Propagation and Antennas

There are four fundamental interactions in nature: Gravity (acts on mass/energy) Electromagnetism (acts on electric charge) Strong interaction (it confines quarks into hadron particles such as the proton and neutron) Weak interaction (interaction between subatomic particles that causes radioactive decay)

There are two different kinds of particles: Fermions – particles that follow Fermi-Dirac statistics and obey the Pauli exclusion principle (two or more identical fermions cannot occupy the same quantum state); they have half-integer spin; quarks and leptons constitute the elementary fermions; composite fermions (such as protons and neutrons) are the key building blocks of matter Bosons – particles that follow Bose-Einstein statistics; they have integer spin; their statistics do not restrict the number of them that occupy the same quantum state (composite bosons may form Bose-Einstein condensates); elementary bosons are force carriers that function as the ‘glue’ holding matter together

There are five kinds of bosons that are elementary: Four gauge (or vector) bosons with spin 1 (photons, gluons, Z, W±) One scalar boson with spin 0 (the Higgs boson) Additionally, one expects that in quantum gravity a tensor boson, with spin 2, exists; it is called the graviton

Massless particles Name Symbol Antiparticle Charge (e) Spin Interaction mediated Existence Photon γ Self 1 Electromagnetism Confirmed Gluon g Strong interaction Graviton G 2 Gravitation Unconfirmed

In special relativity massless particles always travel with the finite cosmic speed limit: c = 299 792 458 m/s (exact value)

Photon – 1 The quantum of the electromagnetic field (including electromagnetic radiation such as light) The gauge or vector boson (force carrier), with spin 1, of the electromagnetic interaction Massless elementary particle (m = 0) Always moves at the speed c = 299 792 458 m/s in any inertial frame of reference

Photon - 2

Elementary particles Elementary fermions Quarks Leptons Elementary bosons Gauge bosons Higgs boson

The complete Standard Model took a long time to build. Physicist J. J The complete Standard Model took a long time to build. Physicist J.J. Thomson discovered the electron in 1897, and scientists at the Large Hadron Collider found the final piece of the puzzle, the Higgs boson, in 2012. Discovered in 2012, the Higgs boson was the last missing piece of the Standard Model puzzle. It is a different kind of force carrier from the other elementary forces, and it gives mass to quarks as well as the W and Z bosons. Whether it also gives mass to neutrinos remains to be discovered.

Photonics Ray optics Wave optics Electromagnetic optics Quantum optics

Theories for optical phenomena Quantum optics – Provides an explanation of virtually all optical phenomena. Electromagnetic optics – Provides the most complete treatment of light within the confines of classical optics. Wave optics – Provides a scalar approximation of electromagnetic optics. Ray optics – Provides the limit of wave optics when the wavelength is very short.

Ray optics Light travels in the form of rays. An optical medium is characterized by its refractive index n. If vp is the phase velocity and c is the speed of light in vacuum, then n = c / vp. Fermat’s principle – Optical rays traveling between two points, A and B, follow a path such that the time of travel between the two points is an extremum relative to neighboring paths. The extremum of Fermat’s principle is usually a minimum. Then, Fermat’s principle may be simply stated as follows: light rays travel along the path of least time.

Reflection from a mirror The reflected ray lies in the plane of incidence. The angle of reflection equals the angle of incidence. Mirror

Refraction: Snell’s law

Night view of the Luminous Fountain

Snell’s law: Proof (1)

Snell’s law: Proof (2)