Wedding rings showing the date 11.11.11 in Frankfurt, Germany. Credit: Corbis

For many people around the world, today's date holds special meaning. Many believe that today is especially auspicious or significant, and there's been an increase in weddings slated for today.

But it's not just weddings. According to a USA Today story,

Egypt's antiquities authority closed the largest of the Giza pyramids Friday following rumors that groups would try to hold spiritual ceremonies on the site at 11:11 a.m. on Nov. 11, 2011. The authority's head Mustafa Amin said in a statement Friday that the pyramid of Khufu, also known as Cheops, would be closed to visitors until Saturday morning for "necessary maintenance." The closure follows a string of unconfirmed reports in local media that unidentified groups would try to hold "Jewish" or "Masonic" rites on the site to take advantage of mysterious powers coming from the pyramid on the rare date.

Why such interest and excitement over a date?

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There are several reasons why people see significance in numbers. For one thing, it's an “event.” Many Hollywood studios like to premiere their films on “memorable” dates to capitalize the public interest. There's even a new supernatural horror film titled 11/11/11, set on today's date when, according to the press materials, “an entity from another world enters the earthly realm through heaven’s eleventh gate” (whatever that means).

This is nothing new. People held numerology-themed events and parties on the first day of 2001 (01/01/01), for example, and in 2007, engaged couples scheduled their wedding days at triple the normal number for July 7, 2007, eager to tie the knot on 7/7/07.

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Much of the interest is rooted in superstition and numerology, the idea that numbers are inherently lucky (such as 7) or unlucky (such as 13). Numbers are of course artificial and man-made, and they have no more or less significance than humans give them. Still, numerology has been around for millennia and is embraced today by millions of New Agers and others.

We tend to give special significance to certain numbers (or sequences of numbers) because we see them as meaningful when in fact they are not. There is a well-known psychological bias in the way humans perceive and remember our experiences called confirmation bias. Often described as “remembering the hits and forgetting the misses,” it refers to the ways in which our brains selectively recall information. Our minds are good at remembering coincidences and making connections between unrelated events in the world.

For example when we look at a digital clock at 12:34 in the afternoon, we are likely to notice the numerical sequence. Because it’s an “unusual” time, and most people wouldn’t regularly happen to glance at a clock at exactly that time, we remember and notice it. But if we look at the clock during any of the other 1,438 minutes in the day, we won’t see that number combination, and thus not see anything interesting or significant about it. Of course, the time 12:34 is not rare; it occurs exactly as often as 12:33 and 12:35. But our pattern-seeking brains single that number out as special or significant.

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The irony is that all the people who approached today with hope or fear that something special or cosmic would happen got the date wrong.

The correct numerical date for today is not 11/11/11, but instead 11/11/2011. The current year is not 11 but 2011, and you only create a “significant” date if you subtract 2000 from today’s actual date. The number 11 is not the same as the number 2011, and when written correctly, only a two-thirds of the digits in the date are the same.

If you have to arbitrarily add or subtract numbers from the real date to make it interesting, that pretty much demolishes any idea that the date has any mystical significance. (Plus, of course, it’s only the year 2011 under one of many calendar systems, and all units of time and calendars are artificial anyway.)

Though numerology and magical thinking have little to do with reality, they will always be with us, and superstitions are all around us. Many office and apartment buildings, for example, are missing a 13th floor, and some airplanes don’t have a 13th row. (Well, actually they do, it’s just called the 14th floor or row—as if evil forces can do you real harm, but can’t count.)