The Sphere protects

Presentation of the exhibition “The Sphere protects”
Cosmocaixa (Barcelona)
Photography by Carlos Dorce

We can define the three-dimensional sphere as the set S2 = {(x,y,z) ∈ ℝ: x2 + y2 + z2 = R2}. It’s one of the most famous shapes studied in schools and we find it in the nature very easily. In the Cosmocaixa of Barcelona there is a special exhibition about shapes and the sphere is one of the main protagonists of it. The sphere protects and the reason hat we can read in one of the explanations is:

In the inert world, the sphere emerges easily in isotropic conditions, that is, when no one direction in space has priority over another. That is why stars and planets are round. That is why, too, if we blow air into a liquid, the bubble adopts this form, the minimum that contains a given volume. Natural selection favours circular symmetry in living beings (eggs, medusas, sea urchins, fruit, seeds, etc.) for two reasons: a) because it occupies the minimum surface, the sphere is the frontier with the exterior that loses heat most slowly and b) because, not having any edges, it is the most difficult shape to catch or bite. In both cases, then, the sphere protects.

We can also see different examples of this fact like these four examples: 1) These radial aggregates of pyrite crystals from Peru:

Radial aggregates of pyrite crystals
Cosmocaixa (Barcelona)
Photography by Carlos Dorce

2) These Marcasite nodules (FeS2):

Marcasite nodules
Cosmocaixa (Barcelona)
Photography by Carlos Dorce

3) These Dinosaur eggs (Titanosauridae) from China:

Dinosaur eggs (70 million B.C.)
Cosmocaixa (Barcelona)
Photography by Carlos Dorce

4) This colonial coral (Scleractinia) from the Pacific Ocean:

Colonial coral
Cosmocaixa (Barcelona)
Photography by Carlos Dorce

The exhibition is very interesting and it tries to answer the question “Why are some forms more common than others?”:

What do a star like our Sun, a planet, a fish egg, an orange, a bubble and the point of a pen have in common? All these objects, inert, living or manmade, share the same form: they are spheres. Why are there so many spheres, circles and circumferences? Does the fact that something is spherical help in some way? Spheres are found more frequently than other forms. What are the forms that we are most likely to find in nature? Does being circular, spiral, hexagonal or fractal in shape serve any prpose? Do objects with the same form share anything else apart from their shape? Perhaps they share the same function, that is to say, the property that helps the object in question, wether inert, living or manmade, to persist in nature.

As you can imagine, I must talk about spirals, hexagons,… but I’ll do it in next posts!

LocationCosmoCaixa at Barcelona (map)

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