It’s been six months since the attacks of September 11, which is as
good an excuse as any to look back. Quite coincidentally, I recently
reread my own writings from that week
3) which are
very nearly as incoherent as I thought they were at the time.
My September 30
entry manages to present something resembling a rational argument.
The major points: war is a terrible thing, even when it’s the best option
available; we must learn how to minimize the damage possible from future
attacks; understanding why they’re happening can help us prevent future
ones from ever happening. Some people confuse explanation and understanding
with excusing, which is unfortunate. Nothing can excuse or justify the
attacks on the World Trade Center and Pentagon, but understanding the
attackers may help us deal with future attackers and perhaps even prevent
others from becoming terrorists.
If my tone at the time was overly skeptical of war, that was most
likely a reaction to those in the media suggesting that the appropriate
reaction was to nuke Afghanistan into a vast sheet of glass.
My October 17
entry describes my own brush with the anthrax scare and some sane
security advice in the wake of the disaster.
I still remember the confusion of September 11. I learned about the
attacks in my car, driving to work. It was some time before I realized
that the plane they were talking about was a commercial airliner, and
not a small, private plane. I remember walking past a silent piece of
construction equipment in the parking lot at work and hearing the
people on the radio shout in panic as the first tower collapsed—and
not learning what had happened until I got to my office. Very little
work got done that day, obviously. There were huge crowds watching
CNN in the cafeteria,
and later on the big screen down in the auditorium. People walked
around looking dazed. Several people from the middle east—or who
looked like they might be from the middle east—went home early
out of fear of persecution.
I don’t know how many times I saw the planes hit, or how many
times the towers collapsed. It didn’t seem real. Since then,
I’ve visited the
ruins, and I’m still not sure whether it’s really sunk in.
Pictures of the new skyline don’t look wrong, but they
don’t look like New York, either.
How long is six months?
It’s pretty natural to figure that March 11 is six months after
September 11. You start with September, check off six months, and
you end up at March. It’s simple—as long as you’re talking about
If you look at it from a perspective of days, things are different.
March is six months after September, and September is six months after
March, but there aren’t the same number of days involved. In fact,
“six months” can mean anything from 181 to 184 days, depending on which
six months you mean.
Here’s a chart showing the length of a six month period starting
in each month:
(Note that the numbers in the left column include February, and so
are one day longer during leap year.)
Why the variation? First, all the months are not the same
length—especially February. Second, half of 365 is 182.5, which
means that you can’t divide the year into two equally-sized sets of
Aside from the problem with inconsistent length, there is are
other difficulties with calculating six months. For example, what
day is six months after March 31? Since there’s no September 31,
you might guess October 1—but April 1 is six months after October 1,
so April 1 is twelve months after March 31?
There are seven days with no obvious date six months later in
our calender (six, if leap year is involved). One can reduce this
number, but it can’t be eliminated entirely. For example, if we
define “six months” to be “182 days”, we can specify a date
that’s six months later for each day of the year. Unfortunately,
applying the rule twice always gets us to one day before the day
where we started.
We might try defining six months to be 182 days for the first
182 days of the year, and 183 days for the remaining 183. This means
that each day has a defined date that’s six months later. Applying
the rule twice always gets us back where we started—with one exception,
December 31. Without redefining the length of the year, that’s the best
we can do.
Not that we’d ever do that. Even with the seven holes, the current
system is good enough for common usage and easily explained.
(At least, more easily explained than the 182/183-day rule.) There
may be twelve months in the year, but that doesn’t mean that six
months needs to be exactly 182 days, 14 hours, 54 minutes, and 36 seconds.
After all, if you’re going to be that precise, you need to define which
year you’re talking about…