average plunged 520 points, 4.6% amid jitters about europe s debt crisis and growing resignation that the long-term prospects for growth here in the united states are bleak. alison kosik watched the massive selloff up close. john, we had yet another brutal session here on wall street today. you know, there s a lot of uncertainty about the economic outlook here in the u.s. and in europe as well. you know, there s worries about france being downgraded like the u.s. debt was downgraded. they really accelerated the losses in the final minutes of the trading day, and then, of course, there s a fear factor that s around here, you know, investors feel like they re flying blind. no one has any idea of what s coming next or where the economy is headed, and it s that certainty that s feeding this downward spiral, but i also want you to keep in mind, what s also fueling this volatility are the computer models that many institutional investers use to trach stocks, as the market falls,