Friday the 13th - paraskevidekatriaphobiacs beware!

Doctor Q

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Fear of Friday the 13th. It's a common superstition. Do you alter your behavior to avoid this "unlucky" day? I suppose I do, since I talk about it and joke about it all day. But I don't avoid normal activities because I think I'm in danger. Do you, "just in case"?

The medical term for this fear is paraskevidekatriaphobia. Fear of the number thirteen is called triscadekaphobia or triscadecaphobia.

When bad things happen on the 13th, or on Friday the 13th, people often make note of it and present it as evidence that the day is indeed unlucky. Once enough people believe it, it is self perpetuating. Was the Apollo 13 space flight doomed from the start, or did we just pay attention to the number because of the coincidence?

The origins of the superstition are mixed, partly from Christian history, partly from Norse culture, and partly from other sources, such as the arrest of Jacques de Molay, Grand Master of the Knights Templar on Friday the 13th by King Philip IV of France in 1307.

Perhaps instead of doing anything dangerous today, you should stay home and [playlistId=4249065&selectedItemId=4249047]listen to music[/playlistId] or rent an old movie or read a great book!

You can find other interesting information about paraskevidekatriaphobia here and some good links about Friday the 13th here.
 

stubeeef

macrumors 68030
Aug 10, 2004
2,702
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I revel on Fri 13th because I was born on one! 1/13/61.

Has always been a good day for me, and my mom says it was a very lucky day for her!

Go forth and laugh in the face of superstition. In a few minutes I am going to the apple store on Mich Ave in Chicago-how bad luck can that be?
 

realityisterror

macrumors 65816
Aug 30, 2003
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Snellville, GA
Wow! I didn't even notice until I saw this thread :p

I spent an hour and 20 minutes lying on the floor with the girl I love during school, so it can't be that unlucky :D

reality
 

Doctor Q

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My favorite Friday the 13th fact: By chance, the 13th of the month is more likely to be on a Friday than on any other day!

Here's why...

The Gregorian calendar has a cycle that repeats every 400 years due to the leap year rules. Of those 400 years, most have 365 days, but 1/4 of them are leap years (366 days), except for years that are multiples of 100, which are not leap years, except for years that are multiples of 400, which are leap years. So the average number of days per year during the full cycle is 365 + 1/4 - 1/100 + 1/400 = 365.2425.

Since 400 years x 365.2425 days/year = 146097 days = exactly 20871 weeks, and 400 years x 12 months/year = 4800 months, we know that during each 400-year cycle there are 20871 Fridays and 4800 13ths of the month.

But 4800 is not evenly divisible by 7, so the frequency of the 13th cannot be even over the different days of the week. Here's how it works out:
688 out of 4800 times: Friday
687 out of 4800 times: Sunday, Wednesday
685 out of 4800 times: Monday, Tuesday
684 out of 4800 times: Thursday, Saturday​
So, whenever it is Friday, there is a huge 3.30% chance that it is the 13th! :eek:
For Saturday, the chances are a mere 3.28%. :)
 

iGav

macrumors G3
Mar 9, 2002
9,025
1
Doctor Q said:
Perhaps instead of doing anything dangerous today, you should stay home and [playlistId=4249065&selectedItemId=4249047]listen to music[/playlistId] or rent an old movie or read a great book!
I wish you'd have posted this, this morning... would've saved me from the state my wrist is in. :(

Although I doubt it's anything to do with Friday the 13th, and more to do with the fact that at the age of 27... I'm far too old to be riding a BMX. :( :p
 

emw

macrumors G4
Aug 2, 2004
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I had to hurry up and post so I wouldn't be the 13th response to this. ;)

I'm not normally a very superstitious person, and overall today has been pretty good (knock on wood), but I did intentionally schedule a trip so that I wouldn't have to fly back today...
 

ravenvii

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Mar 17, 2004
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Melenkurion Skyweir
You know what Friday the 13th means?

FRIDAY THE 13TH MARATHON!

WOO-HOO!

(I have the whole Friday the 13th saga on DVD. From the original to Jason X to Freddy vs. Jason, I have 'em all.)
 

Doctor Q

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There's a Friday the 13th Club that makes a point of getting together today and breaking mirrors, walking under ladders, and having black cats cross their paths. I'm quite amazed, because I didn't know you could get a cat to do anything.
 

emw

macrumors G4
Aug 2, 2004
11,177
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Doctor Q said:
I'm quite amazed, because I didn't know you could get a cat to do anything.
Well, it's a little misleading. The cat actually sits there and looks disdainfully at them while they walk back and forth in front of it. Motion is relative, after all.
 

puckhead193

macrumors G3
May 25, 2004
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Applespider said:
No, why should I change my usual habits of tossing salt over my shoulder, touching wood, avoiding ladders, getting out of the way of black cats? ;)
what about opening an umbrella inside.... ;)
 

CanadaRAM

macrumors G5
I didn't think so but...

Waiting for the freight company to call, rgarding a 310 lb. colour laser printer, it has to travel 40 miles as the crow flies, I've waited for four weeks for it to arrive, it left Vancouver BC on May 10th and they have.... lost it.

A $10,000 printer, the size of a small refrigerator, comes with its own pallet.

And they, what, misplaced it behind a fern in someone's office?
Didn't notice it was in the glove compartment when the wife took the truck to go shopping?

So I call, put on hold for 20 min. Call the trucking dispatch office, they need to know the Job number. Call back to customer service. Wait 10 minutes, they say thay'll have to transfer me to sales, wait on hold 20 minutes, Sales says I have to talk to customer service, wait 10 minutes, customer service says they have to call the trucking company, wait on hold 15 minutes, come back and say the trucking company has put a trace on it and I'll have to wait another 2 hours.

AAAAAAAGH!
 

joepunk

macrumors 68030
Aug 5, 2004
2,557
13
a profane existence
Doctor Q said:
Perhaps instead of doing anything dangerous today, you should stay home and [playlistId=4249065&selectedItemId=4249047]listen to music[/playlistId] or rent an old movie or read a great book!

You can find other interesting information about paraskevidekatriaphobia here and some good links about Friday the 13th here.
Wish I could stay home but there is this thing called a test in my Archaeology Class today in about 15min. Have been studying pretty much all morning. But, there still is tonight for something to happen as my University is having their quarterly "Late night at the VU," an all night long event with bands, Art Gallery exhibition/reception, games, clubs trying to get attention, XBox networked gaming (probably Halo or Halo2, and free snacks.

Edit: on CBC radio 1 this morning they were giving some other info on Friday 13th. There was a British Sailing ship that was named Friday and was launched on the 13th and was lost. I can't remember if it was never found or it just sunk.
 

Doctor Q

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joepunk said:
There was a British Sailing ship that was named Friday and was launched on the 13th and was lost. I can't remember if it was never found or it just sunk.
That's considered an urban legend, but possibly never proven true or false.

One mention of this story says "In one (probably untue) story a Royal Navy ship HMS Friday was laid down on a Friday, launched on a Friday and captained by a Captain Friday and was never heard of again."

You can read more about it here.

I don't see mention of the incident at snopes.

From another site: "For centuries sailors refused to set sail on a Friday. It is told that when the reluctance of seamen to set sail on a Friday had reached such proportions that it interfered with naval operations, the British Admiralty decided to prove once and for all that it is a fallacy. They laid the keel of a new vessel on a Friday, named her H.M.S. Friday, and launched her on a Friday. On her first voyage, setting sail on a Friday, she was commanded by Captain James Friday. She left the harbour and nothing has since been heard of her or her crew. The identical story has also found its place in American lore."
 

joepunk

macrumors 68030
Aug 5, 2004
2,557
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Doctor Q said:
That's considered an urban legend, but possibly never proven true or false.

One mention of this story says "In one (probably untue) story a Royal Navy ship HMS Friday was laid down on a Friday, launched on a Friday and captained by a Captain Friday and was never heard of again."

You can read more about it here.

I don't see mention of the incident at snopes.

From another site: "For centuries sailors refused to set sail on a Friday. It is told that when the reluctance of seamen to set sail on a Friday had reached such proportions that it interfered with naval operations, the British Admiralty decided to prove once and for all that it is a fallacy. They laid the keel of a new vessel on a Friday, named her H.M.S. Friday, and launched her on a Friday. On her first voyage, setting sail on a Friday, she was commanded by Captain James Friday. She left the harbour and nothing has since been heard of her or her crew. The identical story has also found its place in American lore."
During the test I was thinking about it and it sounded to good to be true. Thanks for the links. I especially like the one about a "The baker's dozen." I could never remember what a bakers dozen was.
 

wdlove

macrumors P6
Oct 20, 2002
16,570
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I'm not superstitious, so no it doesn't bother me at all. Can still remember this girl when I was in the 5th grade. It used to drive her nuts. Of course that year there were several. I know that everyone will think that this isn't me, but I used to enjoy teasing her. The reaction was priceless.

Just when I need a dollar bill I don't have one. A gentleman called into a radio station the I listened to on the way home after my noon meal. The superstition started with the 13 that were at the last supper. Here in the United States there were 13 original colonies. On the dollar bill there are 13 feathers in the Eagle and its holding 13 arrows. That the pyramid also has 13. Maybe Doctor Q has a dollar bill and can validate this, see as how he is our resident statistical expert.
 

clayj

macrumors 604
Jan 14, 2005
7,473
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visiting from downstream
Doctor Q said:
My favorite Friday the 13th fact: By chance, the 13th of the month is more likely to be on a Friday than on any other day!

Here's why...

The Gregorian calendar has a cycle that repeats every 400 years due to the leap year rules. Of those 400 years, most have 365 days, but 1/4 of them are leap years (366 days), except for years that are multiples of 100, which are not leap years, except for years that are multiples of 400, which are leap years. So the average number of days per year during the full cycle is 365 + 1/4 - 1/100 + 1/400 = 365.2425.

Since 400 years x 365.2425 days/year = 146097 days = exactly 20871 weeks, and 400 years x 12 months/year = 4800 months, we know that during each 400-year cycle there are 20871 Fridays and 4800 13ths of the month.

But 4800 is not evenly divisible by 7, so the frequency of the 13th cannot be even over the different days of the week. Here's how it works out:
688 out of 4800 times: Friday
687 out of 4800 times: Sunday, Wednesday
685 out of 4800 times: Monday, Tuesday
684 out of 4800 times: Thursday, Saturday​
So, whenever it is Friday, there is a huge 3.30% chance that it is the 13th! :eek:
For Saturday, the chances are a mere 3.28%. :)
I hate to dispute you, but those figures are for a PARTICULAR 400-year period, are they not? In other words, in the NEXT 400 years, or the 400 years after that, etc. I would wager that some other day of the week would be the most "popular" to host the 13th of each month.
 

Mav451

macrumors 68000
Jul 1, 2003
1,657
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Maryland
I was doing engineering work on ArcGIS in the lab. Never seen it crash so much in my life. And this application is usually stable. Things should be fine tomorrow tho =D
 

Doctor Q

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clayj said:
I hate to dispute you, but those figures are for a PARTICULAR 400-year period, are they not? In other words, in the NEXT 400 years, or the 400 years after that, etc. I would wager that some other day of the week would be the most "popular" to host the 13th of each month.
They are true for every 400-year period. So we're stuck with it this way until the slight error in the 365.2425 approximation (for the number of days in a year) causes enough accumulated error that we have to skip one leap day. As far as I remember, that happens every 80000 years.