Can a tech company surpass big oil?

Recent discussion as to the battle of Apple and Exxon Mobil for the top spot in global company size by market cap has been heating up recently. It's not much of a surprise to many that Exxon Mobil has been at the top for awhile, with the global dominance in energy and oil, and a market cap near half a trillion dollars. But with the rise, especially in the past decade, of Apple's clout on the tech market, many believe Apple can take the top position. Despite the passing of the iconic Steve Jobs, the culture and mindset of the Apple ecosystem can and will continue to dominate innovation, content creation, sales and distribution, and tech device market (including both and hardware & software) for many years to come. The question is if the company is truly worth beyond half a trillion dollars, and if so, what is the true valuation of Apple?