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Physics stepping stones

What are some of the biggest ideas in physics? Find out the stories behind the most significant discoveries that have shaped our understanding of the universe.


Diagram of how the big bang happened.

The big bang

Most physicists believe the universe was born in a big bang 13.8 billion years ago. In it, the energy making up everything in the cosmos we see today was squeezed inside an inconceivably small space –  far tinier than a grain of sand, or even an atom. Then, this unimaginably hot and dense cauldron – for whatever reason – ballooned at a terrifying rate.

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Fun diagram of planets.

The planets

The question 'are we alone?' excites anyone with even a passing interest in our place in the universe. If we are alone, it makes us unique and precious. If we’re not, the idea of seeking out new life and new civilisations moves from the realm of science fiction to a tantalising possibility.

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Diagram saying every atom in your body has a story.

The atom

If you take a piece of paper and cut it in half, and continue to cut it smaller and smaller, what are you left with? This is a similar thought experiment to that which Greek philosopher Democritus pondered in around 400 BCE. Democritus concluded that if you kept on cutting, everything must be made of tiny eternal particles. He called them atomos, meaning indivisibles. It took until the 19th century for Democritus to be proved right, with one important tweak in the 20th century. Atoms do exist but they are certainly not indivisible.

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Diagram of how quantum mechanics works.

Quantum mechanics

Why we replaced our view of the solid universe with uncertainties, split identities and bizarre behaviour. Quantum physicist Richard Feynman famously said: “I think I can safely say that nobody understands quantum mechanics”. But even if this still holds true today, it has not stopped us using the quantum properties of matter in a host of technologies.

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A plastic model kit saying boson with a tube of glue.

The standard model

On 4 July 2012, physicists at the Large Hadron Collider – the biggest machine in the world – announced they had discovered one of nature’s deepest secrets. Detecting the Higgs boson completed the Standard Model of particle physics, a theory describing all the known fundamental particles and how they interact. During the announcement, the audience broke out in wild applause. One of the scientists who first proposed the Higgs particle even shed a tear of joy. Why were they so pleased?

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Diagram of the theory of relativity.

Relativity

When Albert Einstein was born in 1879, Isaac Newton’s idea of how gravity works had been around for nearly 200 years. It explained everything to do with gravity’s pull, from how, when dropped, a cannonball and an egg will hit the ground at the same time, to why we don’t float off into space. But Einstein changed our ideas about space, time and gravity forever.

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Diagram of devices that use Maxwell's equations to work.

Maxwell's equations

The phone in your pocket or the light in your bedroom. The electric cars on the road or the biggest machine in the world, the Large Hadron Collider. If you ask how they work, and keep asking ‘why’ questions like a toddler, you will always end up at Maxwell’s equations.

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Diagram of the things that use nanotechnology.

Nanotechnology/2D materials

Though the term nanotechnology was first uttered in 1974 by Japanese scientist Norio Taniguchi, societies had unwittingly been using nanotechnology for centuries. Find out why thinning sheets to the width of an atom can turn them into supermaterials.

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Diagram of several people around a lightbulb.

Crystallography

It may not be the most familiar branch of science to everyone, but crystallography is one of the most important techniques in helping to understand the world around us. Crystallographers can work out the atomic structure of almost anything. And they use this knowledge to answer why things behave the way they do.

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Diagram of different uses for a laser.

The laser

Our fascination with light starts at an early age. Some of the first questions kids ask their parents are about light. What are rainbows? Why is the sky blue? What are shadows? What kind of light is a laser and what makes it so powerful?

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Diagram depicting soft matter physics and what exists between living and lifeless matter.

Soft matter physics

Boiling a kettle is a good demonstration of the phases of matter we are all familiar with from school. The kettle is solid. The water is liquid. And as the temperature rises, some of this water turns to gas billowing from the spout. But is your skin a solid? Skin’s not hard like a kettle. And luckily it doesn’t flow like water. It’s something in between, something squidgy. Physicists refer to it as soft matter.

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