Ever wondered what the universe is made up of? First, you need to understand that the substance of the known universe is classified as matter. And the known universe itself only represents 5 percent of the entire universe. The remaining 95 percent is made of things we haven’t fully understood yet — dark matter and dark energy.
The 5 percent that we do understand consists of atoms and ions (atoms with missing or extra electrons), which is what matter is made of. However, atoms are not the fundamental particle of the known universe. Atoms are made up of electrons and a nucleus that itself contains protons and neutrons. Protons and neutrons are made up of things called quarks. So basically, atoms are made up of quarks and electrons. Now that this is clear, let us look at the types of fundamental particles that make the universe.
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We can group the fundamental particles into two groups — fermions and bosons. Fermions are particles that make up matter, while bosons are particles that make up the fundamental forces.
Fermions are further divided into two groups — particles and antipartners to these particles. Particles are then divided into three groups called generations. Each generation has six quarks and two leptons. Generation 1 has the up and down quarks as well as electrons and electron neutrinos. Generation 2 has strange and charm quarks as well as muons (heavier electrons) and muon neutrinos. Generation 3 has top and bottom quarks as well as tau (a much heavier version of electrons) and tau neutrinos. Collectively, these represent 24 particles. Correspondingly, there are also 24 antipartners of these particles. As such, Fermions encompass a total of 48 particles.
There are four fundamental forces — gravity, electromagnetism, strong nuclear force, and weak nuclear force. Bosons include particles that mediate three of these forces. The particles that mediate electromagnetism are called protons. The particles of the strong nuclear force, which are responsible for holding together protons and neutrons as well as the atomic nuclei, are called gluons and are of 8 types. The weak nuclear force has three particles, named Z0, W-, and W+. In addition, there is another boson particle called the Higgs-Boson. These are the most recently discovered particles and are responsible for all particles having mass. In all, there are 13 boson particles.
Adding the 48 fermion particles and the 13 boson particles together, we can say that the known universe is made up of 61 fundamental particles. But then again, only 5 percent of the universe is known. What the remaining 95 percent is made up of is something we can’t yet imagine. Some believe that we may never even know about them.
The word “atom” comes from the Greek word for “uncuttable.” For a long time, scientists thought that atoms were the most fundamental particle and that they could not be broken down into smaller things. Now we know better. But the name has stuck and we still call them atoms, although they are made up of smaller particles.
Up to 99.9 percent of an atom is made up of empty space. The nucleus basically is responsible for most of the mass of the atom. The electrons themselves have very little mass. If an atom is equated to a sports arena, then the nucleus would be the size of a pea inside the arena. Interestingly, even though the nucleus itself is much denser when compared to the rest of the atom, it too is made up of mostly empty space.