Beyond Atoms: The Particles which Make Up the Universe
Introduction
Looking around the world, we see such extraordinary creatures and objects on a daily basis. Some of us can’t help but wonder, what is everything made of? Well, lets start of with something everyone has, a human body. The human body is made up of blood, bones, organs, and many more extraordinary things. Let’s take one of the organs, the heart for example, and zoom in. What do we see? Billions upon billions of cells. But let’s go further. Zoom into just one of these cells and we see millions of individual molecules, each with their own complexity. And finally, lets zoom in one more time to just one of these molecules and now we can see atoms, consisting of electron clouds and a nucleus containing protons and neutrons. That is exactly what everything is made of and there is no
possibility that something even smaller exists. Or is there?
The Standard Model
For most people, the subatomic particles of protons, neutrons, and electrons are the smallest things they know of. However, there exists even smaller particles known as elementary particles, which are not made up of anything else. Crazy to think about right? Well, lets zoom in even further.
Quarks
Both Protons and Neutrons are a combination of three particles known as Quarks, which can be seen in the standard model above and come in six different flavours. These flavours are Up, Top, Down, and Bottom, which are not the same, and also Charm and Strange. The Up and Down quarks make up pretty much all the atoms we can see. With a charge of +⅔ and -⅓ respectively, two Up Quarks and one Down Quark makes up a proton (⅔ +⅔ -⅓ = +1) and one Up Quark and two Down Quarks
make up a Neutron (⅔ -⅓ -⅓ = 0).
These Quarks are held together by Gluons, also in the standard model above, which we can think of as the literal ‘glue’ holding the Quarks together. The rest of the Quarks can only be observed in particle accelerators, so we won’t touch on those. An interesting fact about Quarks is that if you try to pull two of them apart by using tons of energy, they will use that force to generate two more Quarks.
Leptons
The first up of the Leptons is the good old electron. Most of us know what electrons are and that they aren’t made of anything smaller. Simple. Next up is the Muon, also known as the ‘big brother’ of the electron, which is 200 times bigger than the electron. Orbiting Electrons are able to be replaced by Muons to create Muonic Atoms also known as Exotic Atoms. Lets go even bigger. If Muons were
the ‘big brother’ of Electrons, Taus are the ‘father’ of Electrons. Although, Taus are rarely observed in the real world due to their short lifetime. The Tau lepton can be seen in the Standard Model shown above.
These are the Electron Neutrino, which corresponds to the electron, the Muon Neutrino, which corresponds to the Muon, and the Tau Neutrino, which corresponds to the Tau Lepton. These Neutrinos are created from the decay of other particles. For example, a banana is able to emit Neutrinos due to the decay of the naturally radioactive potassium component in the fruit. Because Neutrinos are electrically neutral and don’t interact with electromagnetic waves, they can pass
through most matter. There are Trillions of Neutrinos passing through you right now and they could be coming from billions of light years away. The Neutrinos are the smallest elementary particle known.
Bosons:
Bosons are particles which carry a force and there are four fundamental forces of the universe.
1. Gravity
2. Electromagnetism
3. Weak nuclear force
4. Strong nuclear force
As mentioned earlier, we think of the Gluons as the literal ‘glue’ holding the Quarks together, and is therefore a carrier for the Strong nuclear force.
Photons are carriers of the Electromagnetic force and are particles which are massless and travels at the speed of light. They are the reason we are able to see and the reason why you are reading about them right now. Photons are emitted from light sources and when they hit an object, they can be absorbed, reflected, or transmitted. The Photons which are reflected off of objects enter our eyes,
enabling us to see them.
The W and Z bosons are carriers of the Weak nuclear force, responsible for the decay of particles. W bosons help certain particles inside atoms to change into other particles, important for radioactive decay. Z bosons help particles interact without changing the particle type. For example, they help
neutrinos pass through matter, as mentioned earlier.
Well, what about gravity? The Graviton has been a hypothesised particle for some time now, which is a particle meant to mediate the gravitational force. There are many different possible reasons as to why the Graviton remains hypothetical, however, the fact of the matter is, unlike other particles, the Graviton has never been directly observed in experiments.
The Higgs Boson
This is a very special type of Boson and its discovery in 2012 was monumental to the physics world as it explained why particles have mass. It is an elementary particle which is associated with the Higgs field.
The Higgs field as an invisible energy field that fills the entire Universe, with the Higgs Boson as a part of this field. Think of the Higgs field as an ocean, where different marine animals have to push through the water to move. Some marine animals have to push harder than others. Particles gain their mass by interacting with this field and the more they interact, the heavier they get. Particles
which don’t interact with this field are dubbed as massless, like the Photon.
Conclusion
When having a look through what really makes us who we are and what makes the world what it is, our perspectives suddenly shift. We are much larger than we think we are. The more we zoom into what really makes us up, the more extraordinary we become.