# Is phi a mystical number? **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [July 19, 2010, 8:59pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272 "2010-07-19T20:59:54Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [July 20, 2010, 6:34pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/21 "2010-07-20T18:34:58Z")
1 + 2 = 3 3 - 2 = … 1?! _This means something!!!_ ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [July 20, 2010, 6:43pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/22 "2010-07-20T18:43:22Z")
> [@Bryan\_Ekers](#): > > 1 + 2 = 3 > > 3 - 2 = … 1?! > _This means something!!!_ Yup. It means it’s time to get your meds adjusted. ---
**Author:** ![Metrolog](https://avatars.discourse-cdn.com/v4/letter/m/5e9695/32.png) [@Metrolog](https://boards.straightdope.com/u/Metrolog)\ **Post date:** [July 20, 2010, 7:12pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/23 "2010-07-20T19:12:19Z")
> [@Yllaria](#): > > Has any adjustment been made for erosion? If not, then the ratio was different when it was built. The original architectural base-breadth was 9131.05 inches. The difference between the originally and the present measurements were caused by the earthquakes and by the meteorological reasons: the most sun exposed south side of the present Pyramid’s base is the longest side, and the north side, mostly in shadow, is shortest. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [July 20, 2010, 7:23pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/24 "2010-07-20T19:23:32Z")
> [@Metrolog](#): > > The original architectural base-breadth was 9131.05 inches. The difference between the originally and the present measurements were caused by the earthquakes and by the meteorological reasons: the most sun exposed south side of the present Pyramid’s base is the longest side, and the north side, mostly in shadow, is shortest. Cite, please? ---
**Author:** ![FriarTed](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/friarted/32/1052_2.png) [@FriarTed](https://boards.straightdope.com/u/FriarTed)\ **Post date:** [July 20, 2010, 7:52pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/25 "2010-07-20T19:52:35Z")
Anyone who knows anything about the history of numerology soon realizes one thing- in that view of things, ALL numbers are mystical numbers. The debates are- what each number’s mystical significance is and does it have any bearing on reality? ---
**Author:** ![Metrolog](https://avatars.discourse-cdn.com/v4/letter/m/5e9695/32.png) [@Metrolog](https://boards.straightdope.com/u/Metrolog)\ **Post date:** [July 20, 2010, 7:54pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/26 "2010-07-20T19:54:55Z")
> [@Czarcasm](#): > > Cite, please? Length of sides of casing: Socket Sides: 9129.8 inches **9130.8 i** nches 9123.9 inches 9119.2 inches (_The Pyramids and Temples of Gizeh by W. M. Flinders Petrie_) Mean length of the sides obtained by the Royal English Ordnance Surveyors (1869) was **9130**. inches. The original **architectural** base-breadth was **9131.05** inches. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 20, 2010, 8:00pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/27 "2010-07-20T20:00:47Z")
> [@](#): > > Not that anyone’s been taking the OP seriously, but remember folks: φ has but one interesting property of any note: φ[sup]2[/sup] = φ + 1. Well, there are many other interesting things you can get from that, such as that 1/phi = phi - 1, or that the ratio of adjacent Fibonacci numbers converges to phi, or its nice properties for pseudorandom sampling. But of course you can derive all of those from phi^2 = phi + 1. ---
**Author:** ![user\_hostile](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/user_hostile/32/474_2.png) [@user\_hostile](https://boards.straightdope.com/u/user_hostile)\ **Post date:** [July 20, 2010, 8:12pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/28 "2010-07-20T20:12:45Z")
What about 42? Where does that fit in? ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [July 20, 2010, 9:00pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/29 "2010-07-20T21:00:53Z")
It’s probably already been said, but I believe the Egyptians used a measuring wheel in order to lay out their structures. So, having phi in the measurements is pretty much militantly unsurprising. Why people are so astounded by what ancient peoples could do or build is, to me, the real mystery… -XT ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [July 20, 2010, 9:12pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/30 "2010-07-20T21:12:00Z")
> [@Metrolog](#): > > Length of sides of casing: > > Socket Sides: > > 9129.8 inches > **9130.8 i** nches > 9123.9 inches > 9119.2 inches > > (_The Pyramids and Temples of Gizeh by W. M. Flinders Petrie_) > > Mean length of the sides obtained by the Royal English Ordnance Surveyors (1869) > > was **9130**. inches. > > The original **architectural** base-breadth was **9131.05** inches. If y’all would like to read the original measurements without all the mysticism tacked on, [click here.](http://www.ronaldbirdsall.com/gizeh/) ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [July 20, 2010, 9:22pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/31 "2010-07-20T21:22:44Z")
> [@xtisme](#): > > Why people are so astounded by what ancient peoples could do or build is, to me, the real mystery… That’s why I’m quite fond of the series _Engineering an Empire_. There was quite a lot of ingenuity in the ancient world. What will the future say about us - that we cracked the human genome and boy bands roamed the Earth? ---
**Author:** ![Indistinguishable](https://avatars.discourse-cdn.com/v4/letter/i/90ced4/32.png) [@Indistinguishable](https://boards.straightdope.com/u/Indistinguishable)\ **Post date:** [July 20, 2010, 9:29pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/32 "2010-07-20T21:29:35Z")
> [@Chronos](#): > > Well, there are many other interesting things you can get from that, such as that 1/phi = phi - 1, or that the ratio of adjacent Fibonacci numbers converges to phi, or its nice properties for pseudorandom sampling. But of course you can derive all of those from phi^2 = phi + 1. Right, of course (though the first is so similar to the defining equation I’d hardly consider it a separate fact). My point is, if one cannot posit or imagine a mechanism relating some purported instance of the “mysteriously ubiquitous” phi back to that equation, one has left the realm of mathematics for, well, something else. And once one can posit or imagine such a mechanism… well, then, the presence of phi is no longer anything remarkable at all. (Which is good; understanding things is better than finding them remarkable). I’m not familiar with the application of phi in pseudorandom sampling. Could you describe it and/or link to further reading upon it? ---
**Author:** ![Contrapuntal](https://avatars.discourse-cdn.com/v4/letter/c/e274bd/32.png) [@Contrapuntal](https://boards.straightdope.com/u/Contrapuntal)\ **Post date:** [July 20, 2010, 9:32pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/33 "2010-07-20T21:32:35Z")
> [@Metrolog](#): > > Not\* pyramid inches\*, inches! \*Not \*inches, [Angry Inches](http://www.amazon.com/Hedwig-Angry-Inch-Line-Platinum/dp/B00005QW5X). ---
**Author:** ![Metrolog](https://avatars.discourse-cdn.com/v4/letter/m/5e9695/32.png) [@Metrolog](https://boards.straightdope.com/u/Metrolog)\ **Post date:** [July 20, 2010, 9:47pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/34 "2010-07-20T21:47:39Z")
> [@Czarcasm](#): > > If y’all would like to read the original measurements without all the mysticism tacked on, [click here.](http://www.ronaldbirdsall.com/gizeh/) Length of sides of casing: Socket Sides: 9129.8 inches \*\*\*\*9130.8 \*\*\*\*inches 9123.9 inches 9119.2 inches (The Pyramids and Temples of Gizeh by W. M. Flinders Petrie, **20.** p. 38) ---
**Author:** ![Indistinguishable](https://avatars.discourse-cdn.com/v4/letter/i/90ced4/32.png) [@Indistinguishable](https://boards.straightdope.com/u/Indistinguishable)\ **Post date:** [July 20, 2010, 9:51pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/35 "2010-07-20T21:51:01Z")
What’s 9130-something inches got to do with anything in the OP? ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [July 20, 2010, 9:51pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/36 "2010-07-20T21:51:13Z")
> [@Metrolog](#): > > Length of sides of casing: > > Socket Sides: > > 9129.8 inches > \*\*\*\*9130.8 \*\*\*\*inches > 9123.9 inches > 9119.2 inches > > (The Pyramids and Temples of Gizeh by W. M. Flinders Petrie, **20.** p. 38) Have you got anything to say in your own words, or are you just going to copy and paste numbers 'till the chao comes home? ---
**Author:** ![Metrolog](https://avatars.discourse-cdn.com/v4/letter/m/5e9695/32.png) [@Metrolog](https://boards.straightdope.com/u/Metrolog)\ **Post date:** [July 20, 2010, 9:58pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/37 "2010-07-20T21:58:38Z")
Sorry, the numbers speak! ---
**Author:** ![Indistinguishable](https://avatars.discourse-cdn.com/v4/letter/i/90ced4/32.png) [@Indistinguishable](https://boards.straightdope.com/u/Indistinguishable)\ **Post date:** [July 20, 2010, 10:01pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/38 "2010-07-20T22:01:23Z")
I have no idea what the significance of these numbers is… What’s so special about 9130.8? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 20, 2010, 10:02pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/39 "2010-07-20T22:02:12Z")
> [@](#): > > I’m not familiar with the application of phi in pseudorandom sampling. Could you describe it and/or link to further reading upon it? Let’s say you want to select points from, say, the interval [0,1), in such a way that they’re approximately uniformly-spaced. One method would be to just pick points that really are uniformly-spaced, like {0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9}. But if you get interrupted partway through, your partial data set will be far from uniform. Alternately, you could pick points randomly from a uniform distribution: This would always be approximately uniform, even if you got interrupted. But random-number generation is expensive, and besides, maybe you want a repeatable method. But another method is to get each point by adding phi to the previous point and then chopping off the integer part. So your set of points might start off {0, phi-1, 2phi-3, 3phi-4, 4phi-6, 5phi-8…}. Of course, you could do this with any irrational number, not just phi, but with any other number, you’ll get clumping in your points. With phi, your data points will always be approximately uniformly distributed, no matter where you cut off the process. ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [July 20, 2010, 10:03pm UTC](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272/40 "2010-07-20T22:03:45Z")
[QUOTE=Metrolog] Sorry, the numbers speak! [/QUOTE] What do you hear them saying? -XT [Previous page](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272.md?page=1) [Next page](https://boards.straightdope.com/t/is-phi-a-mystical-number/547272.md?page=3)