In the What If? article Falling with Hellium, Randall says:
I managed to lock up my copy of Mathematica several times on balloon-related differential equations, and subsequently got my IP address banned from Wolfram|Alpha for making too many requests.
Since I'm not a user of Mathematica (although I have used Wolfram|Alpha a couple times), I'm not really sure what the emboldened sentence means. Is that the software needs to connect to the server to get the equations, or it's just simply that he uses the equations so much?