Superstitious have Friday on their mind
Friday the 13th gives some folks the jitters, believing it to be the unluckiest of days. Yet, being forever sceptical, Dr Karl thinks superstition's writing is on the wall.
Part of being human is being irrational, and superstitions are a really good example of that.
Most of us will have heard of the Friday-the-13th superstition and how unlucky that day supposedly is. The problem is that some of us actually believe this superstition.
Back in 2004, the UK independent research consultancy, Populus, interviewed 1011 adults by telephone a week before a Friday the 13th.
They found that 86 per cent of adults treated Friday the 13th like any other day. A few people (five per cent) were a bit contrary. They impudently and deliberately became more adventurous to try to prove the Friday-the-13th superstition wrong.
And a cautious four per cent became even more cautious.
But there was an extra-cautious three per cent. They believed so much in this superstition that they actually stayed at home to avoid any bad luck or danger.
Dr Donald Dossey, founder of the Stress Management Center and Phobia Institute in Asheville, North Carolina, estimates that in the USA, on any Friday the 13th, about "$800 or $900 million is lost in business…because people will not fly or do business they would normally do".
This is unfortunate, because a quirk of our Gregorian calendar means that the 13th of the month is more likely (by a microscopic amount) to fall on a Friday than on any other day.
That's right, thanks to the law of maximum inconvenience, the 13th is more likely to be a Friday than any other day of the week!
The Gregorian calendar runs on a 400-year cycle. So each year is 365 days long, except for leap years, which are 366 days long. A leap year happens every fourth year, unless that year (for example, 1600, 2000) is exactly divisible by 400.
Having 12 months in each year means that in 400 years, there is a total of 4800 months. So there are 4800 13ths of the month.
If the Gregorian calendar were totally random, the number of Friday the 13ths in a 400-year cycle would 4800 divided by seven, which works out to 685.714285714285…etc.
But the Gregorian calendar is not totally random. Back in 1933, BH Brown reported in American Mathematical Monthly that in a 400-year Gregorian cycle, there are 688 Fridays the 13th. Sunday and Wednesday come in second at 687, Monday and Tuesday are third at 685, with Thursday and Saturday fourth at 684.
So the 13th is, ever so slightly, more likely to fall on a Friday, than any other day.
But how did Friday the 13th get its bad reputation? Well, it comes down to two separate superstitions.
First, the day Friday is considered unlucky, and second, the number 13 is also considered unlucky.
First, let's look at Friday being unlucky.
In western Christian society, Friday is unlucky for many reasons, not least because it was the day Jesus Christ was crucified.
Furthermore, the Bible has been variously interpreted to assert that Friday also hosted the great flood, Adam and Eve doing some naked forbidden fruit munching with that talking serpent, the unexpected loss of speech of the builders of the tower of Babel, the unfortunate destruction of the temple of Solomon, and so on.
By the late 14th century, Chaucer's The Canterbury Tales thought Fridays to be downright nasty, claiming: "And on a Friday fell all this mischance".
But it took until the mid-17th century for Friday's reputation to be thoroughly soured and besmirched.
Many popular writers of the time allude to Friday being a bad day to launch a ship, to start a business/trip/letter/venture, to receive medical treatment, harvest/reap crops, to get married/born, or to even hear somebody give you the latest news or gossip. And Fridays used to be reserved for hangings in the UK.
So, that's Friday. Now let's look at the number 13 being unlucky.
The number 13 has its own set of issues. As evidence, look at the number of hotel floors and airline seat rows that skip from 12 directly to 14, avoiding that unmentionably evil and odd integer.
In France, even the house numbers run 12, 12½, 14 and so on.
In fact, lots of people had issues with the number 13, and I'll spell that out for you, next time.
Published 12 October 2010
© 2019 Karl S. Kruszelnicki Pty Ltd