Internals of an Atom

Tao of Physics

Terminologies & key notes

1. Atom is made of following particles
    a. electrons
    b. protons
    c. neutrons
    d. photons <== new for me (எல்லா அணுவினுள்ளும் ஒளி அடங்கி கிடக்கிறது!)
    e. ... (more to be discovered)

2. Every particle has anti-particle with equal mass and opposite charge. E.g. electron --> anti-electron

3. An unstable neutron gets converted into following
    neutron --> proton + electron + anti-neutrino;  here anti-neutrino is a mass-less particle that is emanates out.

4. What makes the neutron unstable? (stable in micro or nano-seconds)
    Ans: As long as a neutron is inside the nucleus of an atom, it is stable. But if it comes out, it become unstable and changes itself as in the equation above. (What makes it stable when it is inside and what makes it unstable is not yet clear to this world?)

5. Collision process
    a. Strong interactions - e.g. the force that keeps neutron and proton together - "nuclear force"
    b. Weak interactions - e.g. electromagnetic interactions and gravitational interaction between particles

6. Nuclear force - by far the strongest of all forces in nature.

7. Other strongly interacting particles within atom?
    - There are many known today. There could be many more to be known.
    - Of all particles known today, only 5 particles (and their anti-particles) are DO NOT strongly interact.
        > They are: Photons and four Leptons!

8. Two broad groups of particles
    a) Leptons - less interacting particles
    b) Hadrons - strongly interacting particles are further divided into 2
        i) Baryons - has distinct anti-particles
        ii) Mesons - can be its own anti-particle

9. Hadrons are strong with large mass, hence the distance covered is few particle size (sub-atomic length) hence not experienced in everyday life. But electromagnetic interactions are mediated by mass-less photons, hence their range is infinitely long and also experienced by all in everyday life.

10. It is believed that there is another mass-less particle named 'graviton' exists, which is responsible for Gravitational interactions. But no one has proved its existence yet.