Everything starts with atoms. They are the building blocks of the universe. When put together in the right combinations, they form compounds. One familiar to all of us is water. It is comprised of two atoms of hydrogen and one atom of oxygen. Written scientifically, it is H2O.
By adding or subtracting atoms, you can change the compounds, sometimes dramatically. For example, if you start with the same two hydrogen atoms, add in a sulfur atom, and add three more oxygen atoms, you get sulfuric acid, something far different from water. The notation is H2SO4.
Atoms are comprised of smaller pieces called neutrons, protons, and electrons. The number of each and their arrangement is what distinguishes one atom from another. For a long time, these were thought to be the only parts of atoms. However, physicists suspected the presence of other particles, mostly because of the reactions they saw that could not have occurred without something else being present.
Once particle accelerators came along (also known as atom smashers). Physicists had a tool they could use to study this. They could take particles like electrons and accelerate them almost up to the speed of light, then smash them into atoms and chart the reactions. The first one was small and invented in 1929 by Ernest Lawrence. It was a circular accelerator where the particles go around and around at ever increasing speeds through the use of magnets and electricity. Another type of accelerator is built in a straight line. These can be very long. There is one in Stanford, CA that is over two miles long.
Through work with particle accelerators, physicists are able to understand more about the makeup of the atom. It has turned out to be quite an undertaking, and the journey is not complete yet by any means.
One of the things they have been able to identify as part of atoms is called a Fermion. These are sub-atomic particles, meaning smaller than atoms. They distinguish between matter and anti-matter.
On the matter side, there are currently two kinds of fermions. One is called a leptron, which do not play a role in holding the nucleus of an atom together, and quarks, which do play that role. Both are extremely, extremely small. Leptons have a very tiny mass, travel very fast, and have, so far, no known internal structure or size. Maybe you now get the picture of the difficulty of this kind of physics.
Quarks are also extremely, extremely small and seem to act in ways to hold the nucleus of the atom together. They have very, very tiny electrical charges. Interestingly, an individual quark has never been found, probably because quarks bind together very quickly.
On the anti-matter side, it is the old story of physics. While physicists “know” that it exists from their calculations and extreme mathematics, not very much is really known. The first particle more or less isolated enough that they could say that it exists was the positron, and it is seen to be similar to the electron. Needless to say, this area is under quite intense investigation at present.
There are still other particles that have been discovered. These seem to have relevance to the “Big Bang” theory of how the universe was created.
Hadrons are combinations of quarks. They do have mass and are found within the nucleus of an atom. There are different types of hadrons. The most common are protrons and neutrons. Each is a combination of three quarks in various forms, although why there have to be three remains under study.
Bosons are more interesting in a sense as they have never really been seen. The theory is that when forces like pushes or pulls occur, bosons are exchanged. The effects of the exchange can be measured, and these effects can be categorized into four types. These are Gluons (associated with strong forces), W and Z (associated with weak forces), and Photons (associated with electromagnetic forces). The physicists feel that there is a fifth particle, the Gravitron, which is associated with gravity, but they have never found it.
The people studying these particles and the theories around them are proponents of the Big Bang theory. This theory deals with the creation of the universe. Simplistically, they believe that there was a cataclysmic explosion that began the universe. The theory has it that before the explosion, there were infinite free-floating particles (quarks), it was very small and very hot in the “universe.”
After the explosion, the universe rapidly expanded and cooled (it continues to expand today according to theory), the quarks combined into hadrons. Matter or atoms were then formed, and then condensed as the expansion and cooling continued. Eventually matter came together to form the universe as we know it, complete with all of the stars and planets we experience.
The exciting part for these physicists is trying to understand the makeup of the universe just before the Big Bang. They want to be able to consolidate everything they know into one big theory that will explain everything going forward. Of course, there is still so much that is unknown and subject to speculation. What this means is that there will likely be exciting work ahead for generations of physicists and those who are science-minded.