Conservation of Energy
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Conservation of Energy

All of the energy around you, from the light bouncing into your eyes to the heat coming out of your toaster, comes from an unbroken chain of events going back to the Big Bang.

What’s more, all the energy that will ever exist was created in that moment. This is because energy only ever moves from one place to another, it never truly disappears.

This is the law of the ‘conservation of energy’.

To demonstrate this law, let’s take a closer look at the light coming out of your screen, and where it really comes from.

If you took your screen apart you’d see a backlight, which releases light when electricity (I.e. electrons) flows through it.

An LED backlight
An LED backlight

Whether you’re using a phone, laptop, or desktop, it might have stored those electrons in a battery for a while but originally it would have got them from a wall outlet.

If you follow your outlet’s wires back far enough, along power lines and then high voltage lines, you’ll most likely end up at a hydroelectric dam, a windfarm, a solar farm, or a coal or nuclear plant – depending on where you live.

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All the power lines in a city will generally link up and go back to the same source.

For simplicity let’s just say you’re like me in Sydney and your city is powered by a hydroelectric dam. Once you reach the dam, you’ll find where the electrons came from. The dam has been pushing massive amounts of them into the power lines.

It does this through turbines, which are like giant wheels with blades. Each one contains an electromagnet set up in reverse such that when they turn, they push electrons down the line.

The spinning of the turbines converts one form of energy – movement, into another – electricity.

At the Hoover Dam, water flows underneath this long hall and turns these giant turbines.
At the Hoover Dam, water flows underneath this long hall and turns these giant turbines.

Hydroelectric dams are able to move the turbines because they tap into the energy that flows all over our planet. This is the energy within the water cycle.

Dams are built on rivers, and they let some water flow through the structure. On its way through, the weight of the water pushes its many turbines.

Let’s keep going.

If we follow the river back to its source, we’d find that all of its water once came from rain.

Rain in the Rocky Mountains, upstream of the Colarado River and the Hoover Dam
Rain in the Rocky Mountains, upstream of the Colarado River and the Hoover Dam

Rain was created because water evaporated from lakes and oceans and was pulled into the sky, a natural consequence of the sun’s radiation and heat.

Water from a lake evaporating from the Sun’s heat
Water from a lake evaporating from the Sun’s heat

This radiation travelled through space, and originated on the Sun’s surface, 150 million km away. The Sun is a ball of super heated plasma, and all of this furious energy comes from nuclear fusion deep within its core.

The incredible heat of the sun evaporates water on Earth, 150 million km away
The incredible heat of the sun evaporates water on Earth, 150 million km away

This nuclear fusion releases the latent energy that is held within the hydrogen atoms that make up the majority of the star, and which are also its fuel.

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This energy within hydrogen atoms came from their creation, shortly after the Big Bang.

The Big Bang, the moment that created the raw material for the entire universe, including all of its energy
The Big Bang, the moment that created the raw material for the entire universe, including all of its energy

It is interesting to think that if the turbines at the dam stop turning, then your screen will turn off.

If the rain stops falling, eventually the turbines stop.

If the Sun uses up all of its hydrogen, then it never rains again.

Because all the energy in the universe was created during the Big Bang, and it is always moving from place to place, it won’t ever get used up.

However, it might reach equilibrium, and that will mean the end of all chemistry, life, civilisation, and technology.

To explain how this happens, we can imagine the energy of the universe as like the colours in this trippy video.

Source: The Colors of Feelings from Thomas Blanchard.

Imagine that each colour paint is a different type of energy (like heat, light, or electricity.)

Darker coloured paints represents areas of higher density of energy, like a block of firewood.

Lighter coloured paints represent low areas of a low density of energy, like the surrounding air.

When you light a fire, you are pushing heat and light energy from high energy wood to the low energy air, like darker colour paint smearing over lighter coloured paint.

It’s the same on a larger scale, with stars and outer space.

Everything comes from this type of movement of energy. All light, heat, movement, and electricity are possible because of energy flowing from a higher density spot to a low density spot.

The problem is that eventually, the painting will become a uniform grey blob.

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There will be a point where the paint is fully mixed up, and there is nowhere that is higher density than anywhere else.

No further movement of energy becomes possible. No moves are left, like cars stuck in ultimate gridlock.

This is called the heat death of the universe. It is where every part of the universe, including everything that used to be galaxies, stars, planets, and computer screens, cools to a temperature that is just a bit warmer than outer space.

Heat death is predicted to lie billions and billions of years in the future, which leaves ample time for millions of civilisations, types of consciousness, and technology.

But most scientists believe that in the end, everything in the universe will fade to grey.

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Say hey to Owlbert Einstein

Curator of the Big Ideas Network

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