around a planet. As the mass or density increases, so does the strength of gravitational pull. As things get closer to the mass, they accelerate toward the mass at an increasingly faster velocity.”]
Source: https://datagravitas.com/2010/12/07/data-gravity-in-the-clouds/