At the instant of detonation, high explosives are converted almost immediately into gaseous form, creating a flash of heat and light and a supersonic pressure wave that travels outward at thousands of feet per second. The explosion creates a short-lived vacuum, which is quickly filled by inrushing air and debris; a few objects may end up almost where they were before the explosion, with the difference that once they were whole and now they are irredeemably shattered.

Once: human beings going about their lives. Now: shattered.

This whole infernal summer, I've turned on the news with the near-certainty that I'd have to hear about who and what had gotten blown up in the past 24 hours. I'm surprised that some ratings-crazed TV executives haven't created a special segment for their bouffant anchorpersons to tease: "Coming up at eight minutes past the hour, the explosion of the day. Stay with us."

When the victims are commuters in London, English-speakers carrying briefcases, we pay attention. When they're tourists in Egypt, maybe it rings a bell -- "Sharm el-Sheikh, isn't that where they have the marvelous scuba diving?" When they're Iraqis, we register the body count the way we note the record-high temperatures in the Midwest, and then we move on. Ninety-five in Chicago, imagine that. A hundred just south of Baghdad.

This may be callous, but not intentionally so. Avoidance is an appropriate defense mechanism, a way of dealing with events too horrible to look in the face as we board our subways and buses, as we stroll through our shopping malls. We spent anxious decades in the shadow of the Bomb, and now the threat is less apocalyptic but so much more intimate: the Boom.

How do we incorporate the remote possibility of the Boom into our daily lives? Perhaps we can learn from history. When our fear of the Bomb was fresh, we smothered it with readiness -- I remember being put through duck-and-cover drills at school, as if a desktop could stop an intercontinental ballistic missile. That's where our leaders seem to be now with the Boom, hoping that enough vigilance, police power and Patriot Act restrictions of our civil liberties will keep us safe.

The British response to the Boom in London was seen by many as exemplary: Stiff upper lip, business as usual, must carry on, shoot to kill. But then the cops shot the wrong guy -- Jean Charles de Menezes, a 27-year-old electrician who had plans to soon return to his native Brazil. He had nothing to do with suicide bombers, the police now say; his only sins seem to have been coming out of the wrong building, wearing a coat on a warm day, looking "foreign," and reacting with confusion when accosted by a squad of commandos. Cornering and executing an innocent man is not the ideal way to inspire calm.

We told ourselves we were cutting the Bomb down to size through arms limitation talks, but that was illusory -- to this day, Moscow could vaporize American cities if it wanted. What we really did was just relegate the Bomb to the back of our collective mind. That's so much harder to do with the Boom, though. The Bomb was impossible to anticipate -- "a screaming comes across the sky," as Thomas Pynchon described the flight of the V-2 rocket in "Gravity's Rainbow," and then oblivion. The Boom's approach is right there, decipherable in the eyes of the young man with the backpack, but there's no Rosetta Stone to read those eyes.

And anyway, when was the last time loosely connected groups were blowing things up in an attempt to destabilize the Great Powers? Wasn't it the anarchists before and after World War I? That time, the rough beasts slouching toward Bethlehem to be born included Lenin, Stalin, Hitler, Mussolini and Mao. Who is it this time?

Look, I'm sorry, I know this is all too heavy for a summer whose dog days have come early and seem to want to settle in like the House Guest From Hell. When I need to escape it all, I fire up my iPod and whisper-click the wheel to an old Commodores song that I always find peaceful. The music is easy-listening smooth and the lyrics are as trite and hopeful as they could possibly be, especially this verse:

I wish the world were truly happy

Living as one

I wish the word they call freedom

Someday would come, someday would come.

Graduates of the College of Musical Knowledge will know the song's name: "Zoom."

I hear Zoom and try not to think Boom.