# Is there such thing as a perfect circle? **URL:** \ **Category:** Factual Questions\ **Created:** [August 22, 2011, 4:47pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675 "2011-08-22T16:47:13Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![REDEYZZ](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@REDEYZZ](https://boards.straightdope.com/u/REDEYZZ)\ **Post date:** [August 22, 2011, 4:47pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/1 "2011-08-22T16:47:13Z")
Sure we can idealize the concept of a perfect circle in our mind, a good 360 degrees. But is there really such a thing as a perfect circle? Even on computer monitors we will use pixels to create a circular formation which, the pixels are not perfectly circular themselves. When you keep going down to a next level you reach atoms and even atoms are not a sphere or a circle. They are more of a geometrical shape that is three dimensional with edges, but not a smooth round shape. in mathematics, there exists such a thing as a perfect circle. Consider the unit circle of radius 1, x^2 + y^2 = 1. In our minds, this is a very real object. However in reality (ie. not our minds), nothing is a perfect circle. Particularly when you get down to the atomic level. Or are there atoms that are actually circular? How can one actually be sure that it is spherical? 😕 ---
**Author:** ![FLIPPER](https://avatars.discourse-cdn.com/v4/letter/f/9de053/32.png) [@FLIPPER](https://boards.straightdope.com/u/FLIPPER)\ **Post date:** [August 22, 2011, 5:07pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/3 "2011-08-22T17:07:14Z")
You Mr. are one crazy guy. Everyone knows there is no such thing as a perfect circle. Duh! ---
**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:** [August 22, 2011, 5:07pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/4 "2011-08-22T17:07:32Z")
> [@](#): > > Is there such thing as a perfect circle? > … > in mathematics, there exists such a thing as a perfect circle. Well, then, that answers that, doesn’t it? ---
**Author:** ![Candyman74](https://avatars.discourse-cdn.com/v4/letter/c/ad7895/32.png) [@Candyman74](https://boards.straightdope.com/u/Candyman74)\ **Post date:** [August 22, 2011, 5:08pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/5 "2011-08-22T17:08:41Z")
Would the event horizon of a black hole be a perfect circle? ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [August 22, 2011, 5:29pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/6 "2011-08-22T17:29:20Z")
[A Perfect Circle](http://en.wikipedia.org/wiki/A_Perfect_Circle). ---
**Author:** ![Kobal2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kobal2/32/20_2.png) [@Kobal2](https://boards.straightdope.com/u/Kobal2)\ **Post date:** [August 22, 2011, 5:32pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/7 "2011-08-22T17:32:50Z")
Of course there’s such a thing as a perfect circle. It’s that band the vox guy from Tool plays in now. They’re pretty good, I think. ETA: you’ll pay for this, Ludovic ! _shake fist_ ---
**Author:** ![Rekd](https://avatars.discourse-cdn.com/v4/letter/r/5f8ce5/32.png) [@Rekd](https://boards.straightdope.com/u/Rekd)\ **Post date:** [August 22, 2011, 5:47pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/9 "2011-08-22T17:47:34Z")
> [@REDEYZZ](#): > > But is there really such a thing as a perfect circle? Here, take a look and tell me if this is a perfect circle (turns around grabbing ass-cheeks and shows Redeyzz the ol’ balloon knot). :eek: ---
**Author:** ![SimonMoon5](https://avatars.discourse-cdn.com/v4/letter/s/9f8e36/32.png) [@SimonMoon5](https://boards.straightdope.com/u/SimonMoon5)\ **Post date:** [August 22, 2011, 5:53pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/10 "2011-08-22T17:53:17Z")
There can be no real-world “perfect” circle. The same is true for “points” and “lines”. They exist in theory but not in reality. Euclid defined a point as “that which has no part”. A line was defined as “breadthless length”. All of Euclidean geometry is based on things that don’t exist. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [August 22, 2011, 5:53pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/11 "2011-08-22T17:53:31Z")
> [@REDEYZZ](#): > > Sure we can idealize the concept of a perfect circle in our mind, a good 360 degrees. > > But is there really such a thing as a perfect circle? > … > However in reality (ie. not our minds), nothing is a perfect circle. Particularly when you get down to the atomic level. By your rationale, there is no perfect triangle, square, pentagon, etc. either. There’s no such thing as a perfect straight line, or a perfect right angle. There’s no such thing as a perfect flat plane, since there must be some minimal surface roughness on at least the scale of the atoms involved. There’s not even a perfect point, since a theoretical point has zero length in any dimension, and any real representation of a point (e.g. ink on paper) must have some non-zero width and height. ---
**Author:** ![REDEYZZ](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@REDEYZZ](https://boards.straightdope.com/u/REDEYZZ)\ **Post date:** [August 22, 2011, 5:56pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/12 "2011-08-22T17:56:51Z")
> [@](#): > > By your rationale, there is no perfect triangle, square, pentagon, etc. either. That’s just crazy talk. :smack: 😛 ---
**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:** [August 22, 2011, 6:07pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/13 "2011-08-22T18:07:50Z")
A representation of a thing is not the thing itself. Even setting aside the “perfect” criterion, a drawing of a circle is not a circle. Circles, triangles, points, lines, and so on are all mathematical objects, not arrangements of graphite on paper. And as mathematical objects, perfect circles have just as much reality and existence as imperfect ones. ---
**Author:** ![Saint\_Cad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saint_cad/32/18907_2.png) [@Saint\_Cad](https://boards.straightdope.com/u/Saint_Cad)\ **Post date:** [August 22, 2011, 6:15pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/14 "2011-08-22T18:15:29Z")
> [@SimonMoon5](#): > > There can be no real-world “perfect” circle. The same is true for “points” and “lines”. They exist in theory but not in reality. What is the horizon if not a line? ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [August 22, 2011, 6:16pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/15 "2011-08-22T18:16:54Z")
Electrons are _very close_ to [spherical](http://www.scientificamerican.com/article.cfm?id=electron-perfectly-round-to-one-part-in-million-billion-experiment-finds) (just draw an equator if you want to extract a circle). Are they _perfectly_ spherical? No one knows yet. ---
**Author:** ![Rekd](https://avatars.discourse-cdn.com/v4/letter/r/5f8ce5/32.png) [@Rekd](https://boards.straightdope.com/u/Rekd)\ **Post date:** [August 22, 2011, 6:18pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/16 "2011-08-22T18:18:22Z")
> [@Saint\_Cad](#): > > What is the horizon if not a line? Um, the horizon (as you look out over the ocean) is an arc, which is part of a circle. Not a line. :twak: ---
**Author:** ![Marley23](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Marley23](https://boards.straightdope.com/u/Marley23)\ **Post date:** [August 22, 2011, 8:09pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/17 "2011-08-22T20:09:38Z")
Moved to General Questions from Great Debates and took care of that gross out link. ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [August 22, 2011, 9:47pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/18 "2011-08-22T21:47:36Z")
I have a couple of perfect circles. I keep them in the basement, along with my Platonic forms. ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [August 22, 2011, 10:03pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/19 "2011-08-22T22:03:49Z")
> [@Dr.Strangelove](#): > > Electrons are _very close_ to [spherical](http://www.scientificamerican.com/article.cfm?id=electron-perfectly-round-to-one-part-in-million-billion-experiment-finds) (just draw an equator if you want to extract a circle). > > Are they _perfectly_ spherical? No one knows yet. We had [a thread](http://boards.straightdope.com/sdmb/showthread.php?t=610036) about this recently. The conclusion being that it’s quite misleading to say an electron has any shape, let alone being a little billiard ball. ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [August 22, 2011, 10:15pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/20 "2011-08-22T22:15:42Z")
Shapes imply solids, and there are no solids in nature. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [August 22, 2011, 10:45pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/21 "2011-08-22T22:45:23Z")
> [@Mijin](#): > > We had [a thread](http://boards.straightdope.com/sdmb/showthread.php?t=610036) about this recently. > > The conclusion being that it’s quite misleading to say an electron has any shape, let alone being a little billiard ball. Well, it’s a good thing I didn’t say it’s a little billiard ball :). But what does shape even mean? Heck, take a real billiard ball–why do we say it’s round? Well, it’s because when we poke it from different angles, our finger always stops at a fixed distance from a center point. So what stops our finger? As it turns out–the electromagnetic field pushes our finger back when it gets too close. The electron is no different. It’s safe to say that an electron’s “purpose in life” is as a pure manifestation of the electric field. Therefore, it’s no stretch to say that an electron’s shape is defined by this field. So we can say that an electron’s shape is that surface where the electric field is constant. Size is a bit trickier since there’s no obvious choice for the _value_ of the electric field, but shape is easy–and the answer is that it’s spherical. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [August 22, 2011, 10:49pm UTC](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675/22 "2011-08-22T22:49:07Z")
> [@Alessan](#): > > Shapes imply solids, and there are no solids in nature. Unless you are using the word “solid” in some special, personal, technical sense (and a useless one, because, by your own stipulation, it has no referent), that is manifestly false. In both colloquial and standard scientific usage, there are solids all over the place. As for the original question, it was long ago answered in the negative by Plato, and, as such, might, without too much exaggeration, be said to lie at the foundations of Western culture and science. (Sadly, **REDEYZZ** is well over two millennia too late to take the credit.) [Next page](https://boards.straightdope.com/t/is-there-such-thing-as-a-perfect-circle/593675.md?page=2)