Ancient Cosmology: From Rationalism to Heliocentric Models
Rationalism and Empiricism
Rationalism and Empiricism: Empiricism and Rationalism made people rethink monism. If reality is one thing, then how can there be nothing, or motion, or how can anything be destroyed or created? If the real world is as Parmenides says, is this world not real? What is real?
Pythagoras
Pythagoras: Born c. 585 to 565 BCE on the island of Samos. He studied under Anaximander and founded a quasi-religious “brotherhood” influencing the Croton area of Southern Italy. This was
Read MoreElectrostatics and Magnetism: Key Principles and Laws
Electrostatics and Magnetism: Key Principles
Coulomb’s Law
The force of attraction or repulsion between two point electric charges is directly proportional to the product of the charges and inversely proportional to the square of the distance separating them. The force is directed along the straight line joining the charges. It is repulsive if the charges have the same sign and attractive if they have opposite signs. These are distance forces, and no material medium is needed between the charges.
Read MoreGravitational, Electric, and Magnetic Fields: A Comparison
Conservative and Non-Conservative Fields
Gravitational, electric, and magnetic fields are three examples of vector fields. The first two are conservative, while the magnetic field is not. Let’s recall the main characteristics of conservative fields:
- A: The work required to move a particle from one point to another is independent of the trajectory followed, so the work done in a closed loop is zero.
- B: The circulation of the vector field along a closed line is zero.
- C: There is a scalar function, called
Italian Neorealism: Rossellini, De Sica, and Visconti
Roberto Rossellini
- Neorealism Trilogy:
- Germany Year Zero
- Paisan
- Rome Open City
- There are many kinds of neorealism. Everyone has his own. Mine was a moral position, an effort to understand myself inside a phenomenon.
Rome Open City (1945, right when WWII ended)
- Characters: Giorgio the engineer, Don Pietro the priest, Pina and Francesco, Marcello their son, Giorgio’s ex-girlfriend Marina (betrayed the resistance in exchange for drugs and fur coats)
- Scene when Pina got shot: “Few scenes in cinema have the
Earthquake Waves and Sound: Properties and Behavior
Earthquake Waves and Their Properties
Waves generated by an earthquake are classified into two main types: P-waves and S-waves. P-waves are longitudinal and can travel through both solids and fluids. S-waves are transverse and can only propagate through solid materials. The reflections and refractions of these waves provide valuable information about the Earth’s interior.
Understanding Longitudinal Waves
The wavelength of a longitudinal wave is the distance between successive compressions or rarefactions.
Read MoreLaser Technology: Principles, Properties, and Applications
LASER = Light Amplification by Stimulated Emission of Radiation
A laser is actually an oscillator rather than a simple amplifier. The difference is that an oscillator has positive feedback in addition to the amplifier.