Ten years ago, in the wake of the September 11 terror attacks, Americans felt vulnerable. Our fear was magnified by the 24 hour cable news media and our tendency to attach ourselves voyeuristically to the news. Fear is a very powerful emotion, and it led us to personalize the risk, wondering whether we would be killed next.

And now, almost 10 years after the 9/11 attacks terror mastermind Usama bin Laden is dead. It’s been three days since we learned the news. Tomorrow, President Obama will make an appearance at Ground Zero. So why don’t we feel any safer?

Usama Bin Laden was the very definition of a successful terrorist, because he was able to unhinge an entire society by blowing up two buildings. The terrible mass murderers of the twentieth century killed many millions, whereas Bin Laden, at the beginning of the twenty-first century, his message and evil intent megaphoned via the expanded media, killed only thousands yet frightening many millions more.

Our infectious media-driven worry following 9/11 translated immediately into a fear of flying. This despite the fact that the number of deaths on the U.S. highways in a typical year – more than 40,000 – is more than double the number of people who have died in all commercial airplane accidents in the past 40 years. In 2002, the odds of being killed in a terrorist incident were 1 in 9 million. In that same year, the odds of dying in a traffic accident were 1 in 7,000. So by foregoing flying, many people actually increased their risk of dying.

As I wrote in "False Alarm: the Truth About the Epidemic of Fear," studies have shown that the kind of fear memory that resulted from this event is very easy to re-ignite. In the decade following 9/11 we have become irrationally afraid of health scares. In 2001 it was the anthrax mailings, in 2002 it was smallpox, a sudden concern that rogue terrorist were going to weaponize this dreaded disease. A survey published in the New England Journal of Medicine showed that 65 percent of the American public wanted immediate vaccination despite the fact that there was no smallpox around.

These media-driven scares came and went. By 2003 it was SARS, and by 2006 it was bird flu. A 2006 AP/IPSOS Public Affairs Survey revealed that 35 percent believed that they or a family member would get bird flu over the next year.

The death of Bin Laden appears to have reawakened our fears, as our fear memory brings us back to that fateful September day. Our police and public officials are right to beef up security, as Police Commissioner Ray Kelly says he is doing here in New York, while in Los Angeles security has been increased at LAX and the Staples Center, where the Lakers are participating in the NBA playoffs. A retaliatory terrorist strike would appear to be a rational concern.

But what about the larger issue of our communal terror, our sense of foreboding, our feeling of vulnerability? Will Bin Laden’s death ultimately make us feel safer, because enemy #1 is now gone, or will it make us feel less safe, even as it brings back memories of 9/11?

The scientifically-proven power of fear, which emanates from an almond shaped organ deep in the center of the brain (amygdala) would predict that we will never feel safe. But only time will tell the extent to which we will once again experience the stress and the fear of attack and untimely death. It is heart disease (700,000 deaths per year) and cancer (500,000 deaths per year) that we die from, but it is terrorism that we worry about. It captures our imagination, and we worry that we could be next.

Marc Siegel M.D. is a professor of medicine and medical director of Doctor Radio at NYU Langone Medical Center. He is a Fox News medical contributor and the author of several books including "False Alarm: the Truth About the Epidemic of Fear." His latest book is "THE INNER PULSE: Unlocking the Secret Code for Sickness and Health."