When Facebook goes public, it will enter a new world full of shareholder meetings, earnings reports, and the constant pressure to turn an increasingly bigger profit. But the Facebook IPO isn't just about making money; it's also about expanding the network, in pursuit of Mark Zuckerberg's vision of a more connected world. With that in mind, here are four challenges Facebook will face after its public offering is complete:

There have been some incredible advances in solar power technology over the years, ranging from simple solar panels to solar-thermal power and more efficient panels. But NASA scientists believe the next step in maximizing sun-based energy will come from satellites that would beam harvested solar power down to Earth.

Attempting to deflect criticism of its upcoming privacy policy changes, Google is on the defensive.

Amazon appears to have quietly acquired Yap Inc., a speech recognition start-up company, fueling speculation that the online giant is getting ready to produce a voice command service such as Apple's Siri or Google's Voice Actions for Android.

It's pretty well known at this point that computers are quickly catching up with humanity as far as brain power is concerned. Storage-wise, we've been long surpassed by machines, and powerfully fast computers can run circles around the human brain in solving complex equations. On the other hand, humanity wins in the brain's sheer computational power and energy efficiency.