Physics

General

Surface tension: The meniscus (curvature in liquid surface) is caused by surface tension.
Dewar flask: vacuum flask
Water is highly incompressible (under 'normal conditions') ʳ
Matter and antimatter
Neutrino: almost massless
- NOT the same as neutron
- Its existence was discovered because scientists
Pair production
- 'Creation of a subatomic particle and its antiparticle from netural boson' ʷ
- Eg: high energy photon converted into electron and proton along with neutrino
e: Fundamental charge of an electron
Hamiltonian opertor gives the total energy of a system
Dark matter:
- Hypothesised. Yet to detected.
- Doesn't interact with electromagnetic forces => difficult to detect
- https://www.home.cern/science/physics/dark-matter
Matter and anti-matter:
- They always come in pairs ʳ
- Both have same mass but other properties like charge are opposites
- Eg: Electron and positron
- If matter and antimatter come in contact, they annihilate each other and produce energy as a result
- Laws of nature is not the same for antimatter as it is for matter
- https://www.home.cern/science/physics/matter-antimatter-asymmetry-problem
Light is an electromagnetic radiation
LHC: Large Hydron Collider
- Near Geneva, Switzerland
- Largest and most powerful particle accelerator in the world
- https://www.home.cern/science/accelerators/large-hadron-collider
- https://www.home.cern/science/accelerators/how-accelerator-works
- Particle is accelerated to make it high energy before collision
'Neutron star material, the densest known matter' ʳ
Blackhole: densest possible containers of information ʳ
Quantum field theory's interpretation ???
- Every particle can be seen as a wave in a quantum field ʳ
- Eg: Photon is a wave in the electromagnetic field
Maxwell: Unified theories of electricity and magnetics => electromagnetism
Classical => non-quantum
- Not non-Newtonian
Quantum theory: describes 'micro world'
General relativity theory: describes 'macro world'
Gravitation - Standard textbook on relativity
Absorption refrigerator
- 'Cooling by heating'
- No moving parts
Conductivity of electricity:
- Band theory of materials: Conductors, Semiconductors, Insulator
- Another classification?? Hubbard bands
- Electron-electron Coulombic interaction

Types of forces

Strong force
- Carrier: Gluons
Weak force
- Carrier: W-boson and Z-boson
Electrmagnetic force
- Carrier: Photons
- Range: ∞
Gravitational force
- Graviton (hypothesised. Not yet discovered)
- Range: ∞
Strength: Gravity < Weak < Electromagnetic < Strong
Range: ? < ? < ? < Gravity
All the above 4 forces except gravitational force is due to exchange of bosons
- Bosons are the force carrier particles

Hydrostatic pressure

Pressure exerted by a column of stationary liquid on the walls of its container.

SI unit: N.m⁻²

P = ρgh

where:

ρ: density of liquid
g: acceleration due to gravity
h: height of the liquid column

Relation between force and pressure

F = P.A

where:

P: Pressure
A: Area

SI unit of pressure: N.m⁻² = Pa (ie, Pascal)

When we are calculating force exerted on a surface due to pressure, we consider only a part of that surface whose area is A.

Mass flow rate

Rate with respect to time at which mass going out of a 'container':

r = ρ * A * v

where:

ρ: density of liquid
A: Area of cross-section of pipe
v: velocity of fluid

https://en.wikipedia.org/wiki/Mass_flow_rate

Darcy's law

Flow of a fluid through a porous medium.

(Porous medium like an earthen pot meant to store drinking water.)

https://en.wikipedia.org/wiki/Darcy%27s_law

Non-Newtonian fluids

Newtonian fluid => Viscousity is constant.
- Eg: Air, water
Non-Newtonian fluid => Viscousity can change
- Eg: Ketchup, corn flour with water

Many body problem

It's impossible to measure the exact positions of three bodies

It's possible for <3 bodies, though.

Longitudinal vs transverse waves

Longitudinal: Direction of propagation is same as the direction in which variation/vibration is occurring.
- aka pressure waves
Transverse: Direction of propagation is perpendicular to the direction in which variation is occurring.

Eg:

Sound waves in air are longitudinal.
- Compression/decompression of air

Quantum number

Principal quantum number
- Indicates shell of an electron
Azimuthal quantum number
- Indicates sub-shell of an electron
Magnetic quantum number
- Indicates orbital of electron with sub-shell
Spin magnetic quantum number
- Indicates spin angular momentum of electron within orbital

Standard model of particle

Fermions: Quarks and leptons
- Matter particles
Bosons
- Force carrying particles
Gravity is not covered by the standard model
- But managable since effect of gravity is negligible at sub-atomic level.
Higgs boson
- https://www.home.cern/science/physics/higgs-boson
- Was confirmed to exist in 2012
- By the large hydron collider at CERN
- aka 'God particle'
- Popsci book: The God Particle: If the Universe Is the Answer, What Is the Question? (1993) - Leon M. Lederman, Dick Teresi
Anyon: a 'quasi-particle' occuring in 2D systems
- Not in 3D

See:

https://www.home.cern/science/physics/standard-model

A representation of figure from here:


                    FERMIONS                          BOSONS
       ┌────────────────────────────────┐   ┌────────────────────────┐

            ┌────────┬────────┬────────┐     ┌───────┐    ┌───────┐ 
        ⎧   │   u    │   c    │    t   │     │   g   │ ⎫  │   H   │ ⎫
        ⎮   │        │        │        │     │       │ ⎮  │       │ ⎬ Scalar
        ⎮   │   Up   │ Charm  │   Top  │     │ Gluon │ ⎮  │ Higgs │ ⎮ bosons
 Quarks ⎨   ├────────┼────────┼────────┤     ├───────┤ ⎮  │ Boson │ ⎭
        ⎮   │   d    │   s    │    b   │     │   γ   │ ⎮  └───────┘ 
        ⎮   │        │        │        │     │       │ ⎮
        ⎩   │ Down   │Strange │ Bottom │     │Photon │ ⎮
            └────────┴────────┴────────┘     ├───────┤ ⎮
            ┌────────┬────────┬────────┐     │   Z   │ ⎮ 
        ⎧   │   e    │   μ    │    τ   │     │       │ ⎮ 
        ⎮   │        │        │        │     │Z-Boson│ ⎬ Gauge bosons
        ⎮   │Electron│  Muon  │   Tau  │     ├───────┤ ⎮ (Vector bosons)
Leptons ⎨   ├────────┼────────┼────────┤     │   W   │ ⎮ 
        ⎮   │  ν_e   │  ν_μ   │   ν_τ  │     │       │ ⎮
        ⎮   │        │        │        │     │W-Boson│ ⎭
        ⎮   │Electron│  Muon  │   Tau  │     └───────┘
        ⎩   │neutrino│neutrino│neutrino│
            └────────┴────────┴────────┘

Quarks
- Up and down: has lowest mass among quarks
- All other quarks are unstable and would become up/down eventually
- Up quark: 2/3*e charge
- Down quark: 1/3*e charge
- Left-handed quarks = rotation is clockwise
- Right-handed quarks = rotation is anti-clockwise
- Left-handed up quark can become a right-handed up quark by emitting a W-boson
- No such transformation is possible in the case of right-handed up/down quarks
- Quarks have a type of charge called colour
- Quarks (both left and right handed) change colour by absorbing/emitting gluons
Leptons
- Don't have the charge called 'colour' => no strong force interaction
Gluons
- Carrier of strong force
W-boson
- Carrier of weak force
Electron
- Has left-handed and right-handed varieties
Neutrino
- Left-handed neutrinos exists, but right-handed neutrinos have not yet been found

neutrino is anti-particle
x-neutrino is also called anti-x, where x is anything
Hadrons: Particles built from quarks
- Baryons: made of 3 quarks ʳ
- Mesons: made of 2 quarks
Quark and leptons have 3 'generations' each
- The heavier generations appear to the right in the above picture
- https://www.quantamagazine.org/why-do-matter-particles-come-in-threes-a-physics-titan-weighs-in-20200330/
Doubt: all particles except neutrinos have electric charge ??
- What about neutrons? Is it considered too big for a particle ??
Paritcles interact among themselves by exchanging photons
Standard model doesn't explain everything
- Dark matter and dark energy doesn't fit in this model
Protons and neutrons are made of up/down quarks
Standard model expressed in Lagrangian form:
- https://www.symmetrymagazine.org/article/the-deconstructed-standard-model-equation

Theory of relativity

Newtonian physics => space and time are distinct
Relativity => space-time
- https://www.quantamagazine.org/how-to-think-about-relativitys-concept-of-space-time-20221114/
Minkowski space-time
Gravity = result of curvature in space-time
Twin paradox
- Time 'slows down' ??
Time dilation
Light has no mass but still appear to be affected by sun's gravity.
- Slight variation observed in path of star light during sun eclipse and when the same star is on the other side away from sun.
- This is because of 'bending of space-time'. (??)
- Geodesic
- Particle always try to travel in straight path
- Straight line on a spherical surface is a curve
A practical application of relativity: GPS

Doubt:

Difference between special and general relativity

Maxwell's equations

4 equations
Unified electric theory and magnetic theory => electromagnetic theory

        ρ
∇⋅E = ────
       ε₀


∇⋅B = 0


           ∂B
∇ ⨯ E = ─ ────
           ∂t


           ⎛        ∂E  ⎞
∇ ⨯ B = μ₀ ⎜J + ε₀ ──── ⎟
           ⎝        ∂t  ⎠

E: electric field
B: magnetic field
J: current density
μ₀: vacuum permeability ??
ε₀: vacuum permittivity ??

See:

Dbts

Standard model of particle

Why is neutrino called anti-particle?
- Why is it 'against' particle?
Is there an alternative to particle model?
- What is grand unified theory?
Why is mass measured in charge: MeV (Mega electron volt)?
Hamiltonian of a system
Higgs boson is central to everything??
Higgs field
Origin of neutrinos is still unknown. It seems to be something other than Higgs boson ??
Higgs bosons are excitations of Higgs field
Mass is possible because of electrons reflecting off Higgs bosons ??
- The more interactions a particle has with Higgs boson, the more mass it has
Universe expands. So is there infinite space for it to expand to ??
- When we talk about time, is it expansion that we mean?
Why does LHC accelerate particles

Other:

string in string theory
- What is its relation to finding mass of electron
tachyon
theory with space-time ?? (from relativity theory ??)
What's the need for a theory with space-time
- https://www.quantamagazine.org/john-wheeler-saw-the-tear-in-reality-20240925/
What is field? As in electromagnetic field, quantum field, magnetic field, electric field

Acks

Most of the info here is result of online searches instigated by conversions with the following people: Jithin, Sabareesh