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Many of the things that are part of our normal experience, like flowing rivers and streams, are among the rarest sights in the universe.

Most of the universe is cold outer space, where nebulae form giant clouds of gas and dust, and everything else is frozen solid.

Most of the matter of the universe is concentrated within stars – where conditions are so extreme that is is boiled into unique state of matter called plasma.
Plasma occurs when a gas has been heated or electrified such that its atoms turn into ions and begin to glow. It also looks really cool.

Plasma sounds like a rare and exotic state of matter, but it’s really just rare on Earth.

Down here, we see it in very hot fires and in lightening strikes. We’ve artificially created it in devices like plasma globes, plasma TVs, and in neon lights and Tesla coils like the ones below.

A unique perspective

The funny thing is that it’s often what we see every day on Earth that’s truly rare and exotic.

It’s here we see a mix of the other three states (gasses, liquids, and solids) all in one place, and one of these is particularly rare. Liquid.

It’s only within cosmic specks of dust called planets and moons that liquids show up in the universe. Most often it’s inside them, where geologic activity is strong enough to melt their insides into liquid.

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Even rarer is liquid on their surface.

Titan is -150 degrees.

This happens to a tiny percentage of moons and planets who are near stars but not too far away, in a zone between extreme heat and extreme cold.

Saturn’s largest moon, Titan, has oceans of methane on its surface.

Liquid water has even more stringent requirements of temperature and pressure.

A state of transition

The chart below visualises this zone by showing the state of each element as it moves between extremes of temperatures. The green liquid state only exists for a short period until it gets too hot and it boils into a gas.

The state of each element at different temperatures.

The Earth is special/ has the conditions that led to life because it consistently has a mix of the three states of matter (gasses, liquids, and solids) all in one place.

The difference between states

But why does matter change at all?

To a physicist, the difference between the traditional three states of solids, liquids, and gasses is the closeness of their atoms. Atoms in a gas are far apart, and in a solid they are closely compacted together. In liquids they are somewhere between.

Heat forces their atoms apart. Heat is another word for the vibration of atoms and the higher the temperature, the more the atoms will push each other away.

Heat doesn’t affect all atoms equally, because some of them have a strong attraction for each other.

Metals, like gold and uranium, tend to still be solid at high temperatures because their atoms are strongly bonded, and it takes a large amount of heat to force their atoms apart – that is, to melt them.

Likewise at room temperature water is a liquid but oxygen is a gas. They’re at the same temperature and so are vibrating at the same rate, but water molecules have a moderate attraction to each other, but oxygen molecules do not.

Working under pressure

The last major influence on state comes from pressure. The higher pressure atoms are under, the more they are forced together.

The Earth’s atmosphere exerts pressure on everything below it. If it suddenly disappeared, everything on the surface would be exposed to the vacuum pressure of space. Our oceans would evaporate into gas, along with all the water in our bodies, and many other dire consequences.

This is one of the reasons why astronauts need space suits.

During a test at a NASA facility in 1965, a leaky spacesuit exposed an astronaut to a vacuum. He quickly passed out but when he was revived, he said that the last thing he remembered was feeling the saliva on his tongue boiling away.

A narrow road between extremes

So liquids can only exist in a narrow band between extremes of temperature and pressure, which is what makes them so rare in the universe.

As liquids are the precursor to life, finding the places within this strict balance is crucial in discovering whether or not we are alone in the universe.

Originally posted 2018-07-19 21:20:48. Republished by Blog Post Promoter

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