So these creatures found out that the aim can be further divide into protons, neutrons and electrons, but this was not the end of the story, in fact it was the beginning of the most confusing, wierd and one of the least elegant theories in the history of science-The Standard Model. Despite of its enigmatic features it still remains one of the most successful theories that could explain 3 out of 4 of the fundamental forces in nature.
So according to the standard model there are fundamentally 2 kinds of particles fermions and bosons. One of the major basis of this classification is the kind of equations they obey, fermions obey the Dirac-Fermi statistics while bosons obey the Bose-Einstein statistics, and are, objectively speaking the 'force carriers', (so, yeah they belong to the skywalker family because the force is strong with them.)
First let's take up fermions. These include the particles most of us are acquainted with such as protons, neutrons and electrons. These particles are characterised by a half integer spin. Just to clarify, here spin doesn't mean that the particles are actually spinning, in fact we can't say anything about the conventional spinning of particles as we treat all of them as point masses and hence there is no meaning of rotation or spinning in the case of point particles. Now these fermions are further subdivided into two categories- quarks and leptons.
(From this point the following post will be dedicated solely to quarks.)
So these fascinating particles called quarks come in 6 different 'flavours' (yeah, that's what they call them.) These are up, down, strange, charm, top and bottom. Pretty awkward names for something you can't even see or 'taste', maybe they ran out of baby names...all fermions in the standard model are divided into 3 generations. Up and down quark belong to 1st gen, strange and charm belong to 2nd gen, and top and bottom belong to the 3rd gen, the basic difference between these generations is that the particles belonging to the 3rd gen. are considered to be more heavy,unstable and exotic. In fact up and down quarks are considered to be most stable in the quark family due to their less mass compared to others.
But how do we know these quarks even exist? You might ask that our whole standard model is based upon quarks and till now we haven't even observed a single quark in its own? Quite surprising isn't it. But what if I tell you it's not, scientists are so sure about the existence of quarks because we have observed their properties. We know that they exist because they produce some noticeable effects in their surroundings. For example it is observed that even neutrons possesses magnetic moment, but how do they do it without having any charge? The answer is that they are made up of quarks which do have charges, a neutron is made up of 2 down quarks and 1 up quark, the charge on the down quark is -1/3 and the charge on the up quark is +2/3 which explains why a neutron as a whole is neutral but still possesses magnetic moment.
Now these quarks 'combine' to form hadrons. Hadrons are subdivided into 2 types-mesons and baryons. These hadrons can be defined as a group of quarks held together by the strong force ( one of the 4 fundamental forces). Baryons are the particles most of us are acquainted with-(neutrons and protons). Baryons are basically 3 quarks held together ina group and mesons consist of 2 entities-1 quark + 1 antiquark. Hey but wait, that doesn't look right. A quark and an antiquark should have annihilated each other, not live together peacefully. This argument is correct to some extent, because most mesons are considered to be less stable than baryons and have a short life span. But it is not entirely true that the quark-antiquark pair annihilate, this is only the case in some mesons such as the neutral pion which is formed of a quark and its own antiquark. In fact most of the mesons are formed by a quark and an antiquark of some other quark. But they also decay due to weak interaction.
Pretty interesting, isn't it? Fun fact before I leave- the name "quark" was taken by Murray Gell-Mann from the book "Finnegan's Wake" by James Joyce. The line "Three quarks for Muster Mark..." appears in the fanciful book. Gell-Mann received the 1969 Nobel Prize for his work in classifying elementary particles.
That's it for today. Stay tuned for the next part....
