Triskaidekaphobia

An irrational fear of an ordinary number.

Today is Friday the 13th. Many people fear this day, thinking that the number 13 brings bad luck. The fear of the number 13 is so pervasive that I’ve seen in some buildings, elevators that do not have a button for the 13th floor. That fear is so strong that it has a name: Triskaidekaphobia.

Triskaidekaphobia is a well-known phobia, an unreasonable fear of the number 13. We’ve seen it in popular culture in the movies, on TV and even in the press. But the number 13 is no different than any other number except for its meaning and how people perceive it’s meaning.

Paraskevidekatriaphobia is the fear of Friday the 13th. I’ve read stories of people who refused to get out of bed on this day, or they follow some special ritual to counter the bad luck. I wonder if sick days spike when the 13th of the month falls on a Friday. I got out of bed today. I will be working today. Writing this? It doesn’t feel like work to me, and I’m agnostic about the outcome.

I tend to think of the 13th day of the month as a lucky day, or just another day. I have relatives born on the 13th of a month and they’re fine. California became a state of the Union on November 13th, 1849 and that state is a rather prosperous state. About 250 babies are born every minute, today, and they’ll live regardless of the bad luck associated with Friday the 13th.

People will change their behavior in significant ways when those two conditions are present. They even make plans well in advance for days like today. If you’d like a forecast, here is a list of months and years with Friday the 13th, going into the future to about 2025. You can even extend the list out to 2050 so you can schedule your days off until retirement if you want to.

One thing I like about that list is that there is a recurring pattern in the occurrences of Friday the 13th. On that page, I see that between 2010 and 2020, Friday lands on the 13th day of the month 20 times. I also find it interesting that a week has 7 days, and 2 weeks has 14 days, so the probability that Friday will land on the 13th is not exactly remote. Couldn’t we pick a better number to be afraid of?

What about the people with birthdays that are on the 13th of the month? “Your birthday is on Friday? Sorry, I won’t be able to attend your birthday this year. I just won’t be getting out of bed that day.” What do we say to the hapless souls with a birthday on the 13th and a fear of the number 13? “Hey, it’s just another day.”

Here is a list of 157 historical events that happened on November 13th, calendar errors permitting. That list shows how history goes on blithely without a care for the number 13. Here is a sample:

1553 — English Lady Jane Grey and Archbishop Thomas Cranmer accused of high treason (bad day)

1789 — Ben Franklin writes “Nothing . . . certain but death & taxes” (ok, maybe still a bad day)

1843 — Mt Rainier in Washington State erupts (if you’re a geologist this is pretty cool)

1849 — Peter Burnett elected first governor of California (good day for at least one man)

1921 — “Sheik”, a silent film starring Rudolph Valentino, is released (movie fans rejoice)

Wait. What about those calendar errors? Wikipedia has some interesting history on the evolution of the calendar. Most notably we see the Julian calendar being replaced by the Gregorian calendar. According to that same page:

“The Julian calendar gains against the mean tropical year at the rate of one day in 128 years. For the Gregorian, the figure is one day in 3,226 years.”

That led to some significant efforts to compensate for the length of the year to ensure that the months match the tropical year. The tropical year is based on the relative position of the tilt of the rotational axis of the earth with respect to the sun as the earth orbits the sun.

See how much things change? We try to make time match our perception of reality with calendars and clocks, but the earth, the sun, and the moon keep changing on us. Did I mention that time dilates with respect to the influence of gravity? If you think that time only dilates in staff meetings, you might want to sit down for the next paragraph.

Albert Einstein’s theory of general relativity predicted that time goes slower when we get closer to a source of gravitational attraction. You know, like the earth. I remember this from watching the television series, Nova, in the 1970s. They demonstrated this with two atomic clocks, one on the ground and one was taken into the air high enough and long enough to show a difference. The phenomenon is known as gravitational time dilation. Just how we will keep our clocks straight on our journey to and when we colonize another planet?

So much for the human effort to make their conception of time fit to reality. Even with the way the Universe squirms around us, I doubt that I will ever convince anyone to let go of their fear of Friday the 13th. Have a super fine day. :)

Write on.

Originally published on my blog, The Digital Firehose, Friday, November 13th, 2015. Updated for grammar, clarity, new research and the occasional turn of phrase.

Written by

Husband, father, worker, philosopher, and observer. Plumbing the depths of consciousness to find the spring of happiness. Write on.

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