Universe Structure, Dark Matter, and Cosmic Destiny
Echo of the Big Bang: Background Radiation
The expansion of the universe caused the photons from the initial light radiation to cool down, reaching the current temperature. This cooling reduced the radiation’s intensity and increased its wavelength into the microwave frequencies. This phenomenon is known as the Cosmic Microwave Background (CMB).
The Formation and Eras of Galaxies
Matter organized into atoms of hydrogen, helium, and lithium, forming a vast primordial nebula. Galaxies formed from this
Read MoreUnderstanding Sound and Light: Properties and Behaviors
Understanding Sound and Light
Sound Waves
Audible sounds are produced when a body vibrates at a frequency between 20 Hz and 20,000 Hz.
- A wave is a disturbance of the medium that propagates through space.
- In a wave, energy is propagated, not matter.
- Sound waves consist of a succession of compressions and rarefactions (high and low pressure).
- Sound needs a medium (solid, liquid, or gas) to propagate.
- Sound travels through air at a speed of approximately 340 m/s at normal temperature. The speed is higher
Understanding Wave Motion: Transverse and Longitudinal Waves
Understanding Wave Motion
Most information reaches us through waves. Sound reaches our ears, light our eyes, and electromagnetic signals our radios and TVs through oscillatory motion. Wave motion transfers energy from a source to a receiver without transferring matter between them.
Imagine raising and lowering one end of a rope. A rhythmic disturbance travels along it. Each particle of the rope moves up and down, while the disturbance travels the length of the rope. The medium returns to its initial
Read MoreUnderstanding Classical Physics Limitations and Modern Concepts
Limitations of Classical Physics
Classical mechanics, based on Galilean transformations and Newton’s equations, faced challenges with Maxwell’s equations. These equations confirmed the wave nature of light and allowed for the calculation of its speed in a vacuum, leading to comparisons between light and sound waves.
Characteristics of Sound
- Requires a medium to propagate.
- Propagates at a steady pace with respect to the medium.
- Velocity can be found using the formula for the addition of velocities.
Characteristics
Read MorePhysics Fundamentals: Quantities, Vectors, and Motion
What is Physics?
Physics is the science that studies physical phenomena through observation and experimentation. It aims to interpret knowledge of the laws governing these phenomena and derive practical applications.
What is a Quantity?
A quantity is a property that can be measured. Measuring a quantity involves comparing it with another of the same kind, which is taken as the unit.
Magnitude Scale
A magnitude scale is established when a magnitude is defined by the value of its measure or module. Examples
Read MoreUniverse Models, Solar System Structure, and Star Formation
Geocentric and Heliocentric Universe Models
Geocentric Model (Aristotle)
The Earth is considered the center of the universe, fixed and immobile. A celestial sphere encompasses the sky, the Sun, Moon, planets, and fixed stars. Aristotle’s universe was divided into two parts: the celestial world and the terrestrial world. The celestial realm was perfect, and its only movement was thought to be circular. Tycho Brahe later rejected the existence of crystalline spheres carrying the planets after observing
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