Before I can start telling the story of our world, we must understand it first - what is it made of, how does it work, etc. In the next few posts, I will try and describe the fundamental underpinnings of the workings of our world. If you are familiar with Physics, you may want find a lot of material very familiar and also simplistic at times - the idea is to get a qualitative feel of how things work.
We'll start with the most simple concept - matter. Everything we see around us is matter - it occupies space and has mass.
Mass is somewhat different from weight. You may have noticed that when you get in a swimming pool, your weight reduces, or when you are in an elevator which is going down, or in an airplane that is landing, you feel your weight is reduced. This feeling is accurate since weight is an effect of gravity, and in the above scenarios since either there is a counter force (the buoyant force in water) or because you are moving with the flow (the falling down cases), the effect of gravity felt is reduced, which also reduces the weight felt. Which is why on Moon, where gravity is 1/6th of Earth, your weight would also be 1/6th.
However your mass does not change with gravity - it stays the same. If you throw a ball at a wall in front of you, the force with which it hits the wall would be the same, irrespective of whether you do this on Earth or Moon. This is because the mass of the ball is same on both Moon and Earth, though the weight is different.
All matter is made of atoms. If you take a piece of coal - which is made of Carbon - and blow hard on it, some coal particles would fly off. Each of those particles would consist of several hundred thousand atoms of Carbon. If somehow you could keep slicing and slicing the coal particle till you could slice no more, you would be left with a carbon atom. How tiny is a carbon atom? Well, you could fit 106 (1 followed by six zeroes - a million) atoms side by side on the tip of a hair.
Atoms in turn are made of electrons which surround a nucleus made of neutrons and protons. Electrons have a negative electromagnetic charge, Protons have an equal and opposite positive charge and neutrons have no charge. These particles - protons, electrons and neutrons - are very tiny. The electron for example is less than 10-14 meters across (that means 100 trillionth of a meter - a trillion has 12 zeroes) and weighs around 10-30 kg. (that is a millionth of a trillionth of a trillionth of a kilogram) Similarly, a proton and a neutron are around 10-15 meters across and weigh around 10-26 kg - a thousand times heavier than an electron.
Surprisingly even such tiny particles can be further divided. Protons and Neutrons consist of Quarks. I will not go into details, but there are six types of Quarks. An electron consists of two Leptons - one is the electron lepton (which has most of the mass of the electron) and the second is called the electron neutrino and is nearly massless. There are a total of six types of leptons.
These quarks and leptons cannot be further subdivided. So all matter consists of 12 elementary particles - six Quarks and six Leptons.
Anti-Matter
Quarks and Leptons have anti-particles - anti-quarks and anti-leptons. An anti-particle has the same mass as a particle but an opposite charge. (But what about a neutron, which has no charge? Do not forget that neutrons are also made of quarks. In fact a neutron is made of quarks which have charge, but the total charge on the neutron is zero). Matter made of anti-particles is called anti-matter. Just like all matter consists of 12 types of elementary particles, all anti-matter consists of 12 types of elementary anti-particles - six types of anti-Quarks and six types of anti-Leptons.
Thus there are a total of 24 types of elementary particles which make matter and anti-matter. These particles cannot be further divided. Particles made by combining these particles are called Composite particles. So protons, electrons, anti-neutrons, anti-electrons, etc. are all composite particles.
In subsequent posts, I will talk more about this, but the fact is that anti-matter is very rare in the Universe. You see, when matter and anti-matter interact, they completely annihilate each other, releasing tremendous amounts of energy. This gives rise to another question - why is there not enough anti-matter in the Universe to interact with all the matter and annihilate everything? The answer lies in the processes that went in the creation of the Universe - that is a subject of a future post.
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