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

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

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

The reason patterns often occur in nature is simple: the same basic physical or chemical processes occur in many patterned substances and organisms as they form. Whether it’s plants and animals or rocks, foams and ice crystals, the intricate patterns that occur in nature boil 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 rows of rocks at the Giant’s Causeway in the United Kingdom, the beautiful fractal arrangements of florets on a Romanesco broccoli, and the colorful stripes and spots on tropical fish.

Close-up of bunches of Romanesco broccoli, showing the fractal pattern of the buds
Each bud of a Romanesco broccoli floret is composed of a series of smaller buds arranged in a consistent spiral pattern.
Creative Studio Heinemann/Westend61 via Getty Images

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

Patterns in ice and rock

Imagine delicate frosted crystals on a window pane on a cold day. What creates this pattern?

When water freezes, its molecules begin to clump together. Water molecules have a peculiar bent shape that causes them to stack into hexagon-shaped clusters as they freeze.

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

Frost on an old window.
Ice crystals on an old window in Norway.
Baac3nes/Moment via Getty Images

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

How about the amazing patterns of basalt columns at the Giant’s Causeway? They formed 50 million to 60 million years ago, as lava—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 deeper, hotter layers resisted this pull, creating cracks in the upper layer.

As the lava cooled, cracks spread deeper and deeper into the rock. The particular molecular qualities of basalt, as well as the basic physics of how materials break apart—the universal laws of physics for all substances on Earth—caused the cracks to meet each other at certain angles to create hexagons, just as stacked water. molecules.

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

Animal models

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

Imagine how a drop of food coloring spreads in a glass of water – this is diffusion.

Drops of blue dye diffusing into water.
Drops of blue dye in various stages of diffusion in water.
Science Photo Library via Getty Images

In 1952, the English mathematician Alan Turing showed that such chemical diffusion into another chemical substance can lead to the formation of all kinds of patterns in nature.

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

Female royal bengal tiger in the wild - her stripes blending in with the vegetation around her.
A tiger’s stripes can help it blend in with its surroundings – making it harder to spot prey.
Sourabh Bharti/iStock via Getty Images Plus

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

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

Scientists don’t always know the purpose of a pattern, or even if there is one. The molecular processes involved are simple enough that they could generate a pattern by chance.

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

Color scanning electron microscope image of pollen grains from a variety of common plants
The pollen grains of various common plants such as sunflower, morning glory, prairie hollyhock, oriental lily, evening primrose and castor bean – magnified 500 times and colored in this image – display intricate patterns.
Dartmouth Electron Microscope Facility

We still don’t understand why a plant produces a certain pattern of pollen rather than another. Whatever end use this and other patterns might have in nature, their variety, complexity, and order are amazing.

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