Subatomic science: 10 things we know (and don’t know) about the fabric of the universe
Our understanding of how the physical world works – from the tiniest subatomic particle to the largest galaxy cluster – has advanced rapidly in recent decades. As The Infinite Monkey Cage explores what we know about the subatomic particles that form our universe, we take a look at some of the freaky facts and unsolved mysteries surrounding the substance of the cosmos.
1. The word “atom” comes from the Greek for “indivisible”, but they’re actually made up of many far smaller particles
Scientists have unpicked atoms and the forces that affect them to discover 61 even smaller particles that make up matter within the universe. (There are likely to be more, but it may be some years before we can find them.) This surprising subatomic world contains weak bosons, strange and charm quarks, tau-neutrinos, photons, muons, gluons and other oddly-named entities.
2. We don’t know what makes up over 95% of the universe
Things that are formed of atoms and molecules like we are – such as stars and planets – only make up around 5% of the universe. The other 95% is thought to consist of dark matter (25%) and dark energy (70%). But no one has yet been able to detect the particles that make up either of these invisible elements – we only know they exist because of how they affect other things.
3. There is not enough gravity to hold our galaxy together
The Milky Way contains 200 billion stars, but when scientists calculate how much they weigh and how fast they’re moving, there doesn’t appear to be enough gravity to explain why they don’t all spin off into space. That’s where dark matter comes in: scientists believe that it acts like cosmic scaffolding, shaping where galaxies form and keeping things in place.
4. Massive clumps of dark matter distort space and time
When we look at very distant galaxies, the light that travels back to us through dark matter is warped by it. So, although we don’t know what dark matter actually is, we can map out where pockets of it exist and what size they are.
5. Dark energy makes up 70% of the universe, but 20 years ago we didn’t even know it existed
In 1929, the astronomer Edwin Hubble produced evidence that the universe was expanding, leading to the Big Bang theory. But it wasn’t until the late 1990s that physicists discovered this expansion was actually accelerating. None of our existing rules explained why this would be happening, which led scientists to identify “dark energy” as the mysterious force that is pulling the universe apart.
6. Around 70 billion neutrinos pass through the tip of your nose every second
Hundreds of billions of miniscule particles go right through our bodies every second without us even noticing. Produced by stars and other astrophysical events, neutrinos have almost no mass at all and travel at almost light speed through the universe – the ones passing through your nose right now were created in the core of the sun only eight minutes ago.
The universe does not behave according to our pre-conceived ideas. It continues to surprise us.Stephen Hawking (1995)
7. Almost all the antimatter in the universe has disappeared
For every type of particle that exists there is an anti-particle with the opposite electrical charge, and when they meet they cancel each other out.
It’s thought that the Big Bang produced equal quantities of matter and antimatter, which should have completely annihilated each other within moments. Yet instead we ended up with a universe made of matter – and no one can be sure why.
Physicists think there must simply have been slightly more matter in the first place, but it’s even been speculated that entire antimatter galaxies could exist in a mirror region of the universe.
8. We haven’t found the particle for gravity yet, but we have given it a name
Types of particle known as “bosons” control the forces that act on the things around us, but we’ve yet to uncover a boson for gravity. Scientists still don’t know for sure if such a thing exists, but they’ve named the theoretical particle a “graviton”, and used Einstein’s theory of general relativity to outline the properties they would expect it to have.
9. It took 50 years, billions of pounds and trillions of proton collisions to find the elusive Higgs boson particle
The Higgs boson particle was first proposed by Peter Higgs in 1964. It explained how other particles have mass, and became a fundamental part of our understanding of the universe.
In order to prove the Higgs boson’s existence, scientists had to build a vast, multi-billion pound particle accelerator (the Large Hadron Collider at CERN in Switzerland) to shoot beams of protons at each other and study the resulting data. Even then, only one Higgs was observed for every trillion proton collisions. This gives us an idea of just how difficult it could be to identify the mysterious particles that make up dark matter.
10. Physicists like a laugh
Two of the most popular theories for what’s behind dark matter have involved “weakly interacting massive particles” and “massive astrophysical compact halo objects” – or WIMPs and MACHOs, for short.
(Sources: BBC, NASA, New Scientist, PBS, Live Science.)
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Brian Cox and Robin Ince are the witty pair that present the hugely popular, multi-award winning science/comedy show. They are joined by a variety of scientists and comedy science enthusiasts who take to the stage to discuss everything from the glory of insects to whether free will is just an illusion.
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The modern atomic theory
Early theories of atoms date back to a hypothesis by the Greek philosopher Democritus (460-370 BCE). According to Democritus, atoms were invisible miniscule quantities of matter which could not break. At the time Democritus did not have the technology to provide the evidence to this theory.
The foundations of the modern understanding of the atom was formed in the late 1700s/early 1800s after the English-born chemist John Dalton (1766 - 1844) began exploring atomic weights and structures. Dalton conducted experiments, worked out some atomic weights, and invented symbols for atoms and molecules. His notable conclusions are listed below.
- All matter is made of atoms, and atoms are indestructible and cannot be broken down into pieces
- All the atoms of a particular element are identical to each other and different from the atoms of other elements
- Atoms are rearranged in a chemical reaction
- Compounds are formed when two or more different kinds of atoms join together
The scientist’s theories about atoms were initially resisted by the scientific community, many of whom believed his ideas about gases were flawed.