Module 2: Composition, Origin, and Evolution of the Physical World

Big Bang Theory

• the prevailing scientific explanation for the origin of the universe

• proposes that the universe began as a SINGULARITY, an extremely hot and dense point, approx. 13.8 billion yrs. ago

• This singularity then rapidly expanded and continues to expand, creating space and time known today

Cosmic Expansion

states that the universe is constantly expanding, with galaxies moving away from each other. This expansion is supported by observations such as the REDSHIFT OF LIGHT from distant galaxies

Edwin Hubble (1889-1953)

• proved the existence of other galaxies outside the Milky Way

• took photos of Cepheid variable stars and compared the degrees of luminosity

What is the Cepheid Period-Luminosity Relationship?

• A Cepheid’s pulses timing or period CORRELATES with its inherent brightness

  • Longer pulse rate = more luminous star

  • Farther objects look dimmer

Other accomplishments of Edwin Hubble

• Able to estimate the distance of the Andromeda galaxy from the Milky way

• Galaxies were made up of hundreds of billions of stars

• Studied the movement of other galaxies by observing the wavelength light

What is Hubble’s Law and the Expanding Universe?

• Presented the idea that the universe is expanding

• Hubble showed that the galaxies are receding away from us with a velocity that is proportional to their distance from us:

  • more distant galaxies recede faster than nearby galaxies

What is Red Shift Theory?

• Based on the observation that light from distant galaxies is shifted toward the red end of the spectrum

  • the process of stretching wavelengths of light as the universe expands

    • Longer wavelengths appear red

    • Shorter wavelengths appear blue

• Distant galaxies have all of their visible light shifted into infrared

Cosmic Microwave Background

• confirmed the idea of expanding universe

• a left-over radiation from the Big Bang

What is Cosmic Microwave Background (CMB)?

• one of the strongest pieces of evidence for the Big Bang

• This faint glow is that afterglow of the initial hot and dense state of the universe and was discovered in the 1960s

• scientists argue that a change in volume of the universe is directly correlated with its hotness and coldness

Who are Arno Penzias (1933) and Robert Wilson (1936)?

• Both won a Nobel Prize in Physics of 1978 for their discovery of the Cosmic Microwave Background

What is Holmdel Horn Antenna?

• Located at Bell Telephone Laboratories, New Jersey

• Built in 1959 for pioneering work in communication satellites for the NASA ECHO I.

• used to discover cosmic microwave background

How was the CMB discovered?

• inteded for detecting gas emissions in the Milky way initially

• antenna was pointed to an empty patch sky

• observed a huge amount of noise which they thought was a problem in the system which later od discovered to be the CBM

Nucleosynthesis

refers to the reaction resulted in the formation of first elements, H and He which are the building blocks of stars and galaxies

• formation of atomic nuclei

• mainly occurs when lighter elements combine (fusion)

• heavier elements break apart (fusion)

How old is the universe?

13.8 billion years

Cosmic Evolution

• Radiation Era

• Matter Era

What is the Standard Model?

a fundamental theory in particle physics that describes the fundamental particles and their interactions in the universe.

What is the Standard Model?

• It describes the behavior of particles and their interactions. •

• It is a combination of quantum mechanics and special relativity. •

• It consists of three major families of particles: Quarks, Leptons, Bosons •

• Higgs field à responsible for giving particle its mass. •

• It does not explain the existence of gravity (not a complete theory of universe.

What is Particle Classification?

• Femions

  • QUARKS: make up protons, neutrons

• Bosons

  • force carriers mediates electromagnetism,

  • Nuclear force

• Fermions

  • LEPTONS: Examples: electrons, neutrinos

How does Elementary particles differ from Composite particles?

• Both properties are determined by its interactions with other

  particles which are very complex.

• Elementary particles – cannot be divided into sub-structure and are

  considered to be building blocks.

  • Examples: electrons, neutrino, muon, tau (Lepton family); up, down, charm (quarks family); photons (bosons family)

    • Quarks and Leptons – belongs to a category fermion which is the building blocks of matter

    • Bosons – particles that mediate the fundamental forces of nature.

  • Composite particles – made of smaller particles. They are formed when the elementary particles are held together by strong, weak, and electromagnetic forces.

  • Examples: protons, neutrons, atoms

Democritus and the atomic model

• He proposed that all matter is composed of indivisible and indestructible particles known as atoms

• Atoms: the building blocks of matter

• No explanation of how atoms interact

• Based his theory on observations only