[latebind (OP)]

Besides the very common sphere (planets, stars), can you think of any other examples of natural geometric shapes in the universe or on earth??

Some ones to look for ...

Triangle , square, rectangle, cube, circle...

BTW: Animals can be included, in fact anything that is not made by man can be included!

[LeeE]

Crystalline structures.

[RD]

... I find square is difficult

Table salt is close* to square ...

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http://www.sciencephoto.com/images/imagePopUpDetails.html?pop=1&id=721104829&pviewid=&country=67&search=sem+AND+salt&matchtype=FUZZY [Links inactive - To make links active and clickable, login or click here to register]

* Perfect geometric shapes are idealized mathematical concepts and don't occur in nature.

[latebind (OP)]

Saturn, the sixth planet in our solar system, has caused quite a stir ... when the NASA Cassini Orbiter photographed a six sided geometric shape on the surface of the planet.

http://scienceray.com/astronomy/something-strange-about-saturn/ [Links inactive - To make links active and clickable, login or click here to register]

Great one! WOW!

[latebind (OP)]

... I find square is difficult

Table salt is close* to square ...

http://www.sciencephoto.com/images/imagePopUpDetails.html?pop=1&id=721104829&pviewid=&country=67&search=sem+AND+salt&matchtype=FUZZY [Links inactive - To make links active and clickable, login or click here to register]

* Perfect geometric shapes are idealized mathematical concepts and don't occur in nature.

Very nice with the salt!

I however have to disagree with your statement ...

"* Perfect geometric shapes are idealized mathematical concepts and don't occur in nature."

I believe that they can and do exist, take for example a simple soap bubble, which can easily be a perfect sphere.

[RD]

I however have to disagree with your statement ...

"* Perfect geometric shapes are idealized mathematical concepts and don't occur in nature."

I believe that they can and do exist, take for example a simple soap bubble, which can easily be a perfect sphere.

Nope, gravity makes the soap bubble thicker at the bottom, distorting its shape from the ideal unattainable "perfect sphere".

[latebind (OP)]

Also , we do not yet know if atoms are perfect spheres yet, or if electrons are as well. They both could be perfect.

Also a rainbow is a perfect circle, as well as electric fields I assume.

[RD]

Also a rainbow is a perfect circle.

Perfect geometric shapes cannot be made of lots of little bits, be they rain-drops or atoms.

[RD]

Rainbows (or garden-hose-bows) can be circular ...

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http://www.atoptics.co.uk/fz303.htm [Links inactive - To make links active and clickable, login or click here to register]

but not a perfect circle.

[AllenG]

Light travels in a straight line.

Fullerene comes in several geometric shapes.


Waves of all sorts are mathematically definable shapes.

[RD]

Light travels in a straight line.

Provided no mass is nearby ... http://en.wikipedia.org/wiki/Gravitational_lens [Links inactive - To make links active and clickable, login or click here to register]

Waves of all sorts are mathematically definable shapes.

There can be realistic simulations of natural forms (ocean waves, rocks surfaces) using http://en.wikipedia.org/wiki/Fractal#In_nature [Links inactive - To make links active and clickable, login or click here to register],

but there are no truly perfect geometric forms in nature.

BTW Hokusai apparently was using mathematics in the composition of his wave picture ...

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http://en.wikipedia.org/wiki/Golden_ratio [Links inactive - To make links active and clickable, login or click here to register]

[Nizzle]

Hexagons in a cilinder:

Behold the carbon nanotube



EDIT: oops, I forgot that these tubes don't occur naturally  []

[RD]

Behold the carbon nanotube

EDIT: oops, I forgot that these tubes don't occur naturally  []

There are http://en.wikipedia.org/wiki/Fullerene [Links inactive - To make links active and clickable, login or click here to register] in terrestrial soot and interstellar dust, (i.e. carbon nanotubes do occur naturally)

The not-so-new form of carbon

But it turns out that we've actually been making fullerenes unknowingly for thousands of years – whenever we burn a candle or an oil lamp. The candle's flickering flame vaporises wax molecules containing carbon, hydrogen and oxygen. Some of these molecules burn instantly in the blue heart of the flame. Others move upwards into the yellow tip where the temperature is great enough to split them apart. The result is carbon-rich soot particles that glow, giving off gentle yellow light. Amid this soot are buckyballs.

Buckyballs also exist in interstellar dust and in geological formations on Earth. So while they are new to science they are reasonably common in nature.

http://www.science.org.au/nova/024/024key.htm [Links inactive - To make links active and clickable, login or click here to register]

[Waldo Pepper]

Fractals.

The fern leaf can be expressed as a recursive mathematical sequence.