Is there really such a thing as a perfect circle in nature?

[zeromodz]

My friend and I were debating if there really could be a perfect circle in nature outside the human brain? What do you think? If you think there is, please back it up with evidence.

 

[rock.freak667]

Well I think things like electric field lines are circular.

 

[Dr Lots-o'watts]

What would you call perfect? Any circle has a radius R +- DeltaR. It's just a matter of how small is DeltaR.

A black hole's event horizon or a lone atom surely have very well-defined radius.

But on a regular scale, statistically, I bet could find some on oranges, raisins, eggs, pupils, and perhaps other organic systems.

 

[n.karthick]

well, my navel looks to be a perfect circle when my body is not stretched.

 

[Danger]

With the possible exception of a black hole circumference, as mentioned by Dr. Watts, I don't think that such exists. The Planck length limits the number of incremental steps around a point. I'm not even sure that the black hole would qualify, since its circumference is zero.
This is a damned good question, Zeromodz, and I expect that there will be some serious discussion about it.

 

[lalbatros]

I doubt that even a black hole would define a perfect sphere.
Perturbation fields would for sure perturb the BH event horizon.
Further, the BH must have a history with initital conditions that are for sure not perfectly spherical.
Therefore I don't see why the final BH should be perfectly spherical.

This same reasonning is applicable to any shape.
This should imply that shapes do not exist.

 

[Kmenex]

Human brain is nature, so yes perfect circle in nature is a go!

 

[zomgineer]

Pi is a transcendental number. You can never build anything with a ratio of Circumference=2pi*r using a finite number of points. You can't even square a circle using a finite number of operations*.

Maybe what you would like though is to build a circle with a finite number of objects that are perfectly sitting on on the edge, like dots around a circle. The Heisenberg uncertainty principle tells us that we can't perfectly position anything. Even an event horizon of a black hole is going to be "bubbly" according to Hawking.

*Squaring a circle is a classical problem of geometry. Ancient geometers wondered if one could construct a square with the same area of a circle by using a compass and straight edge. It turned out to be impossible.

 

[Curl]

Circle by definition means a set of all points in R^2 that are equidistant from a point called the center.

First, there are no "points" in nature
Second, no particle can sit still in space.
Third, space is not continuous, as stated above (plank length is somewhere in the 1/10^36 range if i recall correctly).

so no, its impossible.

 

[Danger]

Human brain is nature, so yes perfect circle in nature is a go!

If your brain is a perfect circle, it is not only 2-dimensional rather than the 3-dimensional that most of us prefer... but also not human. You seem to be missing some lobes.

 

[admaw11]

What about bubbles in liquids? aren't they "trying" to be a perfect circle / sphere, I guess gravity could also be squashing them slightly out of shape.
Oil droplets in water? on the surface of water?

 

[Ranger Mike]

rain drop is perfect circle as it handles atmospheric pressure equally around its peripheral ...

 

[admaw11]

Another idea is a perfectly still pond, on a perfectly still day, and something dropping down from dead vertical into the centre of the pond, then the "wave rings" around the item should be theoretically perfect right? but then I guess the item dropping into the pond would also have to be perfectly circular to create perfect "wave rings"

 

[Andy Resnick]

My friend and I were debating if there really could be a perfect circle in nature outside the human brain? What do you think? If you think there is, please back it up with evidence.

A soap bubble (or any liquid drop) on board the space station is, for all practical purposes, a perfect sphere.

Edit: I see I am not the first to think of this.

 

[Wm.Schaffer]

If your brain is a perfect circle, it is not only 2-dimensional rather than the 3-dimensional that most of us prefer... but also not human. You seem to be missing some lobes.

He's referring to the 'concept' of a perfect circle existing inside the brain, not the shape of the brain at all. Maybe you should check your lobes.

And I'm in the Heisenberg Uncertainty camp: If definite location does not exist in nature, then a perfect circle absolutely cannot exist in nature.

 

[Academic]

All the basic geometric shapes are concepts we invent, none of them exist in nature. We use them to model phenomenon that are approximately represented by these ideal shapes.

 

[jnorman]

no. nothing comprised of atoms has a "perfectly smooth" circumference. even if you try to describe a perfect circle within spacetime without regard to any physical entity, you cannot achieve a perfect circle since spacetime is not perfectly smooth - it is limited to discrete fractions at the Planck limit, ie the Planck length.

 

[Dr Lots-o'watts]

Here is something inspiring :



But basically, because of Heisenberg's principle, a length cannot be perfectly defined, so neither can a radius. It just comes down to how small we wish the error on the circle radius DeltaR to be.

 

[Academic]

Circles aren't generally defined to have an error in their radius. The title of the thread uses the term 'perfect circle' to drive home this point.

 

[Studiot]

Surely it should be possible in principle to produce a perfect circle by Lissajous method, if some form of compensating circuit is employed as a filter to the scope inputs?

 

[mugaliens]

No. Absolutely not, as your requirements include the word "perfect," which a neutron star, at a couple of atomic lengths variation might accommodate, still don't fit your bill!

In the meantime, the others have reasonably filled the requirement.

 

[Danger]

He's referring to the 'concept' of a perfect circle existing inside the brain, not the shape of the brain at all. Maybe you should check your lobes

You noticed the "" smiley, right? That indicates that the post was a joke, which is why we have smileys in the first place. Also, the original question specifically asks if a perfect circle can exist outside of the brain, ie: as a tangible object. The post that I was joking about, therefore, was irrelevant to the topic.

 

[Dr Lots-o'watts]

Circles aren't generally defined to have an error in their radius. The title of the thread uses the term 'perfect circle' to drive home this point.

Do you have anything in mind that can be defined without an error?

 

[Academic]

I don't see how error is relevant to a definition. We define things arbitrarily, and usually exactly. Error comes in when we measure and model.

 

[rock.freak667]

I don't see how error is relevant to a definition. We define things arbitrarily, and usually exactly. Error comes in when we measure and model.

Well in order to see a circle in nature you'd need to measure it, that is where the error comes in.

 

[stevenb]

When I was a kid, my Grandfather told me that Leonardo DaVinci was able to draw a perfect circle on a board, free-hand and judged by eye. The legend is that any measurement a person could do on such a drawing indicated the circle was perfect.

I hope nobody is going to call my Grandfather a liar.


Anyway, as alluded to above, a perfect circle exists in the mathematician's mind and in the artist's eye.

http://www.fineartappraiser.com/featureAug97.htm

 

[Kmenex]

All the basic geometric shapes are concepts we invent, none of them exist in nature. We use them to model phenomenon that are approximately represented by these ideal shapes.

Are you sure about that? I study nanotechnology and have seen many first hand examples of how geometric shapes such as tetrahedron, squares, 5 pointed stars, hexagons, e.c.t, have assembled via the natural forces inherent within the synthesis reaction.

 

[Kmenex]

i FIGURED IT OUT!

THE perfect circle is the circle which is not a perfect circle!

 

[stevenb]

The circle of fifth's is perfect. And since fifth's are perfect in themselves. That circle is extra perfect.

Now how many conceptual and linguistic flaws can you find in my statement?

I stopped counting at five which seems fitting.

 

[lalbatros]

rain drop is perfect circle as it handles atmospheric pressure equally around its peripheral ...

If we neglect the drag of air that deforms the drop, and many other small effects.
May the smallest perturbing effect would be the inhomogeneity of the gravitational field!

 

[Danger]

If we neglect the drag of air that deforms the drop, and many other small effects.

Still not in the ballpark. There are definite molecular and atomic "bumps" in the surface.

 

[krononauten]

Well I think things like electric field lines are circular.

That depends on the antenna structure.
Magnetic field lines are circular around a perfect conductor carring a constant current as given in the classic example.

 

[Dr Lots-o'watts]

I don't see how error is relevant to a definition. We define things arbitrarily, and usually exactly.

That's mathematics, the tools in our minds.

Error comes in when we measure and model.

That's physics, the things we measure in nature.

The link between the two : the models that take error into account (such as HUP for the small scale.)

Of course the word "perfect" pretty much excludes anything. Even black holes can't be perfect because there is always something falling in it that breaks the symmetry (or quantum radiation coming out).

 

[robindude]

Suppose there was a perfect circle in nature.

We can measure this to some amount, suppose 14 decimal places (or a thousand, or a googol, whatever you like, I'll use 14 for sake of argument).

We check a possible perfect circle that really IS perfect, to infinite decimal places. We confirm this when our measurements cannot find any flaw.

We check a possible perfect circle that is NOT perfect, but has an error that is smaller than our ability to detect. The circle still appears perfect.

Result: It doesn't matter if there IS a perfect circle in nature or not, we have no way of determining the validity of its existence as perfect, merely as 'perfect to the limit of our ability to measure'.

Just an opinion. Probably not helpful.