In string theory, one of the many vibrational states of the string corresponds to the graviton, a quantum mechanical particle that carries gravitational force. Thus string theory is a theory of quantum gravity.
Their average web application development cost is around $500K and their staff or contractors' salary is in the six figure plus range. Their proposals are usually based on a lot of fluff with the development rate ranging from $400 - $800 per hour. These types of companies focus on custom development.
Well, how much a web developer earns form freelancing sites depends on the work he does at the hourly rate. For example if you work for 20 hours per week at $30/hr you can earn 20*30= $600 per week. The number of hours you work and the rate you charge depends largely on your experience and quality of work.