Why does nature create patterns? A physicist explains the molecular-level processes behind basalt crystals, scratches and columns

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Why does nature always create a pattern? – Saloni G., 16, Alwar, Rajasthan, India

The reason why patterns often appear in nature is simple: the same basic physical or chemical processes occur in many patterned substances and organisms as they form. Whether in plants and animals or in rocks, mosses and ice crystals, the complex patterns that occur in nature come down to what happens at the level of atoms and molecules.

A pattern in nature is any regularly repeating arrangement of shapes or colors. Some of the most striking examples include the hexagonal arrays of rocks at the Giant’s Causeway in the UK, the beautiful fractal arrangements of florets on a Romanesco broccoli, and the colorful stripes and spots on tropical fish.

Patterns like these begin to form on a small scale as materials undergo processes such as drying, freezing, crumpling, diffusion, and reaction. These changes then give rise to complex, larger-scale patterns that people can see.

Patterns in ice and rock

Imagine delicate crystals frozen on glass on a cold day. What creates this pattern?

When water freezes, its molecules begin to group together. Water molecules have a particular curved shape that causes them to pile up in hexagon-shaped clusters when they freeze.

As the cluster grows, many outside factors, including humidity and temperature, begin to affect its overall shape. If water freezes on a window pane, for example, small random imperfections on the glass surface redirect the piling and create a larger pattern.

This same process of stacking molecules is responsible for the striking variety of snowflake shapes.

What about the amazing patterns of the basalt columns of the Giant’s Causeway? These formed 50 to 60 million years ago, when lava – a hot rocky fluid from deep underground – rose to the Earth’s surface and began to lose heat. The cooling caused the upper layer of basalt to contract. The deep, hot layers resisted this pulling, creating cracks in the top layer.

As the lava cooled, the cracks propagated deeper and deeper into the rock. The particular molecular qualities of basalt, together with the basic physics of material fracture – universal laws of physics for all substances on Earth – have caused the cracks to meet at certain angles to create hexagons, much like the piling up of water. molecules.

Eventually, the cooling basalt erupted into the hexagon-shaped rock columns that still create such an impressive pattern millions of years later.

Models in animals

The creation of complex patterns in living organisms also begins with simple mechanisms at the molecular level. An important patterning process involves how diffusing chemicals react with each other.

Imagine how a drop of food coloring spreads through a glass of water, that’s diffusion.

In 1952, the English mathematician Alan Turing showed that a chemical propagating like this into another chemical can lead to the formation of all kinds of patterns in nature.

Scientists have proven that this process replicates the patterns of a leopard’s spots, zebra’s stripes, and many other animal markings.

What makes these markings consistent across generations? As animal species evolved, these chemical reactions evolved with them and became part of their genetic codes. Maybe it’s because the brands helped them survive. For example, a tiger’s stripes camouflage it when hunting in a forest or grassland, making it easier for it to surprise and catch its prey.

However, researchers are still working out the details of which particular chemicals are involved.

Scientists don’t always know the purpose of a pattern, or even if there is one. The molecular processes involved are simple enough to coincidentally generate a pattern.

For example, in my research team’s work on plant pollen grains, we observed a wide variety of patterns, including spikes, stripes, and many more.

We do not yet understand why a plant produces a particular pollen profile rather than another. Whatever the ultimate use of these and other patterns in nature, their variety, complexity, and order are astounding.

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This article is republished from The Conversation under a Creative Commons license. Read the original article here: https://theconversation.com/why-does-nature-create-patterns-a-physicist-explains-the-molecular-level-processes-behind-crystals-stripes-and-basalt-columns-186433.

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